[dragonfly.git] / libexec / rtld-elf / rtld.c

/*-
 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
 * Copyright 2009-2012 Konstantin Belousov <kib@FreeBSD.ORG>.
 * Copyright 2012 John Marino <draco@marino.st>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD$
 */

/*
 * Dynamic linker for ELF.
 *
 * John Polstra <jdp@polstra.com>.
 */

#ifndef __GNUC__
#error "GCC is needed to compile this file"
#endif

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/utsname.h>
#include <sys/ktrace.h>
#include <sys/resident.h>
#include <sys/tls.h>

#include <machine/tls.h>

#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "debug.h"
#include "rtld.h"
#include "libmap.h"
#include "rtld_printf.h"
#include "notes.h"

#define PATH_RTLD       "/usr/libexec/ld-elf.so.2"
#define LD_ARY_CACHE    16

/* Types. */
typedef void (*func_ptr_type)();
typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);

/*
 * Function declarations.
 */
static const char *_getenv_ld(const char *id);
static void die(void) __dead2;
static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
    const Elf_Dyn **, const Elf_Dyn **);
static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
    const Elf_Dyn *);
static void digest_dynamic(Obj_Entry *, int);
static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
static void distribute_static_tls(Objlist *, RtldLockState *);
static Obj_Entry *dlcheck(void *);
static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
    int lo_flags, int mode, RtldLockState *lockstate);
static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
static bool donelist_check(DoneList *, const Obj_Entry *);
static void errmsg_restore(char *);
static char *errmsg_save(void);
static void *fill_search_info(const char *, size_t, void *);
static char *find_library(const char *, const Obj_Entry *, int *);
static const char *gethints(bool);
static void init_dag(Obj_Entry *);
static void init_rtld(caddr_t, Elf_Auxinfo **);
static void initlist_add_neededs(Needed_Entry *, Objlist *);
static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
static void linkmap_add(Obj_Entry *);
static void linkmap_delete(Obj_Entry *);
static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
static void unload_filtees(Obj_Entry *);
static int load_needed_objects(Obj_Entry *, int);
static int load_preload_objects(void);
static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int);
static void map_stacks_exec(RtldLockState *);
static Obj_Entry *obj_from_addr(const void *);
static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
static void objlist_call_init(Objlist *, RtldLockState *);
static void objlist_clear(Objlist *);
static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
static void objlist_init(Objlist *);
static void objlist_push_head(Objlist *, Obj_Entry *);
static void objlist_push_tail(Objlist *, Obj_Entry *);
static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
static void objlist_remove(Objlist *, Obj_Entry *);
static int parse_libdir(const char *);
static void *path_enumerate(const char *, path_enum_proc, void *);
static int relocate_object_dag(Obj_Entry *root, bool bind_now,
    Obj_Entry *rtldobj, int flags, RtldLockState *lockstate);
static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
    int flags, RtldLockState *lockstate);
static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
    RtldLockState *);
static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
    int flags, RtldLockState *lockstate);
static int rtld_dirname(const char *, char *);
static int rtld_dirname_abs(const char *, char *);
static void *rtld_dlopen(const char *name, int fd, int mode);
static void rtld_exit(void);
static char *search_library_path(const char *, const char *);
static char *search_library_pathfds(const char *, const char *, int *);
static const void **get_program_var_addr(const char *, RtldLockState *);
static void set_program_var(const char *, const void *);
static int symlook_default(SymLook *, const Obj_Entry *refobj);
static int symlook_global(SymLook *, DoneList *);
static void symlook_init_from_req(SymLook *, const SymLook *);
static int symlook_list(SymLook *, const Objlist *, DoneList *);
static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
static void trace_loaded_objects(Obj_Entry *);
static void unlink_object(Obj_Entry *);
static void unload_object(Obj_Entry *);
static void unref_dag(Obj_Entry *);
static void ref_dag(Obj_Entry *);
static char *origin_subst_one(char *, const char *, const char *, bool);
static char *origin_subst(char *, const char *);
static void preinit_main(void);
static int  rtld_verify_versions(const Objlist *);
static int  rtld_verify_object_versions(Obj_Entry *);
static void object_add_name(Obj_Entry *, const char *);
static int  object_match_name(const Obj_Entry *, const char *);
static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
    struct dl_phdr_info *phdr_info);
static uint_fast32_t gnu_hash (const char *);
static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
    const unsigned long);

void r_debug_state(struct r_debug *, struct link_map *) __noinline;
void _r_debug_postinit(struct link_map *) __noinline;

/*
 * Data declarations.
 */
static char *error_message;     /* Message for dlerror(), or NULL */
struct r_debug r_debug;         /* for GDB; */
static bool libmap_disable;     /* Disable libmap */
static bool ld_loadfltr;        /* Immediate filters processing */
static char *libmap_override;   /* Maps to use in addition to libmap.conf */
static bool trust;              /* False for setuid and setgid programs */
static bool dangerous_ld_env;   /* True if environment variables have been
                                   used to affect the libraries loaded */
static const char *ld_bind_now; /* Environment variable for immediate binding */
static const char *ld_debug;    /* Environment variable for debugging */
static const char *ld_library_path;     /* Environment variable for search path */
static const char *ld_library_dirs;     /* Env variable for library descriptors */
static char *ld_preload;        /* Environment variable for libraries to
                                   load first */
static const char *ld_elf_hints_path;   /* Env var. for alternative hints path */
static const char *ld_tracing;  /* Called from ldd to print libs */
static const char *ld_utrace;   /* Use utrace() to log events. */
static int (*rtld_functrace)(   /* Optional function call tracing hook */
        const char *caller_obj,
        const char *callee_obj,
        const char *callee_func,
        void *stack);
static const Obj_Entry *rtld_functrace_obj;     /* Object thereof */
static Obj_Entry *obj_list;     /* Head of linked list of shared objects */
static Obj_Entry **obj_tail;    /* Link field of last object in list */
static Obj_Entry **preload_tail;
static Obj_Entry *obj_main;     /* The main program shared object */
static Obj_Entry obj_rtld;      /* The dynamic linker shared object */
static unsigned int obj_count;  /* Number of objects in obj_list */
static unsigned int obj_loads;  /* Number of objects in obj_list */

static int      ld_resident;    /* Non-zero if resident */
static const char *ld_ary[LD_ARY_CACHE];
static int      ld_index;
static Objlist initlist;

static Objlist list_global =    /* Objects dlopened with RTLD_GLOBAL */
  STAILQ_HEAD_INITIALIZER(list_global);
static Objlist list_main =      /* Objects loaded at program startup */
  STAILQ_HEAD_INITIALIZER(list_main);
static Objlist list_fini =      /* Objects needing fini() calls */
  STAILQ_HEAD_INITIALIZER(list_fini);

static Elf_Sym sym_zero;        /* For resolving undefined weak refs. */
const char *__ld_sharedlib_base;

#define GDB_STATE(s,m)  r_debug.r_state = s; r_debug_state(&r_debug,m);

extern Elf_Dyn _DYNAMIC;
#pragma weak _DYNAMIC
#ifndef RTLD_IS_DYNAMIC
#define RTLD_IS_DYNAMIC()       (&_DYNAMIC != NULL)
#endif

#ifdef ENABLE_OSRELDATE
int osreldate;
#endif

static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
#if 0
static int max_stack_flags;
#endif

/*
 * Global declarations normally provided by crt1.  The dynamic linker is
 * not built with crt1, so we have to provide them ourselves.
 */
char *__progname;
char **environ;

/*
 * Used to pass argc, argv to init functions.
 */
int main_argc;
char **main_argv;

/*
 * Globals to control TLS allocation.
 */
size_t tls_last_offset;         /* Static TLS offset of last module */
size_t tls_last_size;           /* Static TLS size of last module */
size_t tls_static_space;        /* Static TLS space allocated */
int tls_dtv_generation = 1;     /* Used to detect when dtv size changes  */
int tls_max_index = 1;          /* Largest module index allocated */

/*
 * Fill in a DoneList with an allocation large enough to hold all of
 * the currently-loaded objects.  Keep this as a macro since it calls
 * alloca and we want that to occur within the scope of the caller.
 */
#define donelist_init(dlp)                                      \
    ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]),   \
    assert((dlp)->objs != NULL),                                \
    (dlp)->num_alloc = obj_count,                               \
    (dlp)->num_used = 0)

#define UTRACE_DLOPEN_START             1
#define UTRACE_DLOPEN_STOP              2
#define UTRACE_DLCLOSE_START            3
#define UTRACE_DLCLOSE_STOP             4
#define UTRACE_LOAD_OBJECT              5
#define UTRACE_UNLOAD_OBJECT            6
#define UTRACE_ADD_RUNDEP               7
#define UTRACE_PRELOAD_FINISHED         8
#define UTRACE_INIT_CALL                9
#define UTRACE_FINI_CALL                10

struct utrace_rtld {
        char sig[4];                    /* 'RTLD' */
        int event;
        void *handle;
        void *mapbase;                  /* Used for 'parent' and 'init/fini' */
        size_t mapsize;
        int refcnt;                     /* Used for 'mode' */
        char name[MAXPATHLEN];
};

#define LD_UTRACE(e, h, mb, ms, r, n) do {                      \
        if (ld_utrace != NULL)                                  \
                ld_utrace_log(e, h, mb, ms, r, n);              \
} while (0)

static void
ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
    int refcnt, const char *name)
{
        struct utrace_rtld ut;

        ut.sig[0] = 'R';
        ut.sig[1] = 'T';
        ut.sig[2] = 'L';
        ut.sig[3] = 'D';
        ut.event = event;
        ut.handle = handle;
        ut.mapbase = mapbase;
        ut.mapsize = mapsize;
        ut.refcnt = refcnt;
        bzero(ut.name, sizeof(ut.name));
        if (name)
                strlcpy(ut.name, name, sizeof(ut.name));
        utrace(&ut, sizeof(ut));
}

/*
 * Main entry point for dynamic linking.  The first argument is the
 * stack pointer.  The stack is expected to be laid out as described
 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
 * Specifically, the stack pointer points to a word containing
 * ARGC.  Following that in the stack is a null-terminated sequence
 * of pointers to argument strings.  Then comes a null-terminated
 * sequence of pointers to environment strings.  Finally, there is a
 * sequence of "auxiliary vector" entries.
 *
 * The second argument points to a place to store the dynamic linker's
 * exit procedure pointer and the third to a place to store the main
 * program's object.
 *
 * The return value is the main program's entry point.
 */
func_ptr_type
_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
{
    Elf_Auxinfo *aux_info[AT_COUNT];
    int i;
    int argc;
    char **argv;
    char **env;
    Elf_Auxinfo *aux;
    Elf_Auxinfo *auxp;
    const char *argv0;
    Objlist_Entry *entry;
    Obj_Entry *obj;
    Obj_Entry *last_interposer;

    /* marino: DO NOT MOVE THESE VARIABLES TO _rtld
             Obj_Entry **preload_tail;
             Objlist initlist;
       from global to here.  It will break the DWARF2 unwind scheme.
    */

    /*
     * On entry, the dynamic linker itself has not been relocated yet.
     * Be very careful not to reference any global data until after
     * init_rtld has returned.  It is OK to reference file-scope statics
     * and string constants, and to call static and global functions.
     */

    /* Find the auxiliary vector on the stack. */
    argc = *sp++;
    argv = (char **) sp;
    sp += argc + 1;     /* Skip over arguments and NULL terminator */
    env = (char **) sp;

    /*
     * If we aren't already resident we have to dig out some more info.
     * Note that auxinfo does not exist when we are resident.
     *
     * I'm not sure about the ld_resident check.  It seems to read zero
     * prior to relocation, which is what we want.  When running from a
     * resident copy everything will be relocated so we are definitely
     * good there.
     */
    if (ld_resident == 0)  {
        while (*sp++ != 0)      /* Skip over environment, and NULL terminator */
            ;
        aux = (Elf_Auxinfo *) sp;

        /* Digest the auxiliary vector. */
        for (i = 0;  i < AT_COUNT;  i++)
            aux_info[i] = NULL;
        for (auxp = aux;  auxp->a_type != AT_NULL;  auxp++) {
            if (auxp->a_type < AT_COUNT)
                aux_info[auxp->a_type] = auxp;
        }

        /* Initialize and relocate ourselves. */
        assert(aux_info[AT_BASE] != NULL);
        init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
    }

    ld_index = 0;       /* don't use old env cache in case we are resident */
    __progname = obj_rtld.path;
    argv0 = argv[0] != NULL ? argv[0] : "(null)";
    environ = env;
    main_argc = argc;
    main_argv = argv;

    trust = !issetugid();

    ld_bind_now = _getenv_ld("LD_BIND_NOW");
    /*
     * If the process is tainted, then we un-set the dangerous environment
     * variables.  The process will be marked as tainted until setuid(2)
     * is called.  If any child process calls setuid(2) we do not want any
     * future processes to honor the potentially un-safe variables.
     */
    if (!trust) {
        if (   unsetenv("LD_DEBUG")
            || unsetenv("LD_PRELOAD")
            || unsetenv("LD_LIBRARY_PATH")
            || unsetenv("LD_LIBRARY_PATH_FDS")
            || unsetenv("LD_ELF_HINTS_PATH")
            || unsetenv("LD_LIBMAP")
            || unsetenv("LD_LIBMAP_DISABLE")
            || unsetenv("LD_LOADFLTR")
            || unsetenv("LD_SHAREDLIB_BASE")
        ) {
                _rtld_error("environment corrupt; aborting");
                die();
        }
    }
    __ld_sharedlib_base = _getenv_ld("LD_SHAREDLIB_BASE");
    ld_debug = _getenv_ld("LD_DEBUG");
    libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL;
    libmap_override = (char *)_getenv_ld("LD_LIBMAP");
    ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
    ld_library_dirs = _getenv_ld("LD_LIBRARY_PATH_FDS");
    ld_preload = (char *)_getenv_ld("LD_PRELOAD");
    ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH");
    ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL;
    dangerous_ld_env = (ld_library_path != NULL)
                        || (ld_preload != NULL)
                        || (ld_elf_hints_path != NULL)
                        || ld_loadfltr
                        || (libmap_override != NULL)
                        || libmap_disable
                        ;
    ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
    ld_utrace = _getenv_ld("LD_UTRACE");

    if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
        ld_elf_hints_path = _PATH_ELF_HINTS;

    if (ld_debug != NULL && *ld_debug != '\0')
        debug = 1;
    dbg("%s is initialized, base address = %p", __progname,
        (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
    dbg("RTLD dynamic = %p", obj_rtld.dynamic);
    dbg("RTLD pltgot  = %p", obj_rtld.pltgot);

    dbg("initializing thread locks");
    lockdflt_init();

    /*
     * If we are resident we can skip work that we have already done.
     * Note that the stack is reset and there is no Elf_Auxinfo
     * when running from a resident image, and the static globals setup
     * between here and resident_skip will have already been setup.
     */
    if (ld_resident)
        goto resident_skip1;

    /*
     * Load the main program, or process its program header if it is
     * already loaded.
     */
    if (aux_info[AT_EXECFD] != NULL) {  /* Load the main program. */
        int fd = aux_info[AT_EXECFD]->a_un.a_val;
        dbg("loading main program");
        obj_main = map_object(fd, argv0, NULL);
        close(fd);
        if (obj_main == NULL)
            die();
#if 0
        max_stack_flags = obj_main->stack_flags;
#endif
    } else {                            /* Main program already loaded. */
        const Elf_Phdr *phdr;
        int phnum;
        caddr_t entry;

        dbg("processing main program's program header");
        assert(aux_info[AT_PHDR] != NULL);
        phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
        assert(aux_info[AT_PHNUM] != NULL);
        phnum = aux_info[AT_PHNUM]->a_un.a_val;
        assert(aux_info[AT_PHENT] != NULL);
        assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
        assert(aux_info[AT_ENTRY] != NULL);
        entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
        if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
            die();
    }

    char buf[MAXPATHLEN];
    if (aux_info[AT_EXECPATH] != NULL) {
        char *kexecpath;

        kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
        dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
        if (kexecpath[0] == '/')
                obj_main->path = kexecpath;
        else if (getcwd(buf, sizeof(buf)) == NULL ||
                strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
                strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
                obj_main->path = xstrdup(argv0);
        else
                obj_main->path = xstrdup(buf);
    } else {
        char resolved[MAXPATHLEN];
        dbg("No AT_EXECPATH");
        if (argv0[0] == '/') {
                if (realpath(argv0, resolved) != NULL)
                        obj_main->path = xstrdup(resolved);
                else
                        obj_main->path = xstrdup(argv0);
        } else {
                if (getcwd(buf, sizeof(buf)) != NULL
                    && strlcat(buf, "/", sizeof(buf)) < sizeof(buf)
                    && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf)
                    && access(buf, R_OK) == 0
                    && realpath(buf, resolved) != NULL)
                        obj_main->path = xstrdup(resolved);
                else
                        obj_main->path = xstrdup(argv0);
        }
    }
    dbg("obj_main path %s", obj_main->path);
    obj_main->mainprog = true;

    if (aux_info[AT_STACKPROT] != NULL &&
      aux_info[AT_STACKPROT]->a_un.a_val != 0)
            stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;

