2 * Copyright (c) 1991, 1993
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33 #include <sys/types.h>
43 * When commands are first encountered, they are entered in a hash table.
44 * This ensures that a full path search will not have to be done for them
47 * We should investigate converting to a linear search, even though that
48 * would make the command name "hash" a misnomer.
72 #define CMDTABLESIZE 31 /* should be prime */
77 struct tblentry *next; /* next entry in hash chain */
78 union param param; /* definition of builtin function */
79 int special; /* flag for special builtin commands */
80 signed char cmdtype; /* index identifying command */
81 char cmdname[]; /* name of command */
85 static struct tblentry *cmdtable[CMDTABLESIZE];
86 static int cmdtable_cd = 0; /* cmdtable contains cd-dependent entries */
89 static void tryexec(char *, char **, char **);
90 static void printentry(struct tblentry *, int);
91 static struct tblentry *cmdlookup(const char *, int);
92 static void delete_cmd_entry(void);
93 static void addcmdentry(const char *, struct cmdentry *);
98 * Exec a program. Never returns. If you change this routine, you may
99 * have to change the find_command routine as well.
101 * The argv array may be changed and element argv[-1] should be writable.
105 shellexec(char **argv, char **envp, const char *path, int idx)
111 if (strchr(argv[0], '/') != NULL) {
112 tryexec(argv[0], argv, envp);
116 while ((cmdname = padvance(&path, &opt, argv[0])) != NULL) {
117 if (--idx < 0 && opt == NULL) {
118 tryexec(cmdname, argv, envp);
119 if (errno != ENOENT && errno != ENOTDIR)
128 /* Map to POSIX errors */
129 if (e == ENOENT || e == ENOTDIR)
130 errorwithstatus(127, "%s: not found", argv[0]);
132 errorwithstatus(126, "%s: %s", argv[0], strerror(e));
137 isbinary(const char *data, size_t len)
142 nul = memchr(data, '\0', len);
146 * POSIX says we shall allow execution if the initial part intended
147 * to be parsed by the shell consists of characters and does not
148 * contain the NUL character. This allows concatenating a shell
149 * script (ending with exec or exit) and a binary payload.
151 * In order to reject common binary files such as PNG images, check
152 * that there is a lowercase letter or expansion before the last
153 * newline before the NUL character, in addition to the check for
154 * the newline character suggested by POSIX.
157 for (p = data; *p != '\0'; p++) {
158 if ((*p >= 'a' && *p <= 'z') || *p == '$' || *p == '`')
160 if (hasletter && *p == '\n')
168 tryexec(char *cmd, char **argv, char **envp)
174 execve(cmd, argv, envp);
178 in = open(cmd, O_RDONLY | O_NONBLOCK);
180 n = pread(in, buf, sizeof buf, 0);
182 if (n > 0 && isbinary(buf, n)) {
188 *--argv = __DECONST(char *, _PATH_BSHELL);
189 execve(_PATH_BSHELL, argv, envp);
195 * Do a path search. The variable path (passed by reference) should be
196 * set to the start of the path before the first call; padvance will update
197 * this value as it proceeds. Successive calls to padvance will return
198 * the possible path expansions in sequence. If popt is not NULL, options
199 * are processed: if an option (indicated by a percent sign) appears in
200 * the path entry then *popt will be set to point to it; else *popt will be
201 * set to NULL. If popt is NULL, percent signs are not special.
205 padvance(const char **path, const char **popt, const char *name)
207 const char *p, *start;
215 for (p = start; *p && *p != ':' && *p != '%'; p++)
218 for (p = start; *p && *p != ':'; p++)
220 namelen = strlen(name);
221 len = p - start + namelen + 2; /* "2" is for '/' and '\0' */
223 CHECKSTRSPACE(len, q);
225 memcpy(q, start, p - start);
229 memcpy(q, name, namelen + 1);
233 while (*p && *p != ':') p++;
246 /*** Command hashing code ***/
250 hashcmd(int argc __unused, char **argv __unused)
252 struct tblentry **pp;
253 struct tblentry *cmdp;
256 struct cmdentry entry;
262 while ((c = nextopt("rv")) != '\0') {
265 } else if (c == 'v') {
269 if (*argptr == NULL) {
270 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
271 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
272 if (cmdp->cmdtype == CMDNORMAL)
273 printentry(cmdp, verbose);
278 while ((name = *argptr) != NULL) {
279 if ((cmdp = cmdlookup(name, 0)) != NULL
280 && cmdp->cmdtype == CMDNORMAL)
282 find_command(name, &entry, DO_ERR, pathval());
283 if (entry.cmdtype == CMDUNKNOWN)
286 cmdp = cmdlookup(name, 0);
288 printentry(cmdp, verbose);
290 outfmt(out2, "%s: not found\n", name);
302 printentry(struct tblentry *cmdp, int verbose)
305 const char *path, *opt;
308 if (cmdp->cmdtype == CMDNORMAL) {
309 idx = cmdp->param.index;
312 name = padvance(&path, &opt, cmdp->cmdname);
314 } while (--idx >= 0);
316 } else if (cmdp->cmdtype == CMDBUILTIN) {
317 out1fmt("builtin %s", cmdp->cmdname);
318 } else if (cmdp->cmdtype == CMDFUNCTION) {
319 out1fmt("function %s", cmdp->cmdname);
322 name = commandtext(getfuncnode(cmdp->param.func));
330 error("internal error: cmdtype %d", cmdp->cmdtype);
339 * Resolve a command name. If you change this routine, you may have to
340 * change the shellexec routine as well.
