exec.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0 
1/*	$NetBSD: exec.c,v 1.37 2003/08/07 09:05:31 agc Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
39#else
40__RCSID("$NetBSD: exec.c,v 1.37 2003/08/07 09:05:31 agc Exp $");
41#endif
42#endif /* not lint */
43
44#include <sys/types.h>
45#include <sys/stat.h>
46#include <sys/wait.h>
47#include <unistd.h>
48#include <fcntl.h>
49#include <errno.h>
50#include <stdio.h>
51#include <stdlib.h>
52
53/*
54 * When commands are first encountered, they are entered in a hash table.
55 * This ensures that a full path search will not have to be done for them
56 * on each invocation.
57 *
58 * We should investigate converting to a linear search, even though that
59 * would make the command name "hash" a misnomer.
60 */
61
62#include "shell.h"
63#include "main.h"
64#include "nodes.h"
65#include "parser.h"
66#include "redir.h"
67#include "eval.h"
68#include "exec.h"
69#include "builtins.h"
70#include "var.h"
71#include "options.h"
72#include "input.h"
73#include "output.h"
74#include "syntax.h"
75#include "memalloc.h"
76#include "error.h"
77#include "init.h"
78#include "mystring.h"
79#include "show.h"
80#include "jobs.h"
81#include "alias.h"
82
83
84#define CMDTABLESIZE 31		/* should be prime */
85#define ARB 1			/* actual size determined at run time */
86
87
88
89struct tblentry {
90	struct tblentry *next;	/* next entry in hash chain */
91	union param param;	/* definition of builtin function */
92	short cmdtype;		/* index identifying command */
93	char rehash;		/* if set, cd done since entry created */
94	char cmdname[ARB];	/* name of command */
95};
96
97
98STATIC struct tblentry *cmdtable[CMDTABLESIZE];
99STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
100int exerrno = 0;			/* Last exec error */
101
102
103STATIC void tryexec(char *, char **, char **, int);
104STATIC void execinterp(char **, char **);
105STATIC void printentry(struct tblentry *, int);
106STATIC void clearcmdentry(int);
107STATIC struct tblentry *cmdlookup(const char *, int);
108STATIC void delete_cmd_entry(void);
109
110
111extern char *const parsekwd[];
112
113/*
114 * Exec a program.  Never returns.  If you change this routine, you may
115 * have to change the find_command routine as well.
116 */
117
118void
119shellexec(char **argv, char **envp, const char *path, int idx, int vforked)
120{
121	char *cmdname;
122	int e;
123
124	if (strchr(argv[0], '/') != NULL) {
125		tryexec(argv[0], argv, envp, vforked);
126		e = errno;
127	} else {
128		e = ENOENT;
129		while ((cmdname = padvance(&path, argv[0])) != NULL) {
130			if (--idx < 0 && pathopt == NULL) {
131				tryexec(cmdname, argv, envp, vforked);
132				if (errno != ENOENT && errno != ENOTDIR)
133					e = errno;
134			}
135			stunalloc(cmdname);
136		}
137	}
138
139	/* Map to POSIX errors */
140	switch (e) {
141	case EACCES:
142		exerrno = 126;
143		break;
144	case ENOENT:
145		exerrno = 127;
146		break;
147	default:
148		exerrno = 2;
149		break;
150	}
151	TRACE(("shellexec failed for %s, errno %d, vforked %d, suppressint %d\n",
152		argv[0], e, vforked, suppressint ));
153	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
154	/* NOTREACHED */
155}
156
157
158STATIC void
159tryexec(char *cmd, char **argv, char **envp, int vforked)
160{
161	int e;
162#ifndef BSD
163	char *p;
164#endif
165
166#ifdef SYSV
167	do {
168		execve(cmd, argv, envp);
169	} while (errno == EINTR);
170#else
171	execve(cmd, argv, envp);
172#endif
173	e = errno;
174	if (e == ENOEXEC) {
175		if (vforked) {
176			/* We are currently vfork(2)ed, so raise an
177			 * exception, and evalcommand will try again
178			 * with a normal fork(2).
