1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Kenneth Almquist.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <unistd.h>
44 #include <fcntl.h>
45 #include <errno.h>
46 #include <paths.h>
47 #include <stdlib.h>
48
49 /*
50 * When commands are first encountered, they are entered in a hash table.
51 * This ensures that a full path search will not have to be done for them
52 * on each invocation.
53 *
54 * We should investigate converting to a linear search, even though that
55 * would make the command name "hash" a misnomer.
56 */
57
58 #include "shell.h"
59 #include "main.h"
60 #include "nodes.h"
61 #include "parser.h"
62 #include "redir.h"
63 #include "eval.h"
64 #include "exec.h"
65 #include "builtins.h"
66 #include "var.h"
67 #include "options.h"
68 #include "input.h"
69 #include "output.h"
70 #include "syntax.h"
71 #include "memalloc.h"
72 #include "error.h"
73 #include "mystring.h"
74 #include "show.h"
75 #include "jobs.h"
76 #include "alias.h"
77
78
79 #define CMDTABLESIZE 31 /* should be prime */
80
81
82
83 struct tblentry {
84 struct tblentry *next; /* next entry in hash chain */
85 union param param; /* definition of builtin function */
86 int special; /* flag for special builtin commands */
87 signed char cmdtype; /* index identifying command */
88 char cmdname[]; /* name of command */
89 };
90
91
92 static struct tblentry *cmdtable[CMDTABLESIZE];
93 static int cmdtable_cd = 0; /* cmdtable contains cd-dependent entries */
94 int exerrno = 0; /* Last exec error */
95
96
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 *);
102
103
104
105 /*
106 * Exec a program. Never returns. If you change this routine, you may
107 * have to change the find_command routine as well.
108 *
109 * The argv array may be changed and element argv[-1] should be writable.
110 */
111
112 void
shellexec(char ** argv,char ** envp,const char * path,int idx)113 shellexec(char **argv, char **envp, const char *path, int idx)
114 {
115 char *cmdname;
116 int e;
117
118 if (strchr(argv[0], '/') != NULL) {
119 tryexec(argv[0], argv, envp);
120 e = errno;
121 } else {
122 e = ENOENT;
123 while ((cmdname = padvance(&path, argv[0])) != NULL) {
124 if (--idx < 0 && pathopt == NULL) {
125 tryexec(cmdname, argv, envp);
126 if (errno != ENOENT && errno != ENOTDIR)
127 e = errno;
128 if (e == ENOEXEC)
129 break;
130 }
131 stunalloc(cmdname);
132 }
133 }
134
135 /* Map to POSIX errors */
136 if (e == ENOENT || e == ENOTDIR) {
137 exerrno = 127;
138 exerror(EXEXEC, "%s: not found", argv[0]);
139 } else {
140 exerrno = 126;
141 exerror(EXEXEC, "%s: %s", argv[0], strerror(e));
142 }
143 }
144
145
146 static void
tryexec(char * cmd,char ** argv,char ** envp)147 tryexec(char *cmd, char **argv, char **envp)
148 {
149 int e, in;
150 ssize_t n;
151 char buf[256];
152
153 execve(cmd, argv, envp);
154 e = errno;
155 if (e == ENOEXEC) {
156 INTOFF;
157 in = open(cmd, O_RDONLY | O_NONBLOCK);
158 if (in != -1) {
159 n = pread(in, buf, sizeof buf, 0);
160 close(in);
161 if (n > 0 && memchr(buf, '\0', n) != NULL) {
162 errno = ENOEXEC;
163 return;
164 }
165 }
166 *argv = cmd;
167 *--argv = __DECONST(char *, _PATH_BSHELL);
168 execve(_PATH_BSHELL, argv, envp);
169 }
170 errno = e;
171 }
172
173 /*
174 * Do a path search. The variable path (passed by reference) should be
175 * set to the start of the path before the first call; padvance will update
176 * this value as it proceeds. Successive calls to padvance will return
177 * the possible path expansions in sequence. If an option (indicated by
178 * a percent sign) appears in the path entry then the global variable
179 * pathopt will be set to point to it; otherwise pathopt will be set to
180 * NULL.
