exec.c revision 2111 
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
38static char sccsid[] = "@(#)exec.c	8.1 (Berkeley) 5/31/93";
39#endif /* not lint */
40
41/*
42 * When commands are first encountered, they are entered in a hash table.
43 * This ensures that a full path search will not have to be done for them
44 * on each invocation.
45 *
46 * We should investigate converting to a linear search, even though that
47 * would make the command name "hash" a misnomer.
48 */
49
50#include "shell.h"
51#include "main.h"
52#include "nodes.h"
53#include "parser.h"
54#include "redir.h"
55#include "eval.h"
56#include "exec.h"
57#include "builtins.h"
58#include "var.h"
59#include "options.h"
60#include "input.h"
61#include "output.h"
62#include "syntax.h"
63#include "memalloc.h"
64#include "error.h"
65#include "init.h"
66#include "mystring.h"
67#include "jobs.h"
68#include <sys/types.h>
69#include <sys/stat.h>
70#include <fcntl.h>
71#include <errno.h>
72
73
74#define CMDTABLESIZE 31		/* should be prime */
75#define ARB 1			/* actual size determined at run time */
76
77
78
79struct tblentry {
80	struct tblentry *next;	/* next entry in hash chain */
81	union param param;	/* definition of builtin function */
82	short cmdtype;		/* index identifying command */
83	char rehash;		/* if set, cd done since entry created */
84	char cmdname[ARB];	/* name of command */
85};
86
87
88STATIC struct tblentry *cmdtable[CMDTABLESIZE];
89STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
90
91
92#ifdef __STDC__
93STATIC void tryexec(char *, char **, char **);
94STATIC void execinterp(char **, char **);
95STATIC void printentry(struct tblentry *, int);
96STATIC void clearcmdentry(int);
97STATIC struct tblentry *cmdlookup(char *, int);
98STATIC void delete_cmd_entry(void);
99#else
100STATIC void tryexec();
101STATIC void execinterp();
102STATIC void printentry();
103STATIC void clearcmdentry();
104STATIC struct tblentry *cmdlookup();
105STATIC void delete_cmd_entry();
106#endif
107
108
109
110/*
111 * Exec a program.  Never returns.  If you change this routine, you may
112 * have to change the find_command routine as well.
113 */
114
115void
116shellexec(argv, envp, path, index)
117	char **argv, **envp;
118	char *path;
119	{
120	char *cmdname;
121	int e;
122
123	if (strchr(argv[0], '/') != NULL) {
124		tryexec(argv[0], argv, envp);
125		e = errno;
126	} else {
127		e = ENOENT;
128		while ((cmdname = padvance(&path, argv[0])) != NULL) {
129			if (--index < 0 && pathopt == NULL) {
130				tryexec(cmdname, argv, envp);
131				if (errno != ENOENT && errno != ENOTDIR)
132					e = errno;
133			}
134			stunalloc(cmdname);
135		}
136	}
137	error2(argv[0], errmsg(e, E_EXEC));
138}
139
140
141STATIC void
142tryexec(cmd, argv, envp)
143	char *cmd;
144	char **argv;
145	char **envp;
146	{
147	int e;
148	char *p;
149
150#ifdef SYSV
151	do {
152		execve(cmd, argv, envp);
153	} while (errno == EINTR);
154#else
155	execve(cmd, argv, envp);
156#endif
157	e = errno;
158	if (e == ENOEXEC) {
159		initshellproc();
160		setinputfile(cmd, 0);
161		commandname = arg0 = savestr(argv[0]);
162#ifndef BSD
163		pgetc(); pungetc();		/* fill up input buffer */
164		p = parsenextc;
165		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
166			argv[0] = cmd;
167			execinterp(argv, envp);
168		}
169#endif
170		setparam(argv + 1);
171		exraise(EXSHELLPROC);
172		/*NOTREACHED*/
173	}
174	errno = e;
175}
176
177
178#ifndef BSD
179/*
180 * Execute an interpreter introduced by "#!", for systems where this
181 * feature has not been built into the kernel.  If the interpreter is
182 * the shell, return (effectively ignoring the "#!").  If the execution
183 * of the interpreter fails, exit.