179			 */
180			exraise(EXSHELLPROC);
181		}
182		initshellproc();
183		setinputfile(cmd, 0);
184		commandname = arg0 = savestr(argv[0]);
185#if !defined(BSD) && !defined(__linux__)
186		pgetc(); pungetc();		/* fill up input buffer */
187		p = parsenextc;
188		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
189			argv[0] = cmd;
190			execinterp(argv, envp);
191		}
192#endif
193		setparam(argv + 1);
194		exraise(EXSHELLPROC);
195	}
196	errno = e;
197}
198
199
200#if !defined(BSD) && !defined(__linux__)
201/*
202 * Execute an interpreter introduced by "#!", for systems where this
203 * feature has not been built into the kernel.  If the interpreter is
204 * the shell, return (effectively ignoring the "#!").  If the execution
205 * of the interpreter fails, exit.
206 *
207 * This code peeks inside the input buffer in order to avoid actually
208 * reading any input.  It would benefit from a rewrite.
209 */
210
211#define NEWARGS 5
212
213STATIC void
214execinterp(char **argv, char **envp)
215{
216	int n;
217	char *inp;
218	char *outp;
219	char c;
220	char *p;
221	char **ap;
222	char *newargs[NEWARGS];
223	int i;
224	char **ap2;
225	char **new;
226
227	n = parsenleft - 2;
228	inp = parsenextc + 2;
229	ap = newargs;
230	for (;;) {
231		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
232			inp++;
233		if (n < 0)
234			goto bad;
235		if ((c = *inp++) == '\n')
236			break;
237		if (ap == &newargs[NEWARGS])
238bad:		  error("Bad #! line");
239		STARTSTACKSTR(outp);
240		do {
241			STPUTC(c, outp);
242		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
243		STPUTC('\0', outp);
244		n++, inp--;
245		*ap++ = grabstackstr(outp);
246	}
247	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
248		p = newargs[0];
249		for (;;) {
250			if (equal(p, "sh") || equal(p, "ash")) {
251				return;
252			}
253			while (*p != '/') {
254				if (*p == '\0')
255					goto break2;
256				p++;
257			}
258			p++;
259		}
260break2:;
261	}
262	i = (char *)ap - (char *)newargs;		/* size in bytes */
263	if (i == 0)
264		error("Bad #! line");
265	for (ap2 = argv ; *ap2++ != NULL ; );
266	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
267	ap = newargs, ap2 = new;
268	while ((i -= sizeof (char **)) >= 0)
269		*ap2++ = *ap++;
270	ap = argv;
271	while (*ap2++ = *ap++);
272	shellexec(new, envp, pathval(), 0);
273	/* NOTREACHED */
274}
275#endif
276
277
278
279/*
280 * Do a path search.  The variable path (passed by reference) should be
281 * set to the start of the path before the first call; padvance will update
282 * this value as it proceeds.  Successive calls to padvance will return
283 * the possible path expansions in sequence.  If an option (indicated by
284 * a percent sign) appears in the path entry then the global variable
285 * pathopt will be set to point to it; otherwise pathopt will be set to
286 * NULL.
