exec.c revision 165930 
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: head/bin/sh/exec.c 165930 2007-01-11 00:19:00Z stefanf $");
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 <stdlib.h>
47
48/*
49 * When commands are first encountered, they are entered in a hash table.
50 * This ensures that a full path search will not have to be done for them
51 * on each invocation.
52 *
53 * We should investigate converting to a linear search, even though that
54 * would make the command name "hash" a misnomer.
55 */
56
57#include "shell.h"
58#include "main.h"
59#include "nodes.h"
60#include "parser.h"
61#include "redir.h"
62#include "eval.h"
63#include "exec.h"
64#include "builtins.h"
65#include "var.h"
66#include "options.h"
67#include "input.h"
68#include "output.h"
69#include "syntax.h"
70#include "memalloc.h"
71#include "error.h"
72#include "init.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#define ARB 1			/* actual size determined at run time */
81
82
83
84struct tblentry {
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	short cmdtype;		/* index identifying command */
89	char rehash;		/* if set, cd done since entry created */
90	char cmdname[ARB];	/* name of command */
91};
92
93
94STATIC struct tblentry *cmdtable[CMDTABLESIZE];
95STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
96int exerrno = 0;			/* Last exec error */
97
98
99STATIC void tryexec(char *, char **, char **);
100STATIC void printentry(struct tblentry *, int);
101STATIC struct tblentry *cmdlookup(char *, int);
102STATIC void delete_cmd_entry(void);
103
104
105
106/*
107 * Exec a program.  Never returns.  If you change this routine, you may
108 * have to change the find_command routine as well.
109 */
110
111void
112shellexec(char **argv, char **envp, char *path, int index)
113{
114	char *cmdname;
115	int e;
116
117	if (strchr(argv[0], '/') != NULL) {
118		tryexec(argv[0], argv, envp);
119		e = errno;
120	} else {
121		e = ENOENT;
122		while ((cmdname = padvance(&path, argv[0])) != NULL) {
123			if (--index < 0 && pathopt == NULL) {
124				tryexec(cmdname, argv, envp);
125				if (errno != ENOENT && errno != ENOTDIR)
126					e = errno;
127			}
128			stunalloc(cmdname);
129		}
130	}
131
132	/* Map to POSIX errors */
133	switch (e) {
134	case EACCES:
135		exerrno = 126;
136		break;
137	case ENOENT:
138		exerrno = 127;
139		break;
140	default:
141		exerrno = 2;
142		break;
143	}
144	if (e == ENOENT || e == ENOTDIR)
145		exerror(EXEXEC, "%s: not found", argv[0]);
146	exerror(EXEXEC, "%s: %s", argv[0], strerror(e));
147}
148
149
150STATIC void
151tryexec(char *cmd, char **argv, char **envp)
152{
153	int e;
154
155	execve(cmd, argv, envp);
156	e = errno;
157	if (e == ENOEXEC) {
158		initshellproc();
159		setinputfile(cmd, 0);
160		commandname = arg0 = savestr(argv[0]);
161		setparam(argv + 1);
162		exraise(EXSHELLPROC);
163		/*NOTREACHED*/
164	}
165	errno = e;
166}
167
168/*
169 * Do a path search.  The variable path (passed by reference) should be
170 * set to the start of the path before the first call; padvance will update
171 * this value as it proceeds.  Successive calls to padvance will return
172 * the possible path expansions in sequence.  If an option (indicated by
173 * a percent sign) appears in the path entry then the global variable
174 * pathopt will be set to point to it; otherwise pathopt will be set to
175 * NULL.