184 *
185 * This code peeks inside the input buffer in order to avoid actually
186 * reading any input.  It would benefit from a rewrite.
187 */
188
189#define NEWARGS 5
190
191STATIC void
192execinterp(argv, envp)
193	char **argv, **envp;
194	{
195	int n;
196	char *inp;
197	char *outp;
198	char c;
199	char *p;
200	char **ap;
201	char *newargs[NEWARGS];
202	int i;
203	char **ap2;
204	char **new;
205
206	n = parsenleft - 2;
207	inp = parsenextc + 2;
208	ap = newargs;
209	for (;;) {
210		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
211			inp++;
212		if (n < 0)
213			goto bad;
214		if ((c = *inp++) == '\n')
215			break;
216		if (ap == &newargs[NEWARGS])
217bad:		  error("Bad #! line");
218		STARTSTACKSTR(outp);
219		do {
220			STPUTC(c, outp);
221		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
222		STPUTC('\0', outp);
223		n++, inp--;
224		*ap++ = grabstackstr(outp);
225	}
226	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
227		p = newargs[0];
228		for (;;) {
229			if (equal(p, "sh") || equal(p, "ash")) {
230				return;
231			}
232			while (*p != '/') {
233				if (*p == '\0')
234					goto break2;
235				p++;
236			}
237			p++;
238		}
239break2:;
240	}
241	i = (char *)ap - (char *)newargs;		/* size in bytes */
242	if (i == 0)
243		error("Bad #! line");
244	for (ap2 = argv ; *ap2++ != NULL ; );
245	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
246	ap = newargs, ap2 = new;
247	while ((i -= sizeof (char **)) >= 0)
248		*ap2++ = *ap++;
249	ap = argv;
250	while (*ap2++ = *ap++);
251	shellexec(new, envp, pathval(), 0);
252}
253#endif
254
255
256
257/*
258 * Do a path search.  The variable path (passed by reference) should be
259 * set to the start of the path before the first call; padvance will update
260 * this value as it proceeds.  Successive calls to padvance will return
261 * the possible path expansions in sequence.  If an option (indicated by
262 * a percent sign) appears in the path entry then the global variable
263 * pathopt will be set to point to it; otherwise pathopt will be set to
264 * NULL.
265 */
266
267char *pathopt;
268
269char *
270padvance(path, name)
271	char **path;
272	char *name;
273	{
274	register char *p, *q;
275	char *start;
276	int len;
277
278	if (*path == NULL)
279		return NULL;
280	start = *path;
281	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
282	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
283	while (stackblocksize() < len)
284		growstackblock();
285	q = stackblock();
286	if (p != start) {
287		bcopy(start, q, p - start);
288		q += p - start;
289		*q++ = '/';
290	}
291	strcpy(q, name);
292	pathopt = NULL;
293	if (*p == '%') {
294		pathopt = ++p;
295		while (*p && *p != ':')  p++;
296	}
297	if (*p == ':')
298		*path = p + 1;
299	else
300		*path = NULL;
301	return stalloc(len);
302}
303
304
305
306/*** Command hashing code ***/
307
308
309hashcmd(argc, argv)  char **argv; {
310	struct tblentry **pp;
311	struct tblentry *cmdp;
312	int c;
313	int verbose;
314	struct cmdentry entry;
315	char *name;
316
317	verbose = 0;
318	while ((c = nextopt("rv")) != '\0') {
319		if (c == 'r') {
320			clearcmdentry(0);
321		} else if (c == 'v') {
322			verbose++;
323		}
324	}
325	if (*argptr == NULL) {
326		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
327			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
328				printentry(cmdp, verbose);
329			}
330		}
331		return 0;
332	}
333	while ((name = *argptr) != NULL) {
334		if ((cmdp = cmdlookup(name, 0)) != NULL
335		 && (cmdp->cmdtype == CMDNORMAL
336		     || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
