/*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Kenneth Almquist. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. * * @(#)exec.c 8.4 (Berkeley) 6/8/95 * $FreeBSD: src/bin/sh/exec.c,v 1.55 2012/02/11 21:06:45 jilles Exp $ */ #include #include #include #include #include #include #include /* * When commands are first encountered, they are entered in a hash table. * This ensures that a full path search will not have to be done for them * on each invocation. * * We should investigate converting to a linear search, even though that * would make the command name "hash" a misnomer. */ #include "shell.h" #include "main.h" #include "nodes.h" #include "parser.h" #include "redir.h" #include "eval.h" #include "exec.h" #include "builtins.h" #include "var.h" #include "options.h" #include "input.h" #include "output.h" #include "syntax.h" #include "memalloc.h" #include "error.h" #include "init.h" #include "mystring.h" #include "show.h" #include "jobs.h" #include "alias.h" #define CMDTABLESIZE 31 /* should be prime */ #define ARB 1 /* actual size determined at run time */ struct tblentry { struct tblentry *next; /* next entry in hash chain */ union param param; /* definition of builtin function */ int special; /* flag for special builtin commands */ short cmdtype; /* index identifying command */ char rehash; /* if set, cd done since entry created */ char cmdname[ARB]; /* name of command */ }; static struct tblentry *cmdtable[CMDTABLESIZE]; int exerrno = 0; /* Last exec error */ static void tryexec(char *, char **, char **); static void printentry(struct tblentry *, int); static struct tblentry *cmdlookup(const char *, int); static void delete_cmd_entry(void); static void addcmdentry(const char *, struct cmdentry *); /* * Exec a program. Never returns. If you change this routine, you may * have to change the find_command routine as well. * * The argv array may be changed and element argv[-1] should be writable. */ void shellexec(char **argv, char **envp, const char *path, int idx) { char *cmdname; int e; if (strchr(argv[0], '/') != NULL) { tryexec(argv[0], argv, envp); e = errno; } else { e = ENOENT; while ((cmdname = padvance(&path, argv[0])) != NULL) { if (--idx < 0 && pathopt == NULL) { tryexec(cmdname, argv, envp); if (errno != ENOENT && errno != ENOTDIR) e = errno; if (e == ENOEXEC) break; } stunalloc(cmdname); } } /* Map to POSIX errors */ if (e == ENOENT || e == ENOTDIR) { exerrno = 127; exerror(EXEXEC, "%s: not found", argv[0]); } else { exerrno = 126; exerror(EXEXEC, "%s: %s", argv[0], strerror(e)); } } static void tryexec(char *cmd, char **argv, char **envp) { int e, in; ssize_t n; char buf[256]; execve(cmd, argv, envp); e = errno; if (e == ENOEXEC) { INTOFF; in = open(cmd, O_RDONLY | O_NONBLOCK); if (in != -1) { n = pread(in, buf, sizeof buf, 0); close(in); if (n > 0 && memchr(buf, '\0', n) != NULL) { errno = ENOEXEC; return; } } *argv = cmd; *--argv = __DECONST(char *, _PATH_BSHELL); execve(_PATH_BSHELL, argv, envp); } errno = e; } /* * Do a path search. The variable path (passed by reference) should be * set to the start of the path before the first call; padvance will update * this value as it proceeds. Successive calls to padvance will return * the possible path expansions in sequence. If an option (indicated by * a percent sign) appears in the path entry then the global variable * pathopt will be set to point to it; otherwise pathopt will be set to * NULL. */ const char *pathopt; char * padvance(const char **path, const char *name) { const char *p, *start; char *q; int len; if (*path == NULL) return NULL; start = *path; for (p = start; *p && *p != ':' && *p != '%'; p++) ; /* nothing */ len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ STARTSTACKSTR(q); CHECKSTRSPACE(len, q); if (p != start) { memcpy(q, start, p - start); q += p - start; *q++ = '/'; } strcpy(q, name); pathopt = NULL; if (*p == '%') { pathopt = ++p; while (*p && *p != ':') p++; } if (*p == ':') *path = p + 1; else *path = NULL; return stalloc(len); } /*** Command hashing code ***/ int hashcmd(int argc __unused, char **argv __unused) { struct tblentry **pp; struct tblentry *cmdp; int c; int verbose; struct cmdentry entry; char *name; int errors; errors = 0; verbose = 0; while ((c = nextopt("rv")) != '\0') { if (c == 'r') { clearcmdentry(); } else if (c == 'v') { verbose++; } } if (*argptr == NULL) { for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { if (cmdp->cmdtype == CMDNORMAL) printentry(cmdp, verbose); } } return 0; } while ((name = *argptr) != NULL) { if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDNORMAL) delete_cmd_entry(); find_command(name, &entry, DO_ERR, pathval()); if (entry.cmdtype == CMDUNKNOWN) errors = 1; else if (verbose) { cmdp = cmdlookup(name, 0); if (cmdp != NULL) printentry(cmdp, verbose); else { outfmt(out2, "%s: not found\n", name); errors = 1; } flushall(); } argptr++; } return errors; } static void printentry(struct tblentry *cmdp, int verbose) { int idx; const char *path; char *name; if (cmdp->cmdtype == CMDNORMAL) { idx = cmdp->param.index; path = pathval(); do { name = padvance(&path, cmdp->cmdname); stunalloc(name); } while (--idx >= 0); out1str(name); } else if (cmdp->cmdtype == CMDBUILTIN) { out1fmt("builtin %s", cmdp->cmdname); } else if (cmdp->cmdtype == CMDFUNCTION) { out1fmt("function %s", cmdp->cmdname); if (verbose) { INTOFF; name = commandtext(getfuncnode(cmdp->param.func)); out1c(' '); out1str(name); ckfree(name); INTON; } #ifdef DEBUG } else { error("internal error: cmdtype %d", cmdp->cmdtype); #endif } if (cmdp->rehash) out1c('*'); out1c('\n'); } /* * Resolve a command name. If you change this routine, you may have to * change the shellexec routine as well. */ void find_command(const char *name, struct cmdentry *entry, int act, const char *path) { struct tblentry *cmdp, loc_cmd; int idx; int prev; char *fullname; struct stat statb; int e; int i; int spec; /* If name contains a slash, don't use the hash table */ if (strchr(name, '/') != NULL) { entry->cmdtype = CMDNORMAL; entry->u.index = 0; return; } /* If name is in the table, and not invalidated by cd, we're done */ if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) { if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC) cmdp = NULL; else goto success; } /* Check for builtin next */ if ((i = find_builtin(name, &spec)) >= 0) { INTOFF; cmdp = cmdlookup(name, 1); if (cmdp->cmdtype == CMDFUNCTION) cmdp = &loc_cmd; cmdp->cmdtype = CMDBUILTIN; cmdp->param.index = i; cmdp->special = spec; INTON; goto success; } /* We have to search path. */ prev = -1; /* where to start */ if (cmdp) { /* doing a rehash */ if (cmdp->cmdtype == CMDBUILTIN) prev = -1; else prev = cmdp->param.index; } e = ENOENT; idx = -1; loop: while ((fullname = padvance(&path, name)) != NULL) { stunalloc(fullname); idx++; if (pathopt) { if (prefix("func", pathopt)) { /* handled below */ } else { goto loop; /* ignore unimplemented options */ } } /* if rehash, don't redo absolute path names */ if (fullname[0] == '/' && idx <= prev) { if (idx < prev) goto loop; TRACE(("searchexec \"%s\": no change\n", name)); goto success; } if (stat(fullname, &statb) < 0) { if (errno != ENOENT && errno != ENOTDIR) e = errno; goto loop; } e = EACCES; /* if we fail, this will be the error */ if (!S_ISREG(statb.st_mode)) goto loop; if (pathopt) { /* this is a %func directory */ stalloc(strlen(fullname) + 1); readcmdfile(fullname); if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) error("%s not defined in %s", name, fullname); stunalloc(fullname); goto success; } #ifdef notdef if (statb.st_uid == geteuid()) { if ((statb.st_mode & 0100) == 0) goto loop; } else if (statb.st_gid == getegid()) { if ((statb.st_mode & 010) == 0) goto loop; } else { if ((statb.st_mode & 01) == 0) goto loop; } #endif TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); INTOFF; cmdp = cmdlookup(name, 1); if (cmdp->cmdtype == CMDFUNCTION) cmdp = &loc_cmd; cmdp->cmdtype = CMDNORMAL; cmdp->param.index = idx; INTON; goto success; } /* We failed. If there was an entry for this command, delete it */ if (cmdp && cmdp->cmdtype != CMDFUNCTION) delete_cmd_entry(); if (act & DO_ERR) { if (e == ENOENT || e == ENOTDIR) outfmt(out2, "%s: not found\n", name); else outfmt(out2, "%s: %s\n", name, strerror(e)); } entry->cmdtype = CMDUNKNOWN; entry->u.index = 0; return; success: if (cmdp) { cmdp->rehash = 0; entry->cmdtype = cmdp->cmdtype; entry->u = cmdp->param; entry->special = cmdp->special; } else entry->cmdtype = CMDUNKNOWN; } /* * Search the table of builtin commands. */ int find_builtin(const char *name, int *special) { const struct builtincmd *bp; for (bp = builtincmd ; bp->name ; bp++) { if (*bp->name == *name && equal(bp->name, name)) { *special = bp->special; return bp->code; } } return -1; } /* * Called when a cd is done. Marks all commands so the next time they * are executed they will be rehashed. */ void hashcd(void) { struct tblentry **pp; struct tblentry *cmdp; for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { if (cmdp->cmdtype == CMDNORMAL) cmdp->rehash = 1; } } } /* * Called before PATH is changed. The argument is the new value of PATH; * pathval() still returns the old value at this point. Called with * interrupts off. */ void changepath(const char *newval __unused) { clearcmdentry(); } /* * Clear