344 find_command(const char *name, struct cmdentry *entry, int act,
347 struct tblentry *cmdp, loc_cmd;
357 /* If name contains a slash, don't use the hash table */
358 if (strchr(name, '/') != NULL) {
359 entry->cmdtype = CMDNORMAL;
367 /* If name is in the table, we're done */
368 if ((cmdp = cmdlookup(name, 0)) != NULL) {
369 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
375 /* Check for builtin next */
376 if ((i = find_builtin(name, &spec)) >= 0) {
378 cmdp = cmdlookup(name, 1);
379 if (cmdp->cmdtype == CMDFUNCTION)
381 cmdp->cmdtype = CMDBUILTIN;
382 cmdp->param.index = i;
383 cmdp->special = spec;
388 /* We have to search path. */
392 for (;(fullname = padvance(&path, &opt, name)) != NULL;
393 stunalloc(fullname)) {
396 if (strncmp(opt, "func", 4) == 0) {
399 continue; /* ignore unimplemented options */
402 if (fullname[0] != '/')
404 if (stat(fullname, &statb) < 0) {
405 if (errno != ENOENT && errno != ENOTDIR)
409 e = EACCES; /* if we fail, this will be the error */
410 if (!S_ISREG(statb.st_mode))
412 if (opt) { /* this is a %func directory */
413 readcmdfile(fullname, -1 /* verify */);
414 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
415 error("%s not defined in %s", name, fullname);
420 if (statb.st_uid == geteuid()) {
421 if ((statb.st_mode & 0100) == 0)
423 } else if (statb.st_gid == getegid()) {
424 if ((statb.st_mode & 010) == 0)
427 if ((statb.st_mode & 01) == 0)
431 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
434 cmdp = cmdlookup(name, 1);
435 if (cmdp->cmdtype == CMDFUNCTION)
437 cmdp->cmdtype = CMDNORMAL;
438 cmdp->param.index = idx;
445 if (e == ENOENT || e == ENOTDIR)
446 outfmt(out2, "%s: not found\n", name);
448 outfmt(out2, "%s: %s\n", name, strerror(e));
450 entry->cmdtype = CMDUNKNOWN;
458 entry->cmdtype = cmdp->cmdtype;
459 entry->u = cmdp->param;
460 entry->special = cmdp->special;
466 * Search the table of builtin commands.
470 find_builtin(const char *name, int *special)
472 const unsigned char *bp;
476 for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
477 if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
478 *special = (bp[1] & BUILTIN_SPECIAL) != 0;
479 return bp[1] & ~BUILTIN_SPECIAL;
488 * Called when a cd is done. If any entry in cmdtable depends on the current
489 * directory, simply clear cmdtable completely.
502 * Called before PATH is changed. The argument is the new value of PATH;
503 * pathval() still returns the old value at this point. Called with
508 changepath(const char *newval __unused)
515 * Clear out cached utility locations.
521 struct tblentry **tblp;
522 struct tblentry **pp;
523 struct tblentry *cmdp;
526 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
528 while ((cmdp = *pp) != NULL) {
529 if (cmdp->cmdtype == CMDNORMAL) {
543 hashname(const char *p)
545 unsigned int hashval;
547 hashval = (unsigned char)*p << 4;
551 return (hashval % CMDTABLESIZE);
556 * Locate a command in the command hash table. If "add" is nonzero,
557 * add the command to the table if it is not already present. The
558 * variable "lastcmdentry" is set to point to the address of the link
559 * pointing to the entry, so that delete_cmd_entry can delete the
563 static struct tblentry **lastcmdentry;
566 static struct tblentry *
567 cmdlookup(const char *name, int add)
569 struct tblentry *cmdp;
570 struct tblentry **pp;
573 pp = &cmdtable[hashname(name)];
574 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
575 if (equal(cmdp->cmdname, name))
579 if (add && cmdp == NULL) {
582 cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
584 cmdp->cmdtype = CMDUNKNOWN;
585 memcpy(cmdp->cmdname, name, len + 1);
593 itercmd(const void *entry, struct cmdentry *result)
595 const struct tblentry *e = entry;
599 if (e->next != NULL) {
603 i = hashname(e->cmdname) + 1;
605 for (; i < CMDTABLESIZE; i++)
606 if ((e = cmdtable[i]) != NULL)
611 result->cmdtype = e->cmdtype;
612 result->cmdname = e->cmdname;
618 * Delete the command entry returned on the last lookup.
