exec.c revision 151810 
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 151810 2005-10-28 18:37:09Z 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	short cmdtype;		/* index identifying command */
88	char rehash;		/* if set, cd done since entry created */
89	char cmdname[ARB];	/* name of command */
90};
91
92
93STATIC struct tblentry *cmdtable[CMDTABLESIZE];
94STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
95int exerrno = 0;			/* Last exec error */
96
97
98STATIC void tryexec(char *, char **, char **);
99STATIC void printentry(struct tblentry *, int);
100STATIC struct tblentry *cmdlookup(char *, int);
101STATIC void delete_cmd_entry(void);
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
110void
111shellexec(char **argv, char **envp, char *path, int index)
112{
113	char *cmdname;
114	int e;
115
116	if (strchr(argv[0], '/') != NULL) {
117		tryexec(argv[0], argv, envp);
118		e = errno;
119	} else {
120		e = ENOENT;
121		while ((cmdname = padvance(&path, argv[0])) != NULL) {
122			if (--index < 0 && pathopt == NULL) {
123				tryexec(cmdname, argv, envp);
124				if (errno != ENOENT && errno != ENOTDIR)
125					e = errno;
126			}
127			stunalloc(cmdname);
128		}
129	}
130
131	/* Map to POSIX errors */
132	switch (e) {
133	case EACCES:
134		exerrno = 126;
135		break;
136	case ENOENT:
137		exerrno = 127;
138		break;
139	default:
140		exerrno = 2;
141		break;
142	}
143	if (e == ENOENT || e == ENOTDIR)
144		exerror(EXEXEC, "%s: not found", argv[0]);
145	exerror(EXEXEC, "%s: %s", argv[0], strerror(e));
146}
147
148
149STATIC void
150tryexec(char *cmd, char **argv, char **envp)
151{
152	int e;
153
154	execve(cmd, argv, envp);
155	e = errno;
156	if (e == ENOEXEC) {
157		initshellproc();
158		setinputfile(cmd, 0);
159		commandname = arg0 = savestr(argv[0]);
160		setparam(argv + 1);
161		exraise(EXSHELLPROC);
162		/*NOTREACHED*/
163	}
164	errno = e;
165}
166
167/*
168 * Do a path search.  The variable path (passed by reference) should be
169 * set to the start of the path before the first call; padvance will update
170 * this value as it proceeds.  Successive calls to padvance will return
171 * the possible path expansions in sequence.  If an option (indicated by
172 * a percent sign) appears in the path entry then the global variable
173 * pathopt will be set to point to it; otherwise pathopt will be set to
174 * NULL.
175 */
176
177char *pathopt;
178
179char *
180padvance(char **path, char *name)
181{
182	char *p, *q;
183	char *start;
184	int len;
185
186	if (*path == NULL)
187		return NULL;
188	start = *path;
189	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
190	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
191	while (stackblocksize() < len)
192		growstackblock();
193	q = stackblock();
194	if (p != start) {
195		memcpy(q, start, p - start);
196		q += p - start;
197		*q++ = '/';
198	}
199	strcpy(q, name);
200	pathopt = NULL;
201	if (*p == '%') {
202		pathopt = ++p;
203		while (*p && *p != ':')  p++;
204	}
205	if (*p == ':')
206		*path = p + 1;
207	else
208		*path = NULL;
209	return stalloc(len);
210}
211
212
213
214/*** Command hashing code ***/
215
216
217int
218hashcmd(int argc __unused, char **argv __unused)
219{
220	struct tblentry **pp;
221	struct tblentry *cmdp;
222	int c;
223	int verbose;
224	struct cmdentry entry;
225	char *name;
226
227	verbose = 0;
228	while ((c = nextopt("rv")) != '\0') {
229		if (c == 'r') {
230			clearcmdentry(0);
231		} else if (c == 'v') {
232			verbose++;
233		}
234	}
235	if (*argptr == NULL) {
