Add kqueue based async I/O support to the virtual kernel. Convert VKE to
[dragonfly.git] / libexec / rtld-elf / rtld.c
CommitLineData
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1/*-
2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $
fb0c631e 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.24 2006/07/16 22:15:38 corecode Exp $
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28 */
29
30/*
31 * Dynamic linker for ELF.
32 *
33 * John Polstra <jdp@polstra.com>.
34 */
35
36#ifndef __GNUC__
37#error "GCC is needed to compile this file"
38#endif
39
40#include <sys/param.h>
41#include <sys/mman.h>
42#include <sys/stat.h>
8ca15ec8 43#include <sys/resident.h>
bc633d63 44#include <sys/tls.h>
984263bc 45
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46#include <machine/tls.h>
47
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48#include <dlfcn.h>
49#include <err.h>
50#include <errno.h>
51#include <fcntl.h>
52#include <stdarg.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <unistd.h>
57
58#include "debug.h"
59#include "rtld.h"
60
a1eee96a 61#define PATH_RTLD "/usr/libexec/ld-elf.so.2"
8ca15ec8 62#define LD_ARY_CACHE 16
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63
64/* Types. */
65typedef void (*func_ptr_type)();
66typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
67
68/*
69 * This structure provides a reentrant way to keep a list of objects and
70 * check which ones have already been processed in some way.
71 */
72typedef struct Struct_DoneList {
73 const Obj_Entry **objs; /* Array of object pointers */
74 unsigned int num_alloc; /* Allocated size of the array */
75 unsigned int num_used; /* Number of array slots used */
76} DoneList;
77
78/*
79 * Function declarations.
80 */
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81static void die(void);
82static void digest_dynamic(Obj_Entry *);
8ca15ec8 83static const char *_getenv_ld(const char *id);
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84static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
85static Obj_Entry *dlcheck(void *);
86static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
87static bool donelist_check(DoneList *, const Obj_Entry *);
88static void errmsg_restore(char *);
89static char *errmsg_save(void);
90static void *fill_search_info(const char *, size_t, void *);
91static char *find_library(const char *, const Obj_Entry *);
b6a22d96 92static Obj_Entry *find_object(const char *);
2d6b58a8 93static Obj_Entry *find_object2(const char *, int *, struct stat *);
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94static const char *gethints(void);
95static void init_dag(Obj_Entry *);
96static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *);
97static void init_rtld(caddr_t);
98static void initlist_add_neededs(Needed_Entry *needed, Objlist *list);
99static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail,
100 Objlist *list);
101static bool is_exported(const Elf_Sym *);
102static void linkmap_add(Obj_Entry *);
103static void linkmap_delete(Obj_Entry *);
104static int load_needed_objects(Obj_Entry *);
105static int load_preload_objects(void);
106static Obj_Entry *load_object(char *);
107static void lock_check(void);
108static Obj_Entry *obj_from_addr(const void *);
109static void objlist_call_fini(Objlist *);
110static void objlist_call_init(Objlist *);
111static void objlist_clear(Objlist *);
112static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
113static void objlist_init(Objlist *);
114static void objlist_push_head(Objlist *, Obj_Entry *);
115static void objlist_push_tail(Objlist *, Obj_Entry *);
116static void objlist_remove(Objlist *, Obj_Entry *);
117static void objlist_remove_unref(Objlist *);
118static void *path_enumerate(const char *, path_enum_proc, void *);
119static int relocate_objects(Obj_Entry *, bool);
120static int rtld_dirname(const char *, char *);
121static void rtld_exit(void);
122static char *search_library_path(const char *, const char *);
123static const void **get_program_var_addr(const char *name);
124static void set_program_var(const char *, const void *);
125static const Elf_Sym *symlook_default(const char *, unsigned long hash,
126 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
127static const Elf_Sym *symlook_list(const char *, unsigned long,
fb0c631e 128 const Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
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129static void trace_loaded_objects(Obj_Entry *obj);
130static void unlink_object(Obj_Entry *);
131static void unload_object(Obj_Entry *);
132static void unref_dag(Obj_Entry *);
133
134void r_debug_state(struct r_debug*, struct link_map*);
135
136/*
137 * Data declarations.
138 */
139static char *error_message; /* Message for dlerror(), or NULL */
140struct r_debug r_debug; /* for GDB; */
141static bool trust; /* False for setuid and setgid programs */
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142static const char *ld_bind_now; /* Environment variable for immediate binding */
143static const char *ld_debug; /* Environment variable for debugging */
144static const char *ld_library_path; /* Environment variable for search path */
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145static char *ld_preload; /* Environment variable for libraries to
146 load first */
8ca15ec8 147static const char *ld_tracing; /* Called from ldd(1) to print libs */
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148static Obj_Entry *obj_list; /* Head of linked list of shared objects */
149static Obj_Entry **obj_tail; /* Link field of last object in list */
8ca15ec8 150static Obj_Entry **preload_tail;
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151static Obj_Entry *obj_main; /* The main program shared object */
152static Obj_Entry obj_rtld; /* The dynamic linker shared object */
153static unsigned int obj_count; /* Number of objects in obj_list */
33a8b578 154static int ld_resident; /* Non-zero if resident */
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155static const char *ld_ary[LD_ARY_CACHE];
156static int ld_index;
a1eee96a 157static Objlist initlist;
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158
159static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
160 STAILQ_HEAD_INITIALIZER(list_global);
161static Objlist list_main = /* Objects loaded at program startup */
162 STAILQ_HEAD_INITIALIZER(list_main);
163static Objlist list_fini = /* Objects needing fini() calls */
164 STAILQ_HEAD_INITIALIZER(list_fini);
165
166static LockInfo lockinfo;
167
168static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
169
170#define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
171
172extern Elf_Dyn _DYNAMIC;
173#pragma weak _DYNAMIC
174
175/*
176 * These are the functions the dynamic linker exports to application
177 * programs. They are the only symbols the dynamic linker is willing
178 * to export from itself.
179 */
180static func_ptr_type exports[] = {
181 (func_ptr_type) &_rtld_error,
182 (func_ptr_type) &dlclose,
183 (func_ptr_type) &dlerror,
184 (func_ptr_type) &dlopen,
185 (func_ptr_type) &dlsym,
186 (func_ptr_type) &dladdr,
984263bc 187 (func_ptr_type) &dlinfo,
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188#ifdef __i386__
189 (func_ptr_type) &___tls_get_addr,
190#endif
191 (func_ptr_type) &__tls_get_addr,
a1eee96a 192 (func_ptr_type) &__tls_get_addr_tcb,
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193 (func_ptr_type) &_rtld_allocate_tls,
194 (func_ptr_type) &_rtld_free_tls,
a1eee96a 195 (func_ptr_type) &_rtld_call_init,
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196 NULL
197};
198
199/*
200 * Global declarations normally provided by crt1. The dynamic linker is
201 * not built with crt1, so we have to provide them ourselves.
202 */
203char *__progname;
204char **environ;
205
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206/*
207 * Globals to control TLS allocation.
208 */
209size_t tls_last_offset; /* Static TLS offset of last module */
210size_t tls_last_size; /* Static TLS size of last module */
211size_t tls_static_space; /* Static TLS space allocated */
212int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
213int tls_max_index = 1; /* Largest module index allocated */
214
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215/*
216 * Fill in a DoneList with an allocation large enough to hold all of
217 * the currently-loaded objects. Keep this as a macro since it calls
218 * alloca and we want that to occur within the scope of the caller.
219 */
220#define donelist_init(dlp) \
221 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
222 assert((dlp)->objs != NULL), \
223 (dlp)->num_alloc = obj_count, \
224 (dlp)->num_used = 0)
225
226static __inline void
227rlock_acquire(void)
228{
229 lockinfo.rlock_acquire(lockinfo.thelock);
230 atomic_incr_int(&lockinfo.rcount);
231 lock_check();
232}
233
234static __inline void
235wlock_acquire(void)
236{
237 lockinfo.wlock_acquire(lockinfo.thelock);
238 atomic_incr_int(&lockinfo.wcount);
239 lock_check();
240}
241
242static __inline void
243rlock_release(void)
244{
245 atomic_decr_int(&lockinfo.rcount);
246 lockinfo.rlock_release(lockinfo.thelock);
247}
248
249static __inline void
250wlock_release(void)
251{
252 atomic_decr_int(&lockinfo.wcount);
253 lockinfo.wlock_release(lockinfo.thelock);
254}
255
256/*
257 * Main entry point for dynamic linking. The first argument is the
258 * stack pointer. The stack is expected to be laid out as described
259 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
260 * Specifically, the stack pointer points to a word containing
261 * ARGC. Following that in the stack is a null-terminated sequence
262 * of pointers to argument strings. Then comes a null-terminated
263 * sequence of pointers to environment strings. Finally, there is a
264 * sequence of "auxiliary vector" entries.
265 *
266 * The second argument points to a place to store the dynamic linker's
267 * exit procedure pointer and the third to a place to store the main
268 * program's object.
269 *
270 * The return value is the main program's entry point.
271 */
a1eee96a 272
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273func_ptr_type
274_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
275{
276 Elf_Auxinfo *aux_info[AT_COUNT];
277 int i;
278 int argc;
279 char **argv;
280 char **env;
281 Elf_Auxinfo *aux;
282 Elf_Auxinfo *auxp;
283 const char *argv0;
55b88cae 284 Objlist_Entry *entry;
984263bc 285 Obj_Entry *obj;
984263bc 286
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287 ld_index = 0; /* don't use old env cache in case we are resident */
288
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289 /*
290 * On entry, the dynamic linker itself has not been relocated yet.
291 * Be very careful not to reference any global data until after
292 * init_rtld has returned. It is OK to reference file-scope statics
293 * and string constants, and to call static and global functions.
294 */
295
296 /* Find the auxiliary vector on the stack. */
297 argc = *sp++;
298 argv = (char **) sp;
299 sp += argc + 1; /* Skip over arguments and NULL terminator */
300 env = (char **) sp;
984263bc 301
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302 /*
303 * If we aren't already resident we have to dig out some more info.
304 * Note that auxinfo does not exist when we are resident.
