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 */
97 static void tryexec(char *, char **, char **);
98 static void printentry(struct tblentry *, int);
99 static struct tblentry *cmdlookup(const char *, int);
100 static void delete_cmd_entry(void);
101 static void addcmdentry(const char *, struct cmdentry *);
106 * Exec a program. Never returns. If you change this routine, you may
107 * have to change the find_command routine as well.
109 * The argv array may be changed and element argv[-1] should be writable.
113 shellexec(char **argv, char **envp, const char *path, int idx)
119 if (strchr(argv[0], '/') != NULL) {
120 tryexec(argv[0], argv, envp);
124 while ((cmdname = padvance(&path, &opt, argv[0])) != NULL) {
125 if (--idx < 0 && opt == NULL) {
126 tryexec(cmdname, argv, envp);
127 if (errno != ENOENT && errno != ENOTDIR)
136 /* Map to POSIX errors */
137 if (e == ENOENT || e == ENOTDIR)
138 errorwithstatus(127, "%s: not found", argv[0]);
140 errorwithstatus(126, "%s: %s", argv[0], strerror(e));
145 isbinary(const char *data, size_t len)
150 nul = memchr(data, '\0', len);
154 * POSIX says we shall allow execution if the initial part intended
155 * to be parsed by the shell consists of characters and does not
156 * contain the NUL character. This allows concatenating a shell
157 * script (ending with exec or exit) and a binary payload.
159 * In order to reject common binary files such as PNG images, check
160 * that there is a lowercase letter or expansion before the last
161 * newline before the NUL character, in addition to the check for
162 * the newline character suggested by POSIX.
165 for (p = data; *p != '\0'; p++) {
166 if ((*p >= 'a' && *p <= 'z') || *p == '$' || *p == '`')
168 if (hasletter && *p == '\n')
176 tryexec(char *cmd, char **argv, char **envp)
182 execve(cmd, argv, envp);
186 in = open(cmd, O_RDONLY | O_NONBLOCK);
188 n = pread(in, buf, sizeof buf, 0);
190 if (n > 0 && isbinary(buf, n)) {
196 *--argv = __DECONST(char *, _PATH_BSHELL);
197 execve(_PATH_BSHELL, argv, envp);
203 * Do a path search. The variable path (passed by reference) should be
204 * set to the start of the path before the first call; padvance will update
205 * this value as it proceeds. Successive calls to padvance will return
206 * the possible path expansions in sequence. If popt is not NULL, options
207 * are processed: if an option (indicated by a percent sign) appears in
208 * the path entry then *popt will be set to point to it; else *popt will be
209 * set to NULL. If popt is NULL, percent signs are not special.
213 padvance(const char **path, const char **popt, const char *name)
215 const char *p, *start;
223 for (p = start; *p && *p != ':' && *p != '%'; p++)
226 for (p = start; *p && *p != ':'; p++)
228 namelen = strlen(name);
229 len = p - start + namelen + 2; /* "2" is for '/' and '\0' */
231 CHECKSTRSPACE(len, q);
233 memcpy(q, start, p - start);
237 memcpy(q, name, namelen + 1);
241 while (*p && *p != ':') p++;
254 /*** Command hashing code ***/
258 hashcmd(int argc __unused, char **argv __unused)
260 struct tblentry **pp;
261 struct tblentry *cmdp;
264 struct cmdentry entry;
270 while ((c = nextopt("rv")) != '\0') {
273 } else if (c == 'v') {
277 if (*argptr == NULL) {
278 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
279 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
280 if (cmdp->cmdtype == CMDNORMAL)
281 printentry(cmdp, verbose);
286 while ((name = *argptr) != NULL) {
287 if ((cmdp = cmdlookup(name, 0)) != NULL
288 && cmdp->cmdtype == CMDNORMAL)
290 find_command(name, &entry, DO_ERR, pathval());
291 if (entry.cmdtype == CMDUNKNOWN)
294 cmdp = cmdlookup(name, 0);
296 printentry(cmdp, verbose);
298 outfmt(out2, "%s: not found\n", name);
310 printentry(struct tblentry *cmdp, int verbose)
313 const char *path, *opt;
316 if (cmdp->cmdtype == CMDNORMAL) {
317 idx = cmdp->param.index;
320 name = padvance(&path, &opt, cmdp->cmdname);
322 } while (--idx >= 0);
324 } else if (cmdp->cmdtype == CMDBUILTIN) {
325 out1fmt("builtin %s", cmdp->cmdname);
326 } else if (cmdp->cmdtype == CMDFUNCTION) {
327 out1fmt("function %s", cmdp->cmdname);
330 name = commandtext(getfuncnode(cmdp->param.func));
338 error("internal error: cmdtype %d", cmdp->cmdtype);
347 * Resolve a command name. If you change this routine, you may have to
348 * change the shellexec routine as well.