287 */
288
289const char *pathopt;
290
291char *
292padvance(const char **path, const char *name)
293{
294	const char *p;
295	char *q;
296	const char *start;
297	int len;
298
299	if (*path == NULL)
300		return NULL;
301	start = *path;
302	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
303	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
304	while (stackblocksize() < len)
305		growstackblock();
306	q = stackblock();
307	if (p != start) {
308		memcpy(q, start, p - start);
309		q += p - start;
310		*q++ = '/';
311	}
312	strcpy(q, name);
313	pathopt = NULL;
314	if (*p == '%') {
315		pathopt = ++p;
316		while (*p && *p != ':')  p++;
317	}
318	if (*p == ':')
319		*path = p + 1;
320	else
321		*path = NULL;
322	return stalloc(len);
323}
324
325
326
327/*** Command hashing code ***/
328
329
330int
331hashcmd(int argc, char **argv)
332{
333	struct tblentry **pp;
334	struct tblentry *cmdp;
335	int c;
336	int verbose;
337	struct cmdentry entry;
338	char *name;
339
340	verbose = 0;
341	while ((c = nextopt("rv")) != '\0') {
342		if (c == 'r') {
343			clearcmdentry(0);
344		} else if (c == 'v') {
345			verbose++;
346		}
347	}
348	if (*argptr == NULL) {
349		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
350			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
351				if (verbose || cmdp->cmdtype == CMDNORMAL)
352					printentry(cmdp, verbose);
353			}
354		}
355		return 0;
356	}
357	while ((name = *argptr) != NULL) {
358		if ((cmdp = cmdlookup(name, 0)) != NULL
359		 && (cmdp->cmdtype == CMDNORMAL
360		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
361			delete_cmd_entry();
362		find_command(name, &entry, DO_ERR, pathval());
363		if (verbose) {
364			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
365				cmdp = cmdlookup(name, 0);
366				printentry(cmdp, verbose);
367			}
368			flushall();
369		}
370		argptr++;
371	}
372	return 0;
373}
374
375
376STATIC void
377printentry(struct tblentry *cmdp, int verbose)
378{
379	int idx;
380	const char *path;
381	char *name;
382
383	switch (cmdp->cmdtype) {
384	case CMDNORMAL:
385		idx = cmdp->param.index;
386		path = pathval();
387		do {
388			name = padvance(&path, cmdp->cmdname);
389			stunalloc(name);
390		} while (--idx >= 0);
391		out1str(name);
392		break;
393	case CMDSPLBLTIN:
394		out1fmt("special builtin %s", cmdp->cmdname);
395		break;
396	case CMDBUILTIN:
397		out1fmt("builtin %s", cmdp->cmdname);
398		break;
399	case CMDFUNCTION:
400		out1fmt("function %s", cmdp->cmdname);
401		if (verbose) {
402			struct procstat ps;
403			INTOFF;
404			commandtext(&ps, cmdp->param.func);
405			INTON;
406			out1str("() { ");
407			out1str(ps.cmd);
408			out1str("; }");
409		}
410		break;
411	default:
412		error("internal error: %s cmdtype %d", cmdp->cmdname, cmdp->cmdtype);
413	}
414	if (cmdp->rehash)
415		out1c('*');
416	out1c('\n');
417}
418
419
420
421/*
422 * Resolve a command name.  If you change this routine, you may have to
423 * change the shellexec routine as well.
424 */
425
426void
427find_command(char *name, struct cmdentry *entry, int act, const char *path)
428{
429	struct tblentry *cmdp, loc_cmd;
430	int idx;
431	int prev;
432	char *fullname;
433	struct stat statb;
434	int e;
435	int (*bltin)(int,char **);
436
437	/* If name contains a slash, don't use PATH or hash table */
438	if (strchr(name, '/') != NULL) {
439		if (act & DO_ABS) {
440			while (stat(name, &statb) < 0) {
441#ifdef SYSV
442				if (errno == EINTR)
443					continue;
444#endif
445				if (errno != ENOENT && errno != ENOTDIR)
446					e = errno;
447				entry->cmdtype = CMDUNKNOWN;
448				entry->u.index = -1;
449				return;
450			}
451			entry->cmdtype = CMDNORMAL;
452			entry->u.index = -1;
453			return;
454		}
455		entry->cmdtype = CMDNORMAL;
456		entry->u.index = 0;
457		return;
458	}
459
460	if (path != pathval())
461		act |= DO_ALTPATH;
462
463	if (act & DO_ALTPATH && strstr(path, "%builtin") != NULL)