176 */
177
178char *pathopt;
179
180char *
181padvance(char **path, char *name)
182{
183	char *p, *q;
184	char *start;
185	int len;
186
187	if (*path == NULL)
188		return NULL;
189	start = *path;
190	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
191	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
192	while (stackblocksize() < len)
193		growstackblock();
194	q = stackblock();
195	if (p != start) {
196		memcpy(q, start, p - start);
197		q += p - start;
198		*q++ = '/';
199	}
200	strcpy(q, name);
201	pathopt = NULL;
202	if (*p == '%') {
203		pathopt = ++p;
204		while (*p && *p != ':')  p++;
205	}
206	if (*p == ':')
207		*path = p + 1;
208	else
209		*path = NULL;
210	return stalloc(len);
211}
212
213
214
215/*** Command hashing code ***/
216
217
218int
219hashcmd(int argc __unused, char **argv __unused)
220{
221	struct tblentry **pp;
222	struct tblentry *cmdp;
223	int c;
224	int verbose;
225	struct cmdentry entry;
226	char *name;
227
228	verbose = 0;
229	while ((c = nextopt("rv")) != '\0') {
230		if (c == 'r') {
231			clearcmdentry(0);
232		} else if (c == 'v') {
233			verbose++;
234		}
235	}
236	if (*argptr == NULL) {
237		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
238			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
239				if (cmdp->cmdtype == CMDNORMAL)
240					printentry(cmdp, verbose);
241			}
242		}
243		return 0;
244	}
245	while ((name = *argptr) != NULL) {
246		if ((cmdp = cmdlookup(name, 0)) != NULL
247		 && (cmdp->cmdtype == CMDNORMAL
248		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
249			delete_cmd_entry();
250		find_command(name, &entry, 1, pathval());
251		if (verbose) {
252			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
253				cmdp = cmdlookup(name, 0);
254				if (cmdp != NULL)
255					printentry(cmdp, verbose);
256				else
257					outfmt(&errout, "%s: not found\n", name);
258			}
259			flushall();
260		}
261		argptr++;
262	}
263	return 0;
264}
265
266
267STATIC void
268printentry(struct tblentry *cmdp, int verbose)
269{
270	int index;
271	char *path;
272	char *name;
273
274	if (cmdp->cmdtype == CMDNORMAL) {
275		index = cmdp->param.index;
276		path = pathval();
277		do {
278			name = padvance(&path, cmdp->cmdname);
279			stunalloc(name);
280		} while (--index >= 0);
281		out1str(name);
282	} else if (cmdp->cmdtype == CMDBUILTIN) {
283		out1fmt("builtin %s", cmdp->cmdname);
284	} else if (cmdp->cmdtype == CMDFUNCTION) {
285		out1fmt("function %s", cmdp->cmdname);
286		if (verbose) {
287			INTOFF;
288			name = commandtext(cmdp->param.func);
289			out1c(' ');
290			out1str(name);
291			ckfree(name);
292			INTON;
293		}
294#ifdef DEBUG
295	} else {
296		error("internal error: cmdtype %d", cmdp->cmdtype);
297#endif
298	}
299	if (cmdp->rehash)
300		out1c('*');
301	out1c('\n');
302}
303
304
305
306/*
307 * Resolve a command name.  If you change this routine, you may have to
308 * change the shellexec routine as well.
309 */
310
311void
312find_command(char *name, struct cmdentry *entry, int printerr, char *path)
313{
314	struct tblentry *cmdp;
315	int index;
316	int prev;
317	char *fullname;
318	struct stat statb;
319	int e;
320	int i;
321	int spec;
322
323	/* If name contains a slash, don't use the hash table */
324	if (strchr(name, '/') != NULL) {
325		entry->cmdtype = CMDNORMAL;
326		entry->u.index = 0;
327		return;
328	}
329
330	/* If name is in the table, and not invalidated by cd, we're done */
331	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
332		goto success;
333
334	/* If %builtin not in path, check for builtin next */
335	if (builtinloc < 0 && (i = find_builtin(name, &spec)) >= 0) {
336		INTOFF;
337		cmdp = cmdlookup(name, 1);
338		cmdp->cmdtype = CMDBUILTIN;
