2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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35 static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95";
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/types.h>
51 * When commands are first encountered, they are entered in a hash table.
52 * This ensures that a full path search will not have to be done for them
55 * We should investigate converting to a linear search, even though that
56 * would make the command name "hash" a misnomer.
80 #define CMDTABLESIZE 31 /* should be prime */
85 struct tblentry *next; /* next entry in hash chain */
86 union param param; /* definition of builtin function */
87 int special; /* flag for special builtin commands */
88 signed char cmdtype; /* index identifying command */
89 char cmdname[]; /* name of command */
93 static struct tblentry *cmdtable[CMDTABLESIZE];
94 static int cmdtable_cd = 0; /* cmdtable contains cd-dependent entries */
95 int exerrno = 0; /* Last exec error */
98 static void tryexec(char *, char **, char **);
99 static void printentry(struct tblentry *, int);
100 static struct tblentry *cmdlookup(const char *, int);
101 static void delete_cmd_entry(void);
102 static void addcmdentry(const char *, struct cmdentry *);
107 * Exec a program. Never returns. If you change this routine, you may
108 * have to change the find_command routine as well.
110 * The argv array may be changed and element argv[-1] should be writable.
114 shellexec(char **argv, char **envp, const char *path, int idx)
120 if (strchr(argv[0], '/') != NULL) {
121 tryexec(argv[0], argv, envp);
125 while ((cmdname = padvance(&path, &opt, argv[0])) != NULL) {
126 if (--idx < 0 && opt == NULL) {
127 tryexec(cmdname, argv, envp);
128 if (errno != ENOENT && errno != ENOTDIR)
137 /* Map to POSIX errors */
138 if (e == ENOENT || e == ENOTDIR) {
140 exerror(EXEXEC, "%s: not found", argv[0]);
143 exerror(EXEXEC, "%s: %s", argv[0], strerror(e));
149 isbinary(const char *data, size_t len)
154 nul = memchr(data, '\0', len);
158 * POSIX says we shall allow execution if the initial part intended
159 * to be parsed by the shell consists of characters and does not
160 * contain the NUL character. This allows concatenating a shell
161 * script (ending with exec or exit) and a binary payload.
163 * In order to reject common binary files such as PNG images, check
164 * that there is a lowercase letter or expansion before the last
165 * newline before the NUL character, in addition to the check for
166 * the newline character suggested by POSIX.
169 for (p = data; *p != '\0'; p++) {
170 if ((*p >= 'a' && *p <= 'z') || *p == '$' || *p == '`')
172 if (hasletter && *p == '\n')
180 tryexec(char *cmd, char **argv, char **envp)
186 execve(cmd, argv, envp);
190 in = open(cmd, O_RDONLY | O_NONBLOCK);
192 n = pread(in, buf, sizeof buf, 0);
194 if (n > 0 && isbinary(buf, n)) {
200 *--argv = __DECONST(char *, _PATH_BSHELL);
201 execve(_PATH_BSHELL, argv, envp);
207 * Do a path search. The variable path (passed by reference) should be
208 * set to the start of the path before the first call; padvance will update
209 * this value as it proceeds. Successive calls to padvance will return
210 * the possible path expansions in sequence. If popt is not NULL, options
211 * are processed: if an option (indicated by a percent sign) appears in
212 * the path entry then *popt will be set to point to it; else *popt will be
213 * set to NULL. If popt is NULL, percent signs are not special.
217 padvance(const char **path, const char **popt, const char *name)
219 const char *p, *start;
227 for (p = start; *p && *p != ':' && *p != '%'; p++)
230 for (p = start; *p && *p != ':'; p++)
232 namelen = strlen(name);
233 len = p - start + namelen + 2; /* "2" is for '/' and '\0' */
235 CHECKSTRSPACE(len, q);
237 memcpy(q, start, p - start);
241 memcpy(q, name, namelen + 1);
245 while (*p && *p != ':') p++;
258 /*** Command hashing code ***/
262 hashcmd(int argc __unused, char **argv __unused)
264 struct tblentry **pp;
265 struct tblentry *cmdp;
268 struct cmdentry entry;
274 while ((c = nextopt("rv")) != '\0') {
277 } else if (c == 'v') {
281 if (*argptr == NULL) {
282 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
283 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
284 if (cmdp->cmdtype == CMDNORMAL)
285 printentry(cmdp, verbose);
290 while ((name = *argptr) != NULL) {
291 if ((cmdp = cmdlookup(name, 0)) != NULL
292 && cmdp->cmdtype == CMDNORMAL)
294 find_command(name, &entry, DO_ERR, pathval());
295 if (entry.cmdtype == CMDUNKNOWN)
298 cmdp = cmdlookup(name, 0);
300 printentry(cmdp, verbose);
302 outfmt(out2, "%s: not found\n", name);
314 printentry(struct tblentry *cmdp, int verbose)
317 const char *path, *opt;
320 if (cmdp->cmdtype == CMDNORMAL) {
321 idx = cmdp->param.index;
324 name = padvance(&path, &opt, cmdp->cmdname);
326 } while (--idx >= 0);
328 } else if (cmdp->cmdtype == CMDBUILTIN) {
329 out1fmt("builtin %s", cmdp->cmdname);
330 } else if (cmdp->cmdtype == CMDFUNCTION) {
331 out1fmt("function %s", cmdp->cmdname);
334 name = commandtext(getfuncnode(cmdp->param.func));
342 error("internal error: cmdtype %d", cmdp->cmdtype);
351 * Resolve a command name. If you change this routine, you may have to
352 * change the shellexec routine as well.