622 delete_cmd_entry(void)
624 struct tblentry *cmdp;
627 cmdp = *lastcmdentry;
628 *lastcmdentry = cmdp->next;
636 * Add a new command entry, replacing any existing command entry for
641 addcmdentry(const char *name, struct cmdentry *entry)
643 struct tblentry *cmdp;
646 cmdp = cmdlookup(name, 1);
647 if (cmdp->cmdtype == CMDFUNCTION) {
648 unreffunc(cmdp->param.func);
650 cmdp->cmdtype = entry->cmdtype;
651 cmdp->param = entry->u;
652 cmdp->special = entry->special;
658 * Define a shell function.
662 defun(const char *name, union node *func)
664 struct cmdentry entry;
667 entry.cmdtype = CMDFUNCTION;
668 entry.u.func = copyfunc(func);
670 addcmdentry(name, &entry);
676 * Delete a function if it exists.
677 * Called with interrupts off.
681 unsetfunc(const char *name)
683 struct tblentry *cmdp;
685 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
686 unreffunc(cmdp->param.func);
695 * Check if a function by a certain name exists.
698 isfunc(const char *name)
700 struct tblentry *cmdp;
701 cmdp = cmdlookup(name, 0);
702 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
707 print_absolute_path(const char *name)
711 if (*name != '/' && (pwd = lookupvar("PWD")) != NULL && *pwd != '\0') {
713 if (strcmp(pwd, "/") != 0)
717 outcslow('\n', out1);
722 * Shared code for the following builtin commands:
723 * type, command -v, command -V
727 typecmd_impl(int argc, char **argv, int cmd, const char *path)
729 struct cmdentry entry;
730 struct tblentry *cmdp;
731 const char *const *pp;
736 if (path != pathval())
739 for (i = 1; i < argc; i++) {
740 /* First look at the keywords */
741 for (pp = parsekwd; *pp; pp++)
742 if (**pp == *argv[i] && equal(*pp, argv[i]))
746 if (cmd == TYPECMD_SMALLV)
747 out1fmt("%s\n", argv[i]);
749 out1fmt("%s is a shell keyword\n", argv[i]);
753 /* Then look at the aliases */
754 if ((ap = lookupalias(argv[i], 1)) != NULL) {
755 if (cmd == TYPECMD_SMALLV) {
756 out1fmt("alias %s=", argv[i]);
758 outcslow('\n', out1);
760 out1fmt("%s is an alias for %s\n", argv[i],
765 /* Then check if it is a tracked alias */
766 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
767 entry.cmdtype = cmdp->cmdtype;
768 entry.u = cmdp->param;
769 entry.special = cmdp->special;
772 /* Finally use brute force */
773 find_command(argv[i], &entry, 0, path);
776 switch (entry.cmdtype) {
778 if (strchr(argv[i], '/') == NULL) {
779 const char *path2 = path;
782 int j = entry.u.index;
784 name = padvance(&path2, &opt2, argv[i]);
787 if (cmd != TYPECMD_SMALLV)
788 out1fmt("%s is%s ", argv[i],
789 (cmdp && cmd == TYPECMD_TYPE) ?
790 " a tracked alias for" : "");
791 print_absolute_path(name);
793 if (eaccess(argv[i], X_OK) == 0) {
794 if (cmd != TYPECMD_SMALLV)
795 out1fmt("%s is ", argv[i]);
796 print_absolute_path(argv[i]);
798 if (cmd != TYPECMD_SMALLV)
799 outfmt(out2, "%s: %s\n",
800 argv[i], strerror(errno));
807 if (cmd == TYPECMD_SMALLV)
808 out1fmt("%s\n", argv[i]);
810 out1fmt("%s is a shell function\n", argv[i]);
814 if (cmd == TYPECMD_SMALLV)
815 out1fmt("%s\n", argv[i]);
816 else if (entry.special)
817 out1fmt("%s is a special shell builtin\n",
820 out1fmt("%s is a shell builtin\n", argv[i]);
824 if (cmd != TYPECMD_SMALLV)
825 outfmt(out2, "%s: not found\n", argv[i]);
831 if (path != pathval())
838 * Locate and print what a word is...
842 typecmd(int argc, char **argv)
844 if (argc > 2 && strcmp(argv[1], "--") == 0)
846 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));