    /*
     * Get the actual dynamic linker pathname from the executable if
     * possible.  (It should always be possible.)  That ensures that
     * gdb will find the right dynamic linker even if a non-standard
     * one is being used.
     */
    if (obj_main->interp != NULL &&
      strcmp(obj_main->interp, obj_rtld.path) != 0) {
        free(obj_rtld.path);
        obj_rtld.path = xstrdup(obj_main->interp);
        __progname = obj_rtld.path;
    }

    digest_dynamic(obj_main, 0);
    dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
        obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
        obj_main->dynsymcount);

    linkmap_add(obj_main);
    linkmap_add(&obj_rtld);

    /* Link the main program into the list of objects. */
    *obj_tail = obj_main;
    obj_tail = &obj_main->next;
    obj_count++;
    obj_loads++;

    /* Initialize a fake symbol for resolving undefined weak references. */
    sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
    sym_zero.st_shndx = SHN_UNDEF;
    sym_zero.st_value = -(uintptr_t)obj_main->relocbase;

    if (!libmap_disable)
        libmap_disable = (bool)lm_init(libmap_override);

    dbg("loading LD_PRELOAD libraries");
    if (load_preload_objects() == -1)
        die();
    preload_tail = obj_tail;

    dbg("loading needed objects");
    if (load_needed_objects(obj_main, 0) == -1)
        die();

    /* Make a list of all objects loaded at startup. */
    last_interposer = obj_main;
    for (obj = obj_list;  obj != NULL;  obj = obj->next) {
        if (obj->z_interpose && obj != obj_main) {
            objlist_put_after(&list_main, last_interposer, obj);
            last_interposer = obj;
        } else {
            objlist_push_tail(&list_main, obj);
        }
        obj->refcount++;
    }

    dbg("checking for required versions");
    if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
        die();

resident_skip1:

    if (ld_tracing) {           /* We're done */
        trace_loaded_objects(obj_main);
        exit(0);
    }

    if (ld_resident)            /* XXX clean this up! */
        goto resident_skip2;

    if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) {
       dump_relocations(obj_main);
       exit (0);
    }

    /* setup TLS for main thread */
    dbg("initializing initial thread local storage");
    STAILQ_FOREACH(entry, &list_main, link) {
        /*
         * Allocate all the initial objects out of the static TLS
         * block even if they didn't ask for it.
         */
        allocate_tls_offset(entry->obj);
    }

    tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;

    /*
     * Do not try to allocate the TLS here, let libc do it itself.
     * (crt1 for the program will call _init_tls())
     */

    if (relocate_objects(obj_main,
      ld_bind_now != NULL && *ld_bind_now != '\0',
      &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
        die();

    dbg("doing copy relocations");
    if (do_copy_relocations(obj_main) == -1)
        die();

resident_skip2:

    if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
        if (exec_sys_unregister(-1) < 0) {
            dbg("exec_sys_unregister failed %d\n", errno);
            exit(errno);
        }
        dbg("exec_sys_unregister success\n");
        exit(0);
    }

    if (_getenv_ld("LD_DUMP_REL_POST") != NULL) {
       dump_relocations(obj_main);
       exit (0);
    }

    dbg("initializing key program variables");
    set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
    set_program_var("environ", env);
    set_program_var("__elf_aux_vector", aux);

    if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
        extern void resident_start(void);
        ld_resident = 1;
        if (exec_sys_register(resident_start) < 0) {
            dbg("exec_sys_register failed %d\n", errno);
            exit(errno);
        }
        dbg("exec_sys_register success\n");
        exit(0);
    }

    /* Make a list of init functions to call. */
    objlist_init(&initlist);
    initlist_add_objects(obj_list, preload_tail, &initlist);

    r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */

    map_stacks_exec(NULL);

    dbg("resolving ifuncs");
    {
            RtldLockState lockstate;

            wlock_acquire(rtld_bind_lock, &lockstate);
            if (resolve_objects_ifunc(
                    obj_main,
                    (ld_bind_now != NULL && *ld_bind_now != '\0'),
                    SYMLOOK_EARLY,
                    &lockstate) == -1) {
                    die();
            }
            lock_release(rtld_bind_lock, &lockstate);
    }

    /*
     * Do NOT call the initlist here, give libc a chance to set up
     * the initial TLS segment.  crt1 will then call _rtld_call_init().
     */

    dbg("transferring control to program entry point = %p", obj_main->entry);

    /* Return the exit procedure and the program entry point. */
    *exit_proc = rtld_exit;
    *objp = obj_main;
    return (func_ptr_type) obj_main->entry;
}

/*
 * Call the initialization list for dynamically loaded libraries.
 * (called from crt1.c).
 */
void
_rtld_call_init(void)
{
    RtldLockState lockstate;
    Obj_Entry *obj;

    if (!obj_main->note_present && obj_main->valid_hash_gnu) {
        /*
         * The use of a linker script with a PHDRS directive that does not include
         * PT_NOTE will block the crt_no_init note.  In this case we'll look for the
         * recently added GNU hash dynamic tag which gets built by default.  It is
         * extremely unlikely to find a pre-3.1 binary without a PT_NOTE header and
         * a gnu hash tag.  If gnu hash found, consider binary to use new crt code.
         */
        obj_main->crt_no_init = true;
        dbg("Setting crt_no_init without presence of PT_NOTE header");
    }

    wlock_acquire(rtld_bind_lock, &lockstate);
    if (obj_main->crt_no_init)
        preinit_main();
    else {
        /*
         * Make sure we don't call the main program's init and fini functions
         * for binaries linked with old crt1 which calls _init itself.
         */
        obj_main->init = obj_main->fini = (Elf_Addr)NULL;
        obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL;
    }
    objlist_call_init(&initlist, &lockstate);
    _r_debug_postinit(&obj_main->linkmap);
    objlist_clear(&initlist);
    dbg("loading filtees");
    for (obj = obj_list->next; obj != NULL; obj = obj->next) {
        if (ld_loadfltr || obj->z_loadfltr)
            load_filtees(obj, 0, &lockstate);
    }
    lock_release(rtld_bind_lock, &lockstate);
}

void *
rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
{
        void *ptr;
        Elf_Addr target;

        ptr = (void *)make_function_pointer(def, obj);
        target = ((Elf_Addr (*)(void))ptr)();
        return ((void *)target);
}

Elf_Addr
_rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack)
{
    const Elf_Rel *rel;
    const Elf_Sym *def;
    const Obj_Entry *defobj;
    Elf_Addr *where;
    Elf_Addr target;
    RtldLockState lockstate;

    rlock_acquire(rtld_bind_lock, &lockstate);
    if (sigsetjmp(lockstate.env, 0) != 0)
            lock_upgrade(rtld_bind_lock, &lockstate);
    if (obj->pltrel)
        rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
    else
        rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);

    where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
    def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
        &lockstate);
    if (def == NULL)
        die();
    if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
        target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
    else
        target = (Elf_Addr)(defobj->relocbase + def->st_value);

    dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
      defobj->strtab + def->st_name, basename(obj->path),
      (void *)target, basename(defobj->path));

    /*
     * If we have a function call tracing hook, and the
     * hook would like to keep tracing this one function,
     * prevent the relocation so we will wind up here
     * the next time again.
     *
     * We don't want to functrace calls from the functracer
     * to avoid recursive loops.
     */
    if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
        if (rtld_functrace(obj->path,
                           defobj->path,
                           defobj->strtab + def->st_name,
                           stack)) {
            lock_release(rtld_bind_lock, &lockstate);
            return target;
        }
    }

    /*
     * Write the new contents for the jmpslot. Note that depending on
     * architecture, the value which we need to return back to the
     * lazy binding trampoline may or may not be the target
     * address. The value returned from reloc_jmpslot() is the value
     * that the trampoline needs.
     */
    target = reloc_jmpslot(where, target, defobj, obj, rel);
    lock_release(rtld_bind_lock, &lockstate);
    return target;
}

/*
 * Error reporting function.  Use it like printf.  If formats the message
 * into a buffer, and sets things up so that the next call to dlerror()
 * will return the message.
 */
void
_rtld_error(const char *fmt, ...)
{
    static char buf[512];
    va_list ap;

    va_start(ap, fmt);
    rtld_vsnprintf(buf, sizeof buf, fmt, ap);
    error_message = buf;
    va_end(ap);
}

/*
 * Return a dynamically-allocated copy of the current error message, if any.
 */
static char *
errmsg_save(void)
{
    return error_message == NULL ? NULL : xstrdup(error_message);
}

/*
 * Restore the current error message from a copy which was previously saved
 * by errmsg_save().  The copy is freed.
 */
static void
errmsg_restore(char *saved_msg)
{
    if (saved_msg == NULL)
        error_message = NULL;
    else {
        _rtld_error("%s", saved_msg);
        free(saved_msg);
    }
}

const char *
basename(const char *name)
{
    const char *p = strrchr(name, '/');
    return p != NULL ? p + 1 : name;
}

static struct utsname uts;

static char *
origin_subst_one(char *real, const char *kw, const char *subst,
    bool may_free)
{
        char *p, *p1, *res, *resp;
        int subst_len, kw_len, subst_count, old_len, new_len;

        kw_len = strlen(kw);

        /*
         * First, count the number of the keyword occurrences, to
         * preallocate the final string.
         */
        for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
                p1 = strstr(p, kw);
                if (p1 == NULL)
                        break;
        }

        /*
         * If the keyword is not found, just return.
         */
        if (subst_count == 0)
                return (may_free ? real : xstrdup(real));

        /*
         * There is indeed something to substitute.  Calculate the
         * length of the resulting string, and allocate it.
         */
        subst_len = strlen(subst);
        old_len = strlen(real);
        new_len = old_len + (subst_len - kw_len) * subst_count;
        res = xmalloc(new_len + 1);

        /*
         * Now, execute the substitution loop.
         */
        for (p = real, resp = res, *resp = '\0';;) {
                p1 = strstr(p, kw);
                if (p1 != NULL) {
                        /* Copy the prefix before keyword. */
                        memcpy(resp, p, p1 - p);
                        resp += p1 - p;
                        /* Keyword replacement. */
                        memcpy(resp, subst, subst_len);
                        resp += subst_len;
                        *resp = '\0';
                        p = p1 + kw_len;
                } else
                        break;
        }

        /* Copy to the end of string and finish. */
        strcat(resp, p);
        if (may_free)
                free(real);
        return (res);
}

static char *
origin_subst(char *real, const char *origin_path)
{
        char *res1, *res2, *res3, *res4;

        if (uts.sysname[0] == '\0') {
                if (uname(&uts) != 0) {
                        _rtld_error("utsname failed: %d", errno);
                        return (NULL);
                }
        }
        res1 = origin_subst_one(real, "$ORIGIN", origin_path, false);
        res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true);
        res3 = origin_subst_one(res2, "$OSREL", uts.release, true);
        res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true);
        return (res4);
}

static void
die(void)
{
    const char *msg = dlerror();

    if (msg == NULL)
        msg = "Fatal error";
    rtld_fdputstr(STDERR_FILENO, msg);
    rtld_fdputchar(STDERR_FILENO, '\n');
    _exit(1);
}

/*
 * Process a shared object's DYNAMIC section, and save the important
 * information in its Obj_Entry structure.
 */
static void
digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
    const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
{
    const Elf_Dyn *dynp;
    Needed_Entry **needed_tail = &obj->needed;
    Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
    Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
    const Elf_Hashelt *hashtab;
    const Elf32_Word *hashval;
    Elf32_Word bkt, nmaskwords;
    int bloom_size32;
    bool nmw_power2;
    int plttype = DT_REL;

    *dyn_rpath = NULL;
    *dyn_soname = NULL;
    *dyn_runpath = NULL;

    obj->bind_now = false;
    for (dynp = obj->dynamic;  dynp->d_tag != DT_NULL;  dynp++) {
        switch (dynp->d_tag) {

        case DT_REL:
            obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_RELSZ:
            obj->relsize = dynp->d_un.d_val;
            break;

        case DT_RELENT:
            assert(dynp->d_un.d_val == sizeof(Elf_Rel));
            break;

        case DT_JMPREL:
            obj->pltrel = (const Elf_Rel *)
              (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_PLTRELSZ:
            obj->pltrelsize = dynp->d_un.d_val;
            break;

        case DT_RELA:
            obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_RELASZ:
            obj->relasize = dynp->d_un.d_val;
            break;

        case DT_RELAENT:
            assert(dynp->d_un.d_val == sizeof(Elf_Rela));
            break;

        case DT_PLTREL:
            plttype = dynp->d_un.d_val;
            assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
            break;

        case DT_SYMTAB:
            obj->symtab = (const Elf_Sym *)
              (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_SYMENT:
            assert(dynp->d_un.d_val == sizeof(Elf_Sym));
            break;

        case DT_STRTAB:
            obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_STRSZ:
            obj->strsize = dynp->d_un.d_val;
            break;

        case DT_VERNEED:
            obj->verneed = (const Elf_Verneed *) (obj->relocbase +
                dynp->d_un.d_val);
            break;

        case DT_VERNEEDNUM:
            obj->verneednum = dynp->d_un.d_val;
            break;

        case DT_VERDEF:
            obj->verdef = (const Elf_Verdef *) (obj->relocbase +
                dynp->d_un.d_val);
            break;

        case DT_VERDEFNUM:
            obj->verdefnum = dynp->d_un.d_val;
            break;

        case DT_VERSYM:
            obj->versyms = (const Elf_Versym *)(obj->relocbase +
                dynp->d_un.d_val);
            break;

        case DT_HASH:
            {
                hashtab = (const Elf_Hashelt *)(obj->relocbase +
                    dynp->d_un.d_ptr);
                obj->nbuckets = hashtab[0];
                obj->nchains = hashtab[1];
                obj->buckets = hashtab + 2;
                obj->chains = obj->buckets + obj->nbuckets;
                obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
                  obj->buckets != NULL;
            }
            break;

        case DT_GNU_HASH:
            {
                hashtab = (const Elf_Hashelt *)(obj->relocbase +
                    dynp->d_un.d_ptr);
                obj->nbuckets_gnu = hashtab[0];
                obj->symndx_gnu = hashtab[1];
                nmaskwords = hashtab[2];
                bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
                /* Number of bitmask words is required to be power of 2 */
                nmw_power2 = powerof2(nmaskwords);
                obj->maskwords_bm_gnu = nmaskwords - 1;
                obj->shift2_gnu = hashtab[3];
                obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
                obj->buckets_gnu = hashtab + 4 + bloom_size32;
                obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
                  obj->symndx_gnu;
                obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 &&
                  obj->buckets_gnu != NULL;
            }
            break;

        case DT_NEEDED:
            if (!obj->rtld) {
                Needed_Entry *nep = NEW(Needed_Entry);
                nep->name = dynp->d_un.d_val;
                nep->obj = NULL;
                nep->next = NULL;

                *needed_tail = nep;
                needed_tail = &nep->next;
            }
            break;

        case DT_FILTER:
            if (!obj->rtld) {
                Needed_Entry *nep = NEW(Needed_Entry);
                nep->name = dynp->d_un.d_val;
                nep->obj = NULL;
                nep->next = NULL;

                *needed_filtees_tail = nep;
                needed_filtees_tail = &nep->next;
            }
            break;

        case DT_AUXILIARY:
            if (!obj->rtld) {
                Needed_Entry *nep = NEW(Needed_Entry);
                nep->name = dynp->d_un.d_val;
                nep->obj = NULL;
                nep->next = NULL;

