exec.c revision 264478 
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
35static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/10/bin/sh/exec.c 264478 2014-04-14 21:26:34Z jilles $");
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
83struct 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
92static struct tblentry *cmdtable[CMDTABLESIZE];
93static int cmdtable_cd = 0;	/* cmdtable contains cd-dependent entries */
94int exerrno = 0;			/* Last exec error */
95
96
97static void tryexec(char *, char **, char **);
98static void printentry(struct tblentry *, int);
99static struct tblentry *cmdlookup(const char *, int);
100static void delete_cmd_entry(void);
101static 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
112void
113shellexec(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
146static void
147tryexec(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
183const char *pathopt;
184
185char *
186padvance(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
224int
225hashcmd(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
276static void
277printentry(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
318void
319find_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;
365loop:
366	while ((fullname = padvance(&path, name)) != NULL) {
367		stunalloc(fullname);
368		idx++;
369		if (pathopt) {
370			if (prefix("func", pathopt)) {
371				/* handled below */
372			} else {
373				goto loop;	/* ignore unimplemented options */
374			}
375		}
376		if (fullname[0] != '/')
377			cd = 1;
378		if (stat(fullname, &statb) < 0) {
379			if (errno != ENOENT && errno != ENOTDIR)
380				e = errno;
381			goto loop;
382		}
383		e = EACCES;	/* if we fail, this will be the error */
384		if (!S_ISREG(statb.st_mode))
385			goto loop;
386		if (pathopt) {		/* this is a %func directory */
387			stalloc(strlen(fullname) + 1);
388			readcmdfile(fullname);
389			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
390				error("%s not defined in %s", name, fullname);
391			stunalloc(fullname);
392			goto success;
393		}
394#ifdef notdef
395		if (statb.st_uid == geteuid()) {
396			if ((statb.st_mode & 0100) == 0)
397				goto loop;
398		} else if (statb.st_gid == getegid()) {
399			if ((statb.st_mode & 010) == 0)
400				goto loop;
401		} else {
402			if ((statb.st_mode & 01) == 0)
403				goto loop;
404		}
405#endif
406		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
407		INTOFF;
408		cmdp = cmdlookup(name, 1);
409		if (cmdp->cmdtype == CMDFUNCTION)
410			cmdp = &loc_cmd;
411		cmdp->cmdtype = CMDNORMAL;
412		cmdp->param.index = idx;
413		INTON;
414		goto success;
415	}
416
417	if (act & DO_ERR) {
418		if (e == ENOENT || e == ENOTDIR)
419			outfmt(out2, "%s: not found\n", name);
420		else
421			outfmt(out2, "%s: %s\n", name, strerror(e));
422	}
423	entry->cmdtype = CMDUNKNOWN;
424	entry->u.index = 0;
425	return;
426
427success:
428	if (cd)
429		cmdtable_cd = 1;
430	entry->cmdtype = cmdp->cmdtype;
431	entry->u = cmdp->param;
432	entry->special = cmdp->special;
433}
434
435
436
437/*
438 * Search the table of builtin commands.
439 */
440
441int
442find_builtin(const char *name, int *special)
443{
444	const struct builtincmd *bp;
445
446	for (bp = builtincmd ; bp->name ; bp++) {
447		if (*bp->name == *name && equal(bp->name, name)) {
448			*special = bp->special;
449			return bp->code;
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
462void
463hashcd(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
477void
478changepath(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
489void
490clearcmdentry(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
521static struct tblentry **lastcmdentry;
522
523
524static struct tblentry *
525cmdlookup(const char *name, int add)
526{
527	int hashval;
528	const char *p;
529	struct tblentry *cmdp;
530	struct tblentry **pp;
531	size_t len;
532
533	p = name;
534	hashval = *p << 4;
535	while (*p)
536		hashval += *p++;
537	hashval &= 0x7FFF;
538	pp = &cmdtable[hashval % CMDTABLESIZE];
539	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
540		if (equal(cmdp->cmdname, name))
541			break;
542		pp = &cmdp->next;
543	}
544	if (add && cmdp == NULL) {
545		INTOFF;
546		len = strlen(name);
547		cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
548		cmdp->next = NULL;
549		cmdp->cmdtype = CMDUNKNOWN;
550		memcpy(cmdp->cmdname, name, len + 1);
551		INTON;
552	}
553	lastcmdentry = pp;
554	return cmdp;
555}
556
557/*
558 * Delete the command entry returned on the last lookup.
559 */
560
561static void
562delete_cmd_entry(void)
563{
564	struct tblentry *cmdp;
565
566	INTOFF;
567	cmdp = *lastcmdentry;
568	*lastcmdentry = cmdp->next;
569	ckfree(cmdp);
570	INTON;
571}
572
573
574
575/*
576 * Add a new command entry, replacing any existing command entry for
577 * the same name.
