xref: /netbsd-src/bin/sh/exec.c (revision ae9172d6cd9432a6a1a56760d86b32c57a66c39c)
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 /*static char sccsid[] = "from: @(#)exec.c	8.1 (Berkeley) 5/31/93";*/
39 static char *rcsid = "$Id: exec.c,v 1.12 1994/12/05 19:07:39 cgd 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 "jobs.h"
69 #include <sys/types.h>
70 #include <sys/stat.h>
71 #include <unistd.h>
72 #include <fcntl.h>
73 #include <errno.h>
74 
75 
76 #define CMDTABLESIZE 31		/* should be prime */
77 #define ARB 1			/* actual size determined at run time */
78 
79 
80 
81 struct tblentry {
82 	struct tblentry *next;	/* next entry in hash chain */
83 	union param param;	/* definition of builtin function */
84 	short cmdtype;		/* index identifying command */
85 	char rehash;		/* if set, cd done since entry created */
86 	char cmdname[ARB];	/* name of command */
87 };
88 
89 
90 STATIC struct tblentry *cmdtable[CMDTABLESIZE];
91 STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
92 
93 
94 #ifdef __STDC__
95 STATIC void tryexec(char *, char **, char **);
96 STATIC void execinterp(char **, char **);
97 STATIC void printentry(struct tblentry *, int);
98 STATIC void clearcmdentry(int);
99 STATIC struct tblentry *cmdlookup(char *, int);
100 STATIC void delete_cmd_entry(void);
101 #else
102 STATIC void tryexec();
103 STATIC void execinterp();
104 STATIC void printentry();
105 STATIC void clearcmdentry();
106 STATIC struct tblentry *cmdlookup();
107 STATIC void delete_cmd_entry();
108 #endif
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 	error2(argv[0], errmsg(e, E_EXEC));
141 }
142 
143 
144 STATIC void
145 tryexec(cmd, argv, envp)
146 	char *cmd;
147 	char **argv;
148 	char **envp;
149 	{
150 	int e;
151 	char *p;
152 
153 #ifdef SYSV
154 	do {
155 		execve(cmd, argv, envp);
156 	} while (errno == EINTR);
157 #else
158 	execve(cmd, argv, envp);
159 #endif
160 	e = errno;
161 	if (e == ENOEXEC) {
162 		initshellproc();
163 		setinputfile(cmd, 0);
164 		commandname = arg0 = savestr(argv[0]);
165 #ifndef BSD
166 		pgetc(); pungetc();		/* fill up input buffer */
167 		p = parsenextc;
168 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
169 			argv[0] = cmd;
170 			execinterp(argv, envp);
171 		}
172 #endif
173 		setparam(argv + 1);
174 		exraise(EXSHELLPROC);
175 		/*NOTREACHED*/
176 	}
177 	errno = e;
178 }
179 
180 
181 #ifndef BSD
182 /*
183  * Execute an interpreter introduced by "#!", for systems where this
184  * feature has not been built into the kernel.  If the interpreter is
185  * the shell, return (effectively ignoring the "#!").  If the execution
186  * of the interpreter fails, exit.
187  *
188  * This code peeks inside the input buffer in order to avoid actually
189  * reading any input.  It would benefit from a rewrite.