                *needed_aux_filtees_tail = nep;
                needed_aux_filtees_tail = &nep->next;
            }
            break;

        case DT_PLTGOT:
            obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_TEXTREL:
            obj->textrel = true;
            break;

        case DT_SYMBOLIC:
            obj->symbolic = true;
            break;

        case DT_RPATH:
            /*
             * We have to wait until later to process this, because we
             * might not have gotten the address of the string table yet.
             */
            *dyn_rpath = dynp;
            break;

        case DT_SONAME:
            *dyn_soname = dynp;
            break;

        case DT_RUNPATH:
            *dyn_runpath = dynp;
            break;

        case DT_INIT:
            obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_PREINIT_ARRAY:
            obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_PREINIT_ARRAYSZ:
            obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
            break;

        case DT_INIT_ARRAY:
            obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_INIT_ARRAYSZ:
            obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
            break;

        case DT_FINI:
            obj->fini = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_FINI_ARRAY:
            obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
            break;

        case DT_FINI_ARRAYSZ:
            obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
            break;

        case DT_DEBUG:
            /* XXX - not implemented yet */
            if (!early)
                dbg("Filling in DT_DEBUG entry");
            ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
            break;

        case DT_FLAGS:
                if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
                    obj->z_origin = true;
                if (dynp->d_un.d_val & DF_SYMBOLIC)
                    obj->symbolic = true;
                if (dynp->d_un.d_val & DF_TEXTREL)
                    obj->textrel = true;
                if (dynp->d_un.d_val & DF_BIND_NOW)
                    obj->bind_now = true;
                if (dynp->d_un.d_val & DF_STATIC_TLS)
                    obj->static_tls = true;
            break;

        case DT_FLAGS_1:
                if (dynp->d_un.d_val & DF_1_NOOPEN)
                    obj->z_noopen = true;
                if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
                    obj->z_origin = true;
                /*if (dynp->d_un.d_val & DF_1_GLOBAL)
                    XXX ;*/
                if (dynp->d_un.d_val & DF_1_BIND_NOW)
                    obj->bind_now = true;
                if (dynp->d_un.d_val & DF_1_NODELETE)
                    obj->z_nodelete = true;
                if (dynp->d_un.d_val & DF_1_LOADFLTR)
                    obj->z_loadfltr = true;
                if (dynp->d_un.d_val & DF_1_INTERPOSE)
                    obj->z_interpose = true;
                if (dynp->d_un.d_val & DF_1_NODEFLIB)
                    obj->z_nodeflib = true;
            break;

        default:
            if (!early) {
                dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
                    (long)dynp->d_tag);
            }
            break;
        }
    }

    obj->traced = false;

    if (plttype == DT_RELA) {
        obj->pltrela = (const Elf_Rela *) obj->pltrel;
        obj->pltrel = NULL;
        obj->pltrelasize = obj->pltrelsize;
        obj->pltrelsize = 0;
    }

    /* Determine size of dynsym table (equal to nchains of sysv hash) */
    if (obj->valid_hash_sysv)
        obj->dynsymcount = obj->nchains;
    else if (obj->valid_hash_gnu) {
        obj->dynsymcount = 0;
        for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
            if (obj->buckets_gnu[bkt] == 0)
                continue;
            hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
            do
                obj->dynsymcount++;
            while ((*hashval++ & 1u) == 0);
        }
        obj->dynsymcount += obj->symndx_gnu;
    }
}

static void
digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
    const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
{

    if (obj->z_origin && obj->origin_path == NULL) {
        obj->origin_path = xmalloc(PATH_MAX);
        if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
            die();
    }

    if (dyn_runpath != NULL) {
        obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
        if (obj->z_origin)
            obj->runpath = origin_subst(obj->runpath, obj->origin_path);
    }
    else if (dyn_rpath != NULL) {
        obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
        if (obj->z_origin)
            obj->rpath = origin_subst(obj->rpath, obj->origin_path);
    }

    if (dyn_soname != NULL)
        object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
}

static void
digest_dynamic(Obj_Entry *obj, int early)
{
        const Elf_Dyn *dyn_rpath;
        const Elf_Dyn *dyn_soname;
        const Elf_Dyn *dyn_runpath;

        digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
        digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
}

/*
 * Process a shared object's program header.  This is used only for the
 * main program, when the kernel has already loaded the main program
 * into memory before calling the dynamic linker.  It creates and
 * returns an Obj_Entry structure.
 */
static Obj_Entry *
digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
{
    Obj_Entry *obj;
    const Elf_Phdr *phlimit = phdr + phnum;
    const Elf_Phdr *ph;
    Elf_Addr note_start, note_end;
    int nsegs = 0;

    obj = obj_new();
    for (ph = phdr;  ph < phlimit;  ph++) {
        if (ph->p_type != PT_PHDR)
            continue;

        obj->phdr = phdr;
        obj->phsize = ph->p_memsz;
        obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
        break;
    }

    obj->stack_flags = PF_X | PF_R | PF_W;

    for (ph = phdr;  ph < phlimit;  ph++) {
        switch (ph->p_type) {

        case PT_INTERP:
            obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
            break;

        case PT_LOAD:
            if (nsegs == 0) {   /* First load segment */
                obj->vaddrbase = trunc_page(ph->p_vaddr);
                obj->mapbase = obj->vaddrbase + obj->relocbase;
                obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
                  obj->vaddrbase;
            } else {            /* Last load segment */
                obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
                  obj->vaddrbase;
            }
            nsegs++;
            break;

        case PT_DYNAMIC:
            obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
            break;

        case PT_TLS:
            obj->tlsindex = 1;
            obj->tlssize = ph->p_memsz;
            obj->tlsalign = ph->p_align;
            obj->tlsinitsize = ph->p_filesz;
            obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
            break;

        case PT_GNU_STACK:
            obj->stack_flags = ph->p_flags;
            break;

        case PT_GNU_RELRO:
            obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
            obj->relro_size = round_page(ph->p_memsz);
            break;

        case PT_NOTE:
            obj->note_present = true;
            note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
            note_end = note_start + ph->p_filesz;
            digest_notes(obj, note_start, note_end);
            break;
        }
    }
    if (nsegs < 1) {
        _rtld_error("%s: too few PT_LOAD segments", path);
        return NULL;
    }

    obj->entry = entry;
    return obj;
}

void
digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
{
        const Elf_Note *note;
        const char *note_name;
        uintptr_t p;

        for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
            note = (const Elf_Note *)((const char *)(note + 1) +
              roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
              roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
                if (note->n_namesz != sizeof(NOTE_VENDOR) ||
                    note->n_descsz != sizeof(int32_t))
                        continue;
                if (note->n_type != ABI_NOTETYPE &&
                    note->n_type != CRT_NOINIT_NOTETYPE)
                        continue;
                note_name = (const char *)(note + 1);
                if (strncmp(NOTE_VENDOR, note_name, sizeof(NOTE_VENDOR)) != 0)
                        continue;
                switch (note->n_type) {
                case ABI_NOTETYPE:
                        /* DragonFly osrel note */
                        p = (uintptr_t)(note + 1);
                        p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
                        obj->osrel = *(const int32_t *)(p);
                        dbg("note osrel %d", obj->osrel);
                        break;
                case CRT_NOINIT_NOTETYPE:
                        /* DragonFly 'crt does not call init' note */
                        obj->crt_no_init = true;
                        dbg("note crt_no_init");
                        break;
                }
        }
}

static Obj_Entry *
dlcheck(void *handle)
{
    Obj_Entry *obj;

    for (obj = obj_list;  obj != NULL;  obj = obj->next)
        if (obj == (Obj_Entry *) handle)
            break;

    if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
        _rtld_error("Invalid shared object handle %p", handle);
        return NULL;
    }
    return obj;
}

/*
 * If the given object is already in the donelist, return true.  Otherwise
 * add the object to the list and return false.
 */
static bool
donelist_check(DoneList *dlp, const Obj_Entry *obj)
{
    unsigned int i;

    for (i = 0;  i < dlp->num_used;  i++)
        if (dlp->objs[i] == obj)
            return true;
    /*
     * Our donelist allocation should always be sufficient.  But if
     * our threads locking isn't working properly, more shared objects
     * could have been loaded since we allocated the list.  That should
     * never happen, but we'll handle it properly just in case it does.
     */
    if (dlp->num_used < dlp->num_alloc)
        dlp->objs[dlp->num_used++] = obj;
    return false;
}

/*
 * Hash function for symbol table lookup.  Don't even think about changing
 * this.  It is specified by the System V ABI.
 */
unsigned long
elf_hash(const char *name)
{
    const unsigned char *p = (const unsigned char *) name;
    unsigned long h = 0;
    unsigned long g;

    while (*p != '\0') {
        h = (h << 4) + *p++;
        if ((g = h & 0xf0000000) != 0)
            h ^= g >> 24;
        h &= ~g;
    }
    return h;
}

/*
 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
 * unsigned in case it's implemented with a wider type.
 */
static uint_fast32_t
gnu_hash(const char *s)
{
        uint_fast32_t h;
        unsigned char c;

        h = 5381;
        for (c = *s; c != '\0'; c = *++s)
                h = h * 33 + c;
        return (h & 0xffffffff);
}


/*
 * Find the library with the given name, and return its full pathname.
 * The returned string is dynamically allocated.  Generates an error
 * message and returns NULL if the library cannot be found.
 *
 * If the second argument is non-NULL, then it refers to an already-
 * loaded shared object, whose library search path will be searched.
 *
 * If a library is successfully located via LD_LIBRARY_PATH_FDS, its
 * descriptor (which is close-on-exec) will be passed out via the third
 * argument.
 *
 * The search order is:
 *   DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
 *   DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
 *   LD_LIBRARY_PATH
 *   DT_RUNPATH in the referencing file
 *   ldconfig hints (if -z nodefaultlib, filter out default library directories
 *       from list)
 *   /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
 *
 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
 */
static char *
find_library(const char *xname, const Obj_Entry *refobj, int *fdp)
{
    char *pathname;
    char *name;
    bool nodeflib, objgiven;

    objgiven = refobj != NULL;
    if (strchr(xname, '/') != NULL) {   /* Hard coded pathname */
        if (xname[0] != '/' && !trust) {
            _rtld_error("Absolute pathname required for shared object \"%s\"",
              xname);
            return NULL;
        }
        if (objgiven && refobj->z_origin) {
                return (origin_subst(__DECONST(char *, xname),
                    refobj->origin_path));
        } else {
                return (xstrdup(xname));
        }
    }

    if (libmap_disable || !objgiven ||
        (name = lm_find(refobj->path, xname)) == NULL)
        name = (char *)xname;

    dbg(" Searching for \"%s\"", name);

    nodeflib = objgiven ? refobj->z_nodeflib : false;
    if ((objgiven &&
      (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
      (objgiven && refobj->runpath == NULL && refobj != obj_main &&
      (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
      (pathname = search_library_path(name, ld_library_path)) != NULL ||
      (objgiven &&
      (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
      (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
      (pathname = search_library_path(name, gethints(nodeflib))) != NULL ||
      (objgiven && !nodeflib &&
      (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
        return (pathname);

    if (objgiven && refobj->path != NULL) {
        _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
          name, basename(refobj->path));
    } else {
        _rtld_error("Shared object \"%s\" not found", name);
    }
    return NULL;
}

/*
 * Given a symbol number in a referencing object, find the corresponding
 * definition of the symbol.  Returns a pointer to the symbol, or NULL if
 * no definition was found.  Returns a pointer to the Obj_Entry of the
 * defining object via the reference parameter DEFOBJ_OUT.
 */
const Elf_Sym *
find_symdef(unsigned long symnum, const Obj_Entry *refobj,
    const Obj_Entry **defobj_out, int flags, SymCache *cache,
    RtldLockState *lockstate)
{
    const Elf_Sym *ref;
    const Elf_Sym *def;
    const Obj_Entry *defobj;
    SymLook req;
    const char *name;
    int res;

    /*
     * If we have already found this symbol, get the information from
     * the cache.
     */
    if (symnum >= refobj->dynsymcount)
        return NULL;    /* Bad object */
    if (cache != NULL && cache[symnum].sym != NULL) {
        *defobj_out = cache[symnum].obj;
        return cache[symnum].sym;
    }

    ref = refobj->symtab + symnum;
    name = refobj->strtab + ref->st_name;
    def = NULL;
    defobj = NULL;

    /*
     * We don't have to do a full scale lookup if the symbol is local.
     * We know it will bind to the instance in this load module; to
     * which we already have a pointer (ie ref). By not doing a lookup,
     * we not only improve performance, but it also avoids unresolvable
     * symbols when local symbols are not in the hash table.
     *
     * This might occur for TLS module relocations, which simply use
     * symbol 0.
     */
    if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
        if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
            _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
                symnum);
        }
        symlook_init(&req, name);
        req.flags = flags;
        req.ventry = fetch_ventry(refobj, symnum);
        req.lockstate = lockstate;
        res = symlook_default(&req, refobj);
        if (res == 0) {
            def = req.sym_out;
            defobj = req.defobj_out;
        }
    } else {
        def = ref;
        defobj = refobj;
    }

    /*
     * If we found no definition and the reference is weak, treat the
     * symbol as having the value zero.
     */
    if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
        def = &sym_zero;
        defobj = obj_main;
    }

    if (def != NULL) {
        *defobj_out = defobj;
        /* Record the information in the cache to avoid subsequent lookups. */
        if (cache != NULL) {
            cache[symnum].sym = def;
            cache[symnum].obj = defobj;
        }
    } else {
        if (refobj != &obj_rtld)
            _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
    }
    return def;
}

/*
 * Return the search path from the ldconfig hints file, reading it if
 * necessary.  If nostdlib is true, then the default search paths are
 * not added to result.
 *
 * Returns NULL if there are problems with the hints file,
 * or if the search path there is empty.
 */
static const char *
gethints(bool nostdlib)
{
        static char *hints, *filtered_path;
        struct elfhints_hdr hdr;
        struct fill_search_info_args sargs, hargs;
        struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
        struct dl_serpath *SLPpath, *hintpath;
        char *p;
        unsigned int SLPndx, hintndx, fndx, fcount;
        int fd;
        size_t flen;
        bool skip;

        /* First call, read the hints file */
        if (hints == NULL) {
                /* Keep from trying again in case the hints file is bad. */
                hints = "";

                if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
                        return (NULL);
                if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
                    hdr.magic != ELFHINTS_MAGIC ||
                    hdr.version != 1) {
                        close(fd);
                        return (NULL);
                }
                p = xmalloc(hdr.dirlistlen + 1);
                if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
                    read(fd, p, hdr.dirlistlen + 1) !=
                    (ssize_t)hdr.dirlistlen + 1) {
                        free(p);
                        close(fd);
                        return (NULL);
                }
                hints = p;
                close(fd);
        }

        /*
         * If caller agreed to receive list which includes the default
         * paths, we are done. Otherwise, if we still have not
         * calculated filtered result, do it now.
         */
        if (!nostdlib)
                return (hints[0] != '\0' ? hints : NULL);
        if (filtered_path != NULL)
                goto filt_ret;

        /*
         * Obtain the list of all configured search paths, and the
         * list of the default paths.
         *
         * First estimate the size of the results.
         */
        smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
        smeta.dls_cnt = 0;
        hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
        hmeta.dls_cnt = 0;

        sargs.request = RTLD_DI_SERINFOSIZE;
        sargs.serinfo = &smeta;
        hargs.request = RTLD_DI_SERINFOSIZE;
        hargs.serinfo = &hmeta;

        path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
        path_enumerate(p, fill_search_info, &hargs);

        SLPinfo = xmalloc(smeta.dls_size);
        hintinfo = xmalloc(hmeta.dls_size);

        /*
         * Next fetch both sets of paths.
         */
        sargs.request = RTLD_DI_SERINFO;
        sargs.serinfo = SLPinfo;
        sargs.serpath = &SLPinfo->dls_serpath[0];
        sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];

        hargs.request = RTLD_DI_SERINFO;
        hargs.serinfo = hintinfo;
        hargs.serpath = &hintinfo->dls_serpath[0];
        hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];

        path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
        path_enumerate(p, fill_search_info, &hargs);

        /*
         * Now calculate the difference between two sets, by excluding
         * standard paths from the full set.
         */
        fndx = 0;
        fcount = 0;
        filtered_path = xmalloc(hdr.dirlistlen + 1);
        hintpath = &hintinfo->dls_serpath[0];
        for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
                skip = false;
                SLPpath = &SLPinfo->dls_serpath[0];
                /*
                 * Check each standard path against current.
                 */
                for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
                        /* matched, skip the path */
                        if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
                                skip = true;
                                break;
                        }
                }
                if (skip)
                        continue;
                /*
                 * Not matched against any standard path, add the path
                 * to result. Separate consecutive paths with ':'.
                 */
                if (fcount > 0) {
                        filtered_path[fndx] = ':';
                        fndx++;
                }
                fcount++;
                flen = strlen(hintpath->dls_name);
                strncpy((filtered_path + fndx), hintpath->dls_name, flen);
                fndx += flen;
        }
        filtered_path[fndx] = '\0';

        free(SLPinfo);
        free(hintinfo);

filt_ret:
        return (filtered_path[0] != '\0' ? filtered_path : NULL);
}

static void
init_dag(Obj_Entry *root)
{
    const Needed_Entry *needed;
    const Objlist_Entry *elm;
    DoneList donelist;

    if (root->dag_inited)
        return;
    donelist_init(&donelist);