578 */
579
580static void
581addcmdentry(const char *name, struct cmdentry *entry)
582{
583	struct tblentry *cmdp;
584
585	INTOFF;
586	cmdp = cmdlookup(name, 1);
587	if (cmdp->cmdtype == CMDFUNCTION) {
588		unreffunc(cmdp->param.func);
589	}
590	cmdp->cmdtype = entry->cmdtype;
591	cmdp->param = entry->u;
592	INTON;
593}
594
595
596/*
597 * Define a shell function.
598 */
599
600void
601defun(const char *name, union node *func)
602{
603	struct cmdentry entry;
604
605	INTOFF;
606	entry.cmdtype = CMDFUNCTION;
607	entry.u.func = copyfunc(func);
608	addcmdentry(name, &entry);
609	INTON;
610}
611
612
613/*
614 * Delete a function if it exists.
615 * Called with interrupts off.
616 */
617
618int
619unsetfunc(const char *name)
620{
621	struct tblentry *cmdp;
622
623	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
624		unreffunc(cmdp->param.func);
625		delete_cmd_entry();
626		return (0);
627	}
628	return (0);
629}
630
631
632/*
633 * Check if a function by a certain name exists.
634 */
635int
636isfunc(const char *name)
637{
638	struct tblentry *cmdp;
639	cmdp = cmdlookup(name, 0);
640	return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
641}
642
643
644/*
645 * Shared code for the following builtin commands:
646 *    type, command -v, command -V
647 */
648
649int
650typecmd_impl(int argc, char **argv, int cmd, const char *path)
651{
652	struct cmdentry entry;
653	struct tblentry *cmdp;
654	const char *const *pp;
655	struct alias *ap;
656	int i;
657	int error1 = 0;
658
659	if (path != pathval())
660		clearcmdentry();
661
662	for (i = 1; i < argc; i++) {
663		/* First look at the keywords */
664		for (pp = parsekwd; *pp; pp++)
665			if (**pp == *argv[i] && equal(*pp, argv[i]))
666				break;
667
668		if (*pp) {
669			if (cmd == TYPECMD_SMALLV)
670				out1fmt("%s\n", argv[i]);
671			else
672				out1fmt("%s is a shell keyword\n", argv[i]);
673			continue;
674		}
675
676		/* Then look at the aliases */
677		if ((ap = lookupalias(argv[i], 1)) != NULL) {
678			if (cmd == TYPECMD_SMALLV) {
679				out1fmt("alias %s=", argv[i]);
680				out1qstr(ap->val);
681				outcslow('\n', out1);
682			} else
683				out1fmt("%s is an alias for %s\n", argv[i],
684				    ap->val);
685			continue;
686		}
687
688		/* Then check if it is a tracked alias */
689		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
690			entry.cmdtype = cmdp->cmdtype;
691			entry.u = cmdp->param;
692			entry.special = cmdp->special;
693		}
694		else {
695			/* Finally use brute force */
696			find_command(argv[i], &entry, 0, path);
697		}
698
699		switch (entry.cmdtype) {
700		case CMDNORMAL: {
701			if (strchr(argv[i], '/') == NULL) {
702				const char *path2 = path;
703				char *name;
704				int j = entry.u.index;
705				do {
706					name = padvance(&path2, argv[i]);
707					stunalloc(name);
708				} while (--j >= 0);
709				if (cmd == TYPECMD_SMALLV)
710					out1fmt("%s\n", name);
711				else
712					out1fmt("%s is%s %s\n", argv[i],
713					    (cmdp && cmd == TYPECMD_TYPE) ?
714						" a tracked alias for" : "",
715					    name);
716			} else {
717				if (eaccess(argv[i], X_OK) == 0) {
718					if (cmd == TYPECMD_SMALLV)
719						out1fmt("%s\n", argv[i]);
720					else
721						out1fmt("%s is %s\n", argv[i],
722						    argv[i]);
723				} else {
724					if (cmd != TYPECMD_SMALLV)
725						outfmt(out2, "%s: %s\n",
726						    argv[i], strerror(errno));
727					error1 |= 127;
728				}
729			}
730			break;
731		}
732		case CMDFUNCTION:
733			if (cmd == TYPECMD_SMALLV)
734				out1fmt("%s\n", argv[i]);
735			else
736				out1fmt("%s is a shell function\n", argv[i]);
737			break;
738
739		case CMDBUILTIN:
740			if (cmd == TYPECMD_SMALLV)
741				out1fmt("%s\n", argv[i]);
742			else if (entry.special)
743				out1fmt("%s is a special shell builtin\n",
744				    argv[i]);
745			else
746				out1fmt("%s is a shell builtin\n", argv[i]);
747			break;
748
749		default:
750			if (cmd != TYPECMD_SMALLV)
751				outfmt(out2, "%s: not found\n", argv[i]);
752			error1 |= 127;
753			break;
754		}
755	}
756
757	if (path != pathval())
758		clearcmdentry();
759
760	return error1;
761}
762
763/*
764 * Locate and print what a word is...
765 */
766
767int
768typecmd(int argc, char **argv)
769{
770	if (argc > 2 && strcmp(argv[1], "--") == 0)
771		argc--, argv++;
772	return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));
773}
774