236		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
237			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
238				if (cmdp->cmdtype == CMDNORMAL)
239					printentry(cmdp, verbose);
240			}
241		}
242		return 0;
243	}
244	while ((name = *argptr) != NULL) {
245		if ((cmdp = cmdlookup(name, 0)) != NULL
246		 && (cmdp->cmdtype == CMDNORMAL
247		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
248			delete_cmd_entry();
249		find_command(name, &entry, 1, pathval());
250		if (verbose) {
251			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
252				cmdp = cmdlookup(name, 0);
253				if (cmdp != NULL)
254					printentry(cmdp, verbose);
255				else
256					outfmt(&errout, "%s: not found\n", name);
257			}
258			flushall();
259		}
260		argptr++;
261	}
262	return 0;
263}
264
265
266STATIC void
267printentry(struct tblentry *cmdp, int verbose)
268{
269	int index;
270	char *path;
271	char *name;
272
273	if (cmdp->cmdtype == CMDNORMAL) {
274		index = cmdp->param.index;
275		path = pathval();
276		do {
277			name = padvance(&path, cmdp->cmdname);
278			stunalloc(name);
279		} while (--index >= 0);
280		out1str(name);
281	} else if (cmdp->cmdtype == CMDBUILTIN) {
282		out1fmt("builtin %s", cmdp->cmdname);
283	} else if (cmdp->cmdtype == CMDFUNCTION) {
284		out1fmt("function %s", cmdp->cmdname);
285		if (verbose) {
286			INTOFF;
287			name = commandtext(cmdp->param.func);
288			out1c(' ');
289			out1str(name);
290			ckfree(name);
291			INTON;
292		}
293#ifdef DEBUG
294	} else {
295		error("internal error: cmdtype %d", cmdp->cmdtype);
296#endif
297	}
298	if (cmdp->rehash)
299		out1c('*');
300	out1c('\n');
301}
302
303
304
305/*
306 * Resolve a command name.  If you change this routine, you may have to
307 * change the shellexec routine as well.
308 */
309
310void
311find_command(char *name, struct cmdentry *entry, int printerr, char *path)
312{
313	struct tblentry *cmdp;
314	int index;
315	int prev;
316	char *fullname;
317	struct stat statb;
318	int e;
319	int i;
320
321	/* If name contains a slash, don't use the hash table */
322	if (strchr(name, '/') != NULL) {
323		entry->cmdtype = CMDNORMAL;
324		entry->u.index = 0;
325		return;
326	}
327
328	/* If name is in the table, and not invalidated by cd, we're done */
329	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
330		goto success;
331
332	/* If %builtin not in path, check for builtin next */
333	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
334		INTOFF;
335		cmdp = cmdlookup(name, 1);
336		cmdp->cmdtype = CMDBUILTIN;
337		cmdp->param.index = i;
338		INTON;
339		goto success;
340	}
341
342	/* We have to search path. */
343	prev = -1;		/* where to start */
344	if (cmdp) {		/* doing a rehash */
345		if (cmdp->cmdtype == CMDBUILTIN)
346			prev = builtinloc;
347		else
348			prev = cmdp->param.index;
349	}
350
351	e = ENOENT;
352	index = -1;
353loop:
354	while ((fullname = padvance(&path, name)) != NULL) {
355		stunalloc(fullname);
356		index++;
357		if (pathopt) {
358			if (prefix("builtin", pathopt)) {
359				if ((i = find_builtin(name)) < 0)
360					goto loop;
361				INTOFF;
362				cmdp = cmdlookup(name, 1);
363				cmdp->cmdtype = CMDBUILTIN;
364				cmdp->param.index = i;
365				INTON;
366				goto success;
367			} else if (prefix("func", pathopt)) {
368				/* handled below */
369			} else {
370				goto loop;	/* ignore unimplemented options */
371			}
372		}
373		/* if rehash, don't redo absolute path names */
374		if (fullname[0] == '/' && index <= prev) {
375			if (index < prev)
376				goto loop;