    /* Root object belongs to own DAG. */
    objlist_push_tail(&root->dldags, root);
    objlist_push_tail(&root->dagmembers, root);
    donelist_check(&donelist, root);

    /*
     * Add dependencies of root object to DAG in breadth order
     * by exploiting the fact that each new object get added
     * to the tail of the dagmembers list.
     */
    STAILQ_FOREACH(elm, &root->dagmembers, link) {
        for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
            if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
                continue;
            objlist_push_tail(&needed->obj->dldags, root);
            objlist_push_tail(&root->dagmembers, needed->obj);
        }
    }
    root->dag_inited = true;
}

static void
process_nodelete(Obj_Entry *root)
{
        const Objlist_Entry *elm;

        /*
         * Walk over object DAG and process every dependent object that
         * is marked as DF_1_NODELETE. They need to grow their own DAG,
         * which then should have its reference upped separately.
         */
        STAILQ_FOREACH(elm, &root->dagmembers, link) {
                if (elm->obj != NULL && elm->obj->z_nodelete &&
                    !elm->obj->ref_nodel) {
                        dbg("obj %s nodelete", elm->obj->path);
                        init_dag(elm->obj);
                        ref_dag(elm->obj);
                        elm->obj->ref_nodel = true;
                }
        }
}

/*
 * Initialize the dynamic linker.  The argument is the address at which
 * the dynamic linker has been mapped into memory.  The primary task of
 * this function is to relocate the dynamic linker.
 */
static void
init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
{
    Obj_Entry objtmp;   /* Temporary rtld object */
    const Elf_Ehdr *ehdr;
    const Elf_Dyn *dyn_rpath;
    const Elf_Dyn *dyn_soname;
    const Elf_Dyn *dyn_runpath;

    /*
     * Conjure up an Obj_Entry structure for the dynamic linker.
     *
     * The "path" member can't be initialized yet because string constants
     * cannot yet be accessed. Below we will set it correctly.
     */
    memset(&objtmp, 0, sizeof(objtmp));
    objtmp.path = NULL;
    objtmp.rtld = true;
    objtmp.mapbase = mapbase;
#ifdef PIC
    objtmp.relocbase = mapbase;
#endif
    if (RTLD_IS_DYNAMIC()) {
        objtmp.dynamic = rtld_dynamic(&objtmp);
        digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
        assert(objtmp.needed == NULL);
        assert(!objtmp.textrel);

        /*
         * Temporarily put the dynamic linker entry into the object list, so
         * that symbols can be found.
         */

        relocate_objects(&objtmp, true, &objtmp, 0, NULL);
    }
    ehdr = (Elf_Ehdr *)mapbase;
    objtmp.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff);
    objtmp.phsize = ehdr->e_phnum * sizeof(objtmp.phdr[0]);

    /* Initialize the object list. */
    obj_tail = &obj_list;

    /* Now that non-local variables can be accesses, copy out obj_rtld. */
    memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));

#ifdef ENABLE_OSRELDATE
    if (aux_info[AT_OSRELDATE] != NULL)
            osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
#endif

    digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);

    /* Replace the path with a dynamically allocated copy. */
    obj_rtld.path = xstrdup(PATH_RTLD);

    r_debug.r_brk = r_debug_state;
    r_debug.r_state = RT_CONSISTENT;
}

/*
 * Add the init functions from a needed object list (and its recursive
 * needed objects) to "list".  This is not used directly; it is a helper
 * function for initlist_add_objects().  The write lock must be held
 * when this function is called.
 */
static void
initlist_add_neededs(Needed_Entry *needed, Objlist *list)
{
    /* Recursively process the successor needed objects. */
    if (needed->next != NULL)
        initlist_add_neededs(needed->next, list);

    /* Process the current needed object. */
    if (needed->obj != NULL)
        initlist_add_objects(needed->obj, &needed->obj->next, list);
}

/*
 * Scan all of the DAGs rooted in the range of objects from "obj" to
 * "tail" and add their init functions to "list".  This recurses over
 * the DAGs and ensure the proper init ordering such that each object's
 * needed libraries are initialized before the object itself.  At the
 * same time, this function adds the objects to the global finalization
 * list "list_fini" in the opposite order.  The write lock must be
 * held when this function is called.
 */
static void
initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
{

    if (obj->init_scanned || obj->init_done)
        return;
    obj->init_scanned = true;

    /* Recursively process the successor objects. */
    if (&obj->next != tail)
        initlist_add_objects(obj->next, tail, list);

    /* Recursively process the needed objects. */
    if (obj->needed != NULL)
        initlist_add_neededs(obj->needed, list);
    if (obj->needed_filtees != NULL)
        initlist_add_neededs(obj->needed_filtees, list);
    if (obj->needed_aux_filtees != NULL)
        initlist_add_neededs(obj->needed_aux_filtees, list);

    /* Add the object to the init list. */
    if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
      obj->init_array != (Elf_Addr)NULL)
        objlist_push_tail(list, obj);

    /* Add the object to the global fini list in the reverse order. */
    if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
      && !obj->on_fini_list) {
        objlist_push_head(&list_fini, obj);
        obj->on_fini_list = true;
    }
}

#ifndef FPTR_TARGET
#define FPTR_TARGET(f)  ((Elf_Addr) (f))
#endif

static void
free_needed_filtees(Needed_Entry *n)
{
    Needed_Entry *needed, *needed1;

    for (needed = n; needed != NULL; needed = needed->next) {
        if (needed->obj != NULL) {
            dlclose(needed->obj);
            needed->obj = NULL;
        }
    }
    for (needed = n; needed != NULL; needed = needed1) {
        needed1 = needed->next;
        free(needed);
    }
}

static void
unload_filtees(Obj_Entry *obj)
{

    free_needed_filtees(obj->needed_filtees);
    obj->needed_filtees = NULL;
    free_needed_filtees(obj->needed_aux_filtees);
    obj->needed_aux_filtees = NULL;
    obj->filtees_loaded = false;
}

static void
load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
    RtldLockState *lockstate)
{

    for (; needed != NULL; needed = needed->next) {
        needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
          flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
          RTLD_LOCAL, lockstate);
    }
}

static void
load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{

    lock_restart_for_upgrade(lockstate);
    if (!obj->filtees_loaded) {
        load_filtee1(obj, obj->needed_filtees, flags, lockstate);
        load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
        obj->filtees_loaded = true;
    }
}

static int
process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
{
    Obj_Entry *obj1;

    for (; needed != NULL; needed = needed->next) {
        obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
          flags & ~RTLD_LO_NOLOAD);
        if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
            return (-1);
    }
    return (0);
}

/*
 * Given a shared object, traverse its list of needed objects, and load
 * each of them.  Returns 0 on success.  Generates an error message and
 * returns -1 on failure.
 */
static int
load_needed_objects(Obj_Entry *first, int flags)
{
    Obj_Entry *obj;

    for (obj = first;  obj != NULL;  obj = obj->next) {
        if (process_needed(obj, obj->needed, flags) == -1)
            return (-1);
    }
    return (0);
}

static int
load_preload_objects(void)
{
    char *p = ld_preload;
    Obj_Entry *obj;
    static const char delim[] = " \t:;";

    if (p == NULL)
        return 0;

    p += strspn(p, delim);
    while (*p != '\0') {
        size_t len = strcspn(p, delim);
        char savech;
        SymLook req;
        int res;

        savech = p[len];
        p[len] = '\0';
        obj = load_object(p, -1, NULL, 0);
        if (obj == NULL)
            return -1;  /* XXX - cleanup */
        obj->z_interpose = true;
        p[len] = savech;
        p += len;
        p += strspn(p, delim);

        /* Check for the magic tracing function */
        symlook_init(&req, RTLD_FUNCTRACE);
        res = symlook_obj(&req, obj);
        if (res == 0) {
            rtld_functrace = (void *)(req.defobj_out->relocbase +
                                      req.sym_out->st_value);
            rtld_functrace_obj = req.defobj_out;
        }
    }
    LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
    return 0;
}

static const char *
printable_path(const char *path)
{

        return (path == NULL ? "<unknown>" : path);
}

/*
 * Load a shared object into memory, if it is not already loaded.  The
 * object may be specified by name or by user-supplied file descriptor
 * fd_u. In the later case, the fd_u descriptor is not closed, but its
 * duplicate is.
 *
 * Returns a pointer to the Obj_Entry for the object.  Returns NULL
 * on failure.
 */
static Obj_Entry *
load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
{
    Obj_Entry *obj;
    int fd;
    struct stat sb;
    char *path;

    fd = -1;
    if (name != NULL) {
        for (obj = obj_list->next;  obj != NULL;  obj = obj->next) {
            if (object_match_name(obj, name))
                return (obj);
        }

        path = find_library(name, refobj, &fd);
        if (path == NULL)
            return (NULL);
    } else
        path = NULL;

    if (fd >= 0) {
        /*
         * search_library_pathfds() opens a fresh file descriptor for the
         * library, so there is no need to dup().
         */
    } else if (fd_u == -1) {
        /*
         * If we didn't find a match by pathname, or the name is not
         * supplied, open the file and check again by device and inode.
         * This avoids false mismatches caused by multiple links or ".."
         * in pathnames.
         *
         * To avoid a race, we open the file and use fstat() rather than
         * using stat().
         */
        if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
            _rtld_error("Cannot open \"%s\"", path);
            free(path);
            return (NULL);
        }
    } else {
        fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
        if (fd == -1) {
            _rtld_error("Cannot dup fd");
            free(path);
            return (NULL);
        }
    }
    if (fstat(fd, &sb) == -1) {
        _rtld_error("Cannot fstat \"%s\"", printable_path(path));
        close(fd);
        free(path);
        return NULL;
    }
    for (obj = obj_list->next;  obj != NULL;  obj = obj->next)
        if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
            break;
    if (obj != NULL && name != NULL) {
        object_add_name(obj, name);
        free(path);
        close(fd);
        return obj;
    }
    if (flags & RTLD_LO_NOLOAD) {
        free(path);
        close(fd);
        return (NULL);
    }

    /* First use of this object, so we must map it in */
    obj = do_load_object(fd, name, path, &sb, flags);
    if (obj == NULL)
        free(path);
    close(fd);

    return obj;
}

static Obj_Entry *
do_load_object(int fd, const char *name, char *path, struct stat *sbp,
  int flags)
{
    Obj_Entry *obj;
    struct statfs fs;

    /*
     * but first, make sure that environment variables haven't been
     * used to circumvent the noexec flag on a filesystem.
     */
    if (dangerous_ld_env) {
        if (fstatfs(fd, &fs) != 0) {
            _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
            return NULL;
        }
        if (fs.f_flags & MNT_NOEXEC) {
            _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
            return NULL;
        }
    }
    dbg("loading \"%s\"", printable_path(path));
    obj = map_object(fd, printable_path(path), sbp);
    if (obj == NULL)
        return NULL;

    /*
     * If DT_SONAME is present in the object, digest_dynamic2 already
     * added it to the object names.
     */
    if (name != NULL)
        object_add_name(obj, name);
    obj->path = path;
    digest_dynamic(obj, 0);
    dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
        obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
    if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
      RTLD_LO_DLOPEN) {
        dbg("refusing to load non-loadable \"%s\"", obj->path);
        _rtld_error("Cannot dlopen non-loadable %s", obj->path);
        munmap(obj->mapbase, obj->mapsize);
        obj_free(obj);
        return (NULL);
    }

    *obj_tail = obj;
    obj_tail = &obj->next;
    obj_count++;
    obj_loads++;
    linkmap_add(obj);   /* for GDB & dlinfo() */
#if 0
    max_stack_flags |= obj->stack_flags;
#endif

    dbg("  %p .. %p: %s", obj->mapbase,
         obj->mapbase + obj->mapsize - 1, obj->path);
    if (obj->textrel)
        dbg("  WARNING: %s has impure text", obj->path);
    LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
        obj->path);

    return obj;
}

static Obj_Entry *
obj_from_addr(const void *addr)
{
    Obj_Entry *obj;

    for (obj = obj_list;  obj != NULL;  obj = obj->next) {
        if (addr < (void *) obj->mapbase)
            continue;
        if (addr < (void *) (obj->mapbase + obj->mapsize))
            return obj;
    }
    return NULL;
}

/*
 * If the main program is defined with a .preinit_array section, call
 * each function in order.  This must occur before the initialization
 * of any shared object or the main program.
 */
static void
preinit_main(void)
{
    Elf_Addr *preinit_addr;
    int index;

    preinit_addr = (Elf_Addr *)obj_main->preinit_array;
    if (preinit_addr == NULL)
        return;

    for (index = 0; index < obj_main->preinit_array_num; index++) {
        if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
            dbg("calling preinit function for %s at %p", obj_main->path,
              (void *)preinit_addr[index]);
            LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
              0, 0, obj_main->path);
            call_init_pointer(obj_main, preinit_addr[index]);
        }
    }
}

/*
 * Call the finalization functions for each of the objects in "list"
 * belonging to the DAG of "root" and referenced once. If NULL "root"
 * is specified, every finalization function will be called regardless
 * of the reference count and the list elements won't be freed. All of
 * the objects are expected to have non-NULL fini functions.
 */
static void
objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
{
    Objlist_Entry *elm;
    char *saved_msg;
    Elf_Addr *fini_addr;
    int index;

    assert(root == NULL || root->refcount == 1);

    /*
     * Preserve the current error message since a fini function might
     * call into the dynamic linker and overwrite it.
     */
    saved_msg = errmsg_save();
    do {
        STAILQ_FOREACH(elm, list, link) {
            if (root != NULL && (elm->obj->refcount != 1 ||
              objlist_find(&root->dagmembers, elm->obj) == NULL))
                continue;

            /* Remove object from fini list to prevent recursive invocation. */
            STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
            /*
             * XXX: If a dlopen() call references an object while the
             * fini function is in progress, we might end up trying to
             * unload the referenced object in dlclose() or the object
             * won't be unloaded although its fini function has been
             * called.
             */
            lock_release(rtld_bind_lock, lockstate);

            /*
             * It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
             * When this happens, DT_FINI_ARRAY is processed first.
             * It is also processed backwards.  It is possible to encounter
             * DT_FINI_ARRAY elements with values of 0 or 1, but they need
             * to be ignored.
             */
            fini_addr = (Elf_Addr *)elm->obj->fini_array;
            if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
                for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
                    if (fini_addr[index] != 0 && fini_addr[index] != 1) {
                        dbg("calling fini array function for %s at %p",
                            elm->obj->path, (void *)fini_addr[index]);
                        LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
                            (void *)fini_addr[index], 0, 0, elm->obj->path);
                        call_initfini_pointer(elm->obj, fini_addr[index]);
                    }
                }
            }
            if (elm->obj->fini != (Elf_Addr)NULL) {
                dbg("calling fini function for %s at %p", elm->obj->path,
                    (void *)elm->obj->fini);
                LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
                    0, 0, elm->obj->path);
                call_initfini_pointer(elm->obj, elm->obj->fini);
            }
            wlock_acquire(rtld_bind_lock, lockstate);
            /* No need to free anything if process is going down. */
            if (root != NULL)
                free(elm);
            /*
             * We must restart the list traversal after every fini call
             * because a dlclose() call from the fini function or from
             * another thread might have modified the reference counts.
             */
            break;
        }
    } while (elm != NULL);
    errmsg_restore(saved_msg);
}

/*
 * Call the initialization functions for each of the objects in
 * "list".  All of the objects are expected to have non-NULL init
 * functions.
 */
static void
objlist_call_init(Objlist *list, RtldLockState *lockstate)
{
    Objlist_Entry *elm;
    Obj_Entry *obj;
    char *saved_msg;
    Elf_Addr *init_addr;
    int index;

    /*
     * Clean init_scanned flag so that objects can be rechecked and
     * possibly initialized earlier if any of vectors called below
     * cause the change by using dlopen.
     */
    for (obj = obj_list;  obj != NULL;  obj = obj->next)
        obj->init_scanned = false;

    /*
     * Preserve the current error message since an init function might
     * call into the dynamic linker and overwrite it.
     */
    saved_msg = errmsg_save();
    STAILQ_FOREACH(elm, list, link) {
        if (elm->obj->init_done) /* Initialized early. */
            continue;

        /*
         * Race: other thread might try to use this object before current
         * one completes the initilization. Not much can be done here
         * without better locking.
         */
        elm->obj->init_done = true;
        lock_release(rtld_bind_lock, lockstate);

