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: releng/11.0/bin/sh/exec.c 296813 2016-03-13 22:54:14Z 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		entry->special = 0;
336		return;
337	}
338
339	cd = 0;
340
341	/* If name is in the table, and not invalidated by cd, we're done */
342	if ((cmdp = cmdlookup(name, 0)) != NULL) {
343		if (cmdp->cmdtype == CMDFUNCTION && act & DO_NOFUNC)
344			cmdp = NULL;
345		else
346			goto success;
347	}
348
349	/* Check for builtin next */
350	if ((i = find_builtin(name, &spec)) >= 0) {
351		INTOFF;
352		cmdp = cmdlookup(name, 1);
353		if (cmdp->cmdtype == CMDFUNCTION)
354			cmdp = &loc_cmd;
355		cmdp->cmdtype = CMDBUILTIN;
356		cmdp->param.index = i;
357		cmdp->special = spec;
358		INTON;
359		goto success;
360	}
361
362	/* We have to search path. */
363
364	e = ENOENT;
365	idx = -1;
366	for (;(fullname = padvance(&path, name)) != NULL; stunalloc(fullname)) {
367		idx++;
368		if (pathopt) {
369			if (strncmp(pathopt, "func", 4) == 0) {
370				/* handled below */
371			} else {
372				continue; /* ignore unimplemented options */
373			}
374		}
375		if (fullname[0] != '/')
376			cd = 1;
377		if (stat(fullname, &statb) < 0) {
378			if (errno != ENOENT && errno != ENOTDIR)
379				e = errno;
380			continue;
381		}
382		e = EACCES;	/* if we fail, this will be the error */
383		if (!S_ISREG(statb.st_mode))
384			continue;
385		if (pathopt) {		/* this is a %func directory */
386			readcmdfile(fullname);
387			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
388				error("%s not defined in %s", name, fullname);
389			stunalloc(fullname);
390			goto success;
391		}
392#ifdef notdef
393		if (statb.st_uid == geteuid()) {
394			if ((statb.st_mode & 0100) == 0)
395				goto loop;
396		} else if (statb.st_gid == getegid()) {
397			if ((statb.st_mode & 010) == 0)
398				goto loop;
399		} else {
400			if ((statb.st_mode & 01) == 0)
401				goto loop;
402		}
403#endif
404		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
405		INTOFF;
406		stunalloc(fullname);
407		cmdp = cmdlookup(name, 1);
408		if (cmdp->cmdtype == CMDFUNCTION)
409			cmdp = &loc_cmd;
410		cmdp->cmdtype = CMDNORMAL;
411		cmdp->param.index = idx;
412		cmdp->special = 0;
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	entry->special = 0;
426	return;
427
428success:
429	if (cd)
430		cmdtable_cd = 1;
431	entry->cmdtype = cmdp->cmdtype;
432	entry->u = cmdp->param;
433	entry->special = cmdp->special;
434}
435
436
437
438/*
439 * Search the table of builtin commands.
440 */
441
442int
443find_builtin(const char *name, int *special)
444{
445	const unsigned char *bp;
446	size_t len;
447
448	len = strlen(name);
449	for (bp = builtincmd ; *bp ; bp += 2 + bp[0]) {
450		if (bp[0] == len && memcmp(bp + 2, name, len) == 0) {
451			*special = (bp[1] & BUILTIN_SPECIAL) != 0;
452			return bp[1] & ~BUILTIN_SPECIAL;
453		}
454	}
455	return -1;
456}
457
458
459
460/*
461 * Called when a cd is done.  If any entry in cmdtable depends on the current
462 * directory, simply clear cmdtable completely.
463 */
464
465void
466hashcd(void)
467{
468	if (cmdtable_cd)
469		clearcmdentry();
470}
471
472
473
474/*
475 * Called before PATH is changed.  The argument is the new value of PATH;
476 * pathval() still returns the old value at this point.  Called with
477 * interrupts off.