181 */
182
183 const char *pathopt;
184
185 char *
padvance(const char ** path,const char * name)186 padvance(const char **path, const char *name)
187 {
188 const char *p, *start;
189 char *q;
190 size_t len, namelen;
191
192 if (*path == NULL)
193 return NULL;
194 start = *path;
195 for (p = start; *p && *p != ':' && *p != '%'; p++)
196 ; /* nothing */
197 namelen = strlen(name);
198 len = p - start + namelen + 2; /* "2" is for '/' and '\0' */
199 STARTSTACKSTR(q);
200 CHECKSTRSPACE(len, q);
201 if (p != start) {
202 memcpy(q, start, p - start);
203 q += p - start;
204 *q++ = '/';
205 }
206 memcpy(q, name, namelen + 1);
207 pathopt = NULL;
208 if (*p == '%') {
209 pathopt = ++p;
210 while (*p && *p != ':') p++;
211 }
212 if (*p == ':')
213 *path = p + 1;
214 else
215 *path = NULL;
216 return stalloc(len);
217 }
218
219
220
221 /*** Command hashing code ***/
222
223
224 int
hashcmd(int argc __unused,char ** argv __unused)225 hashcmd(int argc __unused, char **argv __unused)
226 {
227 struct tblentry **pp;
228 struct tblentry *cmdp;
229 int c;
230 int verbose;
231 struct cmdentry entry;
232 char *name;
233 int errors;
234
235 errors = 0;
236 verbose = 0;
237 while ((c = nextopt("rv")) != '\0') {
238 if (c == 'r') {
239 clearcmdentry();
240 } else if (c == 'v') {
241 verbose++;
242 }
243 }
244 if (*argptr == NULL) {
245 for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
246 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
247 if (cmdp->cmdtype == CMDNORMAL)
248 printentry(cmdp, verbose);
249 }
250 }
251 return 0;
252 }
253 while ((name = *argptr) != NULL) {
254 if ((cmdp = cmdlookup(name, 0)) != NULL
255 && cmdp->cmdtype == CMDNORMAL)
256 delete_cmd_entry();
257 find_command(name, &entry, DO_ERR, pathval());
258 if (entry.cmdtype == CMDUNKNOWN)
259 errors = 1;
260 else if (verbose) {
261 cmdp = cmdlookup(name, 0);
262 if (cmdp != NULL)
263 printentry(cmdp, verbose);
264 else {
265 outfmt(out2, "%s: not found\n", name);
266 errors = 1;
267 }
268 flushall();
269 }
270 argptr++;
271 }
272 return errors;
273 }
274
275
276 static void
printentry(struct tblentry * cmdp,int verbose)277 printentry(struct tblentry *cmdp, int verbose)
278 {
279 int idx;
280 const char *path;
281 char *name;
282
283 if (cmdp->cmdtype == CMDNORMAL) {
284 idx = cmdp->param.index;
285 path = pathval();
286 do {
287 name = padvance(&path, cmdp->cmdname);
288 stunalloc(name);
289 } while (--idx >= 0);
290 out1str(name);
291 } else if (cmdp->cmdtype == CMDBUILTIN) {
292 out1fmt("builtin %s", cmdp->cmdname);
293 } else if (cmdp->cmdtype == CMDFUNCTION) {
294 out1fmt("function %s", cmdp->cmdname);
295 if (verbose) {
296 INTOFF;
297 name = commandtext(getfuncnode(cmdp->param.func));
298 out1c(' ');
299 out1str(name);
300 ckfree(name);
301 INTON;
302 }
303 #ifdef DEBUG
304 } else {
305 error("internal error: cmdtype %d", cmdp->cmdtype);
306 #endif
307 }
308 out1c('\n');
309 }
310
311
312
313 /*
314 * Resolve a command name. If you change this routine, you may have to
315 * change the shellexec routine as well.