464		act |= DO_ALTBLTIN;
465
466	/* If name is in the table, check answer will be ok */
467	if ((cmdp = cmdlookup(name, 0)) != NULL) {
468		do {
469			switch (cmdp->cmdtype) {
470			case CMDNORMAL:
471				if (act & DO_ALTPATH) {
472					cmdp = NULL;
473					continue;
474				}
475				break;
476			case CMDFUNCTION:
477				if (act & DO_NOFUNC) {
478					cmdp = NULL;
479					continue;
480				}
481				break;
482			case CMDBUILTIN:
483				if ((act & DO_ALTBLTIN) || builtinloc >= 0) {
484					cmdp = NULL;
485					continue;
486				}
487				break;
488			}
489			/* if not invalidated by cd, we're done */
490			if (cmdp->rehash == 0)
491				goto success;
492		} while (0);
493	}
494
495	/* If %builtin not in path, check for builtin next */
496	if ((act & DO_ALTPATH ? !(act & DO_ALTBLTIN) : builtinloc < 0) &&
497	    (bltin = find_builtin(name)) != 0)
498		goto builtin_success;
499
500	/* We have to search path. */
501	prev = -1;		/* where to start */
502	if (cmdp) {		/* doing a rehash */
503		if (cmdp->cmdtype == CMDBUILTIN)
504			prev = builtinloc;
505		else
506			prev = cmdp->param.index;
507	}
508
509	e = ENOENT;
510	idx = -1;
511loop:
512	while ((fullname = padvance(&path, name)) != NULL) {
513		stunalloc(fullname);
514		idx++;
515		if (pathopt) {
516			if (prefix("builtin", pathopt)) {
517				if ((bltin = find_builtin(name)) == 0)
518					goto loop;
519				goto builtin_success;
520			} else if (prefix("func", pathopt)) {
521				/* handled below */
522			} else {
523				/* ignore unimplemented options */
524				goto loop;
525			}
526		}
527		/* if rehash, don't redo absolute path names */
528		if (fullname[0] == '/' && idx <= prev) {
529			if (idx < prev)
530				goto loop;
531			TRACE(("searchexec \"%s\": no change\n", name));
532			goto success;
533		}
534		while (stat(fullname, &statb) < 0) {
535#ifdef SYSV
536			if (errno == EINTR)
537				continue;
538#endif
539			if (errno != ENOENT && errno != ENOTDIR)
540				e = errno;
541			goto loop;
542		}
543		e = EACCES;	/* if we fail, this will be the error */
544		if (!S_ISREG(statb.st_mode))
545			goto loop;
546		if (pathopt) {		/* this is a %func directory */
547			if (act & DO_NOFUNC)
548				goto loop;
549			stalloc(strlen(fullname) + 1);
550			readcmdfile(fullname);
551			if ((cmdp = cmdlookup(name, 0)) == NULL ||
552			    cmdp->cmdtype != CMDFUNCTION)
553				error("%s not defined in %s", name, fullname);
554			stunalloc(fullname);
555			goto success;
556		}
557#ifdef notdef
558		/* XXX this code stops root executing stuff, and is buggy
559		   if you need a group from the group list. */
560		if (statb.st_uid == geteuid()) {
561			if ((statb.st_mode & 0100) == 0)
562				goto loop;
563		} else if (statb.st_gid == getegid()) {
564			if ((statb.st_mode & 010) == 0)
565				goto loop;
566		} else {
567			if ((statb.st_mode & 01) == 0)
568				goto loop;
569		}
570#endif
571		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
572		INTOFF;
573		if (act & DO_ALTPATH) {
574			stalloc(strlen(fullname) + 1);
575			cmdp = &loc_cmd;
576		} else
577			cmdp = cmdlookup(name, 1);
578		cmdp->cmdtype = CMDNORMAL;
579		cmdp->param.index = idx;
580		INTON;
581		goto success;
582	}
583
584	/* We failed.  If there was an entry for this command, delete it */
585	if (cmdp)
586		delete_cmd_entry();
587	if (act & DO_ERR)
588		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
589	entry->cmdtype = CMDUNKNOWN;
590	return;
591
592builtin_success:
593	INTOFF;
594	if (act & DO_ALTPATH)
595		cmdp = &loc_cmd;
596	else
597		cmdp = cmdlookup(name, 1);
598	if (cmdp->cmdtype == CMDFUNCTION)
599		/* DO_NOFUNC must have been set */
600		cmdp = &loc_cmd;
601	cmdp->cmdtype = CMDBUILTIN;
602	cmdp->param.bltin = bltin;
603	INTON;
604success:
605	cmdp->rehash = 0;
606	entry->cmdtype = cmdp->cmdtype;
607	entry->u = cmdp->param;
608}
609
610
611
612/*
613 * Search the table of builtin commands.
