exec.c revision 100351 
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 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#ifndef lint
38#if 0
39static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
40#endif
41#endif /* not lint */
42#include <sys/cdefs.h>
43__FBSDID("$FreeBSD: head/bin/sh/exec.c 100351 2002-07-19 08:09:04Z tjr $");
44
45#include <sys/types.h>
46#include <sys/stat.h>
47#include <unistd.h>
48#include <fcntl.h>
49#include <errno.h>
50#include <stdlib.h>
51
52/*
53 * When commands are first encountered, they are entered in a hash table.
54 * This ensures that a full path search will not have to be done for them
55 * on each invocation.
56 *
57 * We should investigate converting to a linear search, even though that
58 * would make the command name "hash" a misnomer.
59 */
60
61#include "shell.h"
62#include "main.h"
63#include "nodes.h"
64#include "parser.h"
65#include "redir.h"
66#include "eval.h"
67#include "exec.h"
68#include "builtins.h"
69#include "var.h"
70#include "options.h"
71#include "input.h"
72#include "output.h"
73#include "syntax.h"
74#include "memalloc.h"
75#include "error.h"
76#include "init.h"
77#include "mystring.h"
78#include "show.h"
79#include "jobs.h"
80#include "alias.h"
81
82
83#define CMDTABLESIZE 31		/* should be prime */
84#define ARB 1			/* actual size determined at run time */
85
86
87
88struct tblentry {
89	struct tblentry *next;	/* next entry in hash chain */
90	union param param;	/* definition of builtin function */
91	short cmdtype;		/* index identifying command */
92	char rehash;		/* if set, cd done since entry created */
93	char cmdname[ARB];	/* name of command */
94};
95
96
97STATIC struct tblentry *cmdtable[CMDTABLESIZE];
98STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
99int exerrno = 0;			/* Last exec error */
100
101
102STATIC void tryexec(char *, char **, char **);
103STATIC void printentry(struct tblentry *, int);
104STATIC struct tblentry *cmdlookup(char *, int);
105STATIC void delete_cmd_entry(void);
106
107
108
109/*
110 * Exec a program.  Never returns.  If you change this routine, you may
111 * have to change the find_command routine as well.
112 */
113
114void
115shellexec(char **argv, char **envp, char *path, int index)
116{
117	char *cmdname;
118	int e;
119
120	if (strchr(argv[0], '/') != NULL) {
121		tryexec(argv[0], argv, envp);
122		e = errno;
123	} else {
124		e = ENOENT;
125		while ((cmdname = padvance(&path, argv[0])) != NULL) {
126			if (--index < 0 && pathopt == NULL) {
127				tryexec(cmdname, argv, envp);
128				if (errno != ENOENT && errno != ENOTDIR)
129					e = errno;
130			}
131			stunalloc(cmdname);
132		}
133	}
134
135	/* Map to POSIX errors */
136	switch (e) {
137	case EACCES:
138		exerrno = 126;
139		break;
140	case ENOENT:
141		exerrno = 127;
142		break;
143	default:
144		exerrno = 2;
145		break;
146	}
147	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
148}
149
150
151STATIC void
152tryexec(char *cmd, char **argv, char **envp)
153{
154	int e;
155
156	execve(cmd, argv, envp);
157	e = errno;
158	if (e == ENOEXEC) {
159		initshellproc();
160		setinputfile(cmd, 0);
161		commandname = arg0 = savestr(argv[0]);
162		setparam(argv + 1);
163		exraise(EXSHELLPROC);
164		/*NOTREACHED*/
165	}
166	errno = e;
167}
168
169/*
170 * Do a path search.  The variable path (passed by reference) should be
171 * set to the start of the path before the first call; padvance will update
172 * this value as it proceeds.  Successive calls to padvance will return
173 * the possible path expansions in sequence.  If an option (indicated by
174 * a percent sign) appears in the path entry then the global variable
175 * pathopt will be set to point to it; otherwise pathopt will be set to
176 * NULL.