305 */
306 if (ld_resident == 0) {
307 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
308 ;
309 aux = (Elf_Auxinfo *) sp;
310
311 /* Digest the auxiliary vector. */
312 for (i = 0; i < AT_COUNT; i++)
313 aux_info[i] = NULL;
314 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
315 if (auxp->a_type < AT_COUNT)
316 aux_info[auxp->a_type] = auxp;
317 }
318
319 /* Initialize and relocate ourselves. */
320 assert(aux_info[AT_BASE] != NULL);
321 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
322 }
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323
324 __progname = obj_rtld.path;
325 argv0 = argv[0] != NULL ? argv[0] : "(null)";
326 environ = env;
327
8ca15ec8 328 trust = (geteuid() == getuid()) && (getegid() == getgid());
984263bc 329
8ca15ec8 330 ld_bind_now = _getenv_ld("LD_BIND_NOW");
984263bc 331 if (trust) {
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332 ld_debug = _getenv_ld("LD_DEBUG");
333 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
334 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
984263bc 335 }
8ca15ec8 336 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
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337
338 if (ld_debug != NULL && *ld_debug != '\0')
339 debug = 1;
340 dbg("%s is initialized, base address = %p", __progname,
341 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
342 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
343 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
344
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345 /*
346 * If we are resident we can skip work that we have already done.
347 * Note that the stack is reset and there is no Elf_Auxinfo
348 * when running from a resident image, and the static globals setup
349 * between here and resident_skip will have already been setup.
350 */
8ca15ec8 351 if (ld_resident)
33a8b578 352 goto resident_skip1;
33a8b578 353
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354 /*
355 * Load the main program, or process its program header if it is
356 * already loaded.
357 */
358 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
359 int fd = aux_info[AT_EXECFD]->a_un.a_val;
360 dbg("loading main program");
361 obj_main = map_object(fd, argv0, NULL);
362 close(fd);
363 if (obj_main == NULL)
364 die();
365 } else { /* Main program already loaded. */
366 const Elf_Phdr *phdr;
367 int phnum;
368 caddr_t entry;
369
370 dbg("processing main program's program header");
371 assert(aux_info[AT_PHDR] != NULL);
372 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
373 assert(aux_info[AT_PHNUM] != NULL);
374 phnum = aux_info[AT_PHNUM]->a_un.a_val;
375 assert(aux_info[AT_PHENT] != NULL);
376 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
377 assert(aux_info[AT_ENTRY] != NULL);
378 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
379 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
380 die();
381 }
382
383 obj_main->path = xstrdup(argv0);
384 obj_main->mainprog = true;
385
386 /*
387 * Get the actual dynamic linker pathname from the executable if
388 * possible. (It should always be possible.) That ensures that
389 * gdb will find the right dynamic linker even if a non-standard
390 * one is being used.
391 */
392 if (obj_main->interp != NULL &&
393 strcmp(obj_main->interp, obj_rtld.path) != 0) {
394 free(obj_rtld.path);
395 obj_rtld.path = xstrdup(obj_main->interp);
b7b05c9f 396 __progname = obj_rtld.path;
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397 }
398
399 digest_dynamic(obj_main);
400
401 linkmap_add(obj_main);
402 linkmap_add(&obj_rtld);
403
404 /* Link the main program into the list of objects. */
405 *obj_tail = obj_main;
406 obj_tail = &obj_main->next;
407 obj_count++;
408 obj_main->refcount++;
409 /* Make sure we don't call the main program's init and fini functions. */
410 obj_main->init = obj_main->fini = NULL;
411
412 /* Initialize a fake symbol for resolving undefined weak references. */
413 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
414 sym_zero.st_shndx = SHN_ABS;
415
416 dbg("loading LD_PRELOAD libraries");
417 if (load_preload_objects() == -1)
418 die();
419 preload_tail = obj_tail;
420
421 dbg("loading needed objects");
422 if (load_needed_objects(obj_main) == -1)
423 die();
424
425 /* Make a list of all objects loaded at startup. */
426 for (obj = obj_list; obj != NULL; obj = obj->next)
427 objlist_push_tail(&list_main, obj);
428
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429resident_skip1:
430
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431 if (ld_tracing) { /* We're done */
432 trace_loaded_objects(obj_main);
433 exit(0);
434 }
435
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436 if (ld_resident) /* XXX clean this up! */
437 goto resident_skip2;
438
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439 if (getenv("LD_DUMP_REL_PRE") != NULL) {
440 dump_relocations(obj_main);
441 exit (0);
442 }
443
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444 /* setup TLS for main thread */
445 dbg("initializing initial thread local storage");
446 STAILQ_FOREACH(entry, &list_main, link) {
447 /*
448 * Allocate all the initial objects out of the static TLS
449 * block even if they didn't ask for it.
450 */
451 allocate_tls_offset(entry->obj);
452 }
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453
454 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
455
456 /*
457 * Do not try to allocate the TLS here, let libc do it itself.
458 * (crt1 for the program will call _init_tls())
459 */
55b88cae 460
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461 if (relocate_objects(obj_main,
462 ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
463 die();
984263bc 464
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465 dbg("doing copy relocations");
466 if (do_copy_relocations(obj_main) == -1)
467 die();
1c76efe5 468
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469resident_skip2:
470
8ca15ec8 471 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
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472 if (exec_sys_unregister(-1) < 0) {
473 dbg("exec_sys_unregister failed %d\n", errno);
474 exit(errno);
475 }
476 dbg("exec_sys_unregister success\n");
477 exit(0);
478 }
984263bc 479
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480 if (getenv("LD_DUMP_REL_POST") != NULL) {
481 dump_relocations(obj_main);
482 exit (0);
483 }
484
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485 dbg("initializing key program variables");
486 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
487 set_program_var("environ", env);
488
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489 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
490 extern void resident_start(void);
491 ld_resident = 1;
492 if (exec_sys_register(resident_start) < 0) {
493 dbg("exec_sys_register failed %d\n", errno);
494 exit(errno);
495 }
496 dbg("exec_sys_register success\n");
497 exit(0);
498 }
499
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500 dbg("initializing thread locks");
501 lockdflt_init(&lockinfo);
502 lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
503
504 /* Make a list of init functions to call. */
505 objlist_init(&initlist);
506 initlist_add_objects(obj_list, preload_tail, &initlist);
507
508 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
509
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510 /*
511 * Do NOT call the initlist here, give libc a chance to set up
512 * the initial TLS segment. crt1 will then call _rtld_call_init().
513 */
8ca15ec8 514
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515 dbg("transferring control to program entry point = %p", obj_main->entry);
516
517 /* Return the exit procedure and the program entry point. */
518 *exit_proc = rtld_exit;
519 *objp = obj_main;
520 return (func_ptr_type) obj_main->entry;
521}
522
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523/*
524 * Call the initialization list for dynamically loaded libraries.
525 * (called from crt1.c).
526 */
527void
528_rtld_call_init(void)
529{
530 objlist_call_init(&initlist);
531 wlock_acquire();
532 objlist_clear(&initlist);
533 wlock_release();
534}
535
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536Elf_Addr
537_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
538{
539 const Elf_Rel *rel;
540 const Elf_Sym *def;
541 const Obj_Entry *defobj;
542 Elf_Addr *where;
543 Elf_Addr target;
544
545 rlock_acquire();
546 if (obj->pltrel)
547 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
548 else
549 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
550
551 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
552 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
553 if (def == NULL)
554 die();
555
556 target = (Elf_Addr)(defobj->relocbase + def->st_value);
557
558 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
559 defobj->strtab + def->st_name, basename(obj->path),
560 (void *)target, basename(defobj->path));
561
562 reloc_jmpslot(where, target);
563 rlock_release();
564 return target;
565}
566
567/*
568 * Error reporting function. Use it like printf. If formats the message
569 * into a buffer, and sets things up so that the next call to dlerror()
570 * will return the message.
571 */
572void
573_rtld_error(const char *fmt, ...)
574{
575 static char buf[512];
576 va_list ap;
577
578 va_start(ap, fmt);
579 vsnprintf(buf, sizeof buf, fmt, ap);
580 error_message = buf;
581 va_end(ap);
582}
583
584/*
585 * Return a dynamically-allocated copy of the current error message, if any.
586 */
587static char *
588errmsg_save(void)
589{
590 return error_message == NULL ? NULL : xstrdup(error_message);
591}
592
593/*
594 * Restore the current error message from a copy which was previously saved
595 * by errmsg_save(). The copy is freed.
596 */
597static void
598errmsg_restore(char *saved_msg)
599{
600 if (saved_msg == NULL)
601 error_message = NULL;
602 else {
603 _rtld_error("%s", saved_msg);
604 free(saved_msg);
605 }
606}
607
1c76efe5 608const char *
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609basename(const char *name)
610{
611 const char *p = strrchr(name, '/');
612 return p != NULL ? p + 1 : name;
613}
614
615static void
616die(void)
617{
618 const char *msg = dlerror();
619
620 if (msg == NULL)
621 msg = "Fatal error";
622 errx(1, "%s", msg);
623}
624
625/*
626 * Process a shared object's DYNAMIC section, and save the important
627 * information in its Obj_Entry structure.
628 */
629static void
630digest_dynamic(Obj_Entry *obj)
631{
632 const Elf_Dyn *dynp;
633 Needed_Entry **needed_tail = &obj->needed;
634 const Elf_Dyn *dyn_rpath = NULL;
635 int plttype = DT_REL;
636
637 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
638 switch (dynp->d_tag) {
639
640 case DT_REL:
641 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
642 break;
643
644 case DT_RELSZ:
645 obj->relsize = dynp->d_un.d_val;
646 break;
647
648 case DT_RELENT:
649 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
650 break;
651
652 case DT_JMPREL:
653 obj->pltrel = (const Elf_Rel *)
654 (obj->relocbase + dynp->d_un.d_ptr);
655 break;
656
657 case DT_PLTRELSZ:
658 obj->pltrelsize = dynp->d_un.d_val;
659 break;
660
661 case DT_RELA:
662 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
663 break;
664
665 case DT_RELASZ:
666 obj->relasize = dynp->d_un.d_val;
667 break;
668
669 case DT_RELAENT:
670 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
671 break;
672
673 case DT_PLTREL:
674 plttype = dynp->d_un.d_val;
675 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
676 break;
677
678 case DT_SYMTAB:
679 obj->symtab = (const Elf_Sym *)
680 (obj->relocbase + dynp->d_un.d_ptr);
681 break;
682
683 case DT_SYMENT:
684 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
685 break;
686
687 case DT_STRTAB:
688 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
689 break;
690
691 case DT_STRSZ:
692 obj->strsize = dynp->d_un.d_val;
693 break;
694
695 case DT_HASH:
696 {
697 const Elf_Addr *hashtab = (const Elf_Addr *)
698 (obj->relocbase + dynp->d_un.d_ptr);
699 obj->nbuckets = hashtab[0];
700 obj->nchains = hashtab[1];
701 obj->buckets = hashtab + 2;
702 obj->chains = obj->buckets + obj->nbuckets;
703 }
704 break;
705
706 case DT_NEEDED:
707 if (!obj->rtld) {
708 Needed_Entry *nep = NEW(Needed_Entry);
709 nep->name = dynp->d_un.d_val;
710 nep->obj = NULL;
711 nep->next = NULL;
712
713 *needed_tail = nep;
714 needed_tail = &nep->next;
715 }
716 break;
717
718 case DT_PLTGOT:
719 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
720 break;
721
722 case DT_TEXTREL:
723 obj->textrel = true;
724 break;
725
726 case DT_SYMBOLIC:
727 obj->symbolic = true;
728 break;
729
730 case DT_RPATH:
167f7029 731 case DT_RUNPATH: /* XXX: process separately */
984263bc
MD
732 /*
733 * We have to wait until later to process this, because we
734 * might not have gotten the address of the string table yet.