352 find_command(const char *name, struct cmdentry *entry, int act,
355 struct tblentry *cmdp, loc_cmd;
365 /* If name contains a slash, don't use the hash table */
366 if (strchr(name, '/') != NULL) {
367 entry->cmdtype = CMDNORMAL;
375 /* If name is in the table, we're done */
376 if ((cmdp = cmdlookup(name, 0)) != NULL) {
377 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
383 /* Check for builtin next */
384 if ((i = find_builtin(name, &spec)) >= 0) {
386 cmdp = cmdlookup(name, 1);
387 if (cmdp->cmdtype == CMDFUNCTION)
389 cmdp->cmdtype = CMDBUILTIN;
390 cmdp->param.index = i;
391 cmdp->special = spec;
396 /* We have to search path. */
400 for (;(fullname = padvance(&path, &opt, name)) != NULL;
401 stunalloc(fullname)) {
404 if (strncmp(opt, "func", 4) == 0) {
407 continue; /* ignore unimplemented options */
410 if (fullname[0] != '/')
412 if (stat(fullname, &statb) < 0) {
413 if (errno != ENOENT && errno != ENOTDIR)
417 e = EACCES; /* if we fail, this will be the error */
418 if (!S_ISREG(statb.st_mode))
420 if (opt) { /* this is a %func directory */
421 readcmdfile(fullname);
422 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
423 error("%s not defined in %s", name, fullname);
428 if (statb.st_uid == geteuid()) {
429 if ((statb.st_mode & 0100) == 0)
431 } else if (statb.st_gid == getegid()) {
432 if ((statb.st_mode & 010) == 0)
435 if ((statb.st_mode & 01) == 0)
439 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
442 cmdp = cmdlookup(name, 1);
443 if (cmdp->cmdtype == CMDFUNCTION)
445 cmdp->cmdtype = CMDNORMAL;
446 cmdp->param.index = idx;
453 if (e == ENOENT || e == ENOTDIR)
454 outfmt(out2, "%s: not found\n", name);
456 outfmt(out2, "%s: %s\n", name, strerror(e));
458 entry->cmdtype = CMDUNKNOWN;
466 entry->cmdtype = cmdp->cmdtype;
467 entry->u = cmdp->param;
468 entry->special = cmdp->special;
474 * Search the table of builtin commands.
478 find_builtin(const char *name, int *special)
480 const unsigned char *bp;
484 for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
485 if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
486 *special = (bp[1] & BUILTIN_SPECIAL) != 0;
487 return bp[1] & ~BUILTIN_SPECIAL;
496 * Called when a cd is done. If any entry in cmdtable depends on the current
497 * directory, simply clear cmdtable completely.
510 * Called before PATH is changed. The argument is the new value of PATH;
511 * pathval() still returns the old value at this point. Called with
516 changepath(const char *newval __unused)
523 * Clear out cached utility locations.
529 struct tblentry **tblp;
530 struct tblentry **pp;
531 struct tblentry *cmdp;
534 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
536 while ((cmdp = *pp) != NULL) {
537 if (cmdp->cmdtype == CMDNORMAL) {
551 * Locate a command in the command hash table. If "add" is nonzero,
552 * add the command to the table if it is not already present. The
553 * variable "lastcmdentry" is set to point to the address of the link
554 * pointing to the entry, so that delete_cmd_entry can delete the
558 static struct tblentry **lastcmdentry;
561 static struct tblentry *
562 cmdlookup(const char *name, int add)
564 unsigned int hashval;
566 struct tblentry *cmdp;
567 struct tblentry **pp;
571 hashval = (unsigned char)*p << 4;
574 pp = &cmdtable[hashval % CMDTABLESIZE];
575 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
576 if (equal(cmdp->cmdname, name))
580 if (add && cmdp == NULL) {
583 cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
585 cmdp->cmdtype = CMDUNKNOWN;
586 memcpy(cmdp->cmdname, name, len + 1);
594 * Delete the command entry returned on the last lookup.