377			TRACE(("searchexec \"%s\": no change\n", name));
378			goto success;
379		}
380		if (stat(fullname, &statb) < 0) {
381			if (errno != ENOENT && errno != ENOTDIR)
382				e = errno;
383			goto loop;
384		}
385		e = EACCES;	/* if we fail, this will be the error */
386		if (!S_ISREG(statb.st_mode))
387			goto loop;
388		if (pathopt) {		/* this is a %func directory */
389			stalloc(strlen(fullname) + 1);
390			readcmdfile(fullname);
391			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
392				error("%s not defined in %s", name, fullname);
393			stunalloc(fullname);
394			goto success;
395		}
396#ifdef notdef
397		if (statb.st_uid == geteuid()) {
398			if ((statb.st_mode & 0100) == 0)
399				goto loop;
400		} else if (statb.st_gid == getegid()) {
401			if ((statb.st_mode & 010) == 0)
402				goto loop;
403		} else {
404			if ((statb.st_mode & 01) == 0)
405				goto loop;
406		}
407#endif
408		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
409		INTOFF;
410		cmdp = cmdlookup(name, 1);
411		cmdp->cmdtype = CMDNORMAL;
412		cmdp->param.index = index;
413		INTON;
414		goto success;
415	}
416
417	/* We failed.  If there was an entry for this command, delete it */
418	if (cmdp)
419		delete_cmd_entry();
420	if (printerr) {
421		if (e == ENOENT || e == ENOTDIR)
422			outfmt(out2, "%s: not found\n", name);
423		else
424			outfmt(out2, "%s: %s\n", name, strerror(e));
425	}
426	entry->cmdtype = CMDUNKNOWN;
427	return;
428
429success:
430	cmdp->rehash = 0;
431	entry->cmdtype = cmdp->cmdtype;
432	entry->u = cmdp->param;
433}
434
435
436
437/*
438 * Search the table of builtin commands.
439 */
440
441int
442find_builtin(char *name)
443{
444	const struct builtincmd *bp;
445
446	for (bp = builtincmd ; bp->name ; bp++) {
447		if (*bp->name == *name && equal(bp->name, name))
448			return bp->code;
449	}
450	return -1;
451}
452
453
454
455/*
456 * Called when a cd is done.  Marks all commands so the next time they
457 * are executed they will be rehashed.
458 */
459
460void
461hashcd(void)
462{
463	struct tblentry **pp;
464	struct tblentry *cmdp;
465
466	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
467		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
468			if (cmdp->cmdtype == CMDNORMAL
469			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
470				cmdp->rehash = 1;
471		}
472	}
473}
474
475
476
477/*
478 * Called before PATH is changed.  The argument is the new value of PATH;
479 * pathval() still returns the old value at this point.  Called with
480 * interrupts off.
481 */
482
483void
484changepath(const char *newval)
485{
486	const char *old, *new;
487	int index;
488	int firstchange;
489	int bltin;
490
491	old = pathval();
492	new = newval;
493	firstchange = 9999;	/* assume no change */
494	index = 0;
495	bltin = -1;
496	for (;;) {
497		if (*old != *new) {
498			firstchange = index;
499			if ((*old == '\0' && *new == ':')
500			 || (*old == ':' && *new == '\0'))
501				firstchange++;
502			old = new;	/* ignore subsequent differences */
503		}
504		if (*new == '\0')
505			break;
506		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
507			bltin = index;
508		if (*new == ':') {
509			index++;
510		}
511		new++, old++;
512	}
513	if (builtinloc < 0 && bltin >= 0)
514		builtinloc = bltin;		/* zap builtins */
515	if (builtinloc >= 0 && bltin < 0)
516		firstchange = 0;
517	clearcmdentry(firstchange);
518	builtinloc = bltin;
519}
520
521
522/*
523 * Clear out command entries.  The argument specifies the first entry in
524 * PATH which has changed.