614 */
615
616int
617(*find_builtin(name))(int, char **)
618	char *name;
619{
620	const struct builtincmd *bp;
621
622	for (bp = builtincmd ; bp->name ; bp++) {
623		if (*bp->name == *name && equal(bp->name, name))
624			return bp->builtin;
625	}
626	return 0;
627}
628
629int
630(*find_splbltin(name))(int, char **)
631	char *name;
632{
633	const struct builtincmd *bp;
634
635	for (bp = splbltincmd ; bp->name ; bp++) {
636		if (*bp->name == *name && equal(bp->name, name))
637			return bp->builtin;
638	}
639	return 0;
640}
641
642/*
643 * At shell startup put special builtins into hash table.
644 * ensures they are executed first (see posix).
645 * We stop functions being added with the same name
646 * (as they are impossible to call)
647 */
648
649void
650hash_special_builtins(void)
651{
652	const struct builtincmd *bp;
653	struct tblentry *cmdp;
654
655	for (bp = splbltincmd ; bp->name ; bp++) {
656		cmdp = cmdlookup(bp->name, 1);
657		cmdp->cmdtype = CMDSPLBLTIN;
658		cmdp->param.bltin = bp->builtin;
659	}
660}
661
662
663
664/*
665 * Called when a cd is done.  Marks all commands so the next time they
666 * are executed they will be rehashed.
667 */
668
669void
670hashcd(void)
671{
672	struct tblentry **pp;
673	struct tblentry *cmdp;
674
675	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
676		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
677			if (cmdp->cmdtype == CMDNORMAL
678			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
679				cmdp->rehash = 1;
680		}
681	}
682}
683
684
685
686/*
687 * Fix command hash table when PATH changed.
688 * Called before PATH is changed.  The argument is the new value of PATH;
689 * pathval() still returns the old value at this point.
690 * Called with interrupts off.
691 */
692
693void
694changepath(const char *newval)
695{
696	const char *old, *new;
697	int idx;
698	int firstchange;
699	int bltin;
700
701	old = pathval();
702	new = newval;
703	firstchange = 9999;	/* assume no change */
704	idx = 0;
705	bltin = -1;
706	for (;;) {
707		if (*old != *new) {
708			firstchange = idx;
709			if ((*old == '\0' && *new == ':')
710			 || (*old == ':' && *new == '\0'))
711				firstchange++;
712			old = new;	/* ignore subsequent differences */
713		}
714		if (*new == '\0')
715			break;
716		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
717			bltin = idx;
718		if (*new == ':') {
719			idx++;
720		}
721		new++, old++;
722	}
723	if (builtinloc < 0 && bltin >= 0)
724		builtinloc = bltin;		/* zap builtins */
725	if (builtinloc >= 0 && bltin < 0)
726		firstchange = 0;
727	clearcmdentry(firstchange);
728	builtinloc = bltin;
729}
730
731
732/*
733 * Clear out command entries.  The argument specifies the first entry in
734 * PATH which has changed.