177 */
178
179char *pathopt;
180
181char *
182padvance(char **path, char *name)
183{
184	char *p, *q;
185	char *start;
186	int len;
187
188	if (*path == NULL)
189		return NULL;
190	start = *path;
191	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
192	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
193	while (stackblocksize() < len)
194		growstackblock();
195	q = stackblock();
196	if (p != start) {
197		memcpy(q, start, p - start);
198		q += p - start;
199		*q++ = '/';
200	}
201	strcpy(q, name);
202	pathopt = NULL;
203	if (*p == '%') {
204		pathopt = ++p;
205		while (*p && *p != ':')  p++;
206	}
207	if (*p == ':')
208		*path = p + 1;
209	else
210		*path = NULL;
211	return stalloc(len);
212}
213
214
215
216/*** Command hashing code ***/
217
218
219int
220hashcmd(int argc __unused, char **argv __unused)
221{
222	struct tblentry **pp;
223	struct tblentry *cmdp;
224	int c;
225	int verbose;
226	struct cmdentry entry;
227	char *name;
228
229	verbose = 0;
230	while ((c = nextopt("rv")) != '\0') {
231		if (c == 'r') {
232			clearcmdentry(0);
233		} else if (c == 'v') {
234			verbose++;
235		}
236	}
237	if (*argptr == NULL) {
238		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
239			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
240				if (cmdp->cmdtype == CMDNORMAL)
241					printentry(cmdp, verbose);
242			}
243		}
244		return 0;
245	}
246	while ((name = *argptr) != NULL) {
247		if ((cmdp = cmdlookup(name, 0)) != NULL
248		 && (cmdp->cmdtype == CMDNORMAL
249		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
250			delete_cmd_entry();
251		find_command(name, &entry, 1, pathval());
252		if (verbose) {
253			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
254				cmdp = cmdlookup(name, 0);
255				if (cmdp != NULL)
256					printentry(cmdp, verbose);
257				else
258					outfmt(&errout, "%s: not found\n", name);
259			}
260			flushall();
261		}
262		argptr++;
263	}
264	return 0;
265}
266
267
268STATIC void
269printentry(struct tblentry *cmdp, int verbose)
270{
271	int index;
272	char *path;
273	char *name;
274
275	if (cmdp->cmdtype == CMDNORMAL) {
276		index = cmdp->param.index;
277		path = pathval();
278		do {
279			name = padvance(&path, cmdp->cmdname);
280			stunalloc(name);
281		} while (--index >= 0);
282		out1str(name);
283	} else if (cmdp->cmdtype == CMDBUILTIN) {
284		out1fmt("builtin %s", cmdp->cmdname);
285	} else if (cmdp->cmdtype == CMDFUNCTION) {
286		out1fmt("function %s", cmdp->cmdname);
287		if (verbose) {
288			INTOFF;
289			name = commandtext(cmdp->param.func);
290			out1c(' ');
291			out1str(name);
292			ckfree(name);
293			INTON;
294		}
295#ifdef DEBUG
296	} else {
297		error("internal error: cmdtype %d", cmdp->cmdtype);
298#endif
299	}
300	if (cmdp->rehash)
301		out1c('*');
302	out1c('\n');
303}
304
305
306
307/*
308 * Resolve a command name.  If you change this routine, you may have to
309 * change the shellexec routine as well.
310 */
311
312void
313find_command(char *name, struct cmdentry *entry, int printerr, char *path)
314{
315	struct tblentry *cmdp;
316	int index;
317	int prev;
318	char *fullname;
319	struct stat statb;
320	int e;
321	int i;
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)) >= 0) {
336		INTOFF;
337		cmdp = cmdlookup(name, 1);
338		cmdp->cmdtype = CMDBUILTIN;
339		cmdp->param.index = i;
340		INTON;
341		goto success;
342	}
343
344	/* We have to search path. */
345	prev = -1;		/* where to start */
346	if (cmdp) {		/* doing a rehash */
347		if (cmdp->cmdtype == CMDBUILTIN)
348			prev = builtinloc;
349		else
350			prev = cmdp->param.index;
351	}
352
353	e = ENOENT;
354	index = -1;
355loop:
356	while ((fullname = padvance(&path, name)) != NULL) {
357		stunalloc(fullname);
358		index++;
359		if (pathopt) {
360			if (prefix("builtin", pathopt)) {
361				if ((i = find_builtin(name)) < 0)
362					goto loop;
363				INTOFF;
364				cmdp = cmdlookup(name, 1);
365				cmdp->cmdtype = CMDBUILTIN;
366				cmdp->param.index = i;
367				INTON;
368				goto success;
369			} else if (prefix("func", pathopt)) {
370				/* handled below */
371			} else {
372				goto loop;	/* ignore unimplemented options */
373			}
374		}
375		/* if rehash, don't redo absolute path names */
376		if (fullname[0] == '/' && index <= prev) {
377			if (index < prev)
378				goto loop;
379			TRACE(("searchexec \"%s\": no change\n", name));
380			goto success;
381		}
382		if (stat(fullname, &statb) < 0) {
383			if (errno != ENOENT && errno != ENOTDIR)
384				e = errno;
385			goto loop;
386		}
387		e = EACCES;	/* if we fail, this will be the error */
388		if (!S_ISREG(statb.st_mode))
389			goto loop;
390		if (pathopt) {		/* this is a %func directory */
391			stalloc(strlen(fullname) + 1);
392			readcmdfile(fullname);
393			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
394				error("%s not defined in %s", name, fullname);
395			stunalloc(fullname);
396			goto success;
397		}
398#ifdef notdef
399		if (statb.st_uid == geteuid()) {
400			if ((statb.st_mode & 0100) == 0)
401				goto loop;
402		} else if (statb.st_gid == getegid()) {
403			if ((statb.st_mode & 010) == 0)
404				goto loop;
405		} else {
406			if ((statb.st_mode & 01) == 0)
407				goto loop;
408		}
409#endif
410		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
411		INTOFF;
412		cmdp = cmdlookup(name, 1);
413		cmdp->cmdtype = CMDNORMAL;
414		cmdp->param.index = index;
415		INTON;
416		goto success;
417	}
418
419	/* We failed.  If there was an entry for this command, delete it */
420	if (cmdp)
421		delete_cmd_entry();
422	if (printerr)
423		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
424	entry->cmdtype = CMDUNKNOWN;
425	return;
426
427success:
428	cmdp->rehash = 0;
429	entry->cmdtype = cmdp->cmdtype;
430	entry->u = cmdp->param;
431}
432
433
434
435/*
436 * Search the table of builtin commands.
