xref: /freebsd/bin/sh/exec.c (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
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
39 static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
40 #endif
41 static const char rcsid[] =
42   "$FreeBSD$";
43 #endif /* not lint */
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 
88 struct 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 
97 STATIC struct tblentry *cmdtable[CMDTABLESIZE];
98 STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
99 int exerrno = 0;			/* Last exec error */
100 
101 
102 STATIC void tryexec __P((char *, char **, char **));
103 #ifndef BSD
104 STATIC void execinterp __P((char **, char **));
105 #endif
106 STATIC void printentry __P((struct tblentry *, int));
107 STATIC struct tblentry *cmdlookup __P((char *, int));
108 STATIC void delete_cmd_entry __P((void));
109 
110 
111 
112 /*
113  * Exec a program.  Never returns.  If you change this routine, you may
114  * have to change the find_command routine as well.
115  */
116 
117 void
118 shellexec(argv, envp, path, index)
119 	char **argv, **envp;
120 	char *path;
121 	int index;
122 {
123 	char *cmdname;
124 	int e;
125 
126 	if (strchr(argv[0], '/') != NULL) {
127 		tryexec(argv[0], argv, envp);
128 		e = errno;
129 	} else {
130 		e = ENOENT;
131 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
132 			if (--index < 0 && pathopt == NULL) {
133 				tryexec(cmdname, argv, envp);
134 				if (errno != ENOENT && errno != ENOTDIR)
135 					e = errno;
136 			}
137 			stunalloc(cmdname);
138 		}
139 	}
140 
141 	/* Map to POSIX errors */
142 	switch (e) {
143 	case EACCES:
144 		exerrno = 126;
145 		break;
146 	case ENOENT:
147 		exerrno = 127;
148 		break;
149 	default:
150 		exerrno = 2;
151 		break;
152 	}
153 	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
154 }
155 
156 
157 STATIC void
158 tryexec(cmd, argv, envp)
159 	char *cmd;
160 	char **argv;
161 	char **envp;
162 	{
163 	int e;
164 #ifndef BSD
165 	char *p;
166 #endif
167 
168 #ifdef SYSV
169 	do {
170 		execve(cmd, argv, envp);
171 	} while (errno == EINTR);
172 #else
173 	execve(cmd, argv, envp);
174 #endif
175 	e = errno;
176 	if (e == ENOEXEC) {
177 		initshellproc();
178 		setinputfile(cmd, 0);
179 		commandname = arg0 = savestr(argv[0]);
180 #ifndef BSD
181 		pgetc(); pungetc();		/* fill up input buffer */
182 		p = parsenextc;
183 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
184 			argv[0] = cmd;
185 			execinterp(argv, envp);
186 		}
187 #endif
188 		setparam(argv + 1);
189 		exraise(EXSHELLPROC);
190 		/*NOTREACHED*/
191 	}
192 	errno = e;
193 }
194 
195 
196 #ifndef BSD
197 /*
198  * Execute an interpreter introduced by "#!", for systems where this
199  * feature has not been built into the kernel.  If the interpreter is
200  * the shell, return (effectively ignoring the "#!").  If the execution
201  * of the interpreter fails, exit.
202  *
203  * This code peeks inside the input buffer in order to avoid actually
204  * reading any input.  It would benefit from a rewrite.
205  */
206 
207 #define NEWARGS 5
208 
209 STATIC void
210 execinterp(argv, envp)
211 	char **argv, **envp;
212 	{
213 	int n;
214 	char *inp;
215 	char *outp;
216 	char c;
217 	char *p;
218 	char **ap;
219 	char *newargs[NEWARGS];
220 	int i;
221 	char **ap2;
222 	char **new;
223 
224 	n = parsenleft - 2;
225 	inp = parsenextc + 2;
226 	ap = newargs;
227 	for (;;) {
228 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
229 			inp++;
230 		if (n < 0)
231 			goto bad;
232 		if ((c = *inp++) == '\n')
233 			break;
234 		if (ap == &newargs[NEWARGS])
235 bad:		  error("Bad #! line");
236 		STARTSTACKSTR(outp);
237 		do {
238 			STPUTC(c, outp);
239 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
240 		STPUTC('\0', outp);
241 		n++, inp--;
242 		*ap++ = grabstackstr(outp);
243 	}
244 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
245 		p = newargs[0];
246 		for (;;) {
247 			if (equal(p, "sh") || equal(p, "ash")) {
248 				return;
249 			}
250 			while (*p != '/') {
251 				if (*p == '\0')
252 					goto break2;
253 				p++;
254 			}
255 			p++;
256 		}
257 break2:;
258 	}
259 	i = (char *)ap - (char *)newargs;		/* size in bytes */
260 	if (i == 0)
261 		error("Bad #! line");
262 	for (ap2 = argv ; *ap2++ != NULL ; );
263 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
264 	ap = newargs, ap2 = new;
265 	while ((i -= sizeof (char **)) >= 0)
266 		*ap2++ = *ap++;
267 	ap = argv;
268 	while (*ap2++ = *ap++);
269 	shellexec(new, envp, pathval(), 0);
270 }
271 #endif
272 
273 
274 
275 /*
276  * Do a path search.  The variable path (passed by reference) should be
277  * set to the start of the path before the first call; padvance will update
278  * this value as it proceeds.  Successive calls to padvance will return
279  * the possible path expansions in sequence.  If an option (indicated by
280  * a percent sign) appears in the path entry then the global variable
281  * pathopt will be set to point to it; otherwise pathopt will be set to
282  * NULL.