735 */
736 dyn_rpath = dynp;
737 break;
738
739 case DT_SONAME:
740 /* Not used by the dynamic linker. */
741 break;
742
743 case DT_INIT:
744 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
745 break;
746
747 case DT_FINI:
748 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
749 break;
750
751 case DT_DEBUG:
752 /* XXX - not implemented yet */
753 dbg("Filling in DT_DEBUG entry");
754 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
755 break;
756
167f7029
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757 case DT_FLAGS:
758 if (dynp->d_un.d_val & DF_ORIGIN) {
759 obj->origin_path = xmalloc(PATH_MAX);
760 if (rtld_dirname(obj->path, obj->origin_path) == -1)
761 die();
762 }
763 if (dynp->d_un.d_val & DF_SYMBOLIC)
764 obj->symbolic = true;
765 if (dynp->d_un.d_val & DF_TEXTREL)
766 obj->textrel = true;
767 if (dynp->d_un.d_val & DF_BIND_NOW)
768 obj->bind_now = true;
769 if (dynp->d_un.d_val & DF_STATIC_TLS)
770 ;
771 break;
772
984263bc
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773 default:
774 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
775 break;
776 }
777 }
778
779 obj->traced = false;
780
781 if (plttype == DT_RELA) {
782 obj->pltrela = (const Elf_Rela *) obj->pltrel;
783 obj->pltrel = NULL;
784 obj->pltrelasize = obj->pltrelsize;
785 obj->pltrelsize = 0;
786 }
787
788 if (dyn_rpath != NULL)
789 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
790}
791
792/*
793 * Process a shared object's program header. This is used only for the
794 * main program, when the kernel has already loaded the main program
795 * into memory before calling the dynamic linker. It creates and
796 * returns an Obj_Entry structure.
797 */
798static Obj_Entry *
799digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
800{
801 Obj_Entry *obj;
802 const Elf_Phdr *phlimit = phdr + phnum;
803 const Elf_Phdr *ph;
804 int nsegs = 0;
805
806 obj = obj_new();
807 for (ph = phdr; ph < phlimit; ph++) {
808 switch (ph->p_type) {
809
810 case PT_PHDR:
811 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
812 _rtld_error("%s: invalid PT_PHDR", path);
813 return NULL;
814 }
815 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
816 obj->phsize = ph->p_memsz;
817 break;
818
819 case PT_INTERP:
820 obj->interp = (const char *) ph->p_vaddr;
821 break;
822
823 case PT_LOAD:
824 if (nsegs == 0) { /* First load segment */
825 obj->vaddrbase = trunc_page(ph->p_vaddr);
826 obj->mapbase = (caddr_t) obj->vaddrbase;
827 obj->relocbase = obj->mapbase - obj->vaddrbase;
828 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
829 obj->vaddrbase;
830 } else { /* Last load segment */
831 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
832 obj->vaddrbase;
833 }
834 nsegs++;
835 break;
836
837 case PT_DYNAMIC:
838 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
839 break;
55b88cae
DX
840
841 case PT_TLS:
842 obj->tlsindex = 1;
843 obj->tlssize = ph->p_memsz;
844 obj->tlsalign = ph->p_align;
845 obj->tlsinitsize = ph->p_filesz;
846 obj->tlsinit = (void*) ph->p_vaddr;
847 break;
984263bc
MD
848 }
849 }
850 if (nsegs < 1) {
851 _rtld_error("%s: too few PT_LOAD segments", path);
852 return NULL;
853 }
854
855 obj->entry = entry;
856 return obj;
857}
858
859static Obj_Entry *
860dlcheck(void *handle)
861{
862 Obj_Entry *obj;
863
864 for (obj = obj_list; obj != NULL; obj = obj->next)
865 if (obj == (Obj_Entry *) handle)
866 break;
867
868 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
869 _rtld_error("Invalid shared object handle %p", handle);
870 return NULL;
871 }
872 return obj;
873}
874
875/*
876 * If the given object is already in the donelist, return true. Otherwise
877 * add the object to the list and return false.
878 */
879static bool
880donelist_check(DoneList *dlp, const Obj_Entry *obj)
881{
882 unsigned int i;
883
884 for (i = 0; i < dlp->num_used; i++)
885 if (dlp->objs[i] == obj)
886 return true;
887 /*
888 * Our donelist allocation should always be sufficient. But if
889 * our threads locking isn't working properly, more shared objects
890 * could have been loaded since we allocated the list. That should
891 * never happen, but we'll handle it properly just in case it does.
892 */
893 if (dlp->num_used < dlp->num_alloc)
894 dlp->objs[dlp->num_used++] = obj;
895 return false;
896}
897
898/*
899 * Hash function for symbol table lookup. Don't even think about changing
900 * this. It is specified by the System V ABI.
901 */
902unsigned long
903elf_hash(const char *name)
904{
905 const unsigned char *p = (const unsigned char *) name;
906 unsigned long h = 0;
907 unsigned long g;
908
909 while (*p != '\0') {
910 h = (h << 4) + *p++;
911 if ((g = h & 0xf0000000) != 0)
912 h ^= g >> 24;
913 h &= ~g;
914 }
915 return h;
916}
917
918/*
919 * Find the library with the given name, and return its full pathname.
920 * The returned string is dynamically allocated. Generates an error
921 * message and returns NULL if the library cannot be found.
922 *
923 * If the second argument is non-NULL, then it refers to an already-
924 * loaded shared object, whose library search path will be searched.
925 *
926 * The search order is:
984263bc 927 * LD_LIBRARY_PATH
4e390e27 928 * rpath in the referencing file
984263bc
MD
929 * ldconfig hints
930 * /usr/lib
931 */
932static char *
933find_library(const char *name, const Obj_Entry *refobj)
934{
935 char *pathname;
936
937 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
938 if (name[0] != '/' && !trust) {
939 _rtld_error("Absolute pathname required for shared object \"%s\"",
940 name);
941 return NULL;
942 }
943 return xstrdup(name);
944 }
945
946 dbg(" Searching for \"%s\"", name);
947
948 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
949 (refobj != NULL &&
950 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
951 (pathname = search_library_path(name, gethints())) != NULL ||
952 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
953 return pathname;
954
446c0d3a
JS
955 if(refobj != NULL && refobj->path != NULL) {
956 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
957 name, basename(refobj->path));
958 } else {
959 _rtld_error("Shared object \"%s\" not found", name);
960 }
984263bc
MD
961 return NULL;
962}
963
964/*
965 * Given a symbol number in a referencing object, find the corresponding
966 * definition of the symbol. Returns a pointer to the symbol, or NULL if
967 * no definition was found. Returns a pointer to the Obj_Entry of the
968 * defining object via the reference parameter DEFOBJ_OUT.
969 */
970const Elf_Sym *
971find_symdef(unsigned long symnum, const Obj_Entry *refobj,
972 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
973{
974 const Elf_Sym *ref;
975 const Elf_Sym *def;
976 const Obj_Entry *defobj;
977 const char *name;
978 unsigned long hash;
979
980 /*
981 * If we have already found this symbol, get the information from
982 * the cache.
983 */
984 if (symnum >= refobj->nchains)
985 return NULL; /* Bad object */
986 if (cache != NULL && cache[symnum].sym != NULL) {
987 *defobj_out = cache[symnum].obj;
988 return cache[symnum].sym;
989 }
990
991 ref = refobj->symtab + symnum;
992 name = refobj->strtab + ref->st_name;
993 hash = elf_hash(name);
994 defobj = NULL;
995
996 def = symlook_default(name, hash, refobj, &defobj, in_plt);
997
998 /*
999 * If we found no definition and the reference is weak, treat the
1000 * symbol as having the value zero.
1001 */
1002 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1003 def = &sym_zero;
1004 defobj = obj_main;
1005 }
1006
1007 if (def != NULL) {
1008 *defobj_out = defobj;
1009 /* Record the information in the cache to avoid subsequent lookups. */
1010 if (cache != NULL) {
1011 cache[symnum].sym = def;
1012 cache[symnum].obj = defobj;
1013 }
1014 } else
1015 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1016 return def;
1017}
1018
1019/*
1020 * Return the search path from the ldconfig hints file, reading it if
1021 * necessary. Returns NULL if there are problems with the hints file,
1022 * or if the search path there is empty.
1023 */
1024static const char *
1025gethints(void)
1026{
1027 static char *hints;
1028
1029 if (hints == NULL) {
1030 int fd;
1031 struct elfhints_hdr hdr;
1032 char *p;
1033
1034 /* Keep from trying again in case the hints file is bad. */
1035 hints = "";
1036
1037 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
1038 return NULL;
1039 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1040 hdr.magic != ELFHINTS_MAGIC ||
1041 hdr.version != 1) {
1042 close(fd);
1043 return NULL;
1044 }
1045 p = xmalloc(hdr.dirlistlen + 1);
1046 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1047 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
1048 free(p);
1049 close(fd);
1050 return NULL;
1051 }
1052 hints = p;
1053 close(fd);
1054 }
1055 return hints[0] != '\0' ? hints : NULL;
1056}
1057
1058static void
1059init_dag(Obj_Entry *root)
1060{
1061 DoneList donelist;
1062
1063 donelist_init(&donelist);
1064 init_dag1(root, root, &donelist);
1065}
1066
1067static void
1068init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1069{
1070 const Needed_Entry *needed;
1071
1072 if (donelist_check(dlp, obj))
1073 return;
1074 objlist_push_tail(&obj->dldags, root);
1075 objlist_push_tail(&root->dagmembers, obj);
1076 for (needed = obj->needed; needed != NULL; needed = needed->next)
1077 if (needed->obj != NULL)
1078 init_dag1(root, needed->obj, dlp);
1079}
1080
1081/*
1082 * Initialize the dynamic linker. The argument is the address at which
1083 * the dynamic linker has been mapped into memory. The primary task of
1084 * this function is to relocate the dynamic linker.
