xref: /netbsd-src/bin/sh/exec.c (revision 5f7096188587a2c7c95fa3c69b78e1ec9c7923d0)
1 /*-
2  * Copyright (c) 1991 The Regents of the University of California.
3  * 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 /*static char sccsid[] = "from: @(#)exec.c	5.2 (Berkeley) 3/13/91";*/
39 static char rcsid[] = "$Id: exec.c,v 1.6 1993/09/23 23:32:19 mycroft Exp $";
40 #endif /* not lint */
41 
42 /*
43  * When commands are first encountered, they are entered in a hash table.
44  * This ensures that a full path search will not have to be done for them
45  * on each invocation.
46  *
47  * We should investigate converting to a linear search, even though that
48  * would make the command name "hash" a misnomer.
49  */
50 
51 #include "shell.h"
52 #include "main.h"
53 #include "nodes.h"
54 #include "parser.h"
55 #include "redir.h"
56 #include "eval.h"
57 #include "exec.h"
58 #include "builtins.h"
59 #include "var.h"
60 #include "options.h"
61 #include "input.h"
62 #include "output.h"
63 #include "syntax.h"
64 #include "memalloc.h"
65 #include "error.h"
66 #include "init.h"
67 #include "mystring.h"
68 #include <sys/types.h>
69 #include <sys/stat.h>
70 #include <fcntl.h>
71 #include <errno.h>
72 #ifdef  BSD
73 #undef BSD      /* temporary, already defined in <sys/param.h> */
74 #include <sys/param.h>
75 #include <unistd.h>
76 #endif
77 
78 
79 #define CMDTABLESIZE 31		/* should be prime */
80 #define ARB 1			/* actual size determined at run time */
81 
82 
83 
84 struct 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 
93 STATIC struct tblentry *cmdtable[CMDTABLESIZE];
94 STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
95 
96 
97 #ifdef __STDC__
98 STATIC void tryexec(char *, char **, char **);
99 STATIC void execinterp(char **, char **);
100 STATIC void printentry(struct tblentry *);
101 STATIC void clearcmdentry(int);
102 STATIC struct tblentry *cmdlookup(char *, int);
103 STATIC void delete_cmd_entry(void);
104 #else
105 STATIC void tryexec();
106 STATIC void execinterp();
107 STATIC void printentry();
108 STATIC void clearcmdentry();
109 STATIC struct tblentry *cmdlookup();
110 STATIC void delete_cmd_entry();
111 #endif
112 
113 
114 
115 /*
116  * Exec a program.  Never returns.  If you change this routine, you may
117  * have to change the find_command routine as well.
118  */
119 
120 void
121 shellexec(argv, envp, path, index)
122 	char **argv, **envp;
123 	char *path;
124 	{
125 	char *cmdname;
126 	int e;
127 
128 	if (strchr(argv[0], '/') != NULL) {
129 		tryexec(argv[0], argv, envp);
130 		e = errno;
131 	} else {
132 		e = ENOENT;
133 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
134 			if (--index < 0 && pathopt == NULL) {
135 				tryexec(cmdname, argv, envp);
136 				if (errno != ENOENT && errno != ENOTDIR)
137 					e = errno;
138 			}
139 			stunalloc(cmdname);
140 		}
141 	}
142 	error2(argv[0], errmsg(e, E_EXEC));
143 }
144 
145 
146 STATIC void
147 tryexec(cmd, argv, envp)
148 	char *cmd;
149 	char **argv;
150 	char **envp;
151 	{
152 	int e;
153 	char *p;
154 
155 #ifdef SYSV
156 	do {
157 		execve(cmd, argv, envp);
158 	} while (errno == EINTR);
159 #else
160 	execve(cmd, argv, envp);
161 #endif
162 	e = errno;
163 	if (e == ENOEXEC) {
164 		initshellproc();
165 		setinputfile(cmd, 0);
166 		commandname = arg0 = savestr(argv[0]);
167 #ifndef BSD
168 		pgetc(); pungetc();		/* fill up input buffer */
169 		p = parsenextc;
170 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
171 			argv[0] = cmd;
172 			execinterp(argv, envp);
173 		}
174 #endif
175 		setparam(argv + 1);
176 		exraise(EXSHELLPROC);
177 		/*NOTREACHED*/
178 	}
179 	errno = e;
180 }
181 
182 
183 #ifndef BSD
184 /*
185  * Execute an interpreter introduced by "#!", for systems where this
186  * feature has not been built into the kernel.  If the interpreter is
187  * the shell, return (effectively ignoring the "#!").  If the execution
188  * of the interpreter fails, exit.