283  */
284 
285 char *pathopt;
286 
287 char *
288 padvance(path, name)
289 	char **path;
290 	char *name;
291 	{
292 	char *p, *q;
293 	char *start;
294 	int len;
295 
296 	if (*path == NULL)
297 		return NULL;
298 	start = *path;
299 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
300 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
301 	while (stackblocksize() < len)
302 		growstackblock();
303 	q = stackblock();
304 	if (p != start) {
305 		memcpy(q, start, p - start);
306 		q += p - start;
307 		*q++ = '/';
308 	}
309 	strcpy(q, name);
310 	pathopt = NULL;
311 	if (*p == '%') {
312 		pathopt = ++p;
313 		while (*p && *p != ':')  p++;
314 	}
315 	if (*p == ':')
316 		*path = p + 1;
317 	else
318 		*path = NULL;
319 	return stalloc(len);
320 }
321 
322 
323 
324 /*** Command hashing code ***/
325 
326 
327 int
328 hashcmd(argc, argv)
329 	int argc __unused;
330 	char **argv __unused;
331 {
332 	struct tblentry **pp;
333 	struct tblentry *cmdp;
334 	int c;
335 	int verbose;
336 	struct cmdentry entry;
337 	char *name;
338 
339 	verbose = 0;
340 	while ((c = nextopt("rv")) != '\0') {
341 		if (c == 'r') {
342 			clearcmdentry(0);
343 		} else if (c == 'v') {
344 			verbose++;
345 		}
346 	}
347 	if (*argptr == NULL) {
348 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
349 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
350 				printentry(cmdp, verbose);
351 			}
352 		}
353 		return 0;
354 	}
355 	while ((name = *argptr) != NULL) {
356 		if ((cmdp = cmdlookup(name, 0)) != NULL
357 		 && (cmdp->cmdtype == CMDNORMAL
358 		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
359 			delete_cmd_entry();
360 		find_command(name, &entry, 1, pathval());
361 		if (verbose) {
362 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
363 				cmdp = cmdlookup(name, 0);
364 				printentry(cmdp, verbose);
365 			}
366 			flushall();
367 		}
368 		argptr++;
369 	}
370 	return 0;
371 }
372 
373 
374 STATIC void
375 printentry(cmdp, verbose)
376 	struct tblentry *cmdp;
377 	int verbose;
378 	{
379 	int index;
380 	char *path;
381 	char *name;
382 
383 	if (cmdp->cmdtype == CMDNORMAL) {
384 		index = cmdp->param.index;
385 		path = pathval();
386 		do {
387 			name = padvance(&path, cmdp->cmdname);
388 			stunalloc(name);
389 		} while (--index >= 0);
390 		out1str(name);
391 	} else if (cmdp->cmdtype == CMDBUILTIN) {
392 		out1fmt("builtin %s", cmdp->cmdname);
393 	} else if (cmdp->cmdtype == CMDFUNCTION) {
394 		out1fmt("function %s", cmdp->cmdname);
395 		if (verbose) {
396 			INTOFF;
397 			name = commandtext(cmdp->param.func);
398 			out1c(' ');
399 			out1str(name);
400 			ckfree(name);
401 			INTON;
402 		}
403 #ifdef DEBUG
404 	} else {
405 		error("internal error: cmdtype %d", cmdp->cmdtype);
406 #endif
407 	}
408 	if (cmdp->rehash)
409 		out1c('*');
410 	out1c('\n');
411 }
412 
413 
414 
415 /*
416  * Resolve a command name.  If you change this routine, you may have to
417  * change the shellexec routine as well.