339		cmdp->param.index = i;
340		cmdp->special = spec;
341		INTON;
342		goto success;
343	}
344
345	/* We have to search path. */
346	prev = -1;		/* where to start */
347	if (cmdp) {		/* doing a rehash */
348		if (cmdp->cmdtype == CMDBUILTIN)
349			prev = builtinloc;
350		else
351			prev = cmdp->param.index;
352	}
353
354	e = ENOENT;
355	index = -1;
356loop:
357	while ((fullname = padvance(&path, name)) != NULL) {
358		stunalloc(fullname);
359		index++;
360		if (pathopt) {
361			if (prefix("builtin", pathopt)) {
362				if ((i = find_builtin(name, &spec)) < 0)
363					goto loop;
364				INTOFF;
365				cmdp = cmdlookup(name, 1);
366				cmdp->cmdtype = CMDBUILTIN;
367				cmdp->param.index = i;
368				cmdp->special = spec;
369				INTON;
370				goto success;
371			} else if (prefix("func", pathopt)) {
372				/* handled below */
373			} else {
374				goto loop;	/* ignore unimplemented options */
375			}
376		}
377		/* if rehash, don't redo absolute path names */
378		if (fullname[0] == '/' && index <= prev) {
379			if (index < prev)
380				goto loop;
381			TRACE(("searchexec \"%s\": no change\n", name));
382			goto success;
383		}
384		if (stat(fullname, &statb) < 0) {
385			if (errno != ENOENT && errno != ENOTDIR)
386				e = errno;
387			goto loop;
388		}
389		e = EACCES;	/* if we fail, this will be the error */
390		if (!S_ISREG(statb.st_mode))
391			goto loop;
392		if (pathopt) {		/* this is a %func directory */
393			stalloc(strlen(fullname) + 1);
394			readcmdfile(fullname);
395			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
396				error("%s not defined in %s", name, fullname);
397			stunalloc(fullname);
398			goto success;
399		}
400#ifdef notdef
401		if (statb.st_uid == geteuid()) {
402			if ((statb.st_mode & 0100) == 0)
403				goto loop;
404		} else if (statb.st_gid == getegid()) {
405			if ((statb.st_mode & 010) == 0)
406				goto loop;
407		} else {
408			if ((statb.st_mode & 01) == 0)
409				goto loop;
410		}
411#endif
412		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
413		INTOFF;
414		cmdp = cmdlookup(name, 1);
415		cmdp->cmdtype = CMDNORMAL;
416		cmdp->param.index = index;
417		INTON;
418		goto success;
419	}
420
421	/* We failed.  If there was an entry for this command, delete it */
422	if (cmdp)
423		delete_cmd_entry();
424	if (printerr) {
425		if (e == ENOENT || e == ENOTDIR)
426			outfmt(out2, "%s: not found\n", name);
427		else
428			outfmt(out2, "%s: %s\n", name, strerror(e));
429	}
430	entry->cmdtype = CMDUNKNOWN;
431	return;
432
433success:
434	cmdp->rehash = 0;
435	entry->cmdtype = cmdp->cmdtype;
436	entry->u = cmdp->param;
437	entry->special = cmdp->special;
438}
439
440
441
442/*
443 * Search the table of builtin commands.
444 */
445
446int
447find_builtin(char *name, int *special)
448{
449	const struct builtincmd *bp;
450
451	for (bp = builtincmd ; bp->name ; bp++) {
452		if (*bp->name == *name && equal(bp->name, name)) {
453			*special = bp->special;
454			return bp->code;
455		}
456	}
457	return -1;
458}
459
460
461
462/*
463 * Called when a cd is done.  Marks all commands so the next time they
464 * are executed they will be rehashed.
465 */
466
467void
468hashcd(void)
469{
470	struct tblentry **pp;
471	struct tblentry *cmdp;
472
473	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
474		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
475			if (cmdp->cmdtype == CMDNORMAL
476			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
477				cmdp->rehash = 1;
478		}
479	}
480}
481
482
483
484/*
485 * Called before PATH is changed.  The argument is the new value of PATH;
486 * pathval() still returns the old value at this point.  Called with
487 * interrupts off.
