1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/types.h>
36#include <sys/stat.h>
37#include <unistd.h>
38#include <fcntl.h>
39#include <errno.h>
40#include <paths.h>
41#include <stdlib.h>
42
43/*
44 * When commands are first encountered, they are entered in a hash table.
45 * This ensures that a full path search will not have to be done for them
46 * on each invocation.
47 *
48 * We should investigate converting to a linear search, even though that
49 * would make the command name "hash" a misnomer.
50 */
51
52#include "shell.h"
53#include "main.h"
54#include "nodes.h"
55#include "parser.h"
56#include "redir.h"
57#include "eval.h"
58#include "exec.h"
59#include "builtins.h"
60#include "var.h"
61#include "options.h"
62#include "input.h"
63#include "output.h"
64#include "syntax.h"
65#include "memalloc.h"
66#include "error.h"
67#include "mystring.h"
68#include "show.h"
69#include "jobs.h"
70#include "alias.h"
71
72
73#define CMDTABLESIZE 31 /* should be prime */
74
75
76
77struct tblentry {
78 struct tblentry *next; /* next entry in hash chain */
79 union param param; /* definition of builtin function */
80 int special; /* flag for special builtin commands */
81 signed char cmdtype; /* index identifying command */
82 char cmdname[]; /* name of command */
83};
84
85
86static struct tblentry *cmdtable[CMDTABLESIZE];
87static int cmdtable_cd = 0; /* cmdtable contains cd-dependent entries */
88
89
90static void tryexec(char *, char **, char **);
91static void printentry(struct tblentry *, int);
92static struct tblentry *cmdlookup(const char *, int);
93static void delete_cmd_entry(void);
94static void addcmdentry(const char *, struct cmdentry *);
95
96
97
98/*
99 * Exec a program. Never returns. If you change this routine, you may
100 * have to change the find_command routine as well.
101 *
102 * The argv array may be changed and element argv[-1] should be writable.
103 */
104
105void
106shellexec(char **argv, char **envp, const char *path, int idx)
107{
108 char *cmdname;
109 const char *opt;
110 int e;
111
112 if (strchr(argv[0], '/') != NULL) {
113 tryexec(argv[0], argv, envp);
114 e = errno;
115 } else {
116 e = ENOENT;
117 while ((cmdname = padvance(&path, &opt, argv[0])) != NULL) {
118 if (--idx < 0 && opt == NULL) {
119 tryexec(cmdname, argv, envp);
120 if (errno != ENOENT && errno != ENOTDIR)
121 e = errno;
122 if (e == ENOEXEC)
123 break;
124 }
125 stunalloc(cmdname);
126 }
127 }
128
129 /* Map to POSIX errors */
130 if (e == ENOENT || e == ENOTDIR)
131 errorwithstatus(127, "%s: not found", argv[0]);
132 else
133 errorwithstatus(126, "%s: %s", argv[0], strerror(e));
134}
135
136
137static int
138isbinary(const char *data, size_t len)
139{
140 const char *nul, *p;
141 int hasletter;
142
143 nul = memchr(data, '\0', len);
144 if (nul == NULL)
145 return 0;
146 /*
147 * POSIX says we shall allow execution if the initial part intended
148 * to be parsed by the shell consists of characters and does not
149 * contain the NUL character. This allows concatenating a shell
150 * script (ending with exec or exit) and a binary payload.
151 *
152 * In order to reject common binary files such as PNG images, check
153 * that there is a lowercase letter or expansion before the last
154 * newline before the NUL character, in addition to the check for
155 * the newline character suggested by POSIX.
156 */
157 hasletter = 0;
158 for (p = data; *p != '\0'; p++) {
159 if ((*p >= 'a' && *p <= 'z') || *p == '$' || *p == '`')
160 hasletter = 1;
161 if (hasletter && *p == '\n')
162 return 0;
163 }
164 return 1;
165}
166
167
168static void
169tryexec(char *cmd, char **argv, char **envp)
170{
171 int e, in;
172 ssize_t n;
173 char buf[256];
174
175 execve(cmd, argv, envp);
176 e = errno;
177 if (e == ENOEXEC) {
178 INTOFF;
179 in = open(cmd, O_RDONLY | O_NONBLOCK);
180 if (in != -1) {
181 n = pread(in, buf, sizeof buf, 0);
182 close(in);
183 if (n > 0 && isbinary(buf, n)) {
184 errno = ENOEXEC;
185 return;
186 }
187 }
188 *argv = cmd;
189 *--argv = __DECONST(char *, _PATH_BSHELL);
190 execve(_PATH_BSHELL, argv, envp);
191 }
192 errno = e;
193}
194
195/*
196 * Do a path search. The variable path (passed by reference) should be
197 * set to the start of the path before the first call; padvance will update
198 * this value as it proceeds. Successive calls to padvance will return
199 * the possible path expansions in sequence. If popt is not NULL, options
200 * are processed: if an option (indicated by a percent sign) appears in
201 * the path entry then *popt will be set to point to it; else *popt will be
202 * set to NULL. If popt is NULL, percent signs are not special.