478 */
479
480void
481changepath(const char *newval __unused)
482{
483	clearcmdentry();
484}
485
486
487/*
488 * Clear out command entries.  The argument specifies the first entry in
489 * PATH which has changed.
490 */
491
492void
493clearcmdentry(void)
494{
495	struct tblentry **tblp;
496	struct tblentry **pp;
497	struct tblentry *cmdp;
498
499	INTOFF;
500	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
501		pp = tblp;
502		while ((cmdp = *pp) != NULL) {
503			if (cmdp->cmdtype == CMDNORMAL) {
504				*pp = cmdp->next;
505				ckfree(cmdp);
506			} else {
507				pp = &cmdp->next;
508			}
509		}
510	}
511	cmdtable_cd = 0;
512	INTON;
513}
514
515
516/*
517 * Locate a command in the command hash table.  If "add" is nonzero,
518 * add the command to the table if it is not already present.  The
519 * variable "lastcmdentry" is set to point to the address of the link
520 * pointing to the entry, so that delete_cmd_entry can delete the
521 * entry.
522 */
523
524static struct tblentry **lastcmdentry;
525
526
527static struct tblentry *
528cmdlookup(const char *name, int add)
529{
530	unsigned int hashval;
531	const char *p;
532	struct tblentry *cmdp;
533	struct tblentry **pp;
534	size_t len;
535
536	p = name;
537	hashval = (unsigned char)*p << 4;
538	while (*p)
539		hashval += *p++;
540	pp = &cmdtable[hashval % CMDTABLESIZE];
541	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
542		if (equal(cmdp->cmdname, name))
543			break;
544		pp = &cmdp->next;
545	}
546	if (add && cmdp == NULL) {
547		INTOFF;
548		len = strlen(name);
549		cmdp = *pp = ckmalloc(sizeof (struct tblentry) + len + 1);
550		cmdp->next = NULL;
551		cmdp->cmdtype = CMDUNKNOWN;
552		memcpy(cmdp->cmdname, name, len + 1);
553		INTON;
554	}
555	lastcmdentry = pp;
556	return cmdp;
557}
558
559/*
560 * Delete the command entry returned on the last lookup.
561 */
562
563static void
564delete_cmd_entry(void)
565{
566	struct tblentry *cmdp;
567
568	INTOFF;
569	cmdp = *lastcmdentry;
570	*lastcmdentry = cmdp->next;
571	ckfree(cmdp);
572	INTON;
573}
574
575
576
577/*
578 * Add a new command entry, replacing any existing command entry for
579 * the same name.
580 */
581
582static void
583addcmdentry(const char *name, struct cmdentry *entry)
584{
585	struct tblentry *cmdp;
586
587	INTOFF;
588	cmdp = cmdlookup(name, 1);
589	if (cmdp->cmdtype == CMDFUNCTION) {
590		unreffunc(cmdp->param.func);
591	}
592	cmdp->cmdtype = entry->cmdtype;
593	cmdp->param = entry->u;
594	cmdp->special = entry->special;
595	INTON;
596}
597
598
599/*
600 * Define a shell function.
601 */
602
603void
604defun(const char *name, union node *func)
605{
606	struct cmdentry entry;
607
608	INTOFF;
609	entry.cmdtype = CMDFUNCTION;
610	entry.u.func = copyfunc(func);
611	entry.special = 0;
612	addcmdentry(name, &entry);
613	INTON;
614}
615
616
617/*
618 * Delete a function if it exists.
619 * Called with interrupts off.
620 */
621
622int
623unsetfunc(const char *name)
624{
625	struct tblentry *cmdp;
626
627	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
628		unreffunc(cmdp->param.func);
629		delete_cmd_entry();
630		return (0);
631	}
632	return (0);
633}
634
635
636/*
637 * Check if a function by a certain name exists.