1085 */
1086static void
1087init_rtld(caddr_t mapbase)
1088{
1089 /*
1090 * Conjure up an Obj_Entry structure for the dynamic linker.
1091 *
1092 * The "path" member is supposed to be dynamically-allocated, but we
1093 * aren't yet initialized sufficiently to do that. Below we will
1094 * replace the static version with a dynamically-allocated copy.
1095 */
1096 obj_rtld.path = PATH_RTLD;
1097 obj_rtld.rtld = true;
1098 obj_rtld.mapbase = mapbase;
1099#ifdef PIC
1100 obj_rtld.relocbase = mapbase;
1101#endif
1102 if (&_DYNAMIC != 0) {
1103 obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1104 digest_dynamic(&obj_rtld);
1105 assert(obj_rtld.needed == NULL);
1106 assert(!obj_rtld.textrel);
1107
1108 /*
1109 * Temporarily put the dynamic linker entry into the object list, so
1110 * that symbols can be found.
1111 */
1112 obj_list = &obj_rtld;
1113 obj_tail = &obj_rtld.next;
1114 obj_count = 1;
1115
1116 relocate_objects(&obj_rtld, true);
1117 }
1118
1119 /* Make the object list empty again. */
1120 obj_list = NULL;
1121 obj_tail = &obj_list;
1122 obj_count = 0;
1123
1124 /* Replace the path with a dynamically allocated copy. */
1125 obj_rtld.path = xstrdup(obj_rtld.path);
1126
1127 r_debug.r_brk = r_debug_state;
1128 r_debug.r_state = RT_CONSISTENT;
1129}
1130
1131/*
1132 * Add the init functions from a needed object list (and its recursive
1133 * needed objects) to "list". This is not used directly; it is a helper
1134 * function for initlist_add_objects(). The write lock must be held
1135 * when this function is called.
1136 */
1137static void
1138initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1139{
1140 /* Recursively process the successor needed objects. */
1141 if (needed->next != NULL)
1142 initlist_add_neededs(needed->next, list);
1143
1144 /* Process the current needed object. */
1145 if (needed->obj != NULL)
1146 initlist_add_objects(needed->obj, &needed->obj->next, list);
1147}
1148
1149/*
1150 * Scan all of the DAGs rooted in the range of objects from "obj" to
1151 * "tail" and add their init functions to "list". This recurses over
1152 * the DAGs and ensure the proper init ordering such that each object's
1153 * needed libraries are initialized before the object itself. At the
1154 * same time, this function adds the objects to the global finalization
1155 * list "list_fini" in the opposite order. The write lock must be
1156 * held when this function is called.
1157 */
1158static void
1159initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1160{
1161 if (obj->init_done)
1162 return;
1163 obj->init_done = true;
1164
1165 /* Recursively process the successor objects. */
1166 if (&obj->next != tail)
1167 initlist_add_objects(obj->next, tail, list);
1168
1169 /* Recursively process the needed objects. */
1170 if (obj->needed != NULL)
1171 initlist_add_neededs(obj->needed, list);
1172
1173 /* Add the object to the init list. */
1174 if (obj->init != NULL)
1175 objlist_push_tail(list, obj);
1176
1177 /* Add the object to the global fini list in the reverse order. */
1178 if (obj->fini != NULL)
1179 objlist_push_head(&list_fini, obj);
1180}
1181
1182static bool
1183is_exported(const Elf_Sym *def)
1184{
1185 func_ptr_type value;
1186 const func_ptr_type *p;
1187
1188 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1189 for (p = exports; *p != NULL; p++)
1190 if (*p == value)
1191 return true;
1192 return false;
1193}
1194
1195/*
1196 * Given a shared object, traverse its list of needed objects, and load
1197 * each of them. Returns 0 on success. Generates an error message and
1198 * returns -1 on failure.
1199 */
1200static int
1201load_needed_objects(Obj_Entry *first)
1202{
1203 Obj_Entry *obj;
1204
1205 for (obj = first; obj != NULL; obj = obj->next) {
1206 Needed_Entry *needed;
1207
1208 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1209 const char *name = obj->strtab + needed->name;
1210 char *path = find_library(name, obj);
1211
1212 needed->obj = NULL;
1213 if (path == NULL && !ld_tracing)
1214 return -1;
1215
1216 if (path) {
1217 needed->obj = load_object(path);
1218 if (needed->obj == NULL && !ld_tracing)
1219 return -1; /* XXX - cleanup */
1220 }
1221 }
1222 }
1223
1224 return 0;
1225}
1226
1227static int
1228load_preload_objects(void)
1229{
1230 char *p = ld_preload;
1231 static const char delim[] = " \t:;";
1232
1233 if (p == NULL)
1234 return NULL;
1235
1236 p += strspn(p, delim);
1237 while (*p != '\0') {
1238 size_t len = strcspn(p, delim);
1239 char *path;
1240 char savech;
1241
1242 savech = p[len];
1243 p[len] = '\0';
1244 if ((path = find_library(p, NULL)) == NULL)
1245 return -1;
1246 if (load_object(path) == NULL)
1247 return -1; /* XXX - cleanup */
1248 p[len] = savech;
1249 p += len;
1250 p += strspn(p, delim);
1251 }
1252 return 0;
1253}
1254
b6a22d96 1255/*
2d6b58a8 1256 * Returns a pointer to the Obj_Entry for the object with the given path.
b6a22d96
JS
1257 * Returns NULL if no matching object was found.
1258 */
1259static Obj_Entry *
1260find_object(const char *path)
1261{
1262 Obj_Entry *obj;
1263
1264 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1265 if (strcmp(obj->path, path) == 0)
1266 return(obj);
1267 }
1268 return(NULL);
1269}
1270
2d6b58a8
JS
1271/*
1272 * Returns a pointer to the Obj_Entry for the object matching device and
1273 * inode of the given path. If no matching object was found, the descriptor
1274 * is returned in fd.
1275 * Returns with obj == NULL && fd == -1 on error.
1276 */
1277static Obj_Entry *
1278find_object2(const char *path, int *fd, struct stat *sb)
1279{
1280 Obj_Entry *obj;
1281
1282 if ((*fd = open(path, O_RDONLY)) == -1) {
1283 _rtld_error("Cannot open \"%s\"", path);
1284 return(NULL);
1285 }
1286
1287 if (fstat(*fd, sb) == -1) {
1288 _rtld_error("Cannot fstat \"%s\"", path);
1289 close(*fd);
1290 *fd = -1;
1291 return NULL;
1292 }
1293
1294 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1295 if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) {
1296 close(*fd);
1297 break;
1298 }
1299 }
1300
1301 return(obj);
1302}
1303
984263bc
MD
1304/*
1305 * Load a shared object into memory, if it is not already loaded. The
1306 * argument must be a string allocated on the heap. This function assumes
1307 * responsibility for freeing it when necessary.
1308 *
1309 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1310 * on failure.
1311 */
1312static Obj_Entry *
1313load_object(char *path)
1314{
1315 Obj_Entry *obj;
1316 int fd = -1;
1317 struct stat sb;
1318
b6a22d96 1319 obj = find_object(path);
2d6b58a8 1320 if (obj != NULL) {
588c673f 1321 obj->refcount++;
2d6b58a8
JS
1322 free(path);
1323 return(obj);
1324 }
984263bc 1325
2d6b58a8 1326 obj = find_object2(path, &fd, &sb);
588c673f
JS
1327 if (obj != NULL) {
1328 obj->refcount++;
2d6b58a8
JS
1329 free(path);
1330 return(obj);
588c673f
JS
1331 } else if (fd == -1) {
1332 free(path);
1333 return(NULL);
984263bc
MD
1334 }
1335
2d6b58a8
JS
1336 dbg("loading \"%s\"", path);
1337 obj = map_object(fd, path, &sb);
1338 close(fd);
1339 if (obj == NULL) {
1340 free(path);
1341 return NULL;
1342 }
984263bc 1343
2d6b58a8
JS
1344 obj->path = path;
1345 digest_dynamic(obj);
984263bc 1346
2d6b58a8
JS
1347 *obj_tail = obj;
1348 obj_tail = &obj->next;
1349 obj_count++;
1350 linkmap_add(obj); /* for GDB & dlinfo() */
984263bc 1351
2d6b58a8
JS
1352 dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1,
1353 obj->path);
1354 if (obj->textrel)
1355 dbg(" WARNING: %s has impure text", obj->path);
984263bc
MD
1356
1357 obj->refcount++;
1358 return obj;
1359}
1360
1361/*
1362 * Check for locking violations and die if one is found.
1363 */
1364static void
1365lock_check(void)
1366{
1367 int rcount, wcount;
1368
1369 rcount = lockinfo.rcount;
1370 wcount = lockinfo.wcount;
1371 assert(rcount >= 0);
1372 assert(wcount >= 0);
1373 if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1374 _rtld_error("Application locking error: %d readers and %d writers"
1375 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1376 rcount, wcount);
1377 die();
1378 }
1379}
1380
1381static Obj_Entry *
1382obj_from_addr(const void *addr)
1383{
984263bc
MD
1384 Obj_Entry *obj;
1385
984263bc 1386 for (obj = obj_list; obj != NULL; obj = obj->next) {
984263bc
MD
1387 if (addr < (void *) obj->mapbase)
1388 continue;
c6873e56 1389 if (addr < (void *) (obj->mapbase + obj->mapsize))
984263bc
MD
1390 return obj;
1391 }
1392 return NULL;
1393}
1394
1395/*
1396 * Call the finalization functions for each of the objects in "list"
1397 * which are unreferenced. All of the objects are expected to have
1398 * non-NULL fini functions.
1399 */
1400static void
1401objlist_call_fini(Objlist *list)
1402{
1403 Objlist_Entry *elm;
1404 char *saved_msg;
1405
1406 /*
1407 * Preserve the current error message since a fini function might
1408 * call into the dynamic linker and overwrite it.