203 */
204
205char *
206padvance(const char **path, const char **popt, const char *name)
207{
208 const char *p, *start;
209 char *q;
210 size_t len, namelen;
211
212 if (*path == NULL)
213 return NULL;
214 start = *path;
215 if (popt != NULL)
216 for (p = start; *p && *p != ':' && *p != '%'; p++)
217 ; /* nothing */
218 else
219 for (p = start; *p && *p != ':'; p++)
220 ; /* nothing */
221 namelen = strlen(name);
222 len = p - start + namelen + 2; /* "2" is for '/' and '\0' */
223 STARTSTACKSTR(q);
224 CHECKSTRSPACE(len, q);
225 if (p != start) {
226 memcpy(q, start, p - start);
227 q += p - start;
228 *q++ = '/';
229 }
230 memcpy(q, name, namelen + 1);
231 if (popt != NULL) {
232 if (*p == '%') {
233 *popt = ++p;
234 while (*p && *p != ':') p++;
235 } else
236 *popt = NULL;
237 }
238 if (*p == ':')
239 *path = p + 1;
240 else
241 *path = NULL;
242 return stalloc(len);
243}
244
245
246
247/*** Command hashing code ***/
248
249
250int
251hashcmd(int argc __unused, char **argv __unused)
252{
253 struct tblentry **pp;
254 struct tblentry *cmdp;
255 int c;
256 int verbose;
257 struct cmdentry entry;
258 char *name;
259 int errors;
260
261 errors = 0;
262 verbose = 0;
263 while ((c = nextopt("rv")) != '\0') {
264 if (c == 'r') {
265 clearcmdentry();
266 } else if (c == 'v') {
267 verbose++;
268 }
269 }
270 if (*argptr == NULL) {
271 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
272 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
273 if (cmdp->cmdtype == CMDNORMAL)
274 printentry(cmdp, verbose);
275 }
276 }
277 return 0;
278 }
279 while ((name = *argptr) != NULL) {
280 if ((cmdp = cmdlookup(name, 0)) != NULL
281 && cmdp->cmdtype == CMDNORMAL)
282 delete_cmd_entry();
283 find_command(name, &entry, DO_ERR, pathval());
284 if (entry.cmdtype == CMDUNKNOWN)
285 errors = 1;
286 else if (verbose) {
287 cmdp = cmdlookup(name, 0);
288 if (cmdp != NULL)
289 printentry(cmdp, verbose);
290 else {
291 outfmt(out2, "%s: not found\n", name);
292 errors = 1;
293 }
294 flushall();
295 }
296 argptr++;
297 }
298 return errors;
299}
300
301
302static void
303printentry(struct tblentry *cmdp, int verbose)
304{
305 int idx;
306 const char *path, *opt;
307 char *name;
308
309 if (cmdp->cmdtype == CMDNORMAL) {
310 idx = cmdp->param.index;
311 path = pathval();
312 do {
313 name = padvance(&path, &opt, cmdp->cmdname);
314 stunalloc(name);
315 } while (--idx >= 0);
316 out1str(name);
317 } else if (cmdp->cmdtype == CMDBUILTIN) {
318 out1fmt("builtin %s", cmdp->cmdname);
319 } else if (cmdp->cmdtype == CMDFUNCTION) {
320 out1fmt("function %s", cmdp->cmdname);
321 if (verbose) {
322 INTOFF;
323 name = commandtext(getfuncnode(cmdp->param.func));
324 out1c(' ');
325 out1str(name);
326 ckfree(name);
327 INTON;
328 }
329#ifdef DEBUG
330 } else {
331 error("internal error: cmdtype %d", cmdp->cmdtype);
332#endif
333 }
334 out1c('\n');
335}
336
337
338
339/*
340 * Resolve a command name. If you change this routine, you may have to
341 * change the shellexec routine as well.