316 */
317
318 void
find_command(const char * name,struct cmdentry * entry,int act,const char * path)319 find_command(const char *name, struct cmdentry *entry, int act,
320 const char *path)
321 {
322 struct tblentry *cmdp, loc_cmd;
323 int idx;
324 char *fullname;
325 struct stat statb;
326 int e;
327 int i;
328 int spec;
329 int cd;
330
331 /* If name contains a slash, don't use the hash table */
332 if (strchr(name, '/') != NULL) {
333 entry->cmdtype = CMDNORMAL;
334 entry->u.index = 0;
335 return;
336 }
337
338 cd = 0;
339
340 /* If name is in the table, and not invalidated by cd, we're done */
341 if ((cmdp = cmdlookup(name, 0)) != NULL) {
342 if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
343 cmdp = NULL;
344 else
345 goto success;
346 }
347
348 /* Check for builtin next */
349 if ((i = find_builtin(name, &spec)) >= 0) {
350 INTOFF;
351 cmdp = cmdlookup(name, 1);
352 if (cmdp->cmdtype == CMDFUNCTION)
353 cmdp = &loc_cmd;
354 cmdp->cmdtype = CMDBUILTIN;
355 cmdp->param.index = i;
356 cmdp->special = spec;
357 INTON;
358 goto success;
359 }
360
361 /* We have to search path. */
362
363 e = ENOENT;
364 idx = -1;
365 for (;(fullname = padvance(&path, name)) != NULL; stunalloc(fullname)) {
366 idx++;
367 if (pathopt) {
368 if (strncmp(pathopt, "func", 4) == 0) {
369 /* handled below */
370 } else {
371 continue; /* ignore unimplemented options */
372 }
373 }
374 if (fullname[0] != '/')
375 cd = 1;
376 if (stat(fullname, &statb) < 0) {
377 if (errno != ENOENT && errno != ENOTDIR)
378 e = errno;
379 continue;
380 }
381 e = EACCES; /* if we fail, this will be the error */
382 if (!S_ISREG(statb.st_mode))
383 continue;
384 if (pathopt) { /* this is a %func directory */
385 readcmdfile(fullname);
386 if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
387 error("%s not defined in %s", name, fullname);
388 stunalloc(fullname);
389 goto success;
390 }
391 #ifdef notdef
392 if (statb.st_uid == geteuid()) {
393 if ((statb.st_mode & 0100) == 0)
394 goto loop;
395 } else if (statb.st_gid == getegid()) {
396 if ((statb.st_mode & 010) == 0)
397 goto loop;
398 } else {
399 if ((statb.st_mode & 01) == 0)
400 goto loop;
401 }
402 #endif
403 TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
404 INTOFF;
405 stunalloc(fullname);
406 cmdp = cmdlookup(name, 1);
407 if (cmdp->cmdtype == CMDFUNCTION)
408 cmdp = &loc_cmd;
409 cmdp->cmdtype = CMDNORMAL;
410 cmdp->param.index = idx;
411 INTON;
412 goto success;
413 }
414
415 if (act & DO_ERR) {
416 if (e == ENOENT || e == ENOTDIR)
417 outfmt(out2, "%s: not found\n", name);
418 else
419 outfmt(out2, "%s: %s\n", name, strerror(e));
420 }
421 entry->cmdtype = CMDUNKNOWN;
422 entry->u.index = 0;
423 return;
424
425 success:
426 if (cd)
427 cmdtable_cd = 1;
428 entry->cmdtype = cmdp->cmdtype;
429 entry->u = cmdp->param;
430 entry->special = cmdp->special;
431 }
432
433
434
435 /*
436 * Search the table of builtin commands.
437 */
438
439 int
find_builtin(const char * name,int * special)440 find_builtin(const char *name, int *special)
441 {
442 const unsigned char *bp;
443 size_t len;
444
445 len = strlen(name);
446 for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
447 if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
448 *special = (bp[1] & BUILTIN_SPECIAL) != 0;
449 return bp[1] & ~BUILTIN_SPECIAL;
450 }
451 }
452 return -1;
453 }
454
455
456
457 /*
458 * Called when a cd is done. If any entry in cmdtable depends on the current
459 * directory, simply clear cmdtable completely.
460 */
461
462 void
hashcd(void)463 hashcd(void)
464 {
465 if (cmdtable_cd)
466 clearcmdentry();
467 }
468
469
470
471 /*
472 * Called before PATH is changed. The argument is the new value of PATH;
473 * pathval() still returns the old value at this point. Called with
474 * interrupts off.