1409 */
1410 saved_msg = errmsg_save();
1411 STAILQ_FOREACH(elm, list, link) {
1412 if (elm->obj->refcount == 0) {
1413 dbg("calling fini function for %s", elm->obj->path);
1414 (*elm->obj->fini)();
1415 }
1416 }
1417 errmsg_restore(saved_msg);
1418}
1419
1420/*
1421 * Call the initialization functions for each of the objects in
1422 * "list". All of the objects are expected to have non-NULL init
1423 * functions.
1424 */
1425static void
1426objlist_call_init(Objlist *list)
1427{
1428 Objlist_Entry *elm;
1429 char *saved_msg;
1430
1431 /*
1432 * Preserve the current error message since an init function might
1433 * call into the dynamic linker and overwrite it.
1434 */
1435 saved_msg = errmsg_save();
1436 STAILQ_FOREACH(elm, list, link) {
1437 dbg("calling init function for %s", elm->obj->path);
1438 (*elm->obj->init)();
1439 }
1440 errmsg_restore(saved_msg);
1441}
1442
1443static void
1444objlist_clear(Objlist *list)
1445{
1446 Objlist_Entry *elm;
1447
1448 while (!STAILQ_EMPTY(list)) {
1449 elm = STAILQ_FIRST(list);
1450 STAILQ_REMOVE_HEAD(list, link);
1451 free(elm);
1452 }
1453}
1454
1455static Objlist_Entry *
1456objlist_find(Objlist *list, const Obj_Entry *obj)
1457{
1458 Objlist_Entry *elm;
1459
1460 STAILQ_FOREACH(elm, list, link)
1461 if (elm->obj == obj)
1462 return elm;
1463 return NULL;
1464}
1465
1466static void
1467objlist_init(Objlist *list)
1468{
1469 STAILQ_INIT(list);
1470}
1471
1472static void
1473objlist_push_head(Objlist *list, Obj_Entry *obj)
1474{
1475 Objlist_Entry *elm;
1476
1477 elm = NEW(Objlist_Entry);
1478 elm->obj = obj;
1479 STAILQ_INSERT_HEAD(list, elm, link);
1480}
1481
1482static void
1483objlist_push_tail(Objlist *list, Obj_Entry *obj)
1484{
1485 Objlist_Entry *elm;
1486
1487 elm = NEW(Objlist_Entry);
1488 elm->obj = obj;
1489 STAILQ_INSERT_TAIL(list, elm, link);
1490}
1491
1492static void
1493objlist_remove(Objlist *list, Obj_Entry *obj)
1494{
1495 Objlist_Entry *elm;
1496
1497 if ((elm = objlist_find(list, obj)) != NULL) {
1498 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1499 free(elm);
1500 }
1501}
1502
1503/*
1504 * Remove all of the unreferenced objects from "list".
1505 */
1506static void
1507objlist_remove_unref(Objlist *list)
1508{
1509 Objlist newlist;
1510 Objlist_Entry *elm;
1511
1512 STAILQ_INIT(&newlist);
1513 while (!STAILQ_EMPTY(list)) {
1514 elm = STAILQ_FIRST(list);
1515 STAILQ_REMOVE_HEAD(list, link);
1516 if (elm->obj->refcount == 0)
1517 free(elm);
1518 else
1519 STAILQ_INSERT_TAIL(&newlist, elm, link);
1520 }
1521 *list = newlist;
1522}
1523
1524/*
1525 * Relocate newly-loaded shared objects. The argument is a pointer to
1526 * the Obj_Entry for the first such object. All objects from the first
1527 * to the end of the list of objects are relocated. Returns 0 on success,
1528 * or -1 on failure.
1529 */
1530static int
1531relocate_objects(Obj_Entry *first, bool bind_now)
1532{
1533 Obj_Entry *obj;
1534
1535 for (obj = first; obj != NULL; obj = obj->next) {
1536 if (obj != &obj_rtld)
1537 dbg("relocating \"%s\"", obj->path);
1538 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1539 obj->symtab == NULL || obj->strtab == NULL) {
1540 _rtld_error("%s: Shared object has no run-time symbol table",
1541 obj->path);
1542 return -1;
1543 }
1544
1545 if (obj->textrel) {
1546 /* There are relocations to the write-protected text segment. */
1547 if (mprotect(obj->mapbase, obj->textsize,
1548 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1549 _rtld_error("%s: Cannot write-enable text segment: %s",
1550 obj->path, strerror(errno));
1551 return -1;
1552 }
1553 }
1554
1555 /* Process the non-PLT relocations. */
1556 if (reloc_non_plt(obj, &obj_rtld))
1557 return -1;
1558
4b89341e
MD
1559 /*
1560 * Reprotect the text segment. Make sure it is included in the
1561 * core dump since we modified it. This unfortunately causes the
1562 * entire text segment to core-out but we don't have much of a
1563 * choice. We could try to only reenable core dumps on pages
1564 * in which relocations occured but that is likely most of the text
1565 * pages anyway, and even that would not work because the rest of
1566 * the text pages would wind up as a read-only OBJT_DEFAULT object
1567 * (created due to our modifications) backed by the original OBJT_VNODE
1568 * object, and the ELF coredump code is currently only able to dump
1569 * vnode records for pure vnode-backed mappings, not vnode backings
1570 * to memory objects.
1571 */
1572 if (obj->textrel) {
1573 madvise(obj->mapbase, obj->textsize, MADV_CORE);
984263bc
MD
1574 if (mprotect(obj->mapbase, obj->textsize,
1575 PROT_READ|PROT_EXEC) == -1) {
1576 _rtld_error("%s: Cannot write-protect text segment: %s",
1577 obj->path, strerror(errno));
1578 return -1;
1579 }
1580 }
1581
1582 /* Process the PLT relocations. */
1583 if (reloc_plt(obj) == -1)
1584 return -1;
1585 /* Relocate the jump slots if we are doing immediate binding. */
167f7029 1586 if (obj->bind_now || bind_now)
984263bc
MD
1587 if (reloc_jmpslots(obj) == -1)
1588 return -1;
1589
1590
1591 /*
1592 * Set up the magic number and version in the Obj_Entry. These
1593 * were checked in the crt1.o from the original ElfKit, so we
1594 * set them for backward compatibility.
1595 */
1596 obj->magic = RTLD_MAGIC;
1597 obj->version = RTLD_VERSION;
1598
1599 /* Set the special PLT or GOT entries. */
1600 init_pltgot(obj);
1601 }
1602
1603 return 0;
1604}
1605
1606/*
1607 * Cleanup procedure. It will be called (by the atexit mechanism) just
1608 * before the process exits.
1609 */
1610static void
1611rtld_exit(void)
1612{
1613 Obj_Entry *obj;
1614
1615 dbg("rtld_exit()");
1616 /* Clear all the reference counts so the fini functions will be called. */
1617 for (obj = obj_list; obj != NULL; obj = obj->next)
1618 obj->refcount = 0;
1619 objlist_call_fini(&list_fini);
1620 /* No need to remove the items from the list, since we are exiting. */
1621}
1622
1623static void *
1624path_enumerate(const char *path, path_enum_proc callback, void *arg)
1625{
1626 if (path == NULL)
1627 return (NULL);
1628
1629 path += strspn(path, ":;");
1630 while (*path != '\0') {
1631 size_t len;
1632 char *res;
1633
1634 len = strcspn(path, ":;");
1635 res = callback(path, len, arg);
1636
1637 if (res != NULL)
1638 return (res);
1639
1640 path += len;
1641 path += strspn(path, ":;");
1642 }
1643
1644 return (NULL);
1645}
1646
1647struct try_library_args {
1648 const char *name;
1649 size_t namelen;
1650 char *buffer;
1651 size_t buflen;
1652};
1653
1654static void *
1655try_library_path(const char *dir, size_t dirlen, void *param)
1656{
1657 struct try_library_args *arg;
1658
1659 arg = param;
1660 if (*dir == '/' || trust) {
1661 char *pathname;
1662
1663 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1664 return (NULL);
1665
1666 pathname = arg->buffer;
1667 strncpy(pathname, dir, dirlen);
1668 pathname[dirlen] = '/';
1669 strcpy(pathname + dirlen + 1, arg->name);
1670
1671 dbg(" Trying \"%s\"", pathname);
1672 if (access(pathname, F_OK) == 0) { /* We found it */
1673 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1674 strcpy(pathname, arg->buffer);
1675 return (pathname);
1676 }
1677 }
1678 return (NULL);
1679}
1680
1681static char *
1682search_library_path(const char *name, const char *path)
1683{
1684 char *p;
1685 struct try_library_args arg;
1686
1687 if (path == NULL)
1688 return NULL;
1689
1690 arg.name = name;
1691 arg.namelen = strlen(name);
1692 arg.buffer = xmalloc(PATH_MAX);
1693 arg.buflen = PATH_MAX;
1694
1695 p = path_enumerate(path, try_library_path, &arg);
1696
1697 free(arg.buffer);
1698
1699 return (p);
1700}
1701
1702int
1703dlclose(void *handle)
1704{
1705 Obj_Entry *root;
1706
1707 wlock_acquire();
1708 root = dlcheck(handle);
1709 if (root == NULL) {
1710 wlock_release();
1711 return -1;
1712 }
1713
1714 /* Unreference the object and its dependencies. */
1715 root->dl_refcount--;
1716 unref_dag(root);
1717
1718 if (root->refcount == 0) {
1719 /*
1720 * The object is no longer referenced, so we must unload it.
1721 * First, call the fini functions with no locks held.