342 */
343
344void
345find_command(const char *name, struct cmdentry *entry, int act,
346 const char *path)
347{
348 struct tblentry *cmdp, loc_cmd;
349 int idx;
350 const char *opt;
351 char *fullname;
352 struct stat statb;
353 int e;
354 int i;
355 int spec;
356 int cd;
357
358 /* If name contains a slash, don't use the hash table */
359 if (strchr(name, '/') != NULL) {
360 entry->cmdtype = CMDNORMAL;
361 entry->u.index = 0;
362 entry->special = 0;
363 return;
364 }
365
366 cd = 0;
367
368 /* If name is in the table, we're done */
369 if ((cmdp = cmdlookup(name, 0)) != NULL) {
370 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
371 cmdp = NULL;
372 else
373 goto success;
374 }
375
376 /* Check for builtin next */
377 if ((i = find_builtin(name, &spec)) >= 0) {
378 INTOFF;
379 cmdp = cmdlookup(name, 1);
380 if (cmdp->cmdtype == CMDFUNCTION)
381 cmdp = &loc_cmd;
382 cmdp->cmdtype = CMDBUILTIN;
383 cmdp->param.index = i;
384 cmdp->special = spec;
385 INTON;
386 goto success;
387 }
388
389 /* We have to search path. */
390
391 e = ENOENT;
392 idx = -1;
393 for (;(fullname = padvance(&path, &opt, name)) != NULL;
394 stunalloc(fullname)) {
395 idx++;
396 if (opt) {
397 if (strncmp(opt, "func", 4) == 0) {
398 /* handled below */
399 } else {
400 continue; /* ignore unimplemented options */
401 }
402 }
403 if (fullname[0] != '/')
404 cd = 1;
405 if (stat(fullname, &statb) < 0) {
406 if (errno != ENOENT && errno != ENOTDIR)
407 e = errno;
408 continue;
409 }
410 e = EACCES; /* if we fail, this will be the error */
411 if (!S_ISREG(statb.st_mode))
412 continue;
413 if (opt) { /* this is a %func directory */
414 readcmdfile(fullname, -1 /* verify */);
415 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
416 error("%s not defined in %s", name, fullname);
417 stunalloc(fullname);
418 goto success;
419 }
420#ifdef notdef
421 if (statb.st_uid == geteuid()) {
422 if ((statb.st_mode & 0100) == 0)
423 goto loop;
424 } else if (statb.st_gid == getegid()) {
425 if ((statb.st_mode & 010) == 0)
426 goto loop;
427 } else {
428 if ((statb.st_mode & 01) == 0)
429 goto loop;
430 }
431#endif
432 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
433 INTOFF;
434 stunalloc(fullname);
435 cmdp = cmdlookup(name, 1);
436 if (cmdp->cmdtype == CMDFUNCTION)
437 cmdp = &loc_cmd;
438 cmdp->cmdtype = CMDNORMAL;
439 cmdp->param.index = idx;
440 cmdp->special = 0;
441 INTON;
442 goto success;
443 }
444
445 if (act & DO_ERR) {
446 if (e == ENOENT || e == ENOTDIR)
447 outfmt(out2, "%s: not found\n", name);
448 else
449 outfmt(out2, "%s: %s\n", name, strerror(e));
450 }
451 entry->cmdtype = CMDUNKNOWN;
452 entry->u.index = 0;
453 entry->special = 0;
454 return;
455
456success:
457 if (cd)
458 cmdtable_cd = 1;
459 entry->cmdtype = cmdp->cmdtype;
460 entry->u = cmdp->param;
461 entry->special = cmdp->special;
462}
463
464
465
466/*
467 * Search the table of builtin commands.
468 */
469
470int
471find_builtin(const char *name, int *special)
472{
473 const unsigned char *bp;
474 size_t len;
475
476 len = strlen(name);
477 for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
478 if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
479 *special = (bp[1] & BUILTIN_SPECIAL) != 0;
480 return bp[1] & ~BUILTIN_SPECIAL;
481 }
482 }
483 return -1;
484}
485
486
487
488/*
489 * Called when a cd is done. If any entry in cmdtable depends on the current
490 * directory, simply clear cmdtable completely.
491 */
492
493void
494hashcd(void)
495{
496 if (cmdtable_cd)
497 clearcmdentry();
498}
499
500
501
502/*
503 * Called before PATH is changed. The argument is the new value of PATH;
504 * pathval() still returns the old value at this point. Called with
505 * interrupts off.