418  */
419 
420 void
421 find_command(name, entry, printerr, path)
422 	char *name;
423 	struct cmdentry *entry;
424 	int printerr;
425 	char *path;
426 {
427 	struct tblentry *cmdp;
428 	int index;
429 	int prev;
430 	char *fullname;
431 	struct stat statb;
432 	int e;
433 	int i;
434 
435 	/* If name contains a slash, don't use the hash table */
436 	if (strchr(name, '/') != NULL) {
437 		entry->cmdtype = CMDNORMAL;
438 		entry->u.index = 0;
439 		return;
440 	}
441 
442 	/* If name is in the table, and not invalidated by cd, we're done */
443 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
444 		goto success;
445 
446 	/* If %builtin not in path, check for builtin next */
447 	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
448 		INTOFF;
449 		cmdp = cmdlookup(name, 1);
450 		cmdp->cmdtype = CMDBUILTIN;
451 		cmdp->param.index = i;
452 		INTON;
453 		goto success;
454 	}
455 
456 	/* We have to search path. */
457 	prev = -1;		/* where to start */
458 	if (cmdp) {		/* doing a rehash */
459 		if (cmdp->cmdtype == CMDBUILTIN)
460 			prev = builtinloc;
461 		else
462 			prev = cmdp->param.index;
463 	}
464 
465 	e = ENOENT;
466 	index = -1;
467 loop:
468 	while ((fullname = padvance(&path, name)) != NULL) {
469 		stunalloc(fullname);
470 		index++;
471 		if (pathopt) {
472 			if (prefix("builtin", pathopt)) {
473 				if ((i = find_builtin(name)) < 0)
474 					goto loop;
475 				INTOFF;
476 				cmdp = cmdlookup(name, 1);
477 				cmdp->cmdtype = CMDBUILTIN;
478 				cmdp->param.index = i;
479 				INTON;
480 				goto success;
481 			} else if (prefix("func", pathopt)) {
482 				/* handled below */
483 			} else {
484 				goto loop;	/* ignore unimplemented options */
485 			}
486 		}
487 		/* if rehash, don't redo absolute path names */
488 		if (fullname[0] == '/' && index <= prev) {
489 			if (index < prev)
490 				goto loop;
491 			TRACE(("searchexec \"%s\": no change\n", name));
492 			goto success;
493 		}
494 		while (stat(fullname, &statb) < 0) {
495 #ifdef SYSV
496 			if (errno == EINTR)
497 				continue;
498 #endif
499 			if (errno != ENOENT && errno != ENOTDIR)
500 				e = errno;
501 			goto loop;
502 		}
503 		e = EACCES;	/* if we fail, this will be the error */
504 		if (!S_ISREG(statb.st_mode))
505 			goto loop;
506 		if (pathopt) {		/* this is a %func directory */
507 			stalloc(strlen(fullname) + 1);
508 			readcmdfile(fullname);
509 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
510 				error("%s not defined in %s", name, fullname);
511 			stunalloc(fullname);
512 			goto success;
513 		}
514 #ifdef notdef
515 		if (statb.st_uid == geteuid()) {
516 			if ((statb.st_mode & 0100) == 0)
517 				goto loop;
518 		} else if (statb.st_gid == getegid()) {
519 			if ((statb.st_mode & 010) == 0)
520 				goto loop;
521 		} else {
522 			if ((statb.st_mode & 01) == 0)
523 				goto loop;
524 		}
525 #endif
526 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
527 		INTOFF;
528 		cmdp = cmdlookup(name, 1);
529 		cmdp->cmdtype = CMDNORMAL;
530 		cmdp->param.index = index;
531 		INTON;
532 		goto success;
533 	}
534 
535 	/* We failed.  If there was an entry for this command, delete it */
536 	if (cmdp)
537 		delete_cmd_entry();
538 	if (printerr)
539 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
540 	entry->cmdtype = CMDUNKNOWN;
541 	return;
542 
543 success:
544 	cmdp->rehash = 0;
545 	entry->cmdtype = cmdp->cmdtype;
546 	entry->u = cmdp->param;
547 }
548 
549 
550 
551 /*
552  * Search the table of builtin commands.
553  */
554 
555 int
556 find_builtin(name)
557 	char *name;
558 {
559 	const struct builtincmd *bp;
560 
561 	for (bp = builtincmd ; bp->name ; bp++) {
562 		if (*bp->name == *name && equal(bp->name, name))
563 			return bp->code;
564 	}
565 	return -1;
566 }
567 
568 
569 
570 /*
571  * Called when a cd is done.  Marks all commands so the next time they
572  * are executed they will be rehashed.