1722 */
1723 wlock_release();
1724 objlist_call_fini(&list_fini);
1725 wlock_acquire();
1726 objlist_remove_unref(&list_fini);
1727
1728 /* Finish cleaning up the newly-unreferenced objects. */
1729 GDB_STATE(RT_DELETE,&root->linkmap);
1730 unload_object(root);
1731 GDB_STATE(RT_CONSISTENT,NULL);
1732 }
1733 wlock_release();
1734 return 0;
1735}
1736
1737const char *
1738dlerror(void)
1739{
1740 char *msg = error_message;
1741 error_message = NULL;
1742 return msg;
1743}
1744
984263bc
MD
1745void *
1746dlopen(const char *name, int mode)
1747{
1748 Obj_Entry **old_obj_tail;
1749 Obj_Entry *obj;
1750 Objlist initlist;
1751 int result;
1752
1753 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1754 if (ld_tracing != NULL)
1755 environ = (char **)*get_program_var_addr("environ");
1756
1757 objlist_init(&initlist);
1758
1759 wlock_acquire();
1760 GDB_STATE(RT_ADD,NULL);
1761
1762 old_obj_tail = obj_tail;
1763 obj = NULL;
1764 if (name == NULL) {
1765 obj = obj_main;
1766 obj->refcount++;
1767 } else {
1768 char *path = find_library(name, obj_main);
1769 if (path != NULL)
1770 obj = load_object(path);
1771 }
1772
1773 if (obj) {
1774 obj->dl_refcount++;
8ca15ec8 1775 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
984263bc
MD
1776 objlist_push_tail(&list_global, obj);
1777 mode &= RTLD_MODEMASK;
1778 if (*old_obj_tail != NULL) { /* We loaded something new. */
1779 assert(*old_obj_tail == obj);
1780
1781 result = load_needed_objects(obj);
1782 if (result != -1 && ld_tracing)
1783 goto trace;
1784
1785 if (result == -1 ||
1786 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1787 obj->dl_refcount--;
1788 unref_dag(obj);
1789 if (obj->refcount == 0)
1790 unload_object(obj);
1791 obj = NULL;
1792 } else {
1793 /* Make list of init functions to call. */
1794 initlist_add_objects(obj, &obj->next, &initlist);
1795 }
1796 } else if (ld_tracing)
1797 goto trace;
1798 }
1799
1800 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1801
1802 /* Call the init functions with no locks held. */
1803 wlock_release();
1804 objlist_call_init(&initlist);
1805 wlock_acquire();
1806 objlist_clear(&initlist);
1807 wlock_release();
1808 return obj;
1809trace:
1810 trace_loaded_objects(obj);
1811 wlock_release();
1812 exit(0);
1813}
1814
1815void *
1816dlsym(void *handle, const char *name)
1817{
1818 const Obj_Entry *obj;
1819 unsigned long hash;
1820 const Elf_Sym *def;
1821 const Obj_Entry *defobj;
1822
1823 hash = elf_hash(name);
1824 def = NULL;
1825 defobj = NULL;
1826
1827 rlock_acquire();
1828 if (handle == NULL || handle == RTLD_NEXT ||
1829 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1830 void *retaddr;
1831
1832 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1833 if ((obj = obj_from_addr(retaddr)) == NULL) {
1834 _rtld_error("Cannot determine caller's shared object");
1835 rlock_release();
1836 return NULL;
1837 }
1838 if (handle == NULL) { /* Just the caller's shared object. */
1839 def = symlook_obj(name, hash, obj, true);
1840 defobj = obj;
1841 } else if (handle == RTLD_NEXT || /* Objects after caller's */
1842 handle == RTLD_SELF) { /* ... caller included */
1843 if (handle == RTLD_NEXT)
1844 obj = obj->next;
1845 for (; obj != NULL; obj = obj->next) {
1846 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1847 defobj = obj;
1848 break;
1849 }
1850 }
1851 } else {
1852 assert(handle == RTLD_DEFAULT);
1853 def = symlook_default(name, hash, obj, &defobj, true);
1854 }
1855 } else {
fb0c631e
SS
1856 DoneList donelist;
1857
984263bc
MD
1858 if ((obj = dlcheck(handle)) == NULL) {
1859 rlock_release();
1860 return NULL;
1861 }
1862
fb0c631e 1863 donelist_init(&donelist);
984263bc 1864 if (obj->mainprog) {
984263bc 1865 /* Search main program and all libraries loaded by it. */
984263bc
MD
1866 def = symlook_list(name, hash, &list_main, &defobj, true,
1867 &donelist);
1868 } else {
fb0c631e
SS
1869 def = symlook_list(name, hash, &(obj->dagmembers), &defobj, true,
1870 &donelist);
984263bc
MD
1871 }
1872 }
1873
1874 if (def != NULL) {
1875 rlock_release();
1876 return defobj->relocbase + def->st_value;
1877 }
1878
1879 _rtld_error("Undefined symbol \"%s\"", name);
1880 rlock_release();
1881 return NULL;
1882}
1883
1884int
1885dladdr(const void *addr, Dl_info *info)
1886{
1887 const Obj_Entry *obj;
1888 const Elf_Sym *def;
1889 void *symbol_addr;
1890 unsigned long symoffset;
1891
1892 rlock_acquire();
1893 obj = obj_from_addr(addr);
1894 if (obj == NULL) {
1895 _rtld_error("No shared object contains address");
1896 rlock_release();
1897 return 0;
1898 }
1899 info->dli_fname = obj->path;
1900 info->dli_fbase = obj->mapbase;
1901 info->dli_saddr = (void *)0;
1902 info->dli_sname = NULL;
1903
1904 /*
1905 * Walk the symbol list looking for the symbol whose address is
1906 * closest to the address sent in.
1907 */
1908 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1909 def = obj->symtab + symoffset;
1910
1911 /*
1912 * For skip the symbol if st_shndx is either SHN_UNDEF or
1913 * SHN_COMMON.
1914 */
1915 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1916 continue;
1917
1918 /*
1919 * If the symbol is greater than the specified address, or if it
1920 * is further away from addr than the current nearest symbol,
1921 * then reject it.
1922 */
1923 symbol_addr = obj->relocbase + def->st_value;
1924 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1925 continue;
1926
1927 /* Update our idea of the nearest symbol. */
1928 info->dli_sname = obj->strtab + def->st_name;
1929 info->dli_saddr = symbol_addr;
1930
1931 /* Exact match? */
1932 if (info->dli_saddr == addr)
1933 break;
1934 }
1935 rlock_release();
1936 return 1;
1937}
1938
1939int
1940dlinfo(void *handle, int request, void *p)
1941{
1942 const Obj_Entry *obj;
1943 int error;
1944
1945 rlock_acquire();
1946
1947 if (handle == NULL || handle == RTLD_SELF) {
1948 void *retaddr;
1949
1950 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1951 if ((obj = obj_from_addr(retaddr)) == NULL)
1952 _rtld_error("Cannot determine caller's shared object");
1953 } else
1954 obj = dlcheck(handle);
1955
1956 if (obj == NULL) {
1957 rlock_release();
1958 return (-1);
1959 }
1960
1961 error = 0;
1962 switch (request) {
1963 case RTLD_DI_LINKMAP:
1964 *((struct link_map const **)p) = &obj->linkmap;
1965 break;
1966 case RTLD_DI_ORIGIN:
1967 error = rtld_dirname(obj->path, p);
1968 break;
1969
1970 case RTLD_DI_SERINFOSIZE:
1971 case RTLD_DI_SERINFO:
1972 error = do_search_info(obj, request, (struct dl_serinfo *)p);
1973 break;
1974
1975 default:
1976 _rtld_error("Invalid request %d passed to dlinfo()", request);
1977 error = -1;
1978 }
1979
1980 rlock_release();
1981
1982 return (error);
1983}
1984
1985struct fill_search_info_args {
1986 int request;
1987 unsigned int flags;
1988 Dl_serinfo *serinfo;
1989 Dl_serpath *serpath;
1990 char *strspace;
1991};
1992
1993static void *
1994fill_search_info(const char *dir, size_t dirlen, void *param)
1995{
1996 struct fill_search_info_args *arg;
1997
1998 arg = param;
1999
2000 if (arg->request == RTLD_DI_SERINFOSIZE) {
2001 arg->serinfo->dls_cnt ++;
2002 arg->serinfo->dls_size += dirlen + 1;
2003 } else {
2004 struct dl_serpath *s_entry;
2005
2006 s_entry = arg->serpath;
2007 s_entry->dls_name = arg->strspace;
2008 s_entry->dls_flags = arg->flags;
2009
2010 strncpy(arg->strspace, dir, dirlen);
2011 arg->strspace[dirlen] = '\0';
2012
2013 arg->strspace += dirlen + 1;
2014 arg->serpath++;
2015 }
2016
2017 return (NULL);
2018}
2019
2020static int
2021do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2022{
2023 struct dl_serinfo _info;
2024 struct fill_search_info_args args;
2025
2026 args.request = RTLD_DI_SERINFOSIZE;
2027 args.serinfo = &_info;
2028
2029 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2030 _info.dls_cnt = 0;
2031
2032 path_enumerate(ld_library_path, fill_search_info, &args);
2033 path_enumerate(obj->rpath, fill_search_info, &args);
2034 path_enumerate(gethints(), fill_search_info, &args);
2035 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2036
2037
2038 if (request == RTLD_DI_SERINFOSIZE) {
2039 info->dls_size = _info.dls_size;
2040 info->dls_cnt = _info.dls_cnt;
2041 return (0);
2042 }
2043
2044 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2045 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2046 return (-1);
2047 }
2048
2049 args.request = RTLD_DI_SERINFO;
2050 args.serinfo = info;
2051 args.serpath = &info->dls_serpath[0];
2052 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2053
2054 args.flags = LA_SER_LIBPATH;
2055 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2056 return (-1);
2057
2058 args.flags = LA_SER_RUNPATH;
2059 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2060 return (-1);
2061
2062 args.flags = LA_SER_CONFIG;
2063 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2064 return (-1);
2065
2066 args.flags = LA_SER_DEFAULT;
2067 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2068 return (-1);
2069 return (0);
2070}
2071
2072static int
2073rtld_dirname(const char *path, char *bname)
2074{
2075 const char *endp;
2076
2077 /* Empty or NULL string gets treated as "." */
2078 if (path == NULL || *path == '\0') {
2079 bname[0] = '.';
2080 bname[1] = '\0';
2081 return (0);
2082 }
2083
2084 /* Strip trailing slashes */
2085 endp = path + strlen(path) - 1;
2086 while (endp > path && *endp == '/')
2087 endp--;
2088
2089 /* Find the start of the dir */
2090 while (endp > path && *endp != '/')
2091 endp--;
2092
2093 /* Either the dir is "/" or there are no slashes */
2094 if (endp == path) {
2095 bname[0] = *endp == '/' ? '/' : '.';
2096 bname[1] = '\0';
2097 return (0);
2098 } else {
2099 do {
2100 endp--;
2101 } while (endp > path && *endp == '/');
2102 }
2103
2104 if (endp - path + 2 > PATH_MAX)
2105 {
2106 _rtld_error("Filename is too long: %s", path);
2107 return(-1);
2108 }
2109
2110 strncpy(bname, path, endp - path + 1);
2111 bname[endp - path + 1] = '\0';
2112 return (0);
2113}
2114
2115static void
2116linkmap_add(Obj_Entry *obj)
2117{
2118 struct link_map *l = &obj->linkmap;
2119 struct link_map *prev;
2120
2121 obj->linkmap.l_name = obj->path;
2122 obj->linkmap.l_addr = obj->mapbase;
2123 obj->linkmap.l_ld = obj->dynamic;
2124#ifdef __mips__
2125 /* GDB needs load offset on MIPS to use the symbols */
2126 obj->linkmap.l_offs = obj->relocbase;
2127#endif
2128
2129 if (r_debug.r_map == NULL) {
2130 r_debug.r_map = l;
2131 return;
2132 }
2133
2134 /*
2135 * Scan to the end of the list, but not past the entry for the
2136 * dynamic linker, which we want to keep at the very end.