189  *
190  * This code peeks inside the input buffer in order to avoid actually
191  * reading any input.  It would benefit from a rewrite.
192  */
193 
194 #define NEWARGS 5
195 
196 STATIC void
197 execinterp(argv, envp)
198 	char **argv, **envp;
199 	{
200 	int n;
201 	char *inp;
202 	char *outp;
203 	char c;
204 	char *p;
205 	char **ap;
206 	char *newargs[NEWARGS];
207 	int i;
208 	char **ap2;
209 	char **new;
210 
211 	n = parsenleft - 2;
212 	inp = parsenextc + 2;
213 	ap = newargs;
214 	for (;;) {
215 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
216 			inp++;
217 		if (n < 0)
218 			goto bad;
219 		if ((c = *inp++) == '\n')
220 			break;
221 		if (ap == &newargs[NEWARGS])
222 bad:		  error("Bad #! line");
223 		STARTSTACKSTR(outp);
224 		do {
225 			STPUTC(c, outp);
226 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
227 		STPUTC('\0', outp);
228 		n++, inp--;
229 		*ap++ = grabstackstr(outp);
230 	}
231 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
232 		p = newargs[0];
233 		for (;;) {
234 			if (equal(p, "sh") || equal(p, "ash")) {
235 				return;
236 			}
237 			while (*p != '/') {
238 				if (*p == '\0')
239 					goto break2;
240 				p++;
241 			}
242 			p++;
243 		}
244 break2:;
245 	}
246 	i = (char *)ap - (char *)newargs;		/* size in bytes */
247 	if (i == 0)
248 		error("Bad #! line");
249 	for (ap2 = argv ; *ap2++ != NULL ; );
250 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
251 	ap = newargs, ap2 = new;
252 	while ((i -= sizeof (char **)) >= 0)
253 		*ap2++ = *ap++;
254 	ap = argv;
255 	while (*ap2++ = *ap++);
256 	shellexec(new, envp, pathval(), 0);
257 }
258 #endif
259 
260 
261 
262 /*
263  * Do a path search.  The variable path (passed by reference) should be
264  * set to the start of the path before the first call; padvance will update
265  * this value as it proceeds.  Successive calls to padvance will return
266  * the possible path expansions in sequence.  If an option (indicated by
267  * a percent sign) appears in the path entry then the global variable
268  * pathopt will be set to point to it; otherwise pathopt will be set to
269  * NULL.
270  */
271 
272 char *pathopt;
273 
274 char *
275 padvance(path, name)
276 	char **path;
277 	char *name;
278 	{
279 	register char *p, *q;
280 	char *start;
281 	int len;
282 
283 	if (*path == NULL)
284 		return NULL;
285 	start = *path;
286 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
287 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
288 	while (stackblocksize() < len)
289 		growstackblock();
290 	q = stackblock();
291 	if (p != start) {
292 		bcopy(start, q, p - start);
293 		q += p - start;
294 		*q++ = '/';
295 	}
296 	strcpy(q, name);
297 	pathopt = NULL;
298 	if (*p == '%') {
299 		pathopt = ++p;
300 		while (*p && *p != ':')  p++;
301 	}
302 	if (*p == ':')
303 		*path = p + 1;
304 	else
305 		*path = NULL;
306 	return stalloc(len);
307 }
308 
309 
310 
311 /*** Command hashing code ***/
312 
313 
314 hashcmd(argc, argv)  char **argv; {
315 	struct tblentry **pp;
316 	struct tblentry *cmdp;
317 	int c;
318 	int verbose;
319 	struct cmdentry entry;
320 	char *name;
321 
322 	if (argc <= 1) {
323 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
324 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
325 				printentry(cmdp);
326 			}
327 		}
328 		return 0;
329 	}
330 	verbose = 0;
331 	while ((c = nextopt("rv")) != '\0') {
332 		if (c == 'r') {
333 			clearcmdentry(0);
334 		} else if (c == 'v') {
335 			verbose++;
336 		}
337 	}
338 	while ((name = *argptr) != NULL) {
339 		if ((cmdp = cmdlookup(name, 0)) != NULL
340 		 && (cmdp->cmdtype == CMDNORMAL
341 		     || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
342 			delete_cmd_entry();
343 		find_command(name, &entry, 1);
344 		if (verbose) {
345 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
346 				cmdp = cmdlookup(name, 0);
347 				printentry(cmdp);
348 			}
349 			flushall();
350 		}
351 		argptr++;
352 	}
353 	return 0;
354 }
355 
356 
357 STATIC void
358 printentry(cmdp)
359 	struct tblentry *cmdp;
360 	{
361 	int index;
362 	char *path;
363 	char *name;
364 
365 	if (cmdp->cmdtype == CMDNORMAL) {
366 		index = cmdp->param.index;
367 		path = pathval();
368 		do {
369 			name = padvance(&path, cmdp->cmdname);
370 			stunalloc(name);
371 		} while (--index >= 0);
372 		out1str(name);
373 	} else if (cmdp->cmdtype == CMDBUILTIN) {
374 		out1fmt("builtin %s", cmdp->cmdname);
375 	} else if (cmdp->cmdtype == CMDFUNCTION) {
376 		out1fmt("function %s", cmdp->cmdname);
377 #ifdef DEBUG
378 	} else {
379 		error("internal error: cmdtype %d", cmdp->cmdtype);
380 #endif
381 	}
382 	if (cmdp->rehash)
383 		out1c('*');
384 	out1c('\n');
385 }
386 
387 
388 
389 /*
390  * Resolve a command name.  If you change this routine, you may have to
391  * change the shellexec routine as well.