190  */
191 
192 #define NEWARGS 5
193 
194 STATIC void
195 execinterp(argv, envp)
196 	char **argv, **envp;
197 	{
198 	int n;
199 	char *inp;
200 	char *outp;
201 	char c;
202 	char *p;
203 	char **ap;
204 	char *newargs[NEWARGS];
205 	int i;
206 	char **ap2;
207 	char **new;
208 
209 	n = parsenleft - 2;
210 	inp = parsenextc + 2;
211 	ap = newargs;
212 	for (;;) {
213 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
214 			inp++;
215 		if (n < 0)
216 			goto bad;
217 		if ((c = *inp++) == '\n')
218 			break;
219 		if (ap == &newargs[NEWARGS])
220 bad:		  error("Bad #! line");
221 		STARTSTACKSTR(outp);
222 		do {
223 			STPUTC(c, outp);
224 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
225 		STPUTC('\0', outp);
226 		n++, inp--;
227 		*ap++ = grabstackstr(outp);
228 	}
229 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
230 		p = newargs[0];
231 		for (;;) {
232 			if (equal(p, "sh") || equal(p, "ash")) {
233 				return;
234 			}
235 			while (*p != '/') {
236 				if (*p == '\0')
237 					goto break2;
238 				p++;
239 			}
240 			p++;
241 		}
242 break2:;
243 	}
244 	i = (char *)ap - (char *)newargs;		/* size in bytes */
245 	if (i == 0)
246 		error("Bad #! line");
247 	for (ap2 = argv ; *ap2++ != NULL ; );
248 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
249 	ap = newargs, ap2 = new;
250 	while ((i -= sizeof (char **)) >= 0)
251 		*ap2++ = *ap++;
252 	ap = argv;
253 	while (*ap2++ = *ap++);
254 	shellexec(new, envp, pathval(), 0);
255 }
256 #endif
257 
258 
259 
260 /*
261  * Do a path search.  The variable path (passed by reference) should be
262  * set to the start of the path before the first call; padvance will update
263  * this value as it proceeds.  Successive calls to padvance will return
264  * the possible path expansions in sequence.  If an option (indicated by
265  * a percent sign) appears in the path entry then the global variable
266  * pathopt will be set to point to it; otherwise pathopt will be set to
267  * NULL.
268  */
269 
270 char *pathopt;
271 
272 char *
273 padvance(path, name)
274 	char **path;
275 	char *name;
276 	{
277 	register char *p, *q;
278 	char *start;
279 	int len;
280 
281 	if (*path == NULL)
282 		return NULL;
283 	start = *path;
284 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
285 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
286 	while (stackblocksize() < len)
287 		growstackblock();
288 	q = stackblock();
289 	if (p != start) {
290 		memcpy(q, start, p - start);
291 		q += p - start;
292 		*q++ = '/';
293 	}
294 	strcpy(q, name);
295 	pathopt = NULL;
296 	if (*p == '%') {
297 		pathopt = ++p;
298 		while (*p && *p != ':')  p++;
299 	}
300 	if (*p == ':')
301 		*path = p + 1;
302 	else
303 		*path = NULL;
304 	return stalloc(len);
305 }
306 
307 
308 
309 /*** Command hashing code ***/
310 
311 
312 int
313 hashcmd(argc, argv)
314 	int argc;
315 	char **argv;
316 {
317 	struct tblentry **pp;
318 	struct tblentry *cmdp;
319 	int c;
320 	int verbose;
321 	struct cmdentry entry;
322 	char *name;
323 
324 	verbose = 0;
325 	while ((c = nextopt("rv")) != '\0') {
326 		if (c == 'r') {
327 			clearcmdentry(0);
328 		} else if (c == 'v') {
329 			verbose++;
330 		}
331 	}
332 	if (*argptr == NULL) {
333 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
334 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
335 				printentry(cmdp, verbose);
336 			}
337 		}
338 		return 0;
339 	}
340 	while ((name = *argptr) != NULL) {
341 		if ((cmdp = cmdlookup(name, 0)) != NULL
342 		 && (cmdp->cmdtype == CMDNORMAL
343 		     || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
344 			delete_cmd_entry();
345 		find_command(name, &entry, 1);
346 		if (verbose) {
347 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
348 				cmdp = cmdlookup(name, 0);
349 				printentry(cmdp, verbose);
350 			}
351 			flushall();
352 		}
353 		argptr++;
354 	}
355 	return 0;
356 }
357 
358 
359 STATIC void
360 printentry(cmdp, verbose)
361 	struct tblentry *cmdp;
362 	int verbose;
363 	{
364 	int index;
365 	char *path;
366 	char *name;
367 
368 	if (cmdp->cmdtype == CMDNORMAL) {
369 		index = cmdp->param.index;
370 		path = pathval();
371 		do {
372 			name = padvance(&path, cmdp->cmdname);
373 			stunalloc(name);
374 		} while (--index >= 0);
375 		out1str(name);
376 	} else if (cmdp->cmdtype == CMDBUILTIN) {
377 		out1fmt("builtin %s", cmdp->cmdname);
378 	} else if (cmdp->cmdtype == CMDFUNCTION) {
379 		out1fmt("function %s", cmdp->cmdname);
380 		if (verbose) {
381 			INTOFF;
382 			name = commandtext(cmdp->param.func);
383 			out1c(' ');
384 			out1str(name);
385 			ckfree(name);
386 			INTON;
387 		}
388 #ifdef DEBUG
389 	} else {
390 		error("internal error: cmdtype %d", cmdp->cmdtype);
391 #endif
392 	}
393 	if (cmdp->rehash)
394 		out1c('*');
395 	out1c('\n');
396 }
397 
398 
399 
400 /*
401  * Resolve a command name.  If you change this routine, you may have to
402  * change the shellexec routine as well.