735 */
736
737STATIC void
738clearcmdentry(int firstchange)
739{
740	struct tblentry **tblp;
741	struct tblentry **pp;
742	struct tblentry *cmdp;
743
744	INTOFF;
745	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
746		pp = tblp;
747		while ((cmdp = *pp) != NULL) {
748			if ((cmdp->cmdtype == CMDNORMAL &&
749			     cmdp->param.index >= firstchange)
750			 || (cmdp->cmdtype == CMDBUILTIN &&
751			     builtinloc >= firstchange)) {
752				*pp = cmdp->next;
753				ckfree(cmdp);
754			} else {
755				pp = &cmdp->next;
756			}
757		}
758	}
759	INTON;
760}
761
762
763/*
764 * Delete all functions.
765 */
766
767#ifdef mkinit
768MKINIT void deletefuncs(void);
769MKINIT void hash_special_builtins(void);
770
771INIT {
772	hash_special_builtins();
773}
774
775SHELLPROC {
776	deletefuncs();
777}
778#endif
779
780void
781deletefuncs(void)
782{
783	struct tblentry **tblp;
784	struct tblentry **pp;
785	struct tblentry *cmdp;
786
787	INTOFF;
788	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
789		pp = tblp;
790		while ((cmdp = *pp) != NULL) {
791			if (cmdp->cmdtype == CMDFUNCTION) {
792				*pp = cmdp->next;
793				freefunc(cmdp->param.func);
794				ckfree(cmdp);
795			} else {
796				pp = &cmdp->next;
797			}
798		}
799	}
800	INTON;
801}
802
803
804
805/*
806 * Locate a command in the command hash table.  If "add" is nonzero,
807 * add the command to the table if it is not already present.  The
808 * variable "lastcmdentry" is set to point to the address of the link
809 * pointing to the entry, so that delete_cmd_entry can delete the
810 * entry.
811 */
812
813struct tblentry **lastcmdentry;
814
815
816STATIC struct tblentry *
817cmdlookup(const char *name, int add)
818{
819	int hashval;
820	const char *p;
821	struct tblentry *cmdp;
822	struct tblentry **pp;
823
824	p = name;
825	hashval = *p << 4;
826	while (*p)
827		hashval += *p++;
828	hashval &= 0x7FFF;
829	pp = &cmdtable[hashval % CMDTABLESIZE];
830	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
831		if (equal(cmdp->cmdname, name))
832			break;
833		pp = &cmdp->next;
834	}
835	if (add && cmdp == NULL) {
836		INTOFF;
837		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
838					+ strlen(name) + 1);
839		cmdp->next = NULL;
840		cmdp->cmdtype = CMDUNKNOWN;
841		cmdp->rehash = 0;
842		strcpy(cmdp->cmdname, name);
843		INTON;
844	}
845	lastcmdentry = pp;
846	return cmdp;
847}
848
849/*
850 * Delete the command entry returned on the last lookup.
851 */
852
853STATIC void
854delete_cmd_entry(void)
855{
856	struct tblentry *cmdp;
857
858	INTOFF;
859	cmdp = *lastcmdentry;
860	*lastcmdentry = cmdp->next;
861	ckfree(cmdp);
862	INTON;
863}
864
865
866
867#ifdef notdef
868void
869getcmdentry(char *name, struct cmdentry *entry)
870{
871	struct tblentry *cmdp = cmdlookup(name, 0);
872
873	if (cmdp) {
874		entry->u = cmdp->param;
875		entry->cmdtype = cmdp->cmdtype;
876	} else {
877		entry->cmdtype = CMDUNKNOWN;
878		entry->u.index = 0;
879	}
880}
881#endif
882
883
884/*
885 * Add a new command entry, replacing any existing command entry for
886 * the same name - except special builtins.