392  */
393 
394 void
395 find_command(name, entry, printerr)
396 	char *name;
397 	struct cmdentry *entry;
398 	{
399 	struct tblentry *cmdp;
400 	int index;
401 	int prev;
402 	char *path;
403 	char *fullname;
404 	struct stat statb;
405 	int e;
406 	int i;
407 
408 	/* If name contains a slash, don't use the hash table */
409 	if (strchr(name, '/') != NULL) {
410 		entry->cmdtype = CMDNORMAL;
411 		entry->u.index = 0;
412 		return;
413 	}
414 
415 	/* If name is in the table, and not invalidated by cd, we're done */
416 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
417 		goto success;
418 
419 	/* If %builtin not in path, check for builtin next */
420 	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
421 		INTOFF;
422 		cmdp = cmdlookup(name, 1);
423 		cmdp->cmdtype = CMDBUILTIN;
424 		cmdp->param.index = i;
425 		INTON;
426 		goto success;
427 	}
428 
429 	/* We have to search path. */
430 	prev = -1;		/* where to start */
431 	if (cmdp) {		/* doing a rehash */
432 		if (cmdp->cmdtype == CMDBUILTIN)
433 			prev = builtinloc;
434 		else
435 			prev = cmdp->param.index;
436 	}
437 
438 	path = pathval();
439 	e = ENOENT;
440 	index = -1;
441 loop:
442 	while ((fullname = padvance(&path, name)) != NULL) {
443 		stunalloc(fullname);
444 		index++;
445 		if (pathopt) {
446 			if (prefix("builtin", pathopt)) {
447 				if ((i = find_builtin(name)) < 0)
448 					goto loop;
449 				INTOFF;
450 				cmdp = cmdlookup(name, 1);
451 				cmdp->cmdtype = CMDBUILTIN;
452 				cmdp->param.index = i;
453 				INTON;
454 				goto success;
455 			} else if (prefix("func", pathopt)) {
456 				/* handled below */
457 			} else {
458 				goto loop;	/* ignore unimplemented options */
459 			}
460 		}
461 		/* if rehash, don't redo absolute path names */
462 		if (fullname[0] == '/' && index <= prev) {
463 			if (index < prev)
464 				goto loop;
465 			TRACE(("searchexec \"%s\": no change\n", name));
466 			goto success;
467 		}
468 		while (stat(fullname, &statb) < 0) {
469 #ifdef SYSV
470 			if (errno == EINTR)
471 				continue;
472 #endif
473 			if (errno != ENOENT && errno != ENOTDIR)
474 				e = errno;
475 			goto loop;
476 		}
477 		e = EACCES;	/* if we fail, this will be the error */
478 		if ((statb.st_mode & S_IFMT) != S_IFREG)
479 			goto loop;
480 		if (pathopt) {		/* this is a %func directory */
481 			stalloc(strlen(fullname) + 1);
482 			readcmdfile(fullname);
483 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
484 				error("%s not defined in %s", name, fullname);
485 			stunalloc(fullname);
486 			goto success;
487 		}
488 		if (geteuid() == 0) {
489 			if ((statb.st_mode & 0111) == 0)
490 				goto loop;
491 		} else if (statb.st_uid == geteuid()) {
492 			if ((statb.st_mode & 0100) == 0)
493 				goto loop;
494 		} else if (statb.st_gid == getegid()) {
495 			if ((statb.st_mode & 010) == 0)
496 				goto loop;
497 		} else {
498 			if ((statb.st_mode & 01) == 0) {
499 #ifdef  BSD
500 				if ((statb.st_mode & 010) == 0)
501 					goto loop;
502 				/* Are you in this group too? */
503 				{
504 					int group_list[NGROUPS];
505 					int ngroups, i;
506 
507 					ngroups = getgroups(NGROUPS, group_list);
508 					for (i = 0; i < ngroups; i++)
509 						if (statb.st_gid == group_list[i])
510 							goto Found;
511 				}
512 #endif
513 				goto loop;