403  */
404 
405 void
406 find_command(name, entry, printerr)
407 	char *name;
408 	struct cmdentry *entry;
409 	int printerr;
410 {
411 	struct tblentry *cmdp;
412 	int index;
413 	int prev;
414 	char *path;
415 	char *fullname;
416 	struct stat statb;
417 	int e;
418 	int i;
419 
420 	/* If name contains a slash, don't use the hash table */
421 	if (strchr(name, '/') != NULL) {
422 		entry->cmdtype = CMDNORMAL;
423 		entry->u.index = 0;
424 		return;
425 	}
426 
427 	/* If name is in the table, and not invalidated by cd, we're done */
428 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
429 		goto success;
430 
431 	/* If %builtin not in path, check for builtin next */
432 	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
433 		INTOFF;
434 		cmdp = cmdlookup(name, 1);
435 		cmdp->cmdtype = CMDBUILTIN;
436 		cmdp->param.index = i;
437 		INTON;
438 		goto success;
439 	}
440 
441 	/* We have to search path. */
442 	prev = -1;		/* where to start */
443 	if (cmdp) {		/* doing a rehash */
444 		if (cmdp->cmdtype == CMDBUILTIN)
445 			prev = builtinloc;
446 		else
447 			prev = cmdp->param.index;
448 	}
449 
450 	path = pathval();
451 	e = ENOENT;
452 	index = -1;
453 loop:
454 	while ((fullname = padvance(&path, name)) != NULL) {
455 		stunalloc(fullname);
456 		index++;
457 		if (pathopt) {
458 			if (prefix("builtin", pathopt)) {
459 				if ((i = find_builtin(name)) < 0)
460 					goto loop;
461 				INTOFF;
462 				cmdp = cmdlookup(name, 1);
463 				cmdp->cmdtype = CMDBUILTIN;
464 				cmdp->param.index = i;
465 				INTON;
466 				goto success;
467 			} else if (prefix("func", pathopt)) {
468 				/* handled below */
469 			} else {
470 				goto loop;	/* ignore unimplemented options */
471 			}
472 		}
473 		/* if rehash, don't redo absolute path names */
474 		if (fullname[0] == '/' && index <= prev) {
475 			if (index < prev)
476 				goto loop;
477 			TRACE(("searchexec \"%s\": no change\n", name));
478 			goto success;
479 		}
480 		while (stat(fullname, &statb) < 0) {
481 #ifdef SYSV
482 			if (errno == EINTR)
483 				continue;
484 #endif
485 			if (errno != ENOENT && errno != ENOTDIR)
486 				e = errno;
487 			goto loop;
488 		}
489 		e = EACCES;	/* if we fail, this will be the error */
490 		if ((statb.st_mode & S_IFMT) != S_IFREG)
491 			goto loop;
492 		if (pathopt) {		/* this is a %func directory */
493 			stalloc(strlen(fullname) + 1);
494 			readcmdfile(fullname);
495 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
496 				error("%s not defined in %s", name, fullname);
497 			stunalloc(fullname);
498 			goto success;
499 		}
500 #ifdef notdef
501 		if (statb.st_uid == geteuid()) {
502 			if ((statb.st_mode & 0100) == 0)
503 				goto loop;
504 		} else if (statb.st_gid == getegid()) {
505 			if ((statb.st_mode & 010) == 0)
506 				goto loop;
507 		} else {
508 			if ((statb.st_mode & 01) == 0)
509 				goto loop;
510 		}
511 #endif
512 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
513 		INTOFF;
514 		cmdp = cmdlookup(name, 1);
515 		cmdp->cmdtype = CMDNORMAL;
516 		cmdp->param.index = index;
517 		INTON;
518 		goto success;
519 	}
520 
521 	/* We failed.  If there was an entry for this command, delete it */
522 	if (cmdp)
523 		delete_cmd_entry();
524 	if (printerr)
525 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
526 	entry->cmdtype = CMDUNKNOWN;
527 	return;
528 
529 success:
530 	cmdp->rehash = 0;
531 	entry->cmdtype = cmdp->cmdtype;
532 	entry->u = cmdp->param;
533 }
534 
535 
536 
537 /*
538  * Search the table of builtin commands.