638 */
639int
640isfunc(const char *name)
641{
642	struct tblentry *cmdp;
643	cmdp = cmdlookup(name, 0);
644	return (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION);
645}
646
647
648/*
649 * Shared code for the following builtin commands:
650 *    type, command -v, command -V
651 */
652
653int
654typecmd_impl(int argc, char **argv, int cmd, const char *path)
655{
656	struct cmdentry entry;
657	struct tblentry *cmdp;
658	const char *const *pp;
659	struct alias *ap;
660	int i;
661	int error1 = 0;
662
663	if (path != pathval())
664		clearcmdentry();
665
666	for (i = 1; i < argc; i++) {
667		/* First look at the keywords */
668		for (pp = parsekwd; *pp; pp++)
669			if (**pp == *argv[i] && equal(*pp, argv[i]))
670				break;
671
672		if (*pp) {
673			if (cmd == TYPECMD_SMALLV)
674				out1fmt("%s\n", argv[i]);
675			else
676				out1fmt("%s is a shell keyword\n", argv[i]);
677			continue;
678		}
679
680		/* Then look at the aliases */
681		if ((ap = lookupalias(argv[i], 1)) != NULL) {
682			if (cmd == TYPECMD_SMALLV) {
683				out1fmt("alias %s=", argv[i]);
684				out1qstr(ap->val);
685				outcslow('\n', out1);
686			} else
687				out1fmt("%s is an alias for %s\n", argv[i],
688				    ap->val);
689			continue;
690		}
691
692		/* Then check if it is a tracked alias */
693		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
694			entry.cmdtype = cmdp->cmdtype;
695			entry.u = cmdp->param;
696			entry.special = cmdp->special;
697		}
698		else {
699			/* Finally use brute force */
700			find_command(argv[i], &entry, 0, path);
701		}
702
703		switch (entry.cmdtype) {
704		case CMDNORMAL: {
705			if (strchr(argv[i], '/') == NULL) {
706				const char *path2 = path;
707				char *name;
708				int j = entry.u.index;
709				do {
710					name = padvance(&path2, argv[i]);
711					stunalloc(name);
712				} while (--j >= 0);
713				if (cmd == TYPECMD_SMALLV)
714					out1fmt("%s\n", name);
715				else
716					out1fmt("%s is%s %s\n", argv[i],
717					    (cmdp && cmd == TYPECMD_TYPE) ?
718						" a tracked alias for" : "",
719					    name);
720			} else {
721				if (eaccess(argv[i], X_OK) == 0) {
722					if (cmd == TYPECMD_SMALLV)
723						out1fmt("%s\n", argv[i]);
724					else
725						out1fmt("%s is %s\n", argv[i],
726						    argv[i]);
727				} else {
728					if (cmd != TYPECMD_SMALLV)
729						outfmt(out2, "%s: %s\n",
730						    argv[i], strerror(errno));
731					error1 |= 127;
732				}
733			}
734			break;
735		}
736		case CMDFUNCTION:
737			if (cmd == TYPECMD_SMALLV)
738				out1fmt("%s\n", argv[i]);
739			else
740				out1fmt("%s is a shell function\n", argv[i]);
741			break;
742
743		case CMDBUILTIN:
744			if (cmd == TYPECMD_SMALLV)
745				out1fmt("%s\n", argv[i]);
746			else if (entry.special)
747				out1fmt("%s is a special shell builtin\n",
748				    argv[i]);
749			else
750				out1fmt("%s is a shell builtin\n", argv[i]);
751			break;
752
753		default:
754			if (cmd != TYPECMD_SMALLV)
755				outfmt(out2, "%s: not found\n", argv[i]);
756			error1 |= 127;
757			break;
758		}
759	}
760
761	if (path != pathval())
762		clearcmdentry();
763
764	return error1;
765}
766
767/*
768 * Locate and print what a word is...
769 */
770
771int
772typecmd(int argc, char **argv)
773{
774	if (argc > 2 && strcmp(argv[1], "--") == 0)
775		argc--, argv++;
776	return typecmd_impl(argc, argv, TYPECMD_TYPE, bltinlookup("PATH", 1));
777}
778