514 			}
515 		}
516 #ifdef  BSD
517 	Found:
518 #endif
519 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
520 		INTOFF;
521 		cmdp = cmdlookup(name, 1);
522 		cmdp->cmdtype = CMDNORMAL;
523 		cmdp->param.index = index;
524 		INTON;
525 		goto success;
526 	}
527 
528 	/* We failed.  If there was an entry for this command, delete it */
529 	if (cmdp)
530 		delete_cmd_entry();
531 	if (printerr)
532 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
533 	entry->cmdtype = CMDUNKNOWN;
534 	return;
535 
536 success:
537 	cmdp->rehash = 0;
538 	entry->cmdtype = cmdp->cmdtype;
539 	entry->u = cmdp->param;
540 }
541 
542 
543 
544 /*
545  * Search the table of builtin commands.
546  */
547 
548 int
549 find_builtin(name)
550 	char *name;
551 	{
552 	const register struct builtincmd *bp;
553 
554 	for (bp = builtincmd ; bp->name ; bp++) {
555 		if (*bp->name == *name && equal(bp->name, name))
556 			return bp->code;
557 	}
558 	return -1;
559 }
560 
561 
562 
563 /*
564  * Called when a cd is done.  Marks all commands so the next time they
565  * are executed they will be rehashed.
566  */
567 
568 void
569 hashcd() {
570 	struct tblentry **pp;
571 	struct tblentry *cmdp;
572 
573 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
574 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
575 			if (cmdp->cmdtype == CMDNORMAL
576 			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)
577 				cmdp->rehash = 1;
578 		}
579 	}
580 }
581 
582 
583 
584 /*
585  * Called before PATH is changed.  The argument is the new value of PATH;
586  * pathval() still returns the old value at this point.  Called with
587  * interrupts off.
588  */
589 
590 void
591 changepath(newval)
592 	char *newval;
593 	{
594 	char *old, *new;
595 	int index;
596 	int firstchange;
597 	int bltin;
598 
599 	old = pathval();
600 	new = newval;
601 	firstchange = 9999;	/* assume no change */
602 	index = 0;
603 	bltin = -1;
604 	for (;;) {
605 		if (*old != *new) {
606 			firstchange = index;
607 			if (*old == '\0' && *new == ':'
608 			 || *old == ':' && *new == '\0')
609 				firstchange++;
610 			old = new;	/* ignore subsequent differences */
611 		}
612 		if (*new == '\0')
613 			break;
614 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
615 			bltin = index;
616 		if (*new == ':') {
617 			index++;
618 		}
619 		new++, old++;
620 	}
621 	if (builtinloc < 0 && bltin >= 0)
622 		builtinloc = bltin;		/* zap builtins */
623 	if (builtinloc >= 0 && bltin < 0)
624 		firstchange = 0;
625 	clearcmdentry(firstchange);
626 	builtinloc = bltin;
627 }
628 
629 
630 /*
631  * Clear out command entries.  The argument specifies the first entry in
632  * PATH which has changed.
633  */
634 
635 STATIC void
636 clearcmdentry(firstchange) {
637 	struct tblentry **tblp;
638 	struct tblentry **pp;
639 	struct tblentry *cmdp;
640 
641 	INTOFF;
642 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
643 		pp = tblp;
644 		while ((cmdp = *pp) != NULL) {
645 			if (cmdp->cmdtype == CMDNORMAL && cmdp->param.index >= firstchange
646 			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= firstchange) {
647 				*pp = cmdp->next;
648 				ckfree(cmdp);
649 			} else {
650 				pp = &cmdp->next;
651 			}
652 		}
653 	}
654 	INTON;
655 }
656 
657 
658 /*
659  * Delete all functions.