573  */
574 
575 void
576 hashcd() {
577 	struct tblentry **pp;
578 	struct tblentry *cmdp;
579 
580 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
581 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
582 			if (cmdp->cmdtype == CMDNORMAL
583 			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
584 				cmdp->rehash = 1;
585 		}
586 	}
587 }
588 
589 
590 
591 /*
592  * Called before PATH is changed.  The argument is the new value of PATH;
593  * pathval() still returns the old value at this point.  Called with
594  * interrupts off.
595  */
596 
597 void
598 changepath(newval)
599 	const char *newval;
600 {
601 	const char *old, *new;
602 	int index;
603 	int firstchange;
604 	int bltin;
605 
606 	old = pathval();
607 	new = newval;
608 	firstchange = 9999;	/* assume no change */
609 	index = 0;
610 	bltin = -1;
611 	for (;;) {
612 		if (*old != *new) {
613 			firstchange = index;
614 			if ((*old == '\0' && *new == ':')
615 			 || (*old == ':' && *new == '\0'))
616 				firstchange++;
617 			old = new;	/* ignore subsequent differences */
618 		}
619 		if (*new == '\0')
620 			break;
621 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
622 			bltin = index;
623 		if (*new == ':') {
624 			index++;
625 		}
626 		new++, old++;
627 	}
628 	if (builtinloc < 0 && bltin >= 0)
629 		builtinloc = bltin;		/* zap builtins */
630 	if (builtinloc >= 0 && bltin < 0)
631 		firstchange = 0;
632 	clearcmdentry(firstchange);
633 	builtinloc = bltin;
634 }
635 
636 
637 /*
638  * Clear out command entries.  The argument specifies the first entry in
639  * PATH which has changed.
640  */
641 
642 void
643 clearcmdentry(firstchange)
644 	int firstchange;
645 {
646 	struct tblentry **tblp;
647 	struct tblentry **pp;
648 	struct tblentry *cmdp;
649 
650 	INTOFF;
651 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
652 		pp = tblp;
653 		while ((cmdp = *pp) != NULL) {
654 			if ((cmdp->cmdtype == CMDNORMAL &&
655 			     cmdp->param.index >= firstchange)
656 			 || (cmdp->cmdtype == CMDBUILTIN &&
657 			     builtinloc >= firstchange)) {
658 				*pp = cmdp->next;
659 				ckfree(cmdp);
660 			} else {
661 				pp = &cmdp->next;
662 			}
663 		}
664 	}
665 	INTON;
666 }
667 
668 
669 /*
670  * Delete all functions.
671  */
672 
673 #ifdef mkinit
674 MKINIT void deletefuncs();
675 
676 SHELLPROC {
677 	deletefuncs();
678 }
679 #endif
680 
681 void
682 deletefuncs() {
683 	struct tblentry **tblp;
684 	struct tblentry **pp;
685 	struct tblentry *cmdp;
686 
687 	INTOFF;
688 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
689 		pp = tblp;
690 		while ((cmdp = *pp) != NULL) {
691 			if (cmdp->cmdtype == CMDFUNCTION) {
692 				*pp = cmdp->next;
693 				freefunc(cmdp->param.func);
694 				ckfree(cmdp);
695 			} else {
696 				pp = &cmdp->next;
697 			}
698 		}
699 	}
700 	INTON;
701 }
702 
703 
704 
705 /*
706  * Locate a command in the command hash table.  If "add" is nonzero,
707  * add the command to the table if it is not already present.  The
708  * variable "lastcmdentry" is set to point to the address of the link
709  * pointing to the entry, so that delete_cmd_entry can delete the
710  * entry.
711  */
712 
713 struct tblentry **lastcmdentry;
714 
715 
716 STATIC struct tblentry *
717 cmdlookup(name, add)
718 	char *name;
719 	int add;
720 {
721 	int hashval;
722 	char *p;
723 	struct tblentry *cmdp;
724 	struct tblentry **pp;
725 
726 	p = name;
727 	hashval = *p << 4;
728 	while (*p)
729 		hashval += *p++;
730 	hashval &= 0x7FFF;
731 	pp = &cmdtable[hashval % CMDTABLESIZE];
732 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
733 		if (equal(cmdp->cmdname, name))
734 			break;
735 		pp = &cmdp->next;
736 	}
737 	if (add && cmdp == NULL) {
738 		INTOFF;
739 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
740 					+ strlen(name) + 1);
741 		cmdp->next = NULL;
742 		cmdp->cmdtype = CMDUNKNOWN;
743 		cmdp->rehash = 0;
744 		strcpy(cmdp->cmdname, name);
745 		INTON;
746 	}
747 	lastcmdentry = pp;
748 	return cmdp;
749 }
750 
751 /*
752  * Delete the command entry returned on the last lookup.