506 */
507
508void
509changepath(const char *newval __unused)
510{
511 clearcmdentry();
512}
513
514
515/*
516 * Clear out cached utility locations.
517 */
518
519void
520clearcmdentry(void)
521{
522 struct tblentry **tblp;
523 struct tblentry **pp;
524 struct tblentry *cmdp;
525
526 INTOFF;
527 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
528 pp = tblp;
529 while ((cmdp = *pp) != NULL) {
530 if (cmdp->cmdtype == CMDNORMAL) {
531 *pp = cmdp->next;
532 ckfree(cmdp);
533 } else {
534 pp = &cmdp->next;
535 }
536 }
537 }
538 cmdtable_cd = 0;
539 INTON;
540}
541
542
543static unsigned int
544hashname(const char *p)
545{
546 unsigned int hashval;
547
548 hashval = (unsigned char)*p << 4;
549 while (*p)
550 hashval += *p++;
551
552 return (hashval % CMDTABLESIZE);
553}
554
555
556/*
557 * Locate a command in the command hash table. If "add" is nonzero,
558 * add the command to the table if it is not already present. The
559 * variable "lastcmdentry" is set to point to the address of the link
560 * pointing to the entry, so that delete_cmd_entry can delete the
561 * entry.
562 */
563
564static struct tblentry **lastcmdentry;
565
566
567static struct tblentry *
568cmdlookup(const char *name, int add)
569{
570 struct tblentry *cmdp;
571 struct tblentry **pp;
572 size_t len;
573
574 pp = &cmdtable[hashname(name)];
575 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
576 if (equal(cmdp->cmdname, name))
577 break;
578 pp = &cmdp->next;
579 }
580 if (add && cmdp == NULL) {
581 INTOFF;
582 len = strlen(name);
583 cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
584 cmdp->next = NULL;
585 cmdp->cmdtype = CMDUNKNOWN;
586 memcpy(cmdp->cmdname, name, len + 1);
587 INTON;
588 }
589 lastcmdentry = pp;
590 return cmdp;
591}
592
593const void *
594itercmd(const void *entry, struct cmdentry *result)
595{
596 const struct tblentry *e = entry;
597 size_t i = 0;
598
599 if (e != NULL) {
600 if (e->next != NULL) {
601 e = e->next;
602 goto success;
603 }
604 i = hashname(e->cmdname) + 1;
605 }
606 for (; i < CMDTABLESIZE; i++)
607 if ((e = cmdtable[i]) != NULL)
608 goto success;
609
610 return (NULL);
611success:
612 result->cmdtype = e->cmdtype;
613 result->cmdname = e->cmdname;
614
615 return (e);
616}
617
618/*
619 * Delete the command entry returned on the last lookup.
620 */
621
622static void
623delete_cmd_entry(void)
624{
625 struct tblentry *cmdp;
626
627 INTOFF;
628 cmdp = *lastcmdentry;
629 *lastcmdentry = cmdp->next;
630 ckfree(cmdp);
631 INTON;
632}
633
634
635
636/*
637 * Add a new command entry, replacing any existing command entry for
638 * the same name.
639 */
640
641static void
642addcmdentry(const char *name, struct cmdentry *entry)
643{
644 struct tblentry *cmdp;
645
646 INTOFF;
647 cmdp = cmdlookup(name, 1);
648 if (cmdp->cmdtype == CMDFUNCTION) {
649 unreffunc(cmdp->param.func);
650 }
651 cmdp->cmdtype = entry->cmdtype;
652 cmdp->param = entry->u;
653 cmdp->special = entry->special;
654 INTON;
655}
656
657
658/*
659 * Define a shell function.
660 */
661
662void
663defun(const char *name, union node *func)
664{
665 struct cmdentry entry;
666
667 INTOFF;
668 entry.cmdtype = CMDFUNCTION;
669 entry.u.func = copyfunc(func);
670 entry.special = 0;
671 addcmdentry(name, &entry);
672 INTON;
673}
674
675
676/*
677 * Delete a function if it exists.
678 * Called with interrupts off.
679 */
680
681int
682unsetfunc(const char *name)
683{
684 struct tblentry *cmdp;
685
686 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
687 unreffunc(cmdp->param.func);
688 delete_cmd_entry();
689 return (0);
690 }
691 return (0);
692}
693
694
695/*
696 * Check if a function by a certain name exists.