437 */
438
439int
440find_builtin(char *name)
441{
442	const struct builtincmd *bp;
443
444	for (bp = builtincmd ; bp->name ; bp++) {
445		if (*bp->name == *name && equal(bp->name, name))
446			return bp->code;
447	}
448	return -1;
449}
450
451
452
453/*
454 * Called when a cd is done.  Marks all commands so the next time they
455 * are executed they will be rehashed.
456 */
457
458void
459hashcd(void)
460{
461	struct tblentry **pp;
462	struct tblentry *cmdp;
463
464	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
465		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
466			if (cmdp->cmdtype == CMDNORMAL
467			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
468				cmdp->rehash = 1;
469		}
470	}
471}
472
473
474
475/*
476 * Called before PATH is changed.  The argument is the new value of PATH;
477 * pathval() still returns the old value at this point.  Called with
478 * interrupts off.
479 */
480
481void
482changepath(const char *newval)
483{
484	const char *old, *new;
485	int index;
486	int firstchange;
487	int bltin;
488
489	old = pathval();
490	new = newval;
491	firstchange = 9999;	/* assume no change */
492	index = 0;
493	bltin = -1;
494	for (;;) {
495		if (*old != *new) {
496			firstchange = index;
497			if ((*old == '\0' && *new == ':')
498			 || (*old == ':' && *new == '\0'))
499				firstchange++;
500			old = new;	/* ignore subsequent differences */
501		}
502		if (*new == '\0')
503			break;
504		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
505			bltin = index;
506		if (*new == ':') {
507			index++;
508		}
509		new++, old++;
510	}
511	if (builtinloc < 0 && bltin >= 0)
512		builtinloc = bltin;		/* zap builtins */
513	if (builtinloc >= 0 && bltin < 0)
514		firstchange = 0;
515	clearcmdentry(firstchange);
516	builtinloc = bltin;
517}
518
519
520/*
521 * Clear out command entries.  The argument specifies the first entry in
522 * PATH which has changed.
523 */
524
525void
526clearcmdentry(int firstchange)
527{
528	struct tblentry **tblp;
529	struct tblentry **pp;
530	struct tblentry *cmdp;
531
532	INTOFF;
533	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
534		pp = tblp;
535		while ((cmdp = *pp) != NULL) {
536			if ((cmdp->cmdtype == CMDNORMAL &&
537			     cmdp->param.index >= firstchange)
538			 || (cmdp->cmdtype == CMDBUILTIN &&
539			     builtinloc >= firstchange)) {
540				*pp = cmdp->next;
541				ckfree(cmdp);
542			} else {
543				pp = &cmdp->next;
544			}
545		}
546	}
547	INTON;
548}
549
550
551/*
552 * Delete all functions.
553 */
554
555#ifdef mkinit
556MKINIT void deletefuncs();
557
558SHELLPROC {
559	deletefuncs();
560}
561#endif
562
563void
564deletefuncs(void)
565{
566	struct tblentry **tblp;
567	struct tblentry **pp;
568	struct tblentry *cmdp;
569
570	INTOFF;
571	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
572		pp = tblp;
573		while ((cmdp = *pp) != NULL) {
574			if (cmdp->cmdtype == CMDFUNCTION) {
575				*pp = cmdp->next;
576				freefunc(cmdp->param.func);
577				ckfree(cmdp);
578			} else {
579				pp = &cmdp->next;
580			}
581		}
582	}
583	INTON;
584}
585
586
587
588/*
589 * Locate a command in the command hash table.  If "add" is nonzero,
590 * add the command to the table if it is not already present.  The
591 * variable "lastcmdentry" is set to point to the address of the link
592 * pointing to the entry, so that delete_cmd_entry can delete the
593 * entry.