2137 */
2138 for (prev = r_debug.r_map;
2139 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2140 prev = prev->l_next)
2141 ;
2142
2143 /* Link in the new entry. */
2144 l->l_prev = prev;
2145 l->l_next = prev->l_next;
2146 if (l->l_next != NULL)
2147 l->l_next->l_prev = l;
2148 prev->l_next = l;
2149}
2150
2151static void
2152linkmap_delete(Obj_Entry *obj)
2153{
2154 struct link_map *l = &obj->linkmap;
2155
2156 if (l->l_prev == NULL) {
2157 if ((r_debug.r_map = l->l_next) != NULL)
2158 l->l_next->l_prev = NULL;
2159 return;
2160 }
2161
2162 if ((l->l_prev->l_next = l->l_next) != NULL)
2163 l->l_next->l_prev = l->l_prev;
2164}
2165
2166/*
2167 * Function for the debugger to set a breakpoint on to gain control.
2168 *
2169 * The two parameters allow the debugger to easily find and determine
2170 * what the runtime loader is doing and to whom it is doing it.
2171 *
2172 * When the loadhook trap is hit (r_debug_state, set at program
2173 * initialization), the arguments can be found on the stack:
2174 *
2175 * +8 struct link_map *m
2176 * +4 struct r_debug *rd
2177 * +0 RetAddr
2178 */
2179void
2180r_debug_state(struct r_debug* rd, struct link_map *m)
2181{
2182}
2183
2184/*
2185 * Get address of the pointer variable in the main program.
2186 */
2187static const void **
2188get_program_var_addr(const char *name)
2189{
2190 const Obj_Entry *obj;
2191 unsigned long hash;
2192
2193 hash = elf_hash(name);
2194 for (obj = obj_main; obj != NULL; obj = obj->next) {
2195 const Elf_Sym *def;
2196
2197 if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2198 const void **addr;
2199
2200 addr = (const void **)(obj->relocbase + def->st_value);
2201 return addr;
2202 }
2203 }
2204 return NULL;
2205}
2206
2207/*
2208 * Set a pointer variable in the main program to the given value. This
2209 * is used to set key variables such as "environ" before any of the
2210 * init functions are called.
2211 */
2212static void
2213set_program_var(const char *name, const void *value)
2214{
2215 const void **addr;
2216
2217 if ((addr = get_program_var_addr(name)) != NULL) {
2218 dbg("\"%s\": *%p <-- %p", name, addr, value);
2219 *addr = value;
2220 }
2221}
2222
8ca15ec8
MD
2223/*
2224 * This is a special version of getenv which is far more efficient
2225 * at finding LD_ environment vars.
2226 */
2227static
2228const char *
2229_getenv_ld(const char *id)
2230{
2231 const char *envp;
2232 int i, j;
2233 int idlen = strlen(id);
2234
2235 if (ld_index == LD_ARY_CACHE)
2236 return(getenv(id));
2237 if (ld_index == 0) {
2238 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2239 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2240 ld_ary[j++] = envp;
2241 }
2242 if (j == 0)
2243 ld_ary[j++] = "";
2244 ld_index = j;
2245 }
2246 for (i = ld_index - 1; i >= 0; --i) {
2247 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2248 return(ld_ary[i] + idlen + 1);
2249 }
2250 return(NULL);
2251}
2252
984263bc
MD
2253/*
2254 * Given a symbol name in a referencing object, find the corresponding
2255 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2256 * no definition was found. Returns a pointer to the Obj_Entry of the
2257 * defining object via the reference parameter DEFOBJ_OUT.
2258 */
2259static const Elf_Sym *
2260symlook_default(const char *name, unsigned long hash,
2261 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2262{
2263 DoneList donelist;
2264 const Elf_Sym *def;
2265 const Elf_Sym *symp;
2266 const Obj_Entry *obj;
2267 const Obj_Entry *defobj;
2268 const Objlist_Entry *elm;
2269 def = NULL;
2270 defobj = NULL;
2271 donelist_init(&donelist);
2272
2273 /* Look first in the referencing object if linked symbolically. */
2274 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2275 symp = symlook_obj(name, hash, refobj, in_plt);
2276 if (symp != NULL) {
2277 def = symp;
2278 defobj = refobj;
2279 }
2280 }
2281
2282 /* Search all objects loaded at program start up. */
2283 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2284 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2285 if (symp != NULL &&
2286 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2287 def = symp;
2288 defobj = obj;
2289 }
2290 }
2291
2292 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2293 STAILQ_FOREACH(elm, &list_global, link) {
2294 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2295 break;
2296 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2297 &donelist);
2298 if (symp != NULL &&
2299 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2300 def = symp;
2301 defobj = obj;
2302 }
2303 }
2304
2305 /* Search all dlopened DAGs containing the referencing object. */
2306 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2307 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2308 break;
2309 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2310 &donelist);
2311 if (symp != NULL &&
2312 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2313 def = symp;
2314 defobj = obj;
2315 }
2316 }
2317
2318 /*
2319 * Search the dynamic linker itself, and possibly resolve the
2320 * symbol from there. This is how the application links to
2321 * dynamic linker services such as dlopen. Only the values listed
2322 * in the "exports" array can be resolved from the dynamic linker.
2323 */
2324 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2325 symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2326 if (symp != NULL && is_exported(symp)) {
2327 def = symp;
2328 defobj = &obj_rtld;
2329 }
2330 }
2331
2332 if (def != NULL)
2333 *defobj_out = defobj;
2334 return def;
2335}
2336
2337static const Elf_Sym *
fb0c631e 2338symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
984263bc
MD
2339 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2340{
2341 const Elf_Sym *symp;
2342 const Elf_Sym *def;
2343 const Obj_Entry *defobj;
2344 const Objlist_Entry *elm;
2345
2346 def = NULL;
2347 defobj = NULL;
2348 STAILQ_FOREACH(elm, objlist, link) {
2349 if (donelist_check(dlp, elm->obj))
2350 continue;
2351 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2352 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2353 def = symp;
2354 defobj = elm->obj;
2355 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2356 break;
2357 }
2358 }
2359 }
2360 if (def != NULL)
2361 *defobj_out = defobj;
2362 return def;
2363}
2364
2365/*
2366 * Search the symbol table of a single shared object for a symbol of
2367 * the given name. Returns a pointer to the symbol, or NULL if no
2368 * definition was found.
2369 *
2370 * The symbol's hash value is passed in for efficiency reasons; that
2371 * eliminates many recomputations of the hash value.
2372 */
2373const Elf_Sym *
2374symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2375 bool in_plt)
2376{
2377 if (obj->buckets != NULL) {
2378 unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2379
2380 while (symnum != STN_UNDEF) {
2381 const Elf_Sym *symp;
2382 const char *strp;
2383
2384 if (symnum >= obj->nchains)
2385 return NULL; /* Bad object */
2386 symp = obj->symtab + symnum;
2387 strp = obj->strtab + symp->st_name;
2388
2389 if (name[0] == strp[0] && strcmp(name, strp) == 0)
2390 return symp->st_shndx != SHN_UNDEF ||
2391 (!in_plt && symp->st_value != 0 &&
2392 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2393
2394 symnum = obj->chains[symnum];
2395 }
2396 }
2397 return NULL;
2398}
2399
2400static void
2401trace_loaded_objects(Obj_Entry *obj)
2402{
8ca15ec8 2403 const char *fmt1, *fmt2, *fmt, *main_local;
984263bc
MD
2404 int c;
2405
8ca15ec8 2406 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
984263bc
MD
2407 main_local = "";
2408
8ca15ec8 2409 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
984263bc
MD
2410 fmt1 = "\t%o => %p (%x)\n";
2411
8ca15ec8 2412 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
984263bc
MD
2413 fmt2 = "\t%o (%x)\n";
2414
2415 for (; obj; obj = obj->next) {
2416 Needed_Entry *needed;
2417 char *name, *path;
2418 bool is_lib;
2419
2420 for (needed = obj->needed; needed; needed = needed->next) {
2421 if (needed->obj != NULL) {
2422 if (needed->obj->traced)
2423 continue;
2424 needed->obj->traced = true;
2425 path = needed->obj->path;
2426 } else
2427 path = "not found";
2428
2429 name = (char *)obj->strtab + needed->name;
2430 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2431
2432 fmt = is_lib ? fmt1 : fmt2;
2433 while ((c = *fmt++) != '\0') {
2434 switch (c) {
2435 default:
2436 putchar(c);
2437 continue;
2438 case '\\':
2439 switch (c = *fmt) {
2440 case '\0':
2441 continue;
2442 case 'n':
2443 putchar('\n');
2444 break;
2445 case 't':
2446 putchar('\t');
2447 break;
2448 }
2449 break;
2450 case '%':
2451 switch (c = *fmt) {
2452 case '\0':
2453 continue;
2454 case '%':
2455 default:
2456 putchar(c);
2457 break;
2458 case 'A':
2459 printf("%s", main_local);
2460 break;
2461 case 'a':
2462 printf("%s", obj_main->path);
2463 break;
2464 case 'o':
2465 printf("%s", name);
2466 break;
2467#if 0
2468 case 'm':
2469 printf("%d", sodp->sod_major);
2470 break;
2471 case 'n':
2472 printf("%d", sodp->sod_minor);
2473 break;
2474#endif
2475 case 'p':
2476 printf("%s", path);
2477 break;
2478 case 'x':
2479 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2480 break;
2481 }
2482 break;
2483 }
2484 ++fmt;
2485 }
2486 }
2487 }
2488}
2489
2490/*
2491 * Unload a dlopened object and its dependencies from memory and from
2492 * our data structures. It is assumed that the DAG rooted in the
2493 * object has already been unreferenced, and that the object has a
2494 * reference count of 0.