660  */
661 
662 #ifdef mkinit
663 MKINIT void deletefuncs();
664 
665 SHELLPROC {
666 	deletefuncs();
667 }
668 #endif
669 
670 void
671 deletefuncs() {
672 	struct tblentry **tblp;
673 	struct tblentry **pp;
674 	struct tblentry *cmdp;
675 
676 	INTOFF;
677 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
678 		pp = tblp;
679 		while ((cmdp = *pp) != NULL) {
680 			if (cmdp->cmdtype == CMDFUNCTION) {
681 				*pp = cmdp->next;
682 				freefunc(cmdp->param.func);
683 				ckfree(cmdp);
684 			} else {
685 				pp = &cmdp->next;
686 			}
687 		}
688 	}
689 	INTON;
690 }
691 
692 
693 
694 /*
695  * Locate a command in the command hash table.  If "add" is nonzero,
696  * add the command to the table if it is not already present.  The
697  * variable "lastcmdentry" is set to point to the address of the link
698  * pointing to the entry, so that delete_cmd_entry can delete the
699  * entry.
700  */
701 
702 struct tblentry **lastcmdentry;
703 
704 
705 STATIC struct tblentry *
706 cmdlookup(name, add)
707 	char *name;
708 	{
709 	int hashval;
710 	register char *p;
711 	struct tblentry *cmdp;
712 	struct tblentry **pp;
713 
714 	p = name;
715 	hashval = *p << 4;
716 	while (*p)
717 		hashval += *p++;
718 	hashval &= 0x7FFF;
719 	pp = &cmdtable[hashval % CMDTABLESIZE];
720 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
721 		if (equal(cmdp->cmdname, name))
722 			break;
723 		pp = &cmdp->next;
724 	}
725 	if (add && cmdp == NULL) {
726 		INTOFF;
727 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
728 					+ strlen(name) + 1);
729 		cmdp->next = NULL;
730 		cmdp->cmdtype = CMDUNKNOWN;
731 		cmdp->rehash = 0;
732 		strcpy(cmdp->cmdname, name);
733 		INTON;
734 	}
735 	lastcmdentry = pp;
736 	return cmdp;
737 }
738 
739 
740 /*
741  * Delete the command entry returned on the last lookup.
742  */
743 
744 STATIC void
745 delete_cmd_entry() {
746 	struct tblentry *cmdp;
747 
748 	INTOFF;
749 	cmdp = *lastcmdentry;
750 	*lastcmdentry = cmdp->next;
751 	ckfree(cmdp);
752 	INTON;
753 }
754 
755 
756 
757 #ifdef notdef
758 void
759 getcmdentry(name, entry)
760 	char *name;
761 	struct cmdentry *entry;
762 	{
763 	struct tblentry *cmdp = cmdlookup(name, 0);
764 
765 	if (cmdp) {
766 		entry->u = cmdp->param;
767 		entry->cmdtype = cmdp->cmdtype;
768 	} else {
769 		entry->cmdtype = CMDUNKNOWN;
770 		entry->u.index = 0;
771 	}
772 }
773 #endif
774 
775 
776 /*
777  * Add a new command entry, replacing any existing command entry for
778  * the same name.
779  */
780 
781 void
782 addcmdentry(name, entry)
783 	char *name;
784 	struct cmdentry *entry;
785 	{
786 	struct tblentry *cmdp;
787 
788 	INTOFF;
789 	cmdp = cmdlookup(name, 1);
790 	if (cmdp->cmdtype == CMDFUNCTION) {
791 		freefunc(cmdp->param.func);
792 	}
793 	cmdp->cmdtype = entry->cmdtype;
794 	cmdp->param = entry->u;
795 	INTON;
796 }
797 
798 
799 /*
800  * Define a shell function.
801  */
802 
803 void
804 defun(name, func)
805 	char *name;
806 	union node *func;
807 	{
808 	struct cmdentry entry;
809 
810 	INTOFF;
811 	entry.cmdtype = CMDFUNCTION;
812 	entry.u.func = copyfunc(func);
813 	addcmdentry(name, &entry);
814 	INTON;
815 }
816 
817 
818 /*
819  * Delete a function if it exists.
820  */
821 
822 void
823 unsetfunc(name)
824 	char *name;
825 	{
826 	struct tblentry *cmdp;
827 
828 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
829 		freefunc(cmdp->param.func);
830 		delete_cmd_entry();
831 	}
832 }
833