598 delete_cmd_entry(void)
600 struct tblentry *cmdp;
603 cmdp = *lastcmdentry;
604 *lastcmdentry = cmdp->next;
612 * Add a new command entry, replacing any existing command entry for
617 addcmdentry(const char *name, struct cmdentry *entry)
619 struct tblentry *cmdp;
622 cmdp = cmdlookup(name, 1);
623 if (cmdp->cmdtype == CMDFUNCTION) {
624 unreffunc(cmdp->param.func);
626 cmdp->cmdtype = entry->cmdtype;
627 cmdp->param = entry->u;
628 cmdp->special = entry->special;
634 * Define a shell function.
638 defun(const char *name, union node *func)
640 struct cmdentry entry;
643 entry.cmdtype = CMDFUNCTION;
644 entry.u.func = copyfunc(func);
646 addcmdentry(name, &entry);
652 * Delete a function if it exists.
653 * Called with interrupts off.
657 unsetfunc(const char *name)
659 struct tblentry *cmdp;
661 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
662 unreffunc(cmdp->param.func);
671 * Check if a function by a certain name exists.
674 isfunc(const char *name)
676 struct tblentry *cmdp;
677 cmdp = cmdlookup(name, 0);
678 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
683 * Shared code for the following builtin commands:
684 * type, command -v, command -V
688 typecmd_impl(int argc, char **argv, int cmd, const char *path)
690 struct cmdentry entry;
691 struct tblentry *cmdp;
692 const char *const *pp;
697 if (path != pathval())
700 for (i = 1; i < argc; i++) {
701 /* First look at the keywords */
702 for (pp = parsekwd; *pp; pp++)
703 if (**pp == *argv[i] && equal(*pp, argv[i]))
707 if (cmd == TYPECMD_SMALLV)
708 out1fmt("%s\n", argv[i]);
710 out1fmt("%s is a shell keyword\n", argv[i]);
714 /* Then look at the aliases */
715 if ((ap = lookupalias(argv[i], 1)) != NULL) {
716 if (cmd == TYPECMD_SMALLV) {
717 out1fmt("alias %s=", argv[i]);
719 outcslow('\n', out1);
721 out1fmt("%s is an alias for %s\n", argv[i],
726 /* Then check if it is a tracked alias */
727 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
728 entry.cmdtype = cmdp->cmdtype;
729 entry.u = cmdp->param;
730 entry.special = cmdp->special;
733 /* Finally use brute force */
734 find_command(argv[i], &entry, 0, path);
737 switch (entry.cmdtype) {
739 if (strchr(argv[i], '/') == NULL) {
740 const char *path2 = path;
743 int j = entry.u.index;
745 name = padvance(&path2, &opt2, argv[i]);
748 if (cmd == TYPECMD_SMALLV)
749 out1fmt("%s\n", name);
751 out1fmt("%s is%s %s\n", argv[i],
752 (cmdp && cmd == TYPECMD_TYPE) ?
753 " a tracked alias for" : "",
756 if (eaccess(argv[i], X_OK) == 0) {
757 if (cmd == TYPECMD_SMALLV)
758 out1fmt("%s\n", argv[i]);
760 out1fmt("%s is %s\n", argv[i],
763 if (cmd != TYPECMD_SMALLV)
764 outfmt(out2, "%s: %s\n",
765 argv[i], strerror(errno));
772 if (cmd == TYPECMD_SMALLV)
773 out1fmt("%s\n", argv[i]);
775 out1fmt("%s is a shell function\n", argv[i]);
779 if (cmd == TYPECMD_SMALLV)
780 out1fmt("%s\n", argv[i]);
781 else if (entry.special)
782 out1fmt("%s is a special shell builtin\n",
785 out1fmt("%s is a shell builtin\n", argv[i]);
789 if (cmd != TYPECMD_SMALLV)
790 outfmt(out2, "%s: not found\n", argv[i]);
796 if (path != pathval())
803 * Locate and print what a word is...
807 typecmd(int argc, char **argv)
809 if (argc > 2 && strcmp(argv[1], "--") == 0)
811 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));