753  */
754 
755 STATIC void
756 delete_cmd_entry() {
757 	struct tblentry *cmdp;
758 
759 	INTOFF;
760 	cmdp = *lastcmdentry;
761 	*lastcmdentry = cmdp->next;
762 	ckfree(cmdp);
763 	INTON;
764 }
765 
766 
767 
768 #ifdef notdef
769 void
770 getcmdentry(name, entry)
771 	char *name;
772 	struct cmdentry *entry;
773 	{
774 	struct tblentry *cmdp = cmdlookup(name, 0);
775 
776 	if (cmdp) {
777 		entry->u = cmdp->param;
778 		entry->cmdtype = cmdp->cmdtype;
779 	} else {
780 		entry->cmdtype = CMDUNKNOWN;
781 		entry->u.index = 0;
782 	}
783 }
784 #endif
785 
786 
787 /*
788  * Add a new command entry, replacing any existing command entry for
789  * the same name.
790  */
791 
792 void
793 addcmdentry(name, entry)
794 	char *name;
795 	struct cmdentry *entry;
796 	{
797 	struct tblentry *cmdp;
798 
799 	INTOFF;
800 	cmdp = cmdlookup(name, 1);
801 	if (cmdp->cmdtype == CMDFUNCTION) {
802 		freefunc(cmdp->param.func);
803 	}
804 	cmdp->cmdtype = entry->cmdtype;
805 	cmdp->param = entry->u;
806 	INTON;
807 }
808 
809 
810 /*
811  * Define a shell function.
812  */
813 
814 void
815 defun(name, func)
816 	char *name;
817 	union node *func;
818 	{
819 	struct cmdentry entry;
820 
821 	INTOFF;
822 	entry.cmdtype = CMDFUNCTION;
823 	entry.u.func = copyfunc(func);
824 	addcmdentry(name, &entry);
825 	INTON;
826 }
827 
828 
829 /*
830  * Delete a function if it exists.
831  */
832 
833 int
834 unsetfunc(name)
835 	char *name;
836 	{
837 	struct tblentry *cmdp;
838 
839 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
840 		freefunc(cmdp->param.func);
841 		delete_cmd_entry();
842 		return (0);
843 	}
844 	return (1);
845 }
846 
847 /*
848  * Locate and print what a word is...
849  */
850 
851 int
852 typecmd(argc, argv)
853 	int argc;
854 	char **argv;
855 {
856 	struct cmdentry entry;
857 	struct tblentry *cmdp;
858 	char **pp;
859 	struct alias *ap;
860 	int i;
861 	int error = 0;
862 	extern char *const parsekwd[];
863 
864 	for (i = 1; i < argc; i++) {
865 		out1str(argv[i]);
866 		/* First look at the keywords */
867 		for (pp = (char **)parsekwd; *pp; pp++)
868 			if (**pp == *argv[i] && equal(*pp, argv[i]))
869 				break;
870 
871 		if (*pp) {
872 			out1str(" is a shell keyword\n");
873 			continue;
874 		}
875 
876 		/* Then look at the aliases */
877 		if ((ap = lookupalias(argv[i], 1)) != NULL) {
878 			out1fmt(" is an alias for %s\n", ap->val);
879 			continue;
880 		}
881 
882 		/* Then check if it is a tracked alias */
883 		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
884 			entry.cmdtype = cmdp->cmdtype;
885 			entry.u = cmdp->param;
886 		}
887 		else {
888 			/* Finally use brute force */
889 			find_command(argv[i], &entry, 0, pathval());
890 		}
891 
892 		switch (entry.cmdtype) {
893 		case CMDNORMAL: {
894 			if (strchr(argv[i], '/') == NULL) {
895 				char *path = pathval(), *name;
896 				int j = entry.u.index;
897 				do {
898 					name = padvance(&path, argv[i]);
899 					stunalloc(name);
900 				} while (--j >= 0);
901 				out1fmt(" is%s %s\n",
902 				    cmdp ? " a tracked alias for" : "", name);
903 			} else {
904 				if (access(argv[i], X_OK) == 0)
905 					out1fmt(" is %s\n", argv[i]);
906 				else
907 					out1fmt(": %s\n", strerror(errno));
908 			}
909 			break;
910 		}
911 		case CMDFUNCTION:
912 			out1str(" is a shell function\n");
913 			break;
914 
915 		case CMDBUILTIN:
916 			out1str(" is a shell builtin\n");
917 			break;
918 
919 		default:
920 			out1str(": not found\n");
921 			error |= 127;
922 			break;
923 		}
924 	}
925 	return error;
926 }
927