539  */
540 
541 int
542 find_builtin(name)
543 	char *name;
544 {
545 	register const struct builtincmd *bp;
546 
547 	for (bp = builtincmd ; bp->name ; bp++) {
548 		if (*bp->name == *name && equal(bp->name, name))
549 			return bp->code;
550 	}
551 	return -1;
552 }
553 
554 
555 
556 /*
557  * Called when a cd is done.  Marks all commands so the next time they
558  * are executed they will be rehashed.
559  */
560 
561 void
562 hashcd() {
563 	struct tblentry **pp;
564 	struct tblentry *cmdp;
565 
566 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
567 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
568 			if (cmdp->cmdtype == CMDNORMAL
569 			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)
570 				cmdp->rehash = 1;
571 		}
572 	}
573 }
574 
575 
576 
577 /*
578  * Called before PATH is changed.  The argument is the new value of PATH;
579  * pathval() still returns the old value at this point.  Called with
580  * interrupts off.
581  */
582 
583 void
584 changepath(newval)
585 	char *newval;
586 	{
587 	char *old, *new;
588 	int index;
589 	int firstchange;
590 	int bltin;
591 	int hasdot;
592 
593 	old = pathval();
594 	new = newval;
595 	firstchange = 9999;	/* assume no change */
596 	index = hasdot = 0;
597 	bltin = -1;
598 	if (*new == ':')
599 		hasdot++;
600 	for (;;) {
601 		if (*old != *new) {
602 			firstchange = index;
603 			if (*old == '\0' && *new == ':'
604 			 || *old == ':' && *new == '\0')
605 				firstchange++;
606 			old = new;	/* ignore subsequent differences */
607 		}
608 		if (*new == '\0')
609 			break;
610 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
611 			bltin = index;
612 		if (*new == ':') {
613 			char c = *(new+1);
614 
615 			index++;
616 			if (c == ':' || c == '\0' || (c == '.' &&
617 			   ((c = *(new+2)) == ':' || c == '\0')))
618 				hasdot++;
619 		}
620 		new++, old++;
621 	}
622 	if (hasdot && geteuid() == 0)
623 		out2str("sh: warning: running as root with dot in PATH\n");
624 	if (builtinloc < 0 && bltin >= 0)
625 		builtinloc = bltin;		/* zap builtins */
626 	if (builtinloc >= 0 && bltin < 0)
627 		firstchange = 0;
628 	clearcmdentry(firstchange);
629 	builtinloc = bltin;
630 }
631 
632 
633 /*
634  * Clear out command entries.  The argument specifies the first entry in
635  * PATH which has changed.
636  */
637 
638 STATIC void
639 clearcmdentry(firstchange)
640 	int firstchange;
641 {
642 	struct tblentry **tblp;
643 	struct tblentry **pp;
644 	struct tblentry *cmdp;
645 
646 	INTOFF;
647 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
648 		pp = tblp;
649 		while ((cmdp = *pp) != NULL) {
650 			if (cmdp->cmdtype == CMDNORMAL && cmdp->param.index >= firstchange
651 			 || cmdp->cmdtype == CMDBUILTIN && builtinloc >= firstchange) {
652 				*pp = cmdp->next;
653 				ckfree(cmdp);
654 			} else {
655 				pp = &cmdp->next;
656 			}
657 		}
658 	}
659 	INTON;
660 }
661 
662 
663 /*
664  * Delete all functions.