356 find_command(const char *name, struct cmdentry *entry, int act,
359 struct tblentry *cmdp, loc_cmd;
369 /* If name contains a slash, don't use the hash table */
370 if (strchr(name, '/') != NULL) {
371 entry->cmdtype = CMDNORMAL;
379 /* If name is in the table, we're done */
380 if ((cmdp = cmdlookup(name, 0)) != NULL) {
381 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
387 /* Check for builtin next */
388 if ((i = find_builtin(name, &spec)) >= 0) {
390 cmdp = cmdlookup(name, 1);
391 if (cmdp->cmdtype == CMDFUNCTION)
393 cmdp->cmdtype = CMDBUILTIN;
394 cmdp->param.index = i;
395 cmdp->special = spec;
400 /* We have to search path. */
404 for (;(fullname = padvance(&path, &opt, name)) != NULL;
405 stunalloc(fullname)) {
408 if (strncmp(opt, "func", 4) == 0) {
411 continue; /* ignore unimplemented options */
414 if (fullname[0] != '/')
416 if (stat(fullname, &statb) < 0) {
417 if (errno != ENOENT && errno != ENOTDIR)
421 e = EACCES; /* if we fail, this will be the error */
422 if (!S_ISREG(statb.st_mode))
424 if (opt) { /* this is a %func directory */
425 readcmdfile(fullname);
426 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
427 error("%s not defined in %s", name, fullname);
432 if (statb.st_uid == geteuid()) {
433 if ((statb.st_mode & 0100) == 0)
435 } else if (statb.st_gid == getegid()) {
436 if ((statb.st_mode & 010) == 0)
439 if ((statb.st_mode & 01) == 0)
443 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
446 cmdp = cmdlookup(name, 1);
447 if (cmdp->cmdtype == CMDFUNCTION)
449 cmdp->cmdtype = CMDNORMAL;
450 cmdp->param.index = idx;
457 if (e == ENOENT || e == ENOTDIR)
458 outfmt(out2, "%s: not found\n", name);
460 outfmt(out2, "%s: %s\n", name, strerror(e));
462 entry->cmdtype = CMDUNKNOWN;
470 entry->cmdtype = cmdp->cmdtype;
471 entry->u = cmdp->param;
472 entry->special = cmdp->special;
478 * Search the table of builtin commands.
482 find_builtin(const char *name, int *special)
484 const unsigned char *bp;
488 for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
489 if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
490 *special = (bp[1] & BUILTIN_SPECIAL) != 0;
491 return bp[1] & ~BUILTIN_SPECIAL;
500 * Called when a cd is done. If any entry in cmdtable depends on the current
501 * directory, simply clear cmdtable completely.
514 * Called before PATH is changed. The argument is the new value of PATH;
515 * pathval() still returns the old value at this point. Called with
520 changepath(const char *newval __unused)
527 * Clear out cached utility locations.
533 struct tblentry **tblp;
534 struct tblentry **pp;
535 struct tblentry *cmdp;
538 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
540 while ((cmdp = *pp) != NULL) {
541 if (cmdp->cmdtype == CMDNORMAL) {
555 * Locate a command in the command hash table. If "add" is nonzero,
556 * add the command to the table if it is not already present. The
557 * variable "lastcmdentry" is set to point to the address of the link
558 * pointing to the entry, so that delete_cmd_entry can delete the
562 static struct tblentry **lastcmdentry;
565 static struct tblentry *
566 cmdlookup(const char *name, int add)
568 unsigned int hashval;
570 struct tblentry *cmdp;
571 struct tblentry **pp;
575 hashval = (unsigned char)*p << 4;
578 pp = &cmdtable[hashval % CMDTABLESIZE];
579 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
580 if (equal(cmdp->cmdname, name))
584 if (add && cmdp == NULL) {
587 cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
589 cmdp->cmdtype = CMDUNKNOWN;
590 memcpy(cmdp->cmdname, name, len + 1);
598 * Delete the command entry returned on the last lookup.