337			delete_cmd_entry();
338		find_command(name, &entry, 1);
339		if (verbose) {
340			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
341				cmdp = cmdlookup(name, 0);
342				printentry(cmdp, verbose);
343			}
344			flushall();
345		}
346		argptr++;
347	}
348	return 0;
349}
350
351
352STATIC void
353printentry(cmdp, verbose)
354	struct tblentry *cmdp;
355	int verbose;
356	{
357	int index;
358	char *path;
359	char *name;
360
361	if (cmdp->cmdtype == CMDNORMAL) {
362		index = cmdp->param.index;
363		path = pathval();
364		do {
365			name = padvance(&path, cmdp->cmdname);
366			stunalloc(name);
367		} while (--index >= 0);
368		out1str(name);
369	} else if (cmdp->cmdtype == CMDBUILTIN) {
370		out1fmt("builtin %s", cmdp->cmdname);
371	} else if (cmdp->cmdtype == CMDFUNCTION) {
372		out1fmt("function %s", cmdp->cmdname);
373		if (verbose) {
374			INTOFF;
375			name = commandtext(cmdp->param.func);
376			out1c(' ');
377			out1str(name);
378			ckfree(name);
379			INTON;
380		}
381#ifdef DEBUG
382	} else {
383		error("internal error: cmdtype %d", cmdp->cmdtype);
384#endif
385	}
386	if (cmdp->rehash)
387		out1c('*');
388	out1c('\n');
389}
390
391
392
393/*
394 * Resolve a command name.  If you change this routine, you may have to
395 * change the shellexec routine as well.
396 */
397
398void
399find_command(name, entry, printerr)
400	char *name;
401	struct cmdentry *entry;
402	{
403	struct tblentry *cmdp;
404	int index;
405	int prev;
406	char *path;
407	char *fullname;
408	struct stat statb;
409	int e;
410	int i;
411
412	/* If name contains a slash, don't use the hash table */
413	if (strchr(name, '/') != NULL) {
414		entry->cmdtype = CMDNORMAL;
415		entry->u.index = 0;
416		return;
417	}
418
419	/* If name is in the table, and not invalidated by cd, we're done */
420	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
421		goto success;
422
423	/* If %builtin not in path, check for builtin next */
424	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
425		INTOFF;
426		cmdp = cmdlookup(name, 1);
427		cmdp->cmdtype = CMDBUILTIN;
428		cmdp->param.index = i;
429		INTON;
430		goto success;
431	}
432
433	/* We have to search path. */
434	prev = -1;		/* where to start */
435	if (cmdp) {		/* doing a rehash */
436		if (cmdp->cmdtype == CMDBUILTIN)
437			prev = builtinloc;
438		else
439			prev = cmdp->param.index;
440	}
441
442	path = pathval();
443	e = ENOENT;
444	index = -1;
445loop:
446	while ((fullname = padvance(&path, name)) != NULL) {
447		stunalloc(fullname);
448		index++;
449		if (pathopt) {
450			if (prefix("builtin", pathopt)) {
451				if ((i = find_builtin(name)) < 0)
452					goto loop;
453				INTOFF;
454				cmdp = cmdlookup(name, 1);
455				cmdp->cmdtype = CMDBUILTIN;
456				cmdp->param.index = i;
457				INTON;
458				goto success;
459			} else if (prefix("func", pathopt)) {
460				/* handled below */
461			} else {
462				goto loop;	/* ignore unimplemented options */
463			}
464		}
465		/* if rehash, don't redo absolute path names */
466		if (fullname[0] == '/' && index <= prev) {
467			if (index < prev)
468				goto loop;
469			TRACE(("searchexec \"%s\": no change\n", name));
470			goto success;
471		}
472		while (stat(fullname, &statb) < 0) {
473#ifdef SYSV
474			if (errno == EINTR)
475				continue;
476#endif
477			if (errno != ENOENT && errno != ENOTDIR)
478				e = errno;
479			goto loop;
480		}
481		e = EACCES;	/* if we fail, this will be the error */
482		if ((statb.st_mode & S_IFMT) != S_IFREG)
483			goto loop;
484		if (pathopt) {		/* this is a %func directory */
485			stalloc(strlen(fullname) + 1);
486			readcmdfile(fullname);