2495 */
2496static void
2497unload_object(Obj_Entry *root)
2498{
2499 Obj_Entry *obj;
2500 Obj_Entry **linkp;
2501
2502 assert(root->refcount == 0);
2503
2504 /*
2505 * Pass over the DAG removing unreferenced objects from
2506 * appropriate lists.
2507 */
2508 unlink_object(root);
2509
2510 /* Unmap all objects that are no longer referenced. */
2511 linkp = &obj_list->next;
2512 while ((obj = *linkp) != NULL) {
2513 if (obj->refcount == 0) {
2514 dbg("unloading \"%s\"", obj->path);
2515 munmap(obj->mapbase, obj->mapsize);
2516 linkmap_delete(obj);
2517 *linkp = obj->next;
2518 obj_count--;
2519 obj_free(obj);
2520 } else
2521 linkp = &obj->next;
2522 }
2523 obj_tail = linkp;
2524}
2525
2526static void
2527unlink_object(Obj_Entry *root)
2528{
2529 const Needed_Entry *needed;
2530 Objlist_Entry *elm;
2531
2532 if (root->refcount == 0) {
2533 /* Remove the object from the RTLD_GLOBAL list. */
2534 objlist_remove(&list_global, root);
2535
2536 /* Remove the object from all objects' DAG lists. */
2537 STAILQ_FOREACH(elm, &root->dagmembers , link)
2538 objlist_remove(&elm->obj->dldags, root);
2539 }
2540
2541 for (needed = root->needed; needed != NULL; needed = needed->next)
2542 if (needed->obj != NULL)
2543 unlink_object(needed->obj);
2544}
2545
2546static void
2547unref_dag(Obj_Entry *root)
2548{
2549 const Needed_Entry *needed;
2550
2551 if (root->refcount == 0)
2552 return;
2553 root->refcount--;
2554 if (root->refcount == 0)
2555 for (needed = root->needed; needed != NULL; needed = needed->next)
2556 if (needed->obj != NULL)
2557 unref_dag(needed->obj);
2558}
55b88cae
DX
2559
2560/*
2561 * Common code for MD __tls_get_addr().
2562 */
2563void *
bc633d63 2564tls_get_addr_common(void **dtvp, int index, size_t offset)
55b88cae
DX
2565{
2566 Elf_Addr* dtv = *dtvp;
2567
2568 /* Check dtv generation in case new modules have arrived */
2569 if (dtv[0] != tls_dtv_generation) {
2570 Elf_Addr* newdtv;
2571 int to_copy;
2572
2573 wlock_acquire();
2574
2575 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
2576 to_copy = dtv[1];
2577 if (to_copy > tls_max_index)
2578 to_copy = tls_max_index;
2579 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
2580 newdtv[0] = tls_dtv_generation;
2581 newdtv[1] = tls_max_index;
2582 free(dtv);
bc633d63 2583 *dtvp = newdtv;
55b88cae
DX
2584
2585 wlock_release();
55b88cae
DX
2586 }
2587
2588 /* Dynamically allocate module TLS if necessary */
2589 if (!dtv[index + 1]) {
2590 /* XXX
2591 * here we should avoid to be re-entered by signal handler
2592 * code, I assume wlock_acquire will masked all signals,
2593 * otherwise there is race and dead lock thread itself.
2594 */
2595 wlock_acquire();
2596 if (!dtv[index + 1])
2597 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
2598 wlock_release();
2599 }
2600
2601 return (void*) (dtv[index + 1] + offset);
2602}
2603
9e2ee207 2604#if defined(RTLD_STATIC_TLS_VARIANT_II)
55b88cae
DX
2605
2606/*
bc633d63
MD
2607 * Allocate the static TLS area. Return a pointer to the TCB. The
2608 * static area is based on negative offsets relative to the tcb.
a1eee96a
MD
2609 *
2610 * The TCB contains an errno pointer for the system call layer, but because
2611 * we are the RTLD we really have no idea how the caller was compiled so
2612 * the information has to be passed in. errno can either be:
2613 *
2614 * type 0 errno is a simple non-TLS global pointer.
2615 * (special case for e.g. libc_rtld)
2616 * type 1 errno accessed by GOT entry (dynamically linked programs)
2617 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
55b88cae 2618 */
bc633d63 2619struct tls_tcb *
a1eee96a 2620allocate_tls(Obj_Entry *objs)
55b88cae
DX
2621{
2622 Obj_Entry *obj;
bc633d63 2623 size_t data_size;
bc633d63
MD
2624 size_t dtv_size;
2625 struct tls_tcb *tcb;
a1eee96a 2626 Elf_Addr *dtv;
bc633d63 2627 Elf_Addr addr;
55b88cae 2628
bc633d63
MD
2629 /*
2630 * Allocate the new TCB. static TLS storage is placed just before the
2631 * TCB to support the %gs:OFFSET (negative offset) model.
2632 */
bc633d63
MD
2633 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2634 ~RTLD_STATIC_TLS_ALIGN_MASK;
f20fd431 2635 tcb = malloc(data_size + sizeof(*tcb));
bc633d63 2636 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
55b88cae 2637
bc633d63
MD
2638 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
2639 dtv = malloc(dtv_size);
2640 bzero(dtv, dtv_size);
55b88cae 2641
9e2ee207
JS
2642#ifdef RTLD_TCB_HAS_SELF_POINTER
2643 tcb->tcb_self = tcb;
2644#endif
2645 tcb->tcb_dtv = dtv;
2646 tcb->tcb_pthread = NULL;
55b88cae
DX
2647
2648 dtv[0] = tls_dtv_generation;
2649 dtv[1] = tls_max_index;
2650
a1eee96a
MD
2651 for (obj = objs; obj; obj = obj->next) {
2652 if (obj->tlsoffset) {
2653 addr = (Elf_Addr)tcb - obj->tlsoffset;
2654 memset((void *)(addr + obj->tlsinitsize),
2655 0, obj->tlssize - obj->tlsinitsize);
2656 if (obj->tlsinit)
2657 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
2658 dtv[obj->tlsindex + 1] = addr;
55b88cae
DX
2659 }
2660 }
bc633d63 2661 return(tcb);
55b88cae
DX
2662}
2663
2664void
f20fd431 2665free_tls(struct tls_tcb *tcb)
bc633d63
MD
2666{
2667 Elf_Addr *dtv;
2668 int dtv_size, i;
2669 Elf_Addr tls_start, tls_end;
2670 size_t data_size;
2671
2672 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
2673 ~RTLD_STATIC_TLS_ALIGN_MASK;
9e2ee207 2674 dtv = tcb->tcb_dtv;
bc633d63
MD
2675 dtv_size = dtv[1];
2676 tls_end = (Elf_Addr)tcb;
2677 tls_start = (Elf_Addr)tcb - data_size;
2678 for (i = 0; i < dtv_size; i++) {
2679 if (dtv[i+2] != NULL && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
2680 free((void *)dtv[i+2]);
55b88cae
DX
2681 }
2682 }
bc633d63 2683 free((void *)tls_start);
55b88cae
DX
2684}
2685
9e2ee207
JS
2686#else
2687#error "Unsupported TLS layout"
55b88cae
DX
2688#endif
2689
2690/*
2691 * Allocate TLS block for module with given index.
2692 */
2693void *
2694allocate_module_tls(int index)
2695{
2696 Obj_Entry* obj;
2697 char* p;
2698
2699 for (obj = obj_list; obj; obj = obj->next) {
2700 if (obj->tlsindex == index)
2701 break;
2702 }
2703 if (!obj) {
2704 _rtld_error("Can't find module with TLS index %d", index);
2705 die();
2706 }
2707
2708 p = malloc(obj->tlssize);
2709 memcpy(p, obj->tlsinit, obj->tlsinitsize);
2710 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
2711
2712 return p;
2713}
2714
2715bool
2716allocate_tls_offset(Obj_Entry *obj)
2717{
2718 size_t off;
2719
2720 if (obj->tls_done)
2721 return true;
2722
2723 if (obj->tlssize == 0) {
2724 obj->tls_done = true;
2725 return true;
2726 }
2727
2728 if (obj->tlsindex == 1)
2729 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
2730 else
2731 off = calculate_tls_offset(tls_last_offset, tls_last_size,
2732 obj->tlssize, obj->tlsalign);
2733
2734 /*
2735 * If we have already fixed the size of the static TLS block, we
2736 * must stay within that size. When allocating the static TLS, we
2737 * leave a small amount of space spare to be used for dynamically
2738 * loading modules which use static TLS.
2739 */
2740 if (tls_static_space) {
2741 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
2742 return false;
2743 }
2744
2745 tls_last_offset = obj->tlsoffset = off;
2746 tls_last_size = obj->tlssize;
2747 obj->tls_done = true;
2748
2749 return true;
2750}
2751
2752void
2753free_tls_offset(Obj_Entry *obj)
2754{
9e2ee207 2755#ifdef RTLD_STATIC_TLS_VARIANT_II
55b88cae
DX
2756 /*
2757 * If we were the last thing to allocate out of the static TLS
2758 * block, we give our space back to the 'allocator'. This is a
2759 * simplistic workaround to allow libGL.so.1 to be loaded and
2760 * unloaded multiple times. We only handle the Variant II
2761 * mechanism for now - this really needs a proper allocator.
2762 */
2763 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
2764 == calculate_tls_end(tls_last_offset, tls_last_size)) {
2765 tls_last_offset -= obj->tlssize;
2766 tls_last_size = 0;
2767 }
2768#endif
2769}
2770
bc633d63 2771struct tls_tcb *
a1eee96a 2772_rtld_allocate_tls(void)
55b88cae 2773{
bc633d63 2774 struct tls_tcb *new_tcb;
55b88cae
DX
2775
2776 wlock_acquire();
a1eee96a 2777 new_tcb = allocate_tls(obj_list);
55b88cae
DX
2778 wlock_release();
2779
bc633d63 2780 return (new_tcb);
55b88cae
DX
2781}
2782
2783void
f20fd431 2784_rtld_free_tls(struct tls_tcb *tcb)
55b88cae
DX
2785{
2786 wlock_acquire();
f20fd431 2787 free_tls(tcb);
55b88cae
DX
2788 wlock_release();
2789}
bc633d63 2790