        /*
         * It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
         * When this happens, DT_INIT is processed first.
         * It is possible to encounter DT_INIT_ARRAY elements with values
         * of 0 or 1, but they need to be ignored.
         */
        if (elm->obj->init != (Elf_Addr)NULL) {
            dbg("calling init function for %s at %p", elm->obj->path,
                (void *)elm->obj->init);
            LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
                0, 0, elm->obj->path);
            call_initfini_pointer(elm->obj, elm->obj->init);
        }
        init_addr = (Elf_Addr *)elm->obj->init_array;
        if (init_addr != NULL) {
            for (index = 0; index < elm->obj->init_array_num; index++) {
                if (init_addr[index] != 0 && init_addr[index] != 1) {
                    dbg("calling init array function for %s at %p", elm->obj->path,
                        (void *)init_addr[index]);
                    LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
                        (void *)init_addr[index], 0, 0, elm->obj->path);
                    call_init_pointer(elm->obj, init_addr[index]);
                }
            }
        }
        wlock_acquire(rtld_bind_lock, lockstate);
    }
    errmsg_restore(saved_msg);
}

static void
objlist_clear(Objlist *list)
{
    Objlist_Entry *elm;

    while (!STAILQ_EMPTY(list)) {
        elm = STAILQ_FIRST(list);
        STAILQ_REMOVE_HEAD(list, link);
        free(elm);
    }
}

static Objlist_Entry *
objlist_find(Objlist *list, const Obj_Entry *obj)
{
    Objlist_Entry *elm;

    STAILQ_FOREACH(elm, list, link)
        if (elm->obj == obj)
            return elm;
    return NULL;
}

static void
objlist_init(Objlist *list)
{
    STAILQ_INIT(list);
}

static void
objlist_push_head(Objlist *list, Obj_Entry *obj)
{
    Objlist_Entry *elm;

    elm = NEW(Objlist_Entry);
    elm->obj = obj;
    STAILQ_INSERT_HEAD(list, elm, link);
}

static void
objlist_push_tail(Objlist *list, Obj_Entry *obj)
{
    Objlist_Entry *elm;

    elm = NEW(Objlist_Entry);
    elm->obj = obj;
    STAILQ_INSERT_TAIL(list, elm, link);
}

static void
objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
{
        Objlist_Entry *elm, *listelm;

        STAILQ_FOREACH(listelm, list, link) {
                if (listelm->obj == listobj)
                        break;
        }
        elm = NEW(Objlist_Entry);
        elm->obj = obj;
        if (listelm != NULL)
                STAILQ_INSERT_AFTER(list, listelm, elm, link);
        else
                STAILQ_INSERT_TAIL(list, elm, link);
}

static void
objlist_remove(Objlist *list, Obj_Entry *obj)
{
    Objlist_Entry *elm;

    if ((elm = objlist_find(list, obj)) != NULL) {
        STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
        free(elm);
    }
}

/*
 * Relocate dag rooted in the specified object.
 * Returns 0 on success, or -1 on failure.
 */

static int
relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
    int flags, RtldLockState *lockstate)
{
        Objlist_Entry *elm;
        int error;

        error = 0;
        STAILQ_FOREACH(elm, &root->dagmembers, link) {
                error = relocate_object(elm->obj, bind_now, rtldobj, flags,
                    lockstate);
                if (error == -1)
                        break;
        }
        return (error);
}

/*
 * Prepare for, or clean after, relocating an object marked with
 * DT_TEXTREL or DF_TEXTREL.  Before relocating, all read-only
 * segments are remapped read-write.  After relocations are done, the
 * segment's permissions are returned back to the modes specified in
 * the phdrs.  If any relocation happened, or always for wired
 * program, COW is triggered.
 */
static int
reloc_textrel_prot(Obj_Entry *obj, bool before)
{
        const Elf_Phdr *ph;
        void *base;
        size_t l, sz;
        int prot;

        for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0;
            l--, ph++) {
                if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0)
                        continue;
                base = obj->relocbase + trunc_page(ph->p_vaddr);
                sz = round_page(ph->p_vaddr + ph->p_filesz) -
                    trunc_page(ph->p_vaddr);
                prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0);
        /*
         * Make sure modified text segments are included in the
         * core dump since we modified it.  This unfortunately causes the
         * entire text segment to core-out but we don't have much of a
         * choice.  We could try to only reenable core dumps on pages
         * in which relocations occured but that is likely most of the text
         * pages anyway, and even that would not work because the rest of
         * the text pages would wind up as a read-only OBJT_DEFAULT object
         * (created due to our modifications) backed by the original OBJT_VNODE
         * object, and the ELF coredump code is currently only able to dump
         * vnode records for pure vnode-backed mappings, not vnode backings
         * to memory objects.
         */
                if (before == false)
                        madvise(base, sz, MADV_CORE);
                if (mprotect(base, sz, prot) == -1) {
                        _rtld_error("%s: Cannot write-%sable text segment: %s",
                            obj->path, before ? "en" : "dis",
                            rtld_strerror(errno));
                        return (-1);
                }
        }
        return (0);
}

/*
 * Relocate single object.
 * Returns 0 on success, or -1 on failure.
 */
static int
relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
    int flags, RtldLockState *lockstate)
{

        if (obj->relocated)
                return (0);
        obj->relocated = true;
        if (obj != rtldobj)
                dbg("relocating \"%s\"", obj->path);

        if (obj->symtab == NULL || obj->strtab == NULL ||
            !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
                _rtld_error("%s: Shared object has no run-time symbol table",
                            obj->path);
                return (-1);
        }

        /* There are relocations to the write-protected text segment. */
        if (obj->textrel && reloc_textrel_prot(obj, true) != 0)
                return (-1);

        /* Process the non-PLT non-IFUNC relocations. */
        if (reloc_non_plt(obj, rtldobj, flags, lockstate))
                return (-1);

        /* Re-protected the text segment. */
        if (obj->textrel && reloc_textrel_prot(obj, false) != 0)
                return (-1);

        /* Set the special PLT or GOT entries. */
        init_pltgot(obj);

        /* Process the PLT relocations. */
        if (reloc_plt(obj) == -1)
                return (-1);
        /* Relocate the jump slots if we are doing immediate binding. */
        if (obj->bind_now || bind_now)
                if (reloc_jmpslots(obj, flags, lockstate) == -1)
                        return (-1);

        /*
         * Process the non-PLT IFUNC relocations.  The relocations are
         * processed in two phases, because IFUNC resolvers may
         * reference other symbols, which must be readily processed
         * before resolvers are called.
         */
        if (obj->non_plt_gnu_ifunc &&
            reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate))
                return (-1);

        /*
         * Set up the magic number and version in the Obj_Entry.  These
         * were checked in the crt1.o from the original ElfKit, so we
         * set them for backward compatibility.
         */
        obj->magic = RTLD_MAGIC;
        obj->version = RTLD_VERSION;

        /*
         * Set relocated data to read-only status if protection specified
         */

        if (obj->relro_size) {
            if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
                _rtld_error("%s: Cannot enforce relro relocation: %s",
                  obj->path, rtld_strerror(errno));
                return (-1);
            }
            obj->relro_protected = true;
        }
        return (0);
}

/*
 * Relocate newly-loaded shared objects.  The argument is a pointer to
 * the Obj_Entry for the first such object.  All objects from the first
 * to the end of the list of objects are relocated.  Returns 0 on success,
 * or -1 on failure.
 */
static int
relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
    int flags, RtldLockState *lockstate)
{
        Obj_Entry *obj;
        int error;

        for (error = 0, obj = first;  obj != NULL;  obj = obj->next) {
                error = relocate_object(obj, bind_now, rtldobj, flags,
                    lockstate);
                if (error == -1)
                        break;
        }
        return (error);
}

/*
 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
 * referencing STT_GNU_IFUNC symbols is postponed till the other
 * relocations are done.  The indirect functions specified as
 * ifunc are allowed to call other symbols, so we need to have
 * objects relocated before asking for resolution from indirects.
 *
 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
 * instead of the usual lazy handling of PLT slots.  It is
 * consistent with how GNU does it.
 */
static int
resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
    RtldLockState *lockstate)
{
        if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
                return (-1);
        if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
            reloc_gnu_ifunc(obj, flags, lockstate) == -1)
                return (-1);
        return (0);
}

static int
resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
    RtldLockState *lockstate)
{
        Obj_Entry *obj;

        for (obj = first;  obj != NULL;  obj = obj->next) {
                if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
                        return (-1);
        }
        return (0);
}

static int
initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
    RtldLockState *lockstate)
{
        Objlist_Entry *elm;

        STAILQ_FOREACH(elm, list, link) {
                if (resolve_object_ifunc(elm->obj, bind_now, flags,
                    lockstate) == -1)
                        return (-1);
        }
        return (0);
}

/*
 * Cleanup procedure.  It will be called (by the atexit mechanism) just
 * before the process exits.
 */
static void
rtld_exit(void)
{
    RtldLockState lockstate;

    wlock_acquire(rtld_bind_lock, &lockstate);
    dbg("rtld_exit()");
    objlist_call_fini(&list_fini, NULL, &lockstate);
    /* No need to remove the items from the list, since we are exiting. */
    if (!libmap_disable)
        lm_fini();
    lock_release(rtld_bind_lock, &lockstate);
}

/*
 * Iterate over a search path, translate each element, and invoke the
 * callback on the result.
 */
static void *
path_enumerate(const char *path, path_enum_proc callback, void *arg)
{
    const char *trans;
    if (path == NULL)
        return (NULL);

    path += strspn(path, ":;");
    while (*path != '\0') {
        size_t len;
        char  *res;

        len = strcspn(path, ":;");
        trans = lm_findn(NULL, path, len);
        if (trans)
            res = callback(trans, strlen(trans), arg);
        else
            res = callback(path, len, arg);

        if (res != NULL)
            return (res);

        path += len;
        path += strspn(path, ":;");
    }

    return (NULL);
}

struct try_library_args {
    const char  *name;
    size_t       namelen;
    char        *buffer;
    size_t       buflen;
};

static void *
try_library_path(const char *dir, size_t dirlen, void *param)
{
    struct try_library_args *arg;

    arg = param;
    if (*dir == '/' || trust) {
        char *pathname;

        if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
                return (NULL);

        pathname = arg->buffer;
        strncpy(pathname, dir, dirlen);
        pathname[dirlen] = '/';
        strcpy(pathname + dirlen + 1, arg->name);

        dbg("  Trying \"%s\"", pathname);
        if (access(pathname, F_OK) == 0) {              /* We found it */
            pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
            strcpy(pathname, arg->buffer);
            return (pathname);
        }
    }
    return (NULL);
}

static char *
search_library_path(const char *name, const char *path)
{
    char *p;
    struct try_library_args arg;

    if (path == NULL)
        return NULL;

    arg.name = name;
    arg.namelen = strlen(name);
    arg.buffer = xmalloc(PATH_MAX);
    arg.buflen = PATH_MAX;

    p = path_enumerate(path, try_library_path, &arg);

    free(arg.buffer);

    return (p);
}


/*
 * Finds the library with the given name using the directory descriptors
 * listed in the LD_LIBRARY_PATH_FDS environment variable.
 *
 * Returns a freshly-opened close-on-exec file descriptor for the library,
 * or -1 if the library cannot be found.
 */
static char *
search_library_pathfds(const char *name, const char *path, int *fdp)
{
        char *envcopy, *fdstr, *found, *last_token;
        size_t len;
        int dirfd, fd;

        dbg("%s('%s', '%s', fdp)", __func__, name, path);

        /* Don't load from user-specified libdirs into setuid binaries. */
        if (!trust)
                return (NULL);

        /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */
        if (path == NULL)
                return (NULL);

        /* LD_LIBRARY_PATH_FDS only works with relative paths. */
        if (name[0] == '/') {
                dbg("Absolute path (%s) passed to %s", name, __func__);
                return (NULL);
        }

        /*
         * Use strtok_r() to walk the FD:FD:FD list.  This requires a local
         * copy of the path, as strtok_r rewrites separator tokens
         * with '\0'.
         */
        found = NULL;
        envcopy = xstrdup(path);
        for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL;
            fdstr = strtok_r(NULL, ":", &last_token)) {
                dirfd = parse_libdir(fdstr);
                if (dirfd < 0)
                        break;
                fd = openat(dirfd, name, O_RDONLY | O_CLOEXEC);
                if (fd >= 0) {
                        *fdp = fd;
                        len = strlen(fdstr) + strlen(name) + 3;
                        found = xmalloc(len);
                        if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) {
                                _rtld_error("error generating '%d/%s'",
                                    dirfd, name);
                                die();
                        }
                        dbg("open('%s') => %d", found, fd);
                        break;
                }
        }
        free(envcopy);

        return (found);
}


int
dlclose(void *handle)
{
    Obj_Entry *root;
    RtldLockState lockstate;

    wlock_acquire(rtld_bind_lock, &lockstate);
    root = dlcheck(handle);
    if (root == NULL) {
        lock_release(rtld_bind_lock, &lockstate);
        return -1;
    }
    LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
        root->path);

    /* Unreference the object and its dependencies. */
    root->dl_refcount--;

    if (root->refcount == 1) {
        /*
         * The object will be no longer referenced, so we must unload it.
         * First, call the fini functions.
         */
        objlist_call_fini(&list_fini, root, &lockstate);

        unref_dag(root);

        /* Finish cleaning up the newly-unreferenced objects. */
        GDB_STATE(RT_DELETE,&root->linkmap);
        unload_object(root);
        GDB_STATE(RT_CONSISTENT,NULL);
    } else
        unref_dag(root);

    LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
    lock_release(rtld_bind_lock, &lockstate);
    return 0;
}

char *
dlerror(void)
{
    char *msg = error_message;
    error_message = NULL;
    return msg;
}

void *
dlopen(const char *name, int mode)
{

        return (rtld_dlopen(name, -1, mode));
}

void *
fdlopen(int fd, int mode)
{

        return (rtld_dlopen(NULL, fd, mode));
}

static void *
rtld_dlopen(const char *name, int fd, int mode)
{
    RtldLockState lockstate;
    int lo_flags;

    LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
    ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
    if (ld_tracing != NULL) {
        rlock_acquire(rtld_bind_lock, &lockstate);
        if (sigsetjmp(lockstate.env, 0) != 0)
            lock_upgrade(rtld_bind_lock, &lockstate);
        environ = (char **)*get_program_var_addr("environ", &lockstate);
        lock_release(rtld_bind_lock, &lockstate);
    }
    lo_flags = RTLD_LO_DLOPEN;
    if (mode & RTLD_NODELETE)
            lo_flags |= RTLD_LO_NODELETE;
    if (mode & RTLD_NOLOAD)
            lo_flags |= RTLD_LO_NOLOAD;
    if (ld_tracing != NULL)
            lo_flags |= RTLD_LO_TRACE;

    return (dlopen_object(name, fd, obj_main, lo_flags,
      mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
}

static void
dlopen_cleanup(Obj_Entry *obj)
{

        obj->dl_refcount--;
        unref_dag(obj);
        if (obj->refcount == 0)
                unload_object(obj);
}

static Obj_Entry *
dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
    int mode, RtldLockState *lockstate)
{
    Obj_Entry **old_obj_tail;
    Obj_Entry *obj;
    Objlist initlist;
    RtldLockState mlockstate;
    int result;

    objlist_init(&initlist);

    if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
        wlock_acquire(rtld_bind_lock, &mlockstate);
        lockstate = &mlockstate;
    }
    GDB_STATE(RT_ADD,NULL);

    old_obj_tail = obj_tail;
    obj = NULL;
    if (name == NULL && fd == -1) {
        obj = obj_main;
        obj->refcount++;
    } else {
        obj = load_object(name, fd, refobj, lo_flags);
    }

    if (obj) {
        obj->dl_refcount++;
        if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
            objlist_push_tail(&list_global, obj);
        if (*old_obj_tail != NULL) {            /* We loaded something new. */
            assert(*old_obj_tail == obj);
            if ((lo_flags & RTLD_LO_EARLY) == 0 && obj->static_tls &&
                !allocate_tls_offset(obj)) {
                    _rtld_error("%s: No space available "
                                "for static TLS",
                                obj->path);
                    result = -1;
            } else {
                    result = 0;
            }
            if (result == 0) {
                result = load_needed_objects(
                            obj,
                            lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
            }
            init_dag(obj);
            ref_dag(obj);
            if (result != -1)
                result = rtld_verify_versions(&obj->dagmembers);
            if (result != -1 && ld_tracing)
                goto trace;
            if (result == -1 || relocate_object_dag(obj,
              (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
              (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
              lockstate) == -1) {
                dlopen_cleanup(obj);
                obj = NULL;
            } else if (lo_flags & RTLD_LO_EARLY) {
                /*
                 * Do not call the init functions for early loaded
                 * filtees.  The image is still not initialized enough
                 * for them to work.
                 *
                 * Our object is found by the global object list and
                 * will be ordered among all init calls done right
                 * before transferring control to main.
                 */
            } else {
                /* Make list of init functions to call. */
                initlist_add_objects(obj, &obj->next, &initlist);
            }
            /*
             * Process all no_delete objects here, given them own
             * DAGs to prevent their dependencies from being unloaded.
             * This has to be done after we have loaded all of the
             * dependencies, so that we do not miss any.
             */
            if (obj != NULL)
                process_nodelete(obj);
        } else {
            /*
             * Bump the reference counts for objects on this DAG.  If
             * this is the first dlopen() call for the object that was
             * already loaded as a dependency, initialize the dag
             * starting at it.
             */
            init_dag(obj);
            ref_dag(obj);

            if ((lo_flags & RTLD_LO_TRACE) != 0)
                goto trace;
        }
        if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
          obj->z_nodelete) && !obj->ref_nodel) {
            dbg("obj %s nodelete", obj->path);
            ref_dag(obj);
            obj->z_nodelete = obj->ref_nodel = true;
        }
    }

    LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
        name);
    GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);

    if ((lo_flags & RTLD_LO_EARLY) == 0) {
        map_stacks_exec(lockstate);
        if (obj)
            distribute_static_tls(&initlist, lockstate);
    }

    if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
      (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
      lockstate) == -1) {
        objlist_clear(&initlist);
        dlopen_cleanup(obj);
        if (lockstate == &mlockstate)
            lock_release(rtld_bind_lock, lockstate);
        return (NULL);
    }

    if (!(lo_flags & RTLD_LO_EARLY)) {
        /* Call the init functions. */
        objlist_call_init(&initlist, lockstate);
    }
    objlist_clear(&initlist);
    if (lockstate == &mlockstate)
        lock_release(rtld_bind_lock, lockstate);
    return obj;
trace:
    trace_loaded_objects(obj);
    if (lockstate == &mlockstate)
        lock_release(rtld_bind_lock, lockstate);
    exit(0);
}

static void *
do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
    int flags)
{
    DoneList donelist;
    const Obj_Entry *obj, *defobj;
    const Elf_Sym *def;
    SymLook req;
    RtldLockState lockstate;
    tls_index ti;
    int res;

    def = NULL;
    defobj = NULL;
    symlook_init(&req, name);
    req.ventry = ve;
    req.flags = flags | SYMLOOK_IN_PLT;
    req.lockstate = &lockstate;

    rlock_acquire(rtld_bind_lock, &lockstate);
    if (sigsetjmp(lockstate.env, 0) != 0)
            lock_upgrade(rtld_bind_lock, &lockstate);
    if (handle == NULL || handle == RTLD_NEXT ||
        handle == RTLD_DEFAULT || handle == RTLD_SELF ||
        handle == RTLD_ALL) {

        if (handle != RTLD_ALL) {
                if ((obj = obj_from_addr(retaddr)) == NULL) {
                    _rtld_error("Cannot determine caller's shared object");
                    lock_release(rtld_bind_lock, &lockstate);
                    return NULL;
                }
        } else {
                obj = obj_list;
        }
        if (handle == NULL) {   /* Just the caller's shared object. */
            res = symlook_obj(&req, obj);
            if (res == 0) {
                def = req.sym_out;
                defobj = req.defobj_out;
            }
        } else if (handle == RTLD_NEXT || /* Objects after caller's */
                   handle == RTLD_SELF || /* ... caller included */
                   handle == RTLD_ALL) {  /* All Objects */
            if (handle == RTLD_NEXT)
                obj = obj->next;
            for (; obj != NULL; obj = obj->next) {
                res = symlook_obj(&req, obj);
                if (res == 0) {
                    if (def == NULL ||
                      ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
                        def = req.sym_out;
                        defobj = req.defobj_out;
                        if (ELF_ST_BIND(def->st_info) != STB_WEAK)
                            break;
                    }
                }
            }
            /*
             * Search the dynamic linker itself, and possibly resolve the
             * symbol from there.  This is how the application links to
             * dynamic linker services such as dlopen.
             */
            if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
                res = symlook_obj(&req, &obj_rtld);
                if (res == 0) {
                    def = req.sym_out;
                    defobj = req.defobj_out;
                }
            }
        } else {
            assert(handle == RTLD_DEFAULT);
            res = symlook_default(&req, obj);
            if (res == 0) {
                defobj = req.defobj_out;
                def = req.sym_out;
            }
        }
    } else {
        if ((obj = dlcheck(handle)) == NULL) {
            lock_release(rtld_bind_lock, &lockstate);
            return NULL;
        }

        donelist_init(&donelist);
        if (obj->mainprog) {
            /* Handle obtained by dlopen(NULL, ...) implies global scope. */
            res = symlook_global(&req, &donelist);
            if (res == 0) {
                def = req.sym_out;
                defobj = req.defobj_out;
            }
            /*
             * Search the dynamic linker itself, and possibly resolve the
             * symbol from there.  This is how the application links to
             * dynamic linker services such as dlopen.
             */
            if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
                res = symlook_obj(&req, &obj_rtld);
                if (res == 0) {
                    def = req.sym_out;
                    defobj = req.defobj_out;
                }
            }
        }
        else {
            /* Search the whole DAG rooted at the given object. */
            res = symlook_list(&req, &obj->dagmembers, &donelist);
            if (res == 0) {
                def = req.sym_out;
                defobj = req.defobj_out;
            }
        }
    }

    if (def != NULL) {
        lock_release(rtld_bind_lock, &lockstate);

        /*
         * The value required by the caller is derived from the value
         * of the symbol. this is simply the relocated value of the
         * symbol.
         */
        if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
            return (make_function_pointer(def, defobj));
        else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
            return (rtld_resolve_ifunc(defobj, def));
        else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
            ti.ti_module = defobj->tlsindex;
            ti.ti_offset = def->st_value;
            return (__tls_get_addr(&ti));
        } else
            return (defobj->relocbase + def->st_value);
    }

    _rtld_error("Undefined symbol \"%s\"", name);
    lock_release(rtld_bind_lock, &lockstate);
    return NULL;
}

void *
dlsym(void *handle, const char *name)
{
        return do_dlsym(handle, name, __builtin_return_address(0), NULL,
            SYMLOOK_DLSYM);
}

dlfunc_t
dlfunc(void *handle, const char *name)
{
        union {
                void *d;
                dlfunc_t f;
        } rv;

        rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
            SYMLOOK_DLSYM);
        return (rv.f);
}

void *
dlvsym(void *handle, const char *name, const char *version)
{
        Ver_Entry ventry;

        ventry.name = version;
        ventry.file = NULL;
        ventry.hash = elf_hash(version);
        ventry.flags= 0;
        return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
            SYMLOOK_DLSYM);
}

int
_rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
{
    const Obj_Entry *obj;
    RtldLockState lockstate;

    rlock_acquire(rtld_bind_lock, &lockstate);
    obj = obj_from_addr(addr);
    if (obj == NULL) {
        _rtld_error("No shared object contains address");
        lock_release(rtld_bind_lock, &lockstate);
        return (0);
    }
    rtld_fill_dl_phdr_info(obj, phdr_info);
    lock_release(rtld_bind_lock, &lockstate);
    return (1);
}

int
dladdr(const void *addr, Dl_info *info)
{
    const Obj_Entry *obj;
    const Elf_Sym *def;
    void *symbol_addr;
    unsigned long symoffset;
    RtldLockState lockstate;

    rlock_acquire(rtld_bind_lock, &lockstate);
    obj = obj_from_addr(addr);
    if (obj == NULL) {
        _rtld_error("No shared object contains address");
        lock_release(rtld_bind_lock, &lockstate);
        return 0;
    }
    info->dli_fname = obj->path;
    info->dli_fbase = obj->mapbase;
    info->dli_saddr = NULL;
    info->dli_sname = NULL;

    /*
     * Walk the symbol list looking for the symbol whose address is
     * closest to the address sent in.
     */
    for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
        def = obj->symtab + symoffset;

        /*
         * For skip the symbol if st_shndx is either SHN_UNDEF or
         * SHN_COMMON.
         */
        if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
            continue;

        /*
         * If the symbol is greater than the specified address, or if it
         * is further away from addr than the current nearest symbol,
         * then reject it.
         */
        symbol_addr = obj->relocbase + def->st_value;
        if (symbol_addr > addr || symbol_addr < info->dli_saddr)
            continue;

        /* Update our idea of the nearest symbol. */
        info->dli_sname = obj->strtab + def->st_name;
        info->dli_saddr = symbol_addr;

        /* Exact match? */
        if (info->dli_saddr == addr)
            break;
    }
    lock_release(rtld_bind_lock, &lockstate);
    return 1;
}

int
dlinfo(void *handle, int request, void *p)
{
    const Obj_Entry *obj;
    RtldLockState lockstate;
    int error;

    rlock_acquire(rtld_bind_lock, &lockstate);

    if (handle == NULL || handle == RTLD_SELF) {
        void *retaddr;

        retaddr = __builtin_return_address(0);  /* __GNUC__ only */
        if ((obj = obj_from_addr(retaddr)) == NULL)
            _rtld_error("Cannot determine caller's shared object");
    } else
        obj = dlcheck(handle);

    if (obj == NULL) {
        lock_release(rtld_bind_lock, &lockstate);
        return (-1);
    }

    error = 0;
    switch (request) {
    case RTLD_DI_LINKMAP:
        *((struct link_map const **)p) = &obj->linkmap;
        break;
    case RTLD_DI_ORIGIN:
        error = rtld_dirname(obj->path, p);
        break;

    case RTLD_DI_SERINFOSIZE:
    case RTLD_DI_SERINFO:
        error = do_search_info(obj, request, (struct dl_serinfo *)p);
        break;

    default:
        _rtld_error("Invalid request %d passed to dlinfo()", request);
        error = -1;
    }

    lock_release(rtld_bind_lock, &lockstate);

    return (error);
}

static void
rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
{

        phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
        phdr_info->dlpi_name = obj->path;
        phdr_info->dlpi_phdr = obj->phdr;
        phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
        phdr_info->dlpi_tls_modid = obj->tlsindex;
        phdr_info->dlpi_tls_data = obj->tlsinit;
        phdr_info->dlpi_adds = obj_loads;
        phdr_info->dlpi_subs = obj_loads - obj_count;
}

int
dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
{
    struct dl_phdr_info phdr_info;
    const Obj_Entry *obj;
    RtldLockState bind_lockstate, phdr_lockstate;
    int error;

    wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
    rlock_acquire(rtld_bind_lock, &bind_lockstate);

    error = 0;

    for (obj = obj_list;  obj != NULL;  obj = obj->next) {
        rtld_fill_dl_phdr_info(obj, &phdr_info);
        if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
                break;

    }
    if (error == 0) {
        rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info);
        error = callback(&phdr_info, sizeof(phdr_info), param);
    }

    lock_release(rtld_bind_lock, &bind_lockstate);
    lock_release(rtld_phdr_lock, &phdr_lockstate);

    return (error);
}

static void *
fill_search_info(const char *dir, size_t dirlen, void *param)
{
    struct fill_search_info_args *arg;

    arg = param;

    if (arg->request == RTLD_DI_SERINFOSIZE) {
        arg->serinfo->dls_cnt ++;
        arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
    } else {
        struct dl_serpath *s_entry;

        s_entry = arg->serpath;
        s_entry->dls_name  = arg->strspace;
        s_entry->dls_flags = arg->flags;

        strncpy(arg->strspace, dir, dirlen);
        arg->strspace[dirlen] = '\0';

        arg->strspace += dirlen + 1;
        arg->serpath++;
    }

    return (NULL);
}

static int
do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
{
    struct dl_serinfo _info;
    struct fill_search_info_args args;

    args.request = RTLD_DI_SERINFOSIZE;
    args.serinfo = &_info;

    _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
    _info.dls_cnt  = 0;

    path_enumerate(obj->rpath, fill_search_info, &args);
    path_enumerate(ld_library_path, fill_search_info, &args);
    path_enumerate(obj->runpath, fill_search_info, &args);
    path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args);
    if (!obj->z_nodeflib)
      path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);


    if (request == RTLD_DI_SERINFOSIZE) {
        info->dls_size = _info.dls_size;
        info->dls_cnt = _info.dls_cnt;
        return (0);
    }

    if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
        _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
        return (-1);
    }

    args.request  = RTLD_DI_SERINFO;
    args.serinfo  = info;
    args.serpath  = &info->dls_serpath[0];
    args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];

    args.flags = LA_SER_RUNPATH;
    if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
        return (-1);

    args.flags = LA_SER_LIBPATH;
    if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
        return (-1);

    args.flags = LA_SER_RUNPATH;
    if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
        return (-1);

    args.flags = LA_SER_CONFIG;
    if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args)
      != NULL)
        return (-1);

    args.flags = LA_SER_DEFAULT;
    if (!obj->z_nodeflib &&
      path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
        return (-1);
    return (0);
}

static int
rtld_dirname(const char *path, char *bname)
{
    const char *endp;

    /* Empty or NULL string gets treated as "." */
    if (path == NULL || *path == '\0') {
        bname[0] = '.';
        bname[1] = '\0';
        return (0);
    }

    /* Strip trailing slashes */
    endp = path + strlen(path) - 1;
    while (endp > path && *endp == '/')
        endp--;

    /* Find the start of the dir */
    while (endp > path && *endp != '/')
        endp--;

    /* Either the dir is "/" or there are no slashes */
    if (endp == path) {
        bname[0] = *endp == '/' ? '/' : '.';
        bname[1] = '\0';
        return (0);
    } else {
        do {
            endp--;
        } while (endp > path && *endp == '/');
    }

    if (endp - path + 2 > PATH_MAX)
    {
        _rtld_error("Filename is too long: %s", path);
        return(-1);
    }

    strncpy(bname, path, endp - path + 1);
    bname[endp - path + 1] = '\0';
    return (0);
}

static int
rtld_dirname_abs(const char *path, char *base)
{
        char base_rel[PATH_MAX];

        if (rtld_dirname(path, base) == -1)
                return (-1);
        if (base[0] == '/')
                return (0);
        if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
            strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
            strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
                return (-1);
        strcpy(base, base_rel);
        return (0);
}

static void
linkmap_add(Obj_Entry *obj)
{
    struct link_map *l = &obj->linkmap;
    struct link_map *prev;

    obj->linkmap.l_name = obj->path;
    obj->linkmap.l_addr = obj->mapbase;
    obj->linkmap.l_ld = obj->dynamic;

    if (r_debug.r_map == NULL) {
        r_debug.r_map = l;
        return;
    }

    /*
     * Scan to the end of the list, but not past the entry for the
     * dynamic linker, which we want to keep at the very end.
     */
    for (prev = r_debug.r_map;
      prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
      prev = prev->l_next)
        ;

    /* Link in the new entry. */
    l->l_prev = prev;
    l->l_next = prev->l_next;
    if (l->l_next != NULL)
        l->l_next->l_prev = l;
    prev->l_next = l;
}

static void
linkmap_delete(Obj_Entry *obj)
{
    struct link_map *l = &obj->linkmap;

    if (l->l_prev == NULL) {
        if ((r_debug.r_map = l->l_next) != NULL)
            l->l_next->l_prev = NULL;
        return;
    }

    if ((l->l_prev->l_next = l->l_next) != NULL)
        l->l_next->l_prev = l->l_prev;
}

/*
 * Function for the debugger to set a breakpoint on to gain control.
 *
 * The two parameters allow the debugger to easily find and determine
 * what the runtime loader is doing and to whom it is doing it.
 *
 * When the loadhook trap is hit (r_debug_state, set at program
 * initialization), the arguments can be found on the stack:
 *
 *  +8   struct link_map *m
 *  +4   struct r_debug  *rd
 *  +0   RetAddr
 */
void
r_debug_state(struct r_debug* rd, struct link_map *m)
{
    /*
     * The following is a hack to force the compiler to emit calls to
     * this function, even when optimizing.  If the function is empty,
     * the compiler is not obliged to emit any code for calls to it,
     * even when marked __noinline.  However, gdb depends on those
     * calls being made.
     */
    __asm __volatile("" : : : "memory");
}

/*
 * A function called after init routines have completed. This can be used to
 * break before a program's entry routine is called, and can be used when
 * main is not available in the symbol table.
 */
void
_r_debug_postinit(struct link_map *m)
{

        /* See r_debug_state(). */
        __asm __volatile("" : : : "memory");
}

/*
 * Get address of the pointer variable in the main program.
 * Prefer non-weak symbol over the weak one.
 */
static const void **
get_program_var_addr(const char *name, RtldLockState *lockstate)
{
    SymLook req;
    DoneList donelist;

    symlook_init(&req, name);
    req.lockstate = lockstate;
    donelist_init(&donelist);
    if (symlook_global(&req, &donelist) != 0)
        return (NULL);
    if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
        return ((const void **)make_function_pointer(req.sym_out,
          req.defobj_out));
    else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
        return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
    else
        return ((const void **)(req.defobj_out->relocbase +
          req.sym_out->st_value));
}