525 */
526
527void
528clearcmdentry(int firstchange)
529{
530	struct tblentry **tblp;
531	struct tblentry **pp;
532	struct tblentry *cmdp;
533
534	INTOFF;
535	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
536		pp = tblp;
537		while ((cmdp = *pp) != NULL) {
538			if ((cmdp->cmdtype == CMDNORMAL &&
539			     cmdp->param.index >= firstchange)
540			 || (cmdp->cmdtype == CMDBUILTIN &&
541			     builtinloc >= firstchange)) {
542				*pp = cmdp->next;
543				ckfree(cmdp);
544			} else {
545				pp = &cmdp->next;
546			}
547		}
548	}
549	INTON;
550}
551
552
553/*
554 * Delete all functions.
555 */
556
557#ifdef mkinit
558MKINIT void deletefuncs(void);
559
560SHELLPROC {
561	deletefuncs();
562}
563#endif
564
565void
566deletefuncs(void)
567{
568	struct tblentry **tblp;
569	struct tblentry **pp;
570	struct tblentry *cmdp;
571
572	INTOFF;
573	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
574		pp = tblp;
575		while ((cmdp = *pp) != NULL) {
576			if (cmdp->cmdtype == CMDFUNCTION) {
577				*pp = cmdp->next;
578				freefunc(cmdp->param.func);
579				ckfree(cmdp);
580			} else {
581				pp = &cmdp->next;
582			}
583		}
584	}
585	INTON;
586}
587
588
589
590/*
591 * Locate a command in the command hash table.  If "add" is nonzero,
592 * add the command to the table if it is not already present.  The
593 * variable "lastcmdentry" is set to point to the address of the link
594 * pointing to the entry, so that delete_cmd_entry can delete the
595 * entry.
596 */
597
598STATIC struct tblentry **lastcmdentry;
599
600
601STATIC struct tblentry *
602cmdlookup(char *name, int add)
603{
604	int hashval;
605	char *p;
606	struct tblentry *cmdp;
607	struct tblentry **pp;
608
609	p = name;
610	hashval = *p << 4;
611	while (*p)
612		hashval += *p++;
613	hashval &= 0x7FFF;
614	pp = &cmdtable[hashval % CMDTABLESIZE];
615	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
616		if (equal(cmdp->cmdname, name))
617			break;
618		pp = &cmdp->next;
619	}
620	if (add && cmdp == NULL) {
621		INTOFF;
622		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
623					+ strlen(name) + 1);
624		cmdp->next = NULL;
625		cmdp->cmdtype = CMDUNKNOWN;
626		cmdp->rehash = 0;
627		strcpy(cmdp->cmdname, name);
628		INTON;
629	}
630	lastcmdentry = pp;
631	return cmdp;
632}
633
634/*
635 * Delete the command entry returned on the last lookup.
636 */
637
638STATIC void
639delete_cmd_entry(void)
640{
641	struct tblentry *cmdp;
642
643	INTOFF;
644	cmdp = *lastcmdentry;
645	*lastcmdentry = cmdp->next;
646	ckfree(cmdp);
647	INTON;
648}
649
650
651
652/*
653 * Add a new command entry, replacing any existing command entry for
654 * the same name.
655 */
656
657void
658addcmdentry(char *name, struct cmdentry *entry)
659{
660	struct tblentry *cmdp;
661
662	INTOFF;
663	cmdp = cmdlookup(name, 1);
664	if (cmdp->cmdtype == CMDFUNCTION) {
665		freefunc(cmdp->param.func);
666	}
667	cmdp->cmdtype = entry->cmdtype;
668	cmdp->param = entry->u;
669	INTON;
670}
671
672
673/*
674 * Define a shell function.