475 */
476
477 void
changepath(const char * newval __unused)478 changepath(const char *newval __unused)
479 {
480 clearcmdentry();
481 }
482
483
484 /*
485 * Clear out command entries. The argument specifies the first entry in
486 * PATH which has changed.
487 */
488
489 void
clearcmdentry(void)490 clearcmdentry(void)
491 {
492 struct tblentry **tblp;
493 struct tblentry **pp;
494 struct tblentry *cmdp;
495
496 INTOFF;
497 for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
498 pp = tblp;
499 while ((cmdp = *pp) != NULL) {
500 if (cmdp->cmdtype == CMDNORMAL) {
501 *pp = cmdp->next;
502 ckfree(cmdp);
503 } else {
504 pp = &cmdp->next;
505 }
506 }
507 }
508 cmdtable_cd = 0;
509 INTON;
510 }
511
512
513 /*
514 * Locate a command in the command hash table. If "add" is nonzero,
515 * add the command to the table if it is not already present. The
516 * variable "lastcmdentry" is set to point to the address of the link
517 * pointing to the entry, so that delete_cmd_entry can delete the
518 * entry.
519 */
520
521 static struct tblentry **lastcmdentry;
522
523
524 static struct tblentry *
cmdlookup(const char * name,int add)525 cmdlookup(const char *name, int add)
526 {
527 unsigned int hashval;
528 const char *p;
529 struct tblentry *cmdp;
530 struct tblentry **pp;
531 size_t len;
532
533 p = name;
534 hashval = (unsigned char)*p << 4;
535 while (*p)
536 hashval += *p++;
537 pp = &cmdtable[hashval % CMDTABLESIZE];
538 for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
539 if (equal(cmdp->cmdname, name))
540 break;
541 pp = &cmdp->next;
542 }
543 if (add && cmdp == NULL) {
544 INTOFF;
545 len = strlen(name);
546 cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
547 cmdp->next = NULL;
548 cmdp->cmdtype = CMDUNKNOWN;
549 memcpy(cmdp->cmdname, name, len + 1);
550 INTON;
551 }
552 lastcmdentry = pp;
553 return cmdp;
554 }
555
556 /*
557 * Delete the command entry returned on the last lookup.
558 */
559
560 static void
delete_cmd_entry(void)561 delete_cmd_entry(void)
562 {
563 struct tblentry *cmdp;
564
565 INTOFF;
566 cmdp = *lastcmdentry;
567 *lastcmdentry = cmdp->next;
568 ckfree(cmdp);
569 INTON;
570 }
571
572
573
574 /*
575 * Add a new command entry, replacing any existing command entry for
576 * the same name.
577 */
578
579 static void
addcmdentry(const char * name,struct cmdentry * entry)580 addcmdentry(const char *name, struct cmdentry *entry)
581 {
582 struct tblentry *cmdp;
583
584 INTOFF;
585 cmdp = cmdlookup(name, 1);
586 if (cmdp->cmdtype == CMDFUNCTION) {
587 unreffunc(cmdp->param.func);
588 }
589 cmdp->cmdtype = entry->cmdtype;
590 cmdp->param = entry->u;
591 INTON;
592 }
593
594
595 /*
596 * Define a shell function.
597 */
598
599 void
defun(const char * name,union node * func)600 defun(const char *name, union node *func)
601 {
602 struct cmdentry entry;
603
604 INTOFF;
605 entry.cmdtype = CMDFUNCTION;
606 entry.u.func = copyfunc(func);
607 addcmdentry(name, &entry);
608 INTON;
609 }
610
611
612 /*
613 * Delete a function if it exists.
614 * Called with interrupts off.
615 */
616
617 int
unsetfunc(const char * name)618 unsetfunc(const char *name)
619 {
620 struct tblentry *cmdp;
621
622 if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
623 unreffunc(cmdp->param.func);
624 delete_cmd_entry();
625 return (0);
626 }
627 return (0);
628 }
629
630
631 /*
632 * Check if a function by a certain name exists.