/*
 * Set a pointer variable in the main program to the given value.  This
 * is used to set key variables such as "environ" before any of the
 * init functions are called.
 */
static void
set_program_var(const char *name, const void *value)
{
    const void **addr;

    if ((addr = get_program_var_addr(name, NULL)) != NULL) {
        dbg("\"%s\": *%p <-- %p", name, addr, value);
        *addr = value;
    }
}

/*
 * Search the global objects, including dependencies and main object,
 * for the given symbol.
 */
static int
symlook_global(SymLook *req, DoneList *donelist)
{
    SymLook req1;
    const Objlist_Entry *elm;
    int res;

    symlook_init_from_req(&req1, req);

    /* Search all objects loaded at program start up. */
    if (req->defobj_out == NULL ||
      ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
        res = symlook_list(&req1, &list_main, donelist);
        if (res == 0 && (req->defobj_out == NULL ||
          ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
            req->sym_out = req1.sym_out;
            req->defobj_out = req1.defobj_out;
            assert(req->defobj_out != NULL);
        }
    }

    /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
    STAILQ_FOREACH(elm, &list_global, link) {
        if (req->defobj_out != NULL &&
          ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
            break;
        res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
        if (res == 0 && (req->defobj_out == NULL ||
          ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
            req->sym_out = req1.sym_out;
            req->defobj_out = req1.defobj_out;
            assert(req->defobj_out != NULL);
        }
    }

    return (req->sym_out != NULL ? 0 : ESRCH);
}

/*
 * This is a special version of getenv which is far more efficient
 * at finding LD_ environment vars.
 */
static
const char *
_getenv_ld(const char *id)
{
    const char *envp;
    int i, j;
    int idlen = strlen(id);

    if (ld_index == LD_ARY_CACHE)
        return(getenv(id));
    if (ld_index == 0) {
        for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
            if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
                ld_ary[j++] = envp;
        }
        if (j == 0)
                ld_ary[j++] = "";
        ld_index = j;
    }
    for (i = ld_index - 1; i >= 0; --i) {
        if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
            return(ld_ary[i] + idlen + 1);
    }
    return(NULL);
}

/*
 * Given a symbol name in a referencing object, find the corresponding
 * definition of the symbol.  Returns a pointer to the symbol, or NULL if
 * no definition was found.  Returns a pointer to the Obj_Entry of the
 * defining object via the reference parameter DEFOBJ_OUT.
 */
static int
symlook_default(SymLook *req, const Obj_Entry *refobj)
{
    DoneList donelist;
    const Objlist_Entry *elm;
    SymLook req1;
    int res;

    donelist_init(&donelist);
    symlook_init_from_req(&req1, req);

    /* Look first in the referencing object if linked symbolically. */
    if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
        res = symlook_obj(&req1, refobj);
        if (res == 0) {
            req->sym_out = req1.sym_out;
            req->defobj_out = req1.defobj_out;
            assert(req->defobj_out != NULL);
        }
    }

    symlook_global(req, &donelist);

    /* Search all dlopened DAGs containing the referencing object. */
    STAILQ_FOREACH(elm, &refobj->dldags, link) {
        if (req->sym_out != NULL &&
          ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
            break;
        res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
        if (res == 0 && (req->sym_out == NULL ||
          ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
            req->sym_out = req1.sym_out;
            req->defobj_out = req1.defobj_out;
            assert(req->defobj_out != NULL);
        }
    }

    /*
     * Search the dynamic linker itself, and possibly resolve the
     * symbol from there.  This is how the application links to
     * dynamic linker services such as dlopen.
     */
    if (req->sym_out == NULL ||
      ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
        res = symlook_obj(&req1, &obj_rtld);
        if (res == 0) {
            req->sym_out = req1.sym_out;
            req->defobj_out = req1.defobj_out;
            assert(req->defobj_out != NULL);
        }
    }

    return (req->sym_out != NULL ? 0 : ESRCH);
}

static int
symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
{
    const Elf_Sym *def;
    const Obj_Entry *defobj;
    const Objlist_Entry *elm;
    SymLook req1;
    int res;

    def = NULL;
    defobj = NULL;
    STAILQ_FOREACH(elm, objlist, link) {
        if (donelist_check(dlp, elm->obj))
            continue;
        symlook_init_from_req(&req1, req);
        if ((res = symlook_obj(&req1, elm->obj)) == 0) {
            if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
                def = req1.sym_out;
                defobj = req1.defobj_out;
                if (ELF_ST_BIND(def->st_info) != STB_WEAK)
                    break;
            }
        }
    }
    if (def != NULL) {
        req->sym_out = def;
        req->defobj_out = defobj;
        return (0);
    }
    return (ESRCH);
}

/*
 * Search the chain of DAGS cointed to by the given Needed_Entry
 * for a symbol of the given name.  Each DAG is scanned completely
 * before advancing to the next one.  Returns a pointer to the symbol,
 * or NULL if no definition was found.
 */
static int
symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
{
    const Elf_Sym *def;
    const Needed_Entry *n;
    const Obj_Entry *defobj;
    SymLook req1;
    int res;

    def = NULL;
    defobj = NULL;
    symlook_init_from_req(&req1, req);
    for (n = needed; n != NULL; n = n->next) {
        if (n->obj == NULL ||
            (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
            continue;
        if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
            def = req1.sym_out;
            defobj = req1.defobj_out;
            if (ELF_ST_BIND(def->st_info) != STB_WEAK)
                break;
        }
    }
    if (def != NULL) {
        req->sym_out = def;
        req->defobj_out = defobj;
        return (0);
    }
    return (ESRCH);
}

/*
 * Search the symbol table of a single shared object for a symbol of
 * the given name and version, if requested.  Returns a pointer to the
 * symbol, or NULL if no definition was found.  If the object is
 * filter, return filtered symbol from filtee.
 *
 * The symbol's hash value is passed in for efficiency reasons; that
 * eliminates many recomputations of the hash value.
 */
int
symlook_obj(SymLook *req, const Obj_Entry *obj)
{
    DoneList donelist;
    SymLook req1;
    int flags, res, mres;

    /*
     * If there is at least one valid hash at this point, we prefer to
     * use the faster GNU version if available.
     */
    if (obj->valid_hash_gnu)
        mres = symlook_obj1_gnu(req, obj);
    else if (obj->valid_hash_sysv)
        mres = symlook_obj1_sysv(req, obj);
    else
        return (EINVAL);

    if (mres == 0) {
        if (obj->needed_filtees != NULL) {
            flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
            load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
            donelist_init(&donelist);
            symlook_init_from_req(&req1, req);
            res = symlook_needed(&req1, obj->needed_filtees, &donelist);
            if (res == 0) {
                req->sym_out = req1.sym_out;
                req->defobj_out = req1.defobj_out;
            }
            return (res);
        }
        if (obj->needed_aux_filtees != NULL) {
            flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
            load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
            donelist_init(&donelist);
            symlook_init_from_req(&req1, req);
            res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
            if (res == 0) {
                req->sym_out = req1.sym_out;
                req->defobj_out = req1.defobj_out;
                return (res);
            }
        }
    }
    return (mres);
}

/* Symbol match routine common to both hash functions */
static bool
matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
    const unsigned long symnum)
{
        Elf_Versym verndx;
        const Elf_Sym *symp;
        const char *strp;

        symp = obj->symtab + symnum;
        strp = obj->strtab + symp->st_name;

        switch (ELF_ST_TYPE(symp->st_info)) {
        case STT_FUNC:
        case STT_NOTYPE:
        case STT_OBJECT:
        case STT_COMMON:
        case STT_GNU_IFUNC:
                if (symp->st_value == 0)
                        return (false);
                /* fallthrough */
        case STT_TLS:
                if (symp->st_shndx != SHN_UNDEF)
                        break;
                else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
                    (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
                        break;
                /* fallthrough */
        default:
                return (false);
        }
        if (strcmp(req->name, strp) != 0)
                return (false);

        if (req->ventry == NULL) {
                if (obj->versyms != NULL) {
                        verndx = VER_NDX(obj->versyms[symnum]);
                        if (verndx > obj->vernum) {
                                _rtld_error(
                                    "%s: symbol %s references wrong version %d",
                                    obj->path, obj->strtab + symnum, verndx);
                                return (false);
                        }
                        /*
                         * If we are not called from dlsym (i.e. this
                         * is a normal relocation from unversioned
                         * binary), accept the symbol immediately if
                         * it happens to have first version after this
                         * shared object became versioned.  Otherwise,
                         * if symbol is versioned and not hidden,
                         * remember it. If it is the only symbol with
                         * this name exported by the shared object, it
                         * will be returned as a match by the calling
                         * function. If symbol is global (verndx < 2)
                         * accept it unconditionally.
                         */
                        if ((req->flags & SYMLOOK_DLSYM) == 0 &&
                            verndx == VER_NDX_GIVEN) {
                                result->sym_out = symp;
                                return (true);
                        }
                        else if (verndx >= VER_NDX_GIVEN) {
                                if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
                                    == 0) {
                                        if (result->vsymp == NULL)
                                                result->vsymp = symp;
                                        result->vcount++;
                                }
                                return (false);
                        }
                }
                result->sym_out = symp;
                return (true);
        }
        if (obj->versyms == NULL) {
                if (object_match_name(obj, req->ventry->name)) {
                        _rtld_error("%s: object %s should provide version %s "
                            "for symbol %s", obj_rtld.path, obj->path,
                            req->ventry->name, obj->strtab + symnum);
                        return (false);
                }
        } else {
                verndx = VER_NDX(obj->versyms[symnum]);
                if (verndx > obj->vernum) {
                        _rtld_error("%s: symbol %s references wrong version %d",
                            obj->path, obj->strtab + symnum, verndx);
                        return (false);
                }
                if (obj->vertab[verndx].hash != req->ventry->hash ||
                    strcmp(obj->vertab[verndx].name, req->ventry->name)) {
                        /*
                         * Version does not match. Look if this is a
                         * global symbol and if it is not hidden. If
                         * global symbol (verndx < 2) is available,
                         * use it. Do not return symbol if we are
                         * called by dlvsym, because dlvsym looks for
                         * a specific version and default one is not
                         * what dlvsym wants.
                         */
                        if ((req->flags & SYMLOOK_DLSYM) ||
                            (verndx >= VER_NDX_GIVEN) ||
                            (obj->versyms[symnum] & VER_NDX_HIDDEN))
                                return (false);
                }
        }
        result->sym_out = symp;
        return (true);
}

/*
 * Search for symbol using SysV hash function.
 * obj->buckets is known not to be NULL at this point; the test for this was
 * performed with the obj->valid_hash_sysv assignment.
 */
static int
symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj)
{
        unsigned long symnum;
        Sym_Match_Result matchres;

        matchres.sym_out = NULL;
        matchres.vsymp = NULL;
        matchres.vcount = 0;

        for (symnum = obj->buckets[req->hash % obj->nbuckets];
            symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
                if (symnum >= obj->nchains)
                        return (ESRCH); /* Bad object */

                if (matched_symbol(req, obj, &matchres, symnum)) {
                        req->sym_out = matchres.sym_out;
                        req->defobj_out = obj;
                        return (0);
                }
        }
        if (matchres.vcount == 1) {
                req->sym_out = matchres.vsymp;
                req->defobj_out = obj;
                return (0);
        }
        return (ESRCH);
}

/* Search for symbol using GNU hash function */
static int
symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj)
{
        Elf_Addr bloom_word;
        const Elf32_Word *hashval;
        Elf32_Word bucket;
        Sym_Match_Result matchres;
        unsigned int h1, h2;
        unsigned long symnum;

        matchres.sym_out = NULL;
        matchres.vsymp = NULL;
        matchres.vcount = 0;

        /* Pick right bitmask word from Bloom filter array */
        bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) &
            obj->maskwords_bm_gnu];

        /* Calculate modulus word size of gnu hash and its derivative */
        h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1);
        h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1));

        /* Filter out the "definitely not in set" queries */
        if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
                return (ESRCH);

        /* Locate hash chain and corresponding value element*/
        bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
        if (bucket == 0)
                return (ESRCH);
        hashval = &obj->chain_zero_gnu[bucket];
        do {
                if (((*hashval ^ req->hash_gnu) >> 1) == 0) {
                        symnum = hashval - obj->chain_zero_gnu;
                        if (matched_symbol(req, obj, &matchres, symnum)) {
                                req->sym_out = matchres.sym_out;
                                req->defobj_out = obj;
                                return (0);
                        }
                }
        } while ((*hashval++ & 1) == 0);
        if (matchres.vcount == 1) {
                req->sym_out = matchres.vsymp;
                req->defobj_out = obj;
                return (0);
        }
        return (ESRCH);
}

static void
trace_loaded_objects(Obj_Entry *obj)
{
    const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
    int         c;

    if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
        main_local = "";

    if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
        fmt1 = "\t%o => %p (%x)\n";

    if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
        fmt2 = "\t%o (%x)\n";

    list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");

    for (; obj; obj = obj->next) {
        Needed_Entry            *needed;
        char                    *name, *path;
        bool                    is_lib;

        if (list_containers && obj->needed != NULL)
            rtld_printf("%s:\n", obj->path);
        for (needed = obj->needed; needed; needed = needed->next) {
            if (needed->obj != NULL) {
                if (needed->obj->traced && !list_containers)
                    continue;
                needed->obj->traced = true;
                path = needed->obj->path;
            } else
                path = "not found";

            name = (char *)obj->strtab + needed->name;
            is_lib = strncmp(name, "lib", 3) == 0;      /* XXX - bogus */

            fmt = is_lib ? fmt1 : fmt2;
            while ((c = *fmt++) != '\0') {
                switch (c) {
                default:
                    rtld_putchar(c);
                    continue;
                case '\\':
                    switch (c = *fmt) {
                    case '\0':
                        continue;
                    case 'n':
                        rtld_putchar('\n');
                        break;
                    case 't':
                        rtld_putchar('\t');
                        break;
                    }
                    break;
                case '%':
                    switch (c = *fmt) {
                    case '\0':
                        continue;
                    case '%':
                    default:
                        rtld_putchar(c);
                        break;
                    case 'A':
                        rtld_putstr(main_local);
                        break;
                    case 'a':
                        rtld_putstr(obj_main->path);
                        break;
                    case 'o':
                        rtld_putstr(name);
                        break;
                    case 'p':
                        rtld_putstr(path);
                        break;
                    case 'x':
                        rtld_printf("%p", needed->obj ? needed->obj->mapbase :
                          0);
                        break;
                    }
                    break;
                }
                ++fmt;
            }
        }
    }
}

/*
 * Unload a dlopened object and its dependencies from memory and from
 * our data structures.  It is assumed that the DAG rooted in the
 * object has already been unreferenced, and that the object has a
 * reference count of 0.
 */
static void
unload_object(Obj_Entry *root)
{
    Obj_Entry *obj;
    Obj_Entry **linkp;

    assert(root->refcount == 0);

    /*
     * Pass over the DAG removing unreferenced objects from
     * appropriate lists.
     */
    unlink_object(root);

    /* Unmap all objects that are no longer referenced. */
    linkp = &obj_list->next;
    while ((obj = *linkp) != NULL) {
        if (obj->refcount == 0) {
            LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
                obj->path);
            dbg("unloading \"%s\"", obj->path);
            unload_filtees(root);
            munmap(obj->mapbase, obj->mapsize);
            linkmap_delete(obj);
            *linkp = obj->next;
            obj_count--;
            obj_free(obj);
        } else
            linkp = &obj->next;
    }
    obj_tail = linkp;
}

static void
unlink_object(Obj_Entry *root)
{
    Objlist_Entry *elm;

    if (root->refcount == 0) {
        /* Remove the object from the RTLD_GLOBAL list. */
        objlist_remove(&list_global, root);

        /* Remove the object from all objects' DAG lists. */
        STAILQ_FOREACH(elm, &root->dagmembers, link) {
            objlist_remove(&elm->obj->dldags, root);
            if (elm->obj != root)
                unlink_object(elm->obj);
        }
    }
}

static void
ref_dag(Obj_Entry *root)
{
    Objlist_Entry *elm;

    assert(root->dag_inited);
    STAILQ_FOREACH(elm, &root->dagmembers, link)
        elm->obj->refcount++;
}

static void
unref_dag(Obj_Entry *root)
{
    Objlist_Entry *elm;

    assert(root->dag_inited);
    STAILQ_FOREACH(elm, &root->dagmembers, link)
        elm->obj->refcount--;
}