594 */
595
596struct tblentry **lastcmdentry;
597
598
599STATIC struct tblentry *
600cmdlookup(char *name, int add)
601{
602	int hashval;
603	char *p;
604	struct tblentry *cmdp;
605	struct tblentry **pp;
606
607	p = name;
608	hashval = *p << 4;
609	while (*p)
610		hashval += *p++;
611	hashval &= 0x7FFF;
612	pp = &cmdtable[hashval % CMDTABLESIZE];
613	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
614		if (equal(cmdp->cmdname, name))
615			break;
616		pp = &cmdp->next;
617	}
618	if (add && cmdp == NULL) {
619		INTOFF;
620		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
621					+ strlen(name) + 1);
622		cmdp->next = NULL;
623		cmdp->cmdtype = CMDUNKNOWN;
624		cmdp->rehash = 0;
625		strcpy(cmdp->cmdname, name);
626		INTON;
627	}
628	lastcmdentry = pp;
629	return cmdp;
630}
631
632/*
633 * Delete the command entry returned on the last lookup.
634 */
635
636STATIC void
637delete_cmd_entry(void)
638{
639	struct tblentry *cmdp;
640
641	INTOFF;
642	cmdp = *lastcmdentry;
643	*lastcmdentry = cmdp->next;
644	ckfree(cmdp);
645	INTON;
646}
647
648
649
650/*
651 * Add a new command entry, replacing any existing command entry for
652 * the same name.
653 */
654
655void
656addcmdentry(char *name, struct cmdentry *entry)
657{
658	struct tblentry *cmdp;
659
660	INTOFF;
661	cmdp = cmdlookup(name, 1);
662	if (cmdp->cmdtype == CMDFUNCTION) {
663		freefunc(cmdp->param.func);
664	}
665	cmdp->cmdtype = entry->cmdtype;
666	cmdp->param = entry->u;
667	INTON;
668}
669
670
671/*
672 * Define a shell function.
673 */
674
675void
676defun(char *name, union node *func)
677{
678	struct cmdentry entry;
679
680	INTOFF;
681	entry.cmdtype = CMDFUNCTION;
682	entry.u.func = copyfunc(func);
683	addcmdentry(name, &entry);
684	INTON;
685}
686
687
688/*
689 * Delete a function if it exists.
690 */
691
692int
693unsetfunc(char *name)
694{
695	struct tblentry *cmdp;
696
697	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
698		freefunc(cmdp->param.func);
699		delete_cmd_entry();
700		return (0);
701	}
702	return (1);
703}
704
705/*
706 * Locate and print what a word is...
707 */
708
709int
710typecmd(int argc, char **argv)
711{
712	struct cmdentry entry;
713	struct tblentry *cmdp;
714	char **pp;
715	struct alias *ap;
716	int i;
717	int error = 0;
718	extern char *const parsekwd[];
719
720	for (i = 1; i < argc; i++) {
721		out1str(argv[i]);
722		/* First look at the keywords */
723		for (pp = (char **)parsekwd; *pp; pp++)
724			if (**pp == *argv[i] && equal(*pp, argv[i]))
725				break;
726
727		if (*pp) {
728			out1str(" is a shell keyword\n");
729			continue;
730		}
731
732		/* Then look at the aliases */
733		if ((ap = lookupalias(argv[i], 1)) != NULL) {
734			out1fmt(" is an alias for %s\n", ap->val);
735			continue;
736		}
737
738		/* Then check if it is a tracked alias */
739		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
740			entry.cmdtype = cmdp->cmdtype;
741			entry.u = cmdp->param;
742		}
743		else {
744			/* Finally use brute force */
745			find_command(argv[i], &entry, 0, pathval());
746		}
747
748		switch (entry.cmdtype) {
749		case CMDNORMAL: {
750			if (strchr(argv[i], '/') == NULL) {
751				char *path = pathval(), *name;
752				int j = entry.u.index;
753				do {
754					name = padvance(&path, argv[i]);
755					stunalloc(name);
756				} while (--j >= 0);
757				out1fmt(" is%s %s\n",
758				    cmdp ? " a tracked alias for" : "", name);
759			} else {
760				if (access(argv[i], X_OK) == 0)
761					out1fmt(" is %s\n", argv[i]);
762				else
763					out1fmt(": %s\n", strerror(errno));
764			}
765			break;
766		}
767		case CMDFUNCTION:
768			out1str(" is a shell function\n");
769			break;
770
771		case CMDBUILTIN:
772			out1str(" is a shell builtin\n");
773			break;
774
775		default:
776			out1str(": not found\n");
777			error |= 127;
778			break;
779		}
780	}
781	return error;
782}
783