675 */
676
677void
678defun(char *name, union node *func)
679{
680	struct cmdentry entry;
681
682	INTOFF;
683	entry.cmdtype = CMDFUNCTION;
684	entry.u.func = copyfunc(func);
685	addcmdentry(name, &entry);
686	INTON;
687}
688
689
690/*
691 * Delete a function if it exists.
692 */
693
694int
695unsetfunc(char *name)
696{
697	struct tblentry *cmdp;
698
699	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
700		freefunc(cmdp->param.func);
701		delete_cmd_entry();
702		return (0);
703	}
704	return (0);
705}
706
707/*
708 * Shared code for the following builtin commands:
709 *    type, command -v, command -V
710 */
711
712int
713typecmd_impl(int argc, char **argv, int cmd)
714{
715	struct cmdentry entry;
716	struct tblentry *cmdp;
717	char **pp;
718	struct alias *ap;
719	int i;
720	int error = 0;
721	extern char *const parsekwd[];
722
723	for (i = 1; i < argc; i++) {
724		if (cmd != TYPECMD_SMALLV)
725			out1str(argv[i]);
726
727		/* First look at the keywords */
728		for (pp = (char **)parsekwd; *pp; pp++)
729			if (**pp == *argv[i] && equal(*pp, argv[i]))
730				break;
731
732		if (*pp) {
733			if (cmd == TYPECMD_SMALLV)
734				out1fmt("%s\n", argv[i]);
735			else
736				out1str(" is a shell keyword\n");
737			continue;
738		}
739
740		/* Then look at the aliases */
741		if ((ap = lookupalias(argv[i], 1)) != NULL) {
742			if (cmd == TYPECMD_SMALLV)
743				out1fmt("alias %s='%s'\n", argv[i], ap->val);
744			else
745				out1fmt(" is an alias for %s\n", ap->val);
746			continue;
747		}
748
749		/* Then check if it is a tracked alias */
750		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
751			entry.cmdtype = cmdp->cmdtype;
752			entry.u = cmdp->param;
753		}
754		else {
755			/* Finally use brute force */
756			find_command(argv[i], &entry, 0, pathval());
757		}
758
759		switch (entry.cmdtype) {
760		case CMDNORMAL: {
761			if (strchr(argv[i], '/') == NULL) {
762				char *path = pathval(), *name;
763				int j = entry.u.index;
764				do {
765					name = padvance(&path, argv[i]);
766					stunalloc(name);
767				} while (--j >= 0);
768				if (cmd == TYPECMD_SMALLV)
769					out1fmt("%s\n", name);
770				else
771					out1fmt(" is%s %s\n",
772					    (cmdp && cmd == TYPECMD_TYPE) ?
773						" a tracked alias for" : "",
774					    name);
775			} else {
776				if (access(argv[i], X_OK) == 0) {
777					if (cmd == TYPECMD_SMALLV)
778						out1fmt("%s\n", argv[i]);
779					else
780						out1fmt(" is %s\n", argv[i]);
781				}
782				else
783					out1fmt(": %s\n", strerror(errno));
784			}
785			break;
786		}
787		case CMDFUNCTION:
788			if (cmd == TYPECMD_SMALLV)
789				out1fmt("%s\n", argv[i]);
790			else
791				out1str(" is a shell function\n");
792			break;
793
794		case CMDBUILTIN:
795			if (cmd == TYPECMD_SMALLV)
796				out1fmt("%s\n", argv[i]);
797			else
798				out1str(" is a shell builtin\n");
799			break;
800
801		default:
802			if (cmd != TYPECMD_SMALLV)
803				out1str(": not found\n");
804			error |= 127;
805			break;
806		}
807	}
808	return error;
809}
810
811/*
812 * Locate and print what a word is...
813 */
814
815int
816typecmd(int argc, char **argv)
817{
818	return typecmd_impl(argc, argv, TYPECMD_TYPE);
819}
820