/*
 * Common code for MD __tls_get_addr().
 */
void *
tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
{
    Elf_Addr* dtv = *dtvp;
    RtldLockState lockstate;

    /* Check dtv generation in case new modules have arrived */
    if (dtv[0] != tls_dtv_generation) {
        Elf_Addr* newdtv;
        int to_copy;

        wlock_acquire(rtld_bind_lock, &lockstate);
        newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
        to_copy = dtv[1];
        if (to_copy > tls_max_index)
            to_copy = tls_max_index;
        memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
        newdtv[0] = tls_dtv_generation;
        newdtv[1] = tls_max_index;
        free(dtv);
        lock_release(rtld_bind_lock, &lockstate);
        dtv = *dtvp = newdtv;
    }

    /* Dynamically allocate module TLS if necessary */
    if (!dtv[index + 1]) {
        /* Signal safe, wlock will block out signals. */
        wlock_acquire(rtld_bind_lock, &lockstate);
        if (!dtv[index + 1])
            dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
        lock_release(rtld_bind_lock, &lockstate);
    }
    return ((void *)(dtv[index + 1] + offset));
}

#if defined(RTLD_STATIC_TLS_VARIANT_II)

/*
 * Allocate the static TLS area.  Return a pointer to the TCB.  The 
 * static area is based on negative offsets relative to the tcb.
 *
 * The TCB contains an errno pointer for the system call layer, but because
 * we are the RTLD we really have no idea how the caller was compiled so
 * the information has to be passed in.  errno can either be:
 *
 *      type 0  errno is a simple non-TLS global pointer.
 *              (special case for e.g. libc_rtld)
 *      type 1  errno accessed by GOT entry     (dynamically linked programs)
 *      type 2  errno accessed by %gs:OFFSET    (statically linked programs)
 */
struct tls_tcb *
allocate_tls(Obj_Entry *objs)
{
    Obj_Entry *obj;
    size_t data_size;
    size_t dtv_size;
    struct tls_tcb *tcb;
    Elf_Addr *dtv;
    Elf_Addr addr;

    /*
     * Allocate the new TCB.  static TLS storage is placed just before the
     * TCB to support the %gs:OFFSET (negative offset) model.
     */
    data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
                ~RTLD_STATIC_TLS_ALIGN_MASK;
    tcb = malloc(data_size + sizeof(*tcb));
    tcb = (void *)((char *)tcb + data_size);    /* actual tcb location */

    dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
    dtv = malloc(dtv_size);
    bzero(dtv, dtv_size);

#ifdef RTLD_TCB_HAS_SELF_POINTER
    tcb->tcb_self = tcb;
#endif
    tcb->tcb_dtv = dtv;
    tcb->tcb_pthread = NULL;

    dtv[0] = tls_dtv_generation;
    dtv[1] = tls_max_index;

    for (obj = objs; obj; obj = obj->next) {
        if (obj->tlsoffset) {
            addr = (Elf_Addr)tcb - obj->tlsoffset;
            memset((void *)(addr + obj->tlsinitsize),
                   0, obj->tlssize - obj->tlsinitsize);
            if (obj->tlsinit) {
                memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
                obj->static_tls_copied = true;
            }
            dtv[obj->tlsindex + 1] = addr;
        }
    }
    return(tcb);
}

void
free_tls(struct tls_tcb *tcb)
{
    Elf_Addr *dtv;
    int dtv_size, i;
    Elf_Addr tls_start, tls_end;
    size_t data_size;

    data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
                ~RTLD_STATIC_TLS_ALIGN_MASK;

    dtv = tcb->tcb_dtv;
    dtv_size = dtv[1];
    tls_end = (Elf_Addr)tcb;
    tls_start = (Elf_Addr)tcb - data_size;
    for (i = 0; i < dtv_size; i++) {
        if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
            free((void *)dtv[i+2]);
        }
    }
    free(dtv);

    free((void*) tls_start);
}

#else
#error "Unsupported TLS layout"
#endif

/*
 * Allocate TLS block for module with given index.
 */
void *
allocate_module_tls(int index)
{
    Obj_Entry* obj;
    char* p;

    for (obj = obj_list; obj; obj = obj->next) {
        if (obj->tlsindex == index)
            break;
    }
    if (!obj) {
        _rtld_error("Can't find module with TLS index %d", index);
        die();
    }

    p = malloc(obj->tlssize);
    if (p == NULL) {
        _rtld_error("Cannot allocate TLS block for index %d", index);
        die();
    }
    memcpy(p, obj->tlsinit, obj->tlsinitsize);
    memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);

    return p;
}

bool
allocate_tls_offset(Obj_Entry *obj)
{
    size_t off;

    if (obj->tls_done)
        return true;

    if (obj->tlssize == 0) {
        obj->tls_done = true;
        return true;
    }

    if (obj->tlsindex == 1)
        off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
    else
        off = calculate_tls_offset(tls_last_offset, tls_last_size,
                                   obj->tlssize, obj->tlsalign);

    /*
     * If we have already fixed the size of the static TLS block, we
     * must stay within that size. When allocating the static TLS, we
     * leave a small amount of space spare to be used for dynamically
     * loading modules which use static TLS.
     */
    if (tls_static_space) {
        if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
            return false;
    }

    tls_last_offset = obj->tlsoffset = off;
    tls_last_size = obj->tlssize;
    obj->tls_done = true;

    return true;
}

void
free_tls_offset(Obj_Entry *obj)
{
#ifdef RTLD_STATIC_TLS_VARIANT_II
    /*
     * If we were the last thing to allocate out of the static TLS
     * block, we give our space back to the 'allocator'. This is a
     * simplistic workaround to allow libGL.so.1 to be loaded and
     * unloaded multiple times. We only handle the Variant II
     * mechanism for now - this really needs a proper allocator.  
     */
    if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
        == calculate_tls_end(tls_last_offset, tls_last_size)) {
        tls_last_offset -= obj->tlssize;
        tls_last_size = 0;
    }
#endif
}

struct tls_tcb *
_rtld_allocate_tls(void)
{
    struct tls_tcb *new_tcb;
    RtldLockState lockstate;

    wlock_acquire(rtld_bind_lock, &lockstate);
    new_tcb = allocate_tls(obj_list);
    lock_release(rtld_bind_lock, &lockstate);

    return (new_tcb);
}

void
_rtld_free_tls(struct tls_tcb *tcb)
{
    RtldLockState lockstate;

    wlock_acquire(rtld_bind_lock, &lockstate);
    free_tls(tcb);
    lock_release(rtld_bind_lock, &lockstate);
}

static void
object_add_name(Obj_Entry *obj, const char *name)
{
    Name_Entry *entry;
    size_t len;

    len = strlen(name);
    entry = malloc(sizeof(Name_Entry) + len);

    if (entry != NULL) {
        strcpy(entry->name, name);
        STAILQ_INSERT_TAIL(&obj->names, entry, link);
    }
}

static int
object_match_name(const Obj_Entry *obj, const char *name)
{
    Name_Entry *entry;

    STAILQ_FOREACH(entry, &obj->names, link) {
        if (strcmp(name, entry->name) == 0)
            return (1);
    }
    return (0);
}

static Obj_Entry *
locate_dependency(const Obj_Entry *obj, const char *name)
{
    const Objlist_Entry *entry;
    const Needed_Entry *needed;

    STAILQ_FOREACH(entry, &list_main, link) {
        if (object_match_name(entry->obj, name))
            return entry->obj;
    }

    for (needed = obj->needed;  needed != NULL;  needed = needed->next) {
        if (strcmp(obj->strtab + needed->name, name) == 0 ||
          (needed->obj != NULL && object_match_name(needed->obj, name))) {
            /*
             * If there is DT_NEEDED for the name we are looking for,
             * we are all set.  Note that object might not be found if
             * dependency was not loaded yet, so the function can
             * return NULL here.  This is expected and handled
             * properly by the caller.
             */
            return (needed->obj);
        }
    }
    _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
        obj->path, name);
    die();
}

static int
check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
    const Elf_Vernaux *vna)
{
    const Elf_Verdef *vd;
    const char *vername;

    vername = refobj->strtab + vna->vna_name;
    vd = depobj->verdef;
    if (vd == NULL) {
        _rtld_error("%s: version %s required by %s not defined",
            depobj->path, vername, refobj->path);
        return (-1);
    }
    for (;;) {
        if (vd->vd_version != VER_DEF_CURRENT) {
            _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
                depobj->path, vd->vd_version);
            return (-1);
        }
        if (vna->vna_hash == vd->vd_hash) {
            const Elf_Verdaux *aux = (const Elf_Verdaux *)
                ((char *)vd + vd->vd_aux);
            if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
                return (0);
        }
        if (vd->vd_next == 0)
            break;
        vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
    }
    if (vna->vna_flags & VER_FLG_WEAK)
        return (0);
    _rtld_error("%s: version %s required by %s not found",
        depobj->path, vername, refobj->path);
    return (-1);
}

static int
rtld_verify_object_versions(Obj_Entry *obj)
{
    const Elf_Verneed *vn;
    const Elf_Verdef  *vd;
    const Elf_Verdaux *vda;
    const Elf_Vernaux *vna;
    const Obj_Entry *depobj;
    int maxvernum, vernum;

    if (obj->ver_checked)
        return (0);
    obj->ver_checked = true;

    maxvernum = 0;
    /*
     * Walk over defined and required version records and figure out
     * max index used by any of them. Do very basic sanity checking
     * while there.
     */
    vn = obj->verneed;
    while (vn != NULL) {
        if (vn->vn_version != VER_NEED_CURRENT) {
            _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
                obj->path, vn->vn_version);
            return (-1);
        }
        vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
        for (;;) {
            vernum = VER_NEED_IDX(vna->vna_other);
            if (vernum > maxvernum)
                maxvernum = vernum;
            if (vna->vna_next == 0)
                 break;
            vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
        }
        if (vn->vn_next == 0)
            break;
        vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
    }

    vd = obj->verdef;
    while (vd != NULL) {
        if (vd->vd_version != VER_DEF_CURRENT) {
            _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
                obj->path, vd->vd_version);
            return (-1);
        }
        vernum = VER_DEF_IDX(vd->vd_ndx);
        if (vernum > maxvernum)
                maxvernum = vernum;
        if (vd->vd_next == 0)
            break;
        vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
    }

    if (maxvernum == 0)
        return (0);

    /*
     * Store version information in array indexable by version index.
     * Verify that object version requirements are satisfied along the
     * way.
     */
    obj->vernum = maxvernum + 1;
    obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));

    vd = obj->verdef;
    while (vd != NULL) {
        if ((vd->vd_flags & VER_FLG_BASE) == 0) {
            vernum = VER_DEF_IDX(vd->vd_ndx);
            assert(vernum <= maxvernum);
            vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
            obj->vertab[vernum].hash = vd->vd_hash;
            obj->vertab[vernum].name = obj->strtab + vda->vda_name;
            obj->vertab[vernum].file = NULL;
            obj->vertab[vernum].flags = 0;
        }
        if (vd->vd_next == 0)
            break;
        vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
    }

    vn = obj->verneed;
    while (vn != NULL) {
        depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
        if (depobj == NULL)
            return (-1);
        vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
        for (;;) {
            if (check_object_provided_version(obj, depobj, vna))
                return (-1);
            vernum = VER_NEED_IDX(vna->vna_other);
            assert(vernum <= maxvernum);
            obj->vertab[vernum].hash = vna->vna_hash;
            obj->vertab[vernum].name = obj->strtab + vna->vna_name;
            obj->vertab[vernum].file = obj->strtab + vn->vn_file;
            obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
                VER_INFO_HIDDEN : 0;
            if (vna->vna_next == 0)
                 break;
            vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
        }
        if (vn->vn_next == 0)
            break;
        vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
    }
    return 0;
}

static int
rtld_verify_versions(const Objlist *objlist)
{
    Objlist_Entry *entry;
    int rc;

    rc = 0;
    STAILQ_FOREACH(entry, objlist, link) {
        /*
         * Skip dummy objects or objects that have their version requirements
         * already checked.
         */
        if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
            continue;
        if (rtld_verify_object_versions(entry->obj) == -1) {
            rc = -1;
            if (ld_tracing == NULL)
                break;
        }
    }
    if (rc == 0 || ld_tracing != NULL)
        rc = rtld_verify_object_versions(&obj_rtld);
    return rc;
}

const Ver_Entry *
fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
{
    Elf_Versym vernum;

    if (obj->vertab) {
        vernum = VER_NDX(obj->versyms[symnum]);
        if (vernum >= obj->vernum) {
            _rtld_error("%s: symbol %s has wrong verneed value %d",
                obj->path, obj->strtab + symnum, vernum);
        } else if (obj->vertab[vernum].hash != 0) {
            return &obj->vertab[vernum];
        }
    }
    return NULL;
}

int
_rtld_get_stack_prot(void)
{

        return (stack_prot);
}

static void
map_stacks_exec(RtldLockState *lockstate)
{
        return;
        /*
         * Stack protection must be implemented in the kernel before the dynamic
         * linker can handle PT_GNU_STACK sections.
         * The following is the FreeBSD implementation of map_stacks_exec()
         * void (*thr_map_stacks_exec)(void);
         *
         * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
         *     return;
         * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
         *     get_program_var_addr("__pthread_map_stacks_exec", lockstate);
         * if (thr_map_stacks_exec != NULL) {
         *     stack_prot |= PROT_EXEC;
         *     thr_map_stacks_exec();
         * }
         */
}

/*
 * Only called after all primary shared libraries are loaded (EARLY is
 * not set).  Resolves the static TLS distribution function at first-call.
 * This is typically a weak libc symbol that is overrideen by the threading
 * library.
 */
static void
distribute_static_tls(Objlist *list, RtldLockState *lockstate)
{
        Objlist_Entry *elm;
        Obj_Entry *obj;
        static void (*dtlsfunc)(size_t, void *, size_t, size_t);

        /*
         * First time, resolve "_pthread_distribute_static_tls".
         */
        if (dtlsfunc == NULL) {
                dtlsfunc = (void *)dlfunc(RTLD_ALL,
                                          "_pthread_distribute_static_tls");
                if (dtlsfunc == NULL)
                        return;
        }

        /*
         * Initialize static TLS data for the object list using the callback
         * function (to either libc or pthreads).
         */
        STAILQ_FOREACH(elm, list, link) {
                obj = elm->obj;
                if (/*obj->marker ||*/ !obj->tls_done || obj->static_tls_copied)
                        continue;
                dtlsfunc(obj->tlsoffset, obj->tlsinit,
                         obj->tlsinitsize, obj->tlssize);
                obj->static_tls_copied = true;
        }
}

void
symlook_init(SymLook *dst, const char *name)
{

        bzero(dst, sizeof(*dst));
        dst->name = name;
        dst->hash = elf_hash(name);
        dst->hash_gnu = gnu_hash(name);
}

static void
symlook_init_from_req(SymLook *dst, const SymLook *src)
{

        dst->name = src->name;
        dst->hash = src->hash;
        dst->hash_gnu = src->hash_gnu;
        dst->ventry = src->ventry;
        dst->flags = src->flags;
        dst->defobj_out = NULL;
        dst->sym_out = NULL;
        dst->lockstate = src->lockstate;
}


/*
 * Parse a file descriptor number without pulling in more of libc (e.g. atoi).
 */
static int
parse_libdir(const char *str)
{
        static const int RADIX = 10;  /* XXXJA: possibly support hex? */
        const char *orig;
        int fd;
        char c;

        orig = str;
        fd = 0;
        for (c = *str; c != '\0'; c = *++str) {
                if (c < '0' || c > '9')
                        return (-1);

                fd *= RADIX;
                fd += c - '0';
        }

        /* Make sure we actually parsed something. */
        if (str == orig) {
                _rtld_error("failed to parse directory FD from '%s'", str);
                return (-1);
        }
        return (fd);
}

#ifdef ENABLE_OSRELDATE
/*
 * Overrides for libc_pic-provided functions.
 */

int
__getosreldate(void)
{
        size_t len;
        int oid[2];
        int error, osrel;

        if (osreldate != 0)
                return (osreldate);

        oid[0] = CTL_KERN;
        oid[1] = KERN_OSRELDATE;
        osrel = 0;
        len = sizeof(osrel);
        error = sysctl(oid, 2, &osrel, &len, NULL, 0);
        if (error == 0 && osrel > 0 && len == sizeof(osrel))
                osreldate = osrel;
        return (osreldate);
}
#endif

/*
 * No unresolved symbols for rtld.
 */
void
__pthread_cxa_finalize(struct dl_phdr_info *a)
{
}

const char *
rtld_strerror(int errnum)
{

        if (errnum < 0 || errnum >= sys_nerr)
                return ("Unknown error");
        return (sys_errlist[errnum]);
}