488 */
489
490void
491changepath(const char *newval)
492{
493	const char *old, *new;
494	int index;
495	int firstchange;
496	int bltin;
497
498	old = pathval();
499	new = newval;
500	firstchange = 9999;	/* assume no change */
501	index = 0;
502	bltin = -1;
503	for (;;) {
504		if (*old != *new) {
505			firstchange = index;
506			if ((*old == '\0' && *new == ':')
507			 || (*old == ':' && *new == '\0'))
508				firstchange++;
509			old = new;	/* ignore subsequent differences */
510		}
511		if (*new == '\0')
512			break;
513		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
514			bltin = index;
515		if (*new == ':') {
516			index++;
517		}
518		new++, old++;
519	}
520	if (builtinloc < 0 && bltin >= 0)
521		builtinloc = bltin;		/* zap builtins */
522	if (builtinloc >= 0 && bltin < 0)
523		firstchange = 0;
524	clearcmdentry(firstchange);
525	builtinloc = bltin;
526}
527
528
529/*
530 * Clear out command entries.  The argument specifies the first entry in
531 * PATH which has changed.
532 */
533
534void
535clearcmdentry(int firstchange)
536{
537	struct tblentry **tblp;
538	struct tblentry **pp;
539	struct tblentry *cmdp;
540
541	INTOFF;
542	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
543		pp = tblp;
544		while ((cmdp = *pp) != NULL) {
545			if ((cmdp->cmdtype == CMDNORMAL &&
546			     cmdp->param.index >= firstchange)
547			 || (cmdp->cmdtype == CMDBUILTIN &&
548			     builtinloc >= firstchange)) {
549				*pp = cmdp->next;
550				ckfree(cmdp);
551			} else {
552				pp = &cmdp->next;
553			}
554		}
555	}
556	INTON;
557}
558
559
560/*
561 * Delete all functions.
562 */
563
564#ifdef mkinit
565MKINIT void deletefuncs(void);
566
567SHELLPROC {
568	deletefuncs();
569}
570#endif
571
572void
573deletefuncs(void)
574{
575	struct tblentry **tblp;
576	struct tblentry **pp;
577	struct tblentry *cmdp;
578
579	INTOFF;
580	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
581		pp = tblp;
582		while ((cmdp = *pp) != NULL) {
583			if (cmdp->cmdtype == CMDFUNCTION) {
584				*pp = cmdp->next;
585				freefunc(cmdp->param.func);
586				ckfree(cmdp);
587			} else {
588				pp = &cmdp->next;
589			}
590		}
591	}
592	INTON;
593}
594
595
596
597/*
598 * Locate a command in the command hash table.  If "add" is nonzero,
599 * add the command to the table if it is not already present.  The
600 * variable "lastcmdentry" is set to point to the address of the link
601 * pointing to the entry, so that delete_cmd_entry can delete the
602 * entry.
603 */
604
605STATIC struct tblentry **lastcmdentry;
606
607
608STATIC struct tblentry *
609cmdlookup(char *name, int add)
610{
611	int hashval;
612	char *p;
613	struct tblentry *cmdp;
614	struct tblentry **pp;
615
616	p = name;
617	hashval = *p << 4;
618	while (*p)
619		hashval += *p++;
620	hashval &= 0x7FFF;
621	pp = &cmdtable[hashval % CMDTABLESIZE];
622	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
623		if (equal(cmdp->cmdname, name))
624			break;
625		pp = &cmdp->next;
626	}
627	if (add && cmdp == NULL) {
628		INTOFF;
629		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
630					+ strlen(name) + 1);
631		cmdp->next = NULL;
632		cmdp->cmdtype = CMDUNKNOWN;
633		cmdp->rehash = 0;
634		strcpy(cmdp->cmdname, name);
635		INTON;
636	}
637	lastcmdentry = pp;
638	return cmdp;
639}
640
641/*
642 * Delete the command entry returned on the last lookup.
643 */
644
645STATIC void
646delete_cmd_entry(void)
647{
648	struct tblentry *cmdp;
649
650	INTOFF;
651	cmdp = *lastcmdentry;
652	*lastcmdentry = cmdp->next;
653	ckfree(cmdp);
654	INTON;
655}
656
657
658
659/*
660 * Add a new command entry, replacing any existing command entry for
661 * the same name.
662 */
663
664void
665addcmdentry(char *name, struct cmdentry *entry)
666{
667	struct tblentry *cmdp;
668
669	INTOFF;
670	cmdp = cmdlookup(name, 1);
671	if (cmdp->cmdtype == CMDFUNCTION) {
672		freefunc(cmdp->param.func);
673	}
674	cmdp->cmdtype = entry->cmdtype;
675	cmdp->param = entry->u;
676	INTON;
677}
678
679
680/*
681 * Define a shell function.