out command entries. The argument specifies the first entry in * PATH which has changed. */ void clearcmdentry(void) { struct tblentry **tblp; struct tblentry **pp; struct tblentry *cmdp; INTOFF; for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { pp = tblp; while ((cmdp = *pp) != NULL) { if (cmdp->cmdtype == CMDNORMAL) { *pp = cmdp->next; ckfree(cmdp); } else { pp = &cmdp->next; } } } INTON; } /* * Locate a command in the command hash table. If "add" is nonzero, * add the command to the table if it is not already present. The * variable "lastcmdentry" is set to point to the address of the link * pointing to the entry, so that delete_cmd_entry can delete the * entry. */ static struct tblentry **lastcmdentry; static struct tblentry * cmdlookup(const char *name, int add) { int hashval; const char *p; struct tblentry *cmdp; struct tblentry **pp; p = name; hashval = *p << 4; while (*p) hashval += *p++; hashval &= 0x7FFF; pp = &cmdtable[hashval % CMDTABLESIZE]; for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { if (equal(cmdp->cmdname, name)) break; pp = &cmdp->next; } if (add && cmdp == NULL) { INTOFF; cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB + strlen(name) + 1); cmdp->next = NULL; cmdp->cmdtype = CMDUNKNOWN; cmdp->rehash = 0; strcpy(cmdp->cmdname, name); INTON; } lastcmdentry = pp; return cmdp; } /* * Delete the command entry returned on the last lookup. */ static void delete_cmd_entry(void) { struct tblentry *cmdp; INTOFF; cmdp = *lastcmdentry; *lastcmdentry = cmdp->next; ckfree(cmdp); INTON; } /* * Add a new command entry, replacing any existing command entry for * the same name. */ static void addcmdentry(const char *name, struct cmdentry *entry) { struct tblentry *cmdp; INTOFF; cmdp = cmdlookup(name, 1); if (cmdp->cmdtype == CMDFUNCTION) { unreffunc(cmdp->param.func); } cmdp->cmdtype = entry->cmdtype; cmdp->param = entry->u; INTON; } /* * Define a shell function. */ void defun(const char *name, union node *func) { struct cmdentry entry; INTOFF; entry.cmdtype = CMDFUNCTION; entry.u.func = copyfunc(func); addcmdentry(name, &entry); INTON; } /* * Delete a function if it exists. */ int unsetfunc(const char *name) { struct tblentry *cmdp; if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { unreffunc(cmdp->param.func); delete_cmd_entry(); } return (0); } /* * Shared code for the following builtin commands: * type, command -v, command -V */ int typecmd_impl(int argc, char **argv, int cmd, const char *path) { struct cmdentry entry; struct tblentry *cmdp; const char * const *pp; struct alias *ap; int i; int err = 0; if (path != pathval()) clearcmdentry(); for (i = 1; i < argc; i++) { /* First look at the keywords */ for (pp = parsekwd; *pp; pp++) if (**pp == *argv[i] && equal(*pp, argv[i])) break; if (*pp) { if (cmd == TYPECMD_SMALLV) out1fmt("%s\n", argv[i]); else out1fmt("%s is a shell keyword\n", argv[i]); continue; } /* Then look at the aliases */ if ((ap = lookupalias(argv[i], 1)) != NULL) { if (cmd == TYPECMD_SMALLV) out1fmt("alias %s='%s'\n", argv[i], ap->val); else out1fmt("%s is an alias for %s\n", argv[i], ap->val); continue; } /* Then check if it is a tracked alias */ if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { entry.cmdtype = cmdp->cmdtype; entry.u = cmdp->param; entry.special = cmdp->special; } else { /* Finally use brute force */ find_command(argv[i], &entry, 0, path); } switch (entry.cmdtype) { case CMDNORMAL: { if (strchr(argv[i], '/') == NULL) { const char *path2 = path; char *name; int j = entry.u.index; do { name = padvance(&path2, argv[i]); stunalloc(name); } while (--j >= 0); if (cmd == TYPECMD_SMALLV) out1fmt("%s\n", name); else out1fmt("%s is%s %s\n", argv[i], (cmdp && cmd == TYPECMD_TYPE) ? " a tracked alias for" : "", name); } else { if (access(argv[i], X_OK) == 0) { if (cmd == TYPECMD_SMALLV) out1fmt("%s\n", argv[i]); else out1fmt("%s is %s\n", argv[i], argv[i]); } else { if (cmd != TYPECMD_SMALLV) outfmt(out2, "%s: %s\n", argv[i], strerror(errno)); err |= 127; } } break; } case CMDFUNCTION: if (cmd == TYPECMD_SMALLV) out1fmt("%s\n", argv[i]); else out1fmt("%s is a shell function\n", argv[i]); break; case CMDBUILTIN: if (cmd == TYPECMD_SMALLV) out1fmt("%s\n", argv[i]); else if (entry.special) out1fmt("%s is a special shell builtin\n", argv[i]); else out1fmt("%s is a shell builtin\n", argv[i]); break; default: if (cmd != TYPECMD_SMALLV) outfmt(out2, "%s: not found\n", argv[i]); err |= 127; break; } } if (path != pathval()) clearcmdentry(); return err; } /* * Locate and print what a word is... */ int typecmd(int argc, char **argv) { return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1)); }