665  */
666 
667 #ifdef mkinit
668 MKINIT void deletefuncs();
669 
670 SHELLPROC {
671 	deletefuncs();
672 }
673 #endif
674 
675 void
676 deletefuncs() {
677 	struct tblentry **tblp;
678 	struct tblentry **pp;
679 	struct tblentry *cmdp;
680 
681 	INTOFF;
682 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
683 		pp = tblp;
684 		while ((cmdp = *pp) != NULL) {
685 			if (cmdp->cmdtype == CMDFUNCTION) {
686 				*pp = cmdp->next;
687 				freefunc(cmdp->param.func);
688 				ckfree(cmdp);
689 			} else {
690 				pp = &cmdp->next;
691 			}
692 		}
693 	}
694 	INTON;
695 }
696 
697 
698 
699 /*
700  * Locate a command in the command hash table.  If "add" is nonzero,
701  * add the command to the table if it is not already present.  The
702  * variable "lastcmdentry" is set to point to the address of the link
703  * pointing to the entry, so that delete_cmd_entry can delete the
704  * entry.
705  */
706 
707 struct tblentry **lastcmdentry;
708 
709 
710 STATIC struct tblentry *
711 cmdlookup(name, add)
712 	char *name;
713 	int add;
714 {
715 	int hashval;
716 	register char *p;
717 	struct tblentry *cmdp;
718 	struct tblentry **pp;
719 
720 	p = name;
721 	hashval = *p << 4;
722 	while (*p)
723 		hashval += *p++;
724 	hashval &= 0x7FFF;
725 	pp = &cmdtable[hashval % CMDTABLESIZE];
726 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
727 		if (equal(cmdp->cmdname, name))
728 			break;
729 		pp = &cmdp->next;
730 	}
731 	if (add && cmdp == NULL) {
732 		INTOFF;
733 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
734 					+ strlen(name) + 1);
735 		cmdp->next = NULL;
736 		cmdp->cmdtype = CMDUNKNOWN;
737 		cmdp->rehash = 0;
738 		strcpy(cmdp->cmdname, name);
739 		INTON;
740 	}
741 	lastcmdentry = pp;
742 	return cmdp;
743 }
744 
745 /*
746  * Delete the command entry returned on the last lookup.
747  */
748 
749 STATIC void
750 delete_cmd_entry() {
751 	struct tblentry *cmdp;
752 
753 	INTOFF;
754 	cmdp = *lastcmdentry;
755 	*lastcmdentry = cmdp->next;
756 	ckfree(cmdp);
757 	INTON;
758 }
759 
760 
761 
762 #ifdef notdef
763 void
764 getcmdentry(name, entry)
765 	char *name;
766 	struct cmdentry *entry;
767 	{
768 	struct tblentry *cmdp = cmdlookup(name, 0);
769 
770 	if (cmdp) {
771 		entry->u = cmdp->param;
772 		entry->cmdtype = cmdp->cmdtype;
773 	} else {
774 		entry->cmdtype = CMDUNKNOWN;
775 		entry->u.index = 0;
776 	}
777 }
778 #endif
779 
780 
781 /*
782  * Add a new command entry, replacing any existing command entry for
783  * the same name.
784  */
785 
786 void
787 addcmdentry(name, entry)
788 	char *name;
789 	struct cmdentry *entry;
790 	{
791 	struct tblentry *cmdp;
792 
793 	INTOFF;
794 	cmdp = cmdlookup(name, 1);
795 	if (cmdp->cmdtype == CMDFUNCTION) {
796 		freefunc(cmdp->param.func);
797 	}
798 	cmdp->cmdtype = entry->cmdtype;
799 	cmdp->param = entry->u;
800 	INTON;
801 }
802 
803 
804 /*
805  * Define a shell function.
806  */
807 
808 void
809 defun(name, func)
810 	char *name;
811 	union node *func;
812 	{
813 	struct cmdentry entry;
814 
815 	INTOFF;
816 	entry.cmdtype = CMDFUNCTION;
817 	entry.u.func = copyfunc(func);
818 	addcmdentry(name, &entry);
819 	INTON;
820 }
821 
822 
823 /*
824  * Delete a function if it exists.
825  */
826 
827 int
828 unsetfunc(name)
829 	char *name;
830 	{
831 	struct tblentry *cmdp;
832 
833 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
834 		freefunc(cmdp->param.func);
835 		delete_cmd_entry();
836 		return (0);
837 	}
838 	return (1);
839 }
840