682 */
683
684void
685defun(char *name, union node *func)
686{
687	struct cmdentry entry;
688
689	INTOFF;
690	entry.cmdtype = CMDFUNCTION;
691	entry.u.func = copyfunc(func);
692	addcmdentry(name, &entry);
693	INTON;
694}
695
696
697/*
698 * Delete a function if it exists.
699 */
700
701int
702unsetfunc(char *name)
703{
704	struct tblentry *cmdp;
705
706	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
707		freefunc(cmdp->param.func);
708		delete_cmd_entry();
709		return (0);
710	}
711	return (0);
712}
713
714/*
715 * Shared code for the following builtin commands:
716 *    type, command -v, command -V
717 */
718
719int
720typecmd_impl(int argc, char **argv, int cmd)
721{
722	struct cmdentry entry;
723	struct tblentry *cmdp;
724	char **pp;
725	struct alias *ap;
726	int i;
727	int error = 0;
728	extern char *const parsekwd[];
729
730	for (i = 1; i < argc; i++) {
731		if (cmd != TYPECMD_SMALLV)
732			out1str(argv[i]);
733
734		/* First look at the keywords */
735		for (pp = (char **)parsekwd; *pp; pp++)
736			if (**pp == *argv[i] && equal(*pp, argv[i]))
737				break;
738
739		if (*pp) {
740			if (cmd == TYPECMD_SMALLV)
741				out1fmt("%s\n", argv[i]);
742			else
743				out1str(" is a shell keyword\n");
744			continue;
745		}
746
747		/* Then look at the aliases */
748		if ((ap = lookupalias(argv[i], 1)) != NULL) {
749			if (cmd == TYPECMD_SMALLV)
750				out1fmt("alias %s='%s'\n", argv[i], ap->val);
751			else
752				out1fmt(" is an alias for %s\n", ap->val);
753			continue;
754		}
755
756		/* Then check if it is a tracked alias */
757		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
758			entry.cmdtype = cmdp->cmdtype;
759			entry.u = cmdp->param;
760		}
761		else {
762			/* Finally use brute force */
763			find_command(argv[i], &entry, 0, pathval());
764		}
765
766		switch (entry.cmdtype) {
767		case CMDNORMAL: {
768			if (strchr(argv[i], '/') == NULL) {
769				char *path = pathval(), *name;
770				int j = entry.u.index;
771				do {
772					name = padvance(&path, argv[i]);
773					stunalloc(name);
774				} while (--j >= 0);
775				if (cmd == TYPECMD_SMALLV)
776					out1fmt("%s\n", name);
777				else
778					out1fmt(" is%s %s\n",
779					    (cmdp && cmd == TYPECMD_TYPE) ?
780						" a tracked alias for" : "",
781					    name);
782			} else {
783				if (access(argv[i], X_OK) == 0) {
784					if (cmd == TYPECMD_SMALLV)
785						out1fmt("%s\n", argv[i]);
786					else
787						out1fmt(" is %s\n", argv[i]);
788				} else {
789					if (cmd != TYPECMD_SMALLV)
790						out1fmt(": %s\n",
791						    strerror(errno));
792					error |= 127;
793				}
794			}
795			break;
796		}
797		case CMDFUNCTION:
798			if (cmd == TYPECMD_SMALLV)
799				out1fmt("%s\n", argv[i]);
800			else
801				out1str(" is a shell function\n");
802			break;
803
804		case CMDBUILTIN:
805			if (cmd == TYPECMD_SMALLV)
806				out1fmt("%s\n", argv[i]);
807			else
808				out1str(" is a shell builtin\n");
809			break;
810
811		default:
812			if (cmd != TYPECMD_SMALLV)
813				out1str(": not found\n");
814			error |= 127;
815			break;
816		}
817	}
818	return error;
819}
820
821/*
822 * Locate and print what a word is...
823 */
824
825int
826typecmd(int argc, char **argv)
827{
828	return typecmd_impl(argc, argv, TYPECMD_TYPE);
829}
830