487			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
488				error("%s not defined in %s", name, fullname);
489			stunalloc(fullname);
490			goto success;
491		}
492#ifdef notdef
493		if (statb.st_uid == geteuid()) {
494			if ((statb.st_mode & 0100) == 0)
495				goto loop;
496		} else if (statb.st_gid == getegid()) {
497			if ((statb.st_mode & 010) == 0)
498				goto loop;
499		} else {
500			if ((statb.st_mode & 01) == 0)
501				goto loop;
502		}
503#endif
504		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
505		INTOFF;
506		cmdp = cmdlookup(name, 1);
507		cmdp->cmdtype = CMDNORMAL;
508		cmdp->param.index = index;
509		INTON;
510		goto success;
511	}
512
513	/* We failed.  If there was an entry for this command, delete it */
514	if (cmdp)
515		delete_cmd_entry();
516	if (printerr)
517		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
518	entry->cmdtype = CMDUNKNOWN;
519	return;
520
521success:
522	cmdp->rehash = 0;
523	entry->cmdtype = cmdp->cmdtype;
524	entry->u = cmdp->param;
525}
526
527
528
529/*
530 * Search the table of builtin commands.
531 */
532
533int
534find_builtin(name)
535	char *name;
536	{
537	const register struct builtincmd *bp;
538
539	for (bp = builtincmd ; bp->name ; bp++) {
540		if (*bp->name == *name && equal(bp->name, name))
541			return bp->code;
542	}
543	return -1;
544}
545
546
547
548/*
549 * Called when a cd is done.  Marks all commands so the next time they
550 * are executed they will be rehashed.
551 */
552
553void
554hashcd() {
555	struct tblentry **pp;
556	struct tblentry *cmdp;
557
558	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
559		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
560			if (cmdp->cmdtype == CMDNORMAL
561			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)
562				cmdp->rehash = 1;
563		}
564	}
565}
566
567
568
569/*
570 * Called before PATH is changed.  The argument is the new value of PATH;
571 * pathval() still returns the old value at this point.  Called with
572 * interrupts off.
573 */
574
575void
576changepath(newval)
577	char *newval;
578	{
579	char *old, *new;
580	int index;
581	int firstchange;
582	int bltin;
583
584	old = pathval();
585	new = newval;
586	firstchange = 9999;	/* assume no change */
587	index = 0;
588	bltin = -1;
589	for (;;) {
590		if (*old != *new) {
591			firstchange = index;
592			if (*old == '\0' && *new == ':'
593			 || *old == ':' && *new == '\0')
594				firstchange++;
595			old = new;	/* ignore subsequent differences */
596		}
597		if (*new == '\0')
598			break;
599		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
600			bltin = index;
601		if (*new == ':') {
602			index++;
603		}
604		new++, old++;
605	}
606	if (builtinloc < 0 && bltin >= 0)
607		builtinloc = bltin;		/* zap builtins */
608	if (builtinloc >= 0 && bltin < 0)
609		firstchange = 0;
610	clearcmdentry(firstchange);
611	builtinloc = bltin;
612}
613
614
615/*
616 * Clear out command entries.  The argument specifies the first entry in
617 * PATH which has changed.
618 */
619
620STATIC void
621clearcmdentry(firstchange) {
622	struct tblentry **tblp;
623	struct tblentry **pp;
624	struct tblentry *cmdp;
625
626	INTOFF;
627	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
628		pp = tblp;
629		while ((cmdp = *pp) != NULL) {
630			if (cmdp->cmdtype == CMDNORMAL && cmdp->param.index >= firstchange
631			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= firstchange) {
632				*pp = cmdp->next;
633				ckfree(cmdp);
634			} else {
635				pp = &cmdp->next;
636			}
637		}
638	}
639	INTON;
640}
641
642
643/*
644 * Delete all functions.