697 */
698int
699isfunc(const char *name)
700{
701 struct tblentry *cmdp;
702 cmdp = cmdlookup(name, 0);
703 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
704}
705
706
707static void
708print_absolute_path(const char *name)
709{
710 const char *pwd;
711
712 if (*name != '/' && (pwd = lookupvar("PWD")) != NULL && *pwd != '\0') {
713 out1str(pwd);
714 if (strcmp(pwd, "/") != 0)
715 outcslow('/', out1);
716 }
717 out1str(name);
718 outcslow('\n', out1);
719}
720
721
722/*
723 * Shared code for the following builtin commands:
724 * type, command -v, command -V
725 */
726
727int
728typecmd_impl(int argc, char **argv, int cmd, const char *path)
729{
730 struct cmdentry entry;
731 struct tblentry *cmdp;
732 const char *const *pp;
733 struct alias *ap;
734 int i;
735 int error1 = 0;
736
737 if (path != pathval())
738 clearcmdentry();
739
740 for (i = 1; i < argc; i++) {
741 /* First look at the keywords */
742 for (pp = parsekwd; *pp; pp++)
743 if (**pp == *argv[i] && equal(*pp, argv[i]))
744 break;
745
746 if (*pp) {
747 if (cmd == TYPECMD_SMALLV)
748 out1fmt("%s\n", argv[i]);
749 else
750 out1fmt("%s is a shell keyword\n", argv[i]);
751 continue;
752 }
753
754 /* Then look at the aliases */
755 if ((ap = lookupalias(argv[i], 1)) != NULL) {
756 if (cmd == TYPECMD_SMALLV) {
757 out1fmt("alias %s=", argv[i]);
758 out1qstr(ap->val);
759 outcslow('\n', out1);
760 } else
761 out1fmt("%s is an alias for %s\n", argv[i],
762 ap->val);
763 continue;
764 }
765
766 /* Then check if it is a tracked alias */
767 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
768 entry.cmdtype = cmdp->cmdtype;
769 entry.u = cmdp->param;
770 entry.special = cmdp->special;
771 }
772 else {
773 /* Finally use brute force */
774 find_command(argv[i], &entry, 0, path);
775 }
776
777 switch (entry.cmdtype) {
778 case CMDNORMAL: {
779 if (strchr(argv[i], '/') == NULL) {
780 const char *path2 = path;
781 const char *opt2;
782 char *name;
783 int j = entry.u.index;
784 do {
785 name = padvance(&path2, &opt2, argv[i]);
786 stunalloc(name);
787 } while (--j >= 0);
788 if (cmd != TYPECMD_SMALLV)
789 out1fmt("%s is%s ", argv[i],
790 (cmdp && cmd == TYPECMD_TYPE) ?
791 " a tracked alias for" : "");
792 print_absolute_path(name);
793 } else {
794 if (eaccess(argv[i], X_OK) == 0) {
795 if (cmd != TYPECMD_SMALLV)
796 out1fmt("%s is ", argv[i]);
797 print_absolute_path(argv[i]);
798 } else {
799 if (cmd != TYPECMD_SMALLV)
800 outfmt(out2, "%s: %s\n",
801 argv[i], strerror(errno));
802 error1 |= 127;
803 }
804 }
805 break;
806 }
807 case CMDFUNCTION:
808 if (cmd == TYPECMD_SMALLV)
809 out1fmt("%s\n", argv[i]);
810 else
811 out1fmt("%s is a shell function\n", argv[i]);
812 break;
813
814 case CMDBUILTIN:
815 if (cmd == TYPECMD_SMALLV)
816 out1fmt("%s\n", argv[i]);
817 else if (entry.special)
818 out1fmt("%s is a special shell builtin\n",
819 argv[i]);
820 else
821 out1fmt("%s is a shell builtin\n", argv[i]);
822 break;
823
824 default:
825 if (cmd != TYPECMD_SMALLV)
826 outfmt(out2, "%s: not found\n", argv[i]);
827 error1 |= 127;
828 break;
829 }
830 }
831
832 if (path != pathval())
833 clearcmdentry();
834
835 return error1;
836}
837
838/*
839 * Locate and print what a word is...
840 */
841
842int
843typecmd(int argc, char **argv)
844{
845 if (argc > 2 && strcmp(argv[1], "--") == 0)
846 argc--, argv++;
847 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));
848}