633 */
634 int
isfunc(const char * name)635 isfunc(const char *name)
636 {
637 struct tblentry *cmdp;
638 cmdp = cmdlookup(name, 0);
639 return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
640 }
641
642
643 /*
644 * Shared code for the following builtin commands:
645 * type, command -v, command -V
646 */
647
648 int
typecmd_impl(int argc,char ** argv,int cmd,const char * path)649 typecmd_impl(int argc, char **argv, int cmd, const char *path)
650 {
651 struct cmdentry entry;
652 struct tblentry *cmdp;
653 const char *const *pp;
654 struct alias *ap;
655 int i;
656 int error1 = 0;
657
658 if (path != pathval())
659 clearcmdentry();
660
661 for (i = 1; i < argc; i++) {
662 /* First look at the keywords */
663 for (pp = parsekwd; *pp; pp++)
664 if (**pp == *argv[i] && equal(*pp, argv[i]))
665 break;
666
667 if (*pp) {
668 if (cmd == TYPECMD_SMALLV)
669 out1fmt("%s\n", argv[i]);
670 else
671 out1fmt("%s is a shell keyword\n", argv[i]);
672 continue;
673 }
674
675 /* Then look at the aliases */
676 if ((ap = lookupalias(argv[i], 1)) != NULL) {
677 if (cmd == TYPECMD_SMALLV) {
678 out1fmt("alias %s=", argv[i]);
679 out1qstr(ap->val);
680 outcslow('\n', out1);
681 } else
682 out1fmt("%s is an alias for %s\n", argv[i],
683 ap->val);
684 continue;
685 }
686
687 /* Then check if it is a tracked alias */
688 if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
689 entry.cmdtype = cmdp->cmdtype;
690 entry.u = cmdp->param;
691 entry.special = cmdp->special;
692 }
693 else {
694 /* Finally use brute force */
695 find_command(argv[i], &entry, 0, path);
696 }
697
698 switch (entry.cmdtype) {
699 case CMDNORMAL: {
700 if (strchr(argv[i], '/') == NULL) {
701 const char *path2 = path;
702 char *name;
703 int j = entry.u.index;
704 do {
705 name = padvance(&path2, argv[i]);
706 stunalloc(name);
707 } while (--j >= 0);
708 if (cmd == TYPECMD_SMALLV)
709 out1fmt("%s\n", name);
710 else
711 out1fmt("%s is%s %s\n", argv[i],
712 (cmdp && cmd == TYPECMD_TYPE) ?
713 " a tracked alias for" : "",
714 name);
715 } else {
716 if (eaccess(argv[i], X_OK) == 0) {
717 if (cmd == TYPECMD_SMALLV)
718 out1fmt("%s\n", argv[i]);
719 else
720 out1fmt("%s is %s\n", argv[i],
721 argv[i]);
722 } else {
723 if (cmd != TYPECMD_SMALLV)
724 outfmt(out2, "%s: %s\n",
725 argv[i], strerror(errno));
726 error1 |= 127;
727 }
728 }
729 break;
730 }
731 case CMDFUNCTION:
732 if (cmd == TYPECMD_SMALLV)
733 out1fmt("%s\n", argv[i]);
734 else
735 out1fmt("%s is a shell function\n", argv[i]);
736 break;
737
738 case CMDBUILTIN:
739 if (cmd == TYPECMD_SMALLV)
740 out1fmt("%s\n", argv[i]);
741 else if (entry.special)
742 out1fmt("%s is a special shell builtin\n",
743 argv[i]);
744 else
745 out1fmt("%s is a shell builtin\n", argv[i]);
746 break;
747
748 default:
749 if (cmd != TYPECMD_SMALLV)
750 outfmt(out2, "%s: not found\n", argv[i]);
751 error1 |= 127;
752 break;
753 }
754 }
755
756 if (path != pathval())
757 clearcmdentry();
758
759 return error1;
760 }
761
762 /*
763 * Locate and print what a word is...
764 */
765
766 int
typecmd(int argc,char ** argv)767 typecmd(int argc, char **argv)
768 {
769 if (argc > 2 && strcmp(argv[1], "--") == 0)
770 argc--, argv++;
771 return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));
772 }
773