645 */
646
647#ifdef mkinit
648MKINIT void deletefuncs();
649
650SHELLPROC {
651	deletefuncs();
652}
653#endif
654
655void
656deletefuncs() {
657	struct tblentry **tblp;
658	struct tblentry **pp;
659	struct tblentry *cmdp;
660
661	INTOFF;
662	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
663		pp = tblp;
664		while ((cmdp = *pp) != NULL) {
665			if (cmdp->cmdtype == CMDFUNCTION) {
666				*pp = cmdp->next;
667				freefunc(cmdp->param.func);
668				ckfree(cmdp);
669			} else {
670				pp = &cmdp->next;
671			}
672		}
673	}
674	INTON;
675}
676
677
678
679/*
680 * Locate a command in the command hash table.  If "add" is nonzero,
681 * add the command to the table if it is not already present.  The
682 * variable "lastcmdentry" is set to point to the address of the link
683 * pointing to the entry, so that delete_cmd_entry can delete the
684 * entry.
685 */
686
687struct tblentry **lastcmdentry;
688
689
690STATIC struct tblentry *
691cmdlookup(name, add)
692	char *name;
693	{
694	int hashval;
695	register char *p;
696	struct tblentry *cmdp;
697	struct tblentry **pp;
698
699	p = name;
700	hashval = *p << 4;
701	while (*p)
702		hashval += *p++;
703	hashval &= 0x7FFF;
704	pp = &cmdtable[hashval % CMDTABLESIZE];
705	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
706		if (equal(cmdp->cmdname, name))
707			break;
708		pp = &cmdp->next;
709	}
710	if (add && cmdp == NULL) {
711		INTOFF;
712		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
713					+ strlen(name) + 1);
714		cmdp->next = NULL;
715		cmdp->cmdtype = CMDUNKNOWN;
716		cmdp->rehash = 0;
717		strcpy(cmdp->cmdname, name);
718		INTON;
719	}
720	lastcmdentry = pp;
721	return cmdp;
722}
723
724/*
725 * Delete the command entry returned on the last lookup.
726 */
727
728STATIC void
729delete_cmd_entry() {
730	struct tblentry *cmdp;
731
732	INTOFF;
733	cmdp = *lastcmdentry;
734	*lastcmdentry = cmdp->next;
735	ckfree(cmdp);
736	INTON;
737}
738
739
740
741#ifdef notdef
742void
743getcmdentry(name, entry)
744	char *name;
745	struct cmdentry *entry;
746	{
747	struct tblentry *cmdp = cmdlookup(name, 0);
748
749	if (cmdp) {
750		entry->u = cmdp->param;
751		entry->cmdtype = cmdp->cmdtype;
752	} else {
753		entry->cmdtype = CMDUNKNOWN;
754		entry->u.index = 0;
755	}
756}
757#endif
758
759
760/*
761 * Add a new command entry, replacing any existing command entry for
762 * the same name.
763 */
764
765void
766addcmdentry(name, entry)
767	char *name;
768	struct cmdentry *entry;
769	{
770	struct tblentry *cmdp;
771
772	INTOFF;
773	cmdp = cmdlookup(name, 1);
774	if (cmdp->cmdtype == CMDFUNCTION) {
775		freefunc(cmdp->param.func);
776	}
777	cmdp->cmdtype = entry->cmdtype;
778	cmdp->param = entry->u;
779	INTON;
780}
781
782
783/*
784 * Define a shell function.
785 */
786
787void
788defun(name, func)
789	char *name;
790	union node *func;
791	{
792	struct cmdentry entry;
793
794	INTOFF;
795	entry.cmdtype = CMDFUNCTION;
796	entry.u.func = copyfunc(func);
797	addcmdentry(name, &entry);
798	INTON;
799}
800
801
802/*
803 * Delete a function if it exists.
804 */
805
806int
807unsetfunc(name)
808	char *name;
809	{
810	struct tblentry *cmdp;
811
812	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
813		freefunc(cmdp->param.func);
814		delete_cmd_entry();
815		return (0);
816	}
817	return (1);
818}
819