602 delete_cmd_entry(void)
604 struct tblentry *cmdp;
607 cmdp = *lastcmdentry;
608 *lastcmdentry = cmdp->next;
616 * Add a new command entry, replacing any existing command entry for
621 addcmdentry(const char *name, struct cmdentry *entry)
623 struct tblentry *cmdp;
626 cmdp = cmdlookup(name, 1);
627 if (cmdp->cmdtype == CMDFUNCTION) {
628 unreffunc(cmdp->param.func);
630 cmdp->cmdtype = entry->cmdtype;
631 cmdp->param = entry->u;
632 cmdp->special = entry->special;
638 * Define a shell function.
642 defun(const char *name, union node *func)
644 struct cmdentry entry;
647 entry.cmdtype = CMDFUNCTION;
648 entry.u.func = copyfunc(func);
650 addcmdentry(name, &entry);
656 * Delete a function if it exists.
657 * Called with interrupts off.
661 unsetfunc(const char *name)
663 struct tblentry *cmdp;
665 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
666 unreffunc(cmdp->param.func);
675 * Check if a function by a certain name exists.
678 isfunc(const char *name)
680 struct tblentry *cmdp;
681 cmdp = cmdlookup(name, 0);
682 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
687 * Shared code for the following builtin commands:
688 * type, command -v, command -V
692 typecmd_impl(int argc, char **argv, int cmd, const char *path)
694 struct cmdentry entry;
695 struct tblentry *cmdp;
696 const char *const *pp;
701 if (path != pathval())
704 for (i = 1; i < argc; i++) {
705 /* First look at the keywords */
706 for (pp = parsekwd; *pp; pp++)
707 if (**pp == *argv[i] && equal(*pp, argv[i]))
711 if (cmd == TYPECMD_SMALLV)
712 out1fmt("%s\n", argv[i]);
714 out1fmt("%s is a shell keyword\n", argv[i]);
718 /* Then look at the aliases */
719 if ((ap = lookupalias(argv[i], 1)) != NULL) {
720 if (cmd == TYPECMD_SMALLV) {
721 out1fmt("alias %s=", argv[i]);
723 outcslow('\n', out1);
725 out1fmt("%s is an alias for %s\n", argv[i],
730 /* Then check if it is a tracked alias */
731 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
732 entry.cmdtype = cmdp->cmdtype;
733 entry.u = cmdp->param;
734 entry.special = cmdp->special;
737 /* Finally use brute force */
738 find_command(argv[i], &entry, 0, path);
741 switch (entry.cmdtype) {
743 if (strchr(argv[i], '/') == NULL) {
744 const char *path2 = path;
747 int j = entry.u.index;
749 name = padvance(&path2, &opt2, argv[i]);
752 if (cmd == TYPECMD_SMALLV)
753 out1fmt("%s\n", name);
755 out1fmt("%s is%s %s\n", argv[i],
756 (cmdp && cmd == TYPECMD_TYPE) ?
757 " a tracked alias for" : "",
760 if (eaccess(argv[i], X_OK) == 0) {
761 if (cmd == TYPECMD_SMALLV)
762 out1fmt("%s\n", argv[i]);
764 out1fmt("%s is %s\n", argv[i],
767 if (cmd != TYPECMD_SMALLV)
768 outfmt(out2, "%s: %s\n",
769 argv[i], strerror(errno));
776 if (cmd == TYPECMD_SMALLV)
777 out1fmt("%s\n", argv[i]);
779 out1fmt("%s is a shell function\n", argv[i]);
783 if (cmd == TYPECMD_SMALLV)
784 out1fmt("%s\n", argv[i]);
785 else if (entry.special)
786 out1fmt("%s is a special shell builtin\n",
789 out1fmt("%s is a shell builtin\n", argv[i]);
793 if (cmd != TYPECMD_SMALLV)
794 outfmt(out2, "%s: not found\n", argv[i]);
800 if (path != pathval())
807 * Locate and print what a word is...
811 typecmd(int argc, char **argv)
813 if (argc > 2 && strcmp(argv[1], "--") == 0)
815 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));