887 */
888
889STATIC void
890addcmdentry(char *name, struct cmdentry *entry)
891{
892	struct tblentry *cmdp;
893
894	INTOFF;
895	cmdp = cmdlookup(name, 1);
896	if (cmdp->cmdtype != CMDSPLBLTIN) {
897		if (cmdp->cmdtype == CMDFUNCTION) {
898			freefunc(cmdp->param.func);
899		}
900		cmdp->cmdtype = entry->cmdtype;
901		cmdp->param = entry->u;
902	}
903	INTON;
904}
905
906
907/*
908 * Define a shell function.
909 */
910
911void
912defun(char *name, union node *func)
913{
914	struct cmdentry entry;
915
916	INTOFF;
917	entry.cmdtype = CMDFUNCTION;
918	entry.u.func = copyfunc(func);
919	addcmdentry(name, &entry);
920	INTON;
921}
922
923
924/*
925 * Delete a function if it exists.
926 */
927
928int
929unsetfunc(char *name)
930{
931	struct tblentry *cmdp;
932
933	if ((cmdp = cmdlookup(name, 0)) != NULL &&
934	    cmdp->cmdtype == CMDFUNCTION) {
935		freefunc(cmdp->param.func);
936		delete_cmd_entry();
937		return (0);
938	}
939	return (1);
940}
941
942/*
943 * Locate and print what a word is...
944 * also used for 'command -[v|V]'
945 */
946
947int
948typecmd(int argc, char **argv)
949{
950	struct cmdentry entry;
951	struct tblentry *cmdp;
952	char * const *pp;
953	struct alias *ap;
954	int err = 0;
955	char *arg;
956	int c;
957	int V_flag = 0;
958	int v_flag = 0;
959	int p_flag = 0;
960
961	while ((c = nextopt("vVp")) != 0) {
962		switch (c) {
963		case 'v': v_flag = 1; break;
964		case 'V': V_flag = 1; break;
965		case 'p': p_flag = 1; break;
966		}
967	}
968
969	if (p_flag && (v_flag || V_flag))
970		error("cannot specify -p with -v or -V");
971
972	while ((arg = *argptr++)) {
973		if (!v_flag)
974			out1str(arg);
975		/* First look at the keywords */
976		for (pp = parsekwd; *pp; pp++)
977			if (**pp == *arg && equal(*pp, arg))
978				break;
979
980		if (*pp) {
981			if (v_flag)
982				err = 1;
983			else
984				out1str(" is a shell keyword\n");
985			continue;
986		}
987
988		/* Then look at the aliases */
989		if ((ap = lookupalias(arg, 1)) != NULL) {
990			if (!v_flag)
991				out1fmt(" is an alias for \n");
992			out1fmt("%s\n", ap->val);
993			continue;
994		}
995
996		/* Then check if it is a tracked alias */
997		if ((cmdp = cmdlookup(arg, 0)) != NULL) {
998			entry.cmdtype = cmdp->cmdtype;
999			entry.u = cmdp->param;
1000		} else {
1001			/* Finally use brute force */
1002			find_command(arg, &entry, DO_ABS, pathval());
1003		}
1004
1005		switch (entry.cmdtype) {
1006		case CMDNORMAL: {
1007			if (strchr(arg, '/') == NULL) {
1008				const char *path = pathval();
1009				char *name;
1010				int j = entry.u.index;
1011				do {
1012					name = padvance(&path, arg);
1013					stunalloc(name);
1014				} while (--j >= 0);
1015				if (!v_flag)
1016					out1fmt(" is%s ",
1017					    cmdp ? " a tracked alias for" : "");
1018				out1fmt("%s\n", name);
1019			} else {
1020				if (access(arg, X_OK) == 0) {
1021					if (!v_flag)
1022						out1fmt(" is ");
1023					out1fmt("%s\n", arg);
1024				} else {
1025					if (!v_flag)
1026						out1fmt(": %s\n",
1027						    strerror(errno));
1028					else
1029						err = 126;
1030				}
1031			}
1032 			break;
1033		}
1034		case CMDFUNCTION:
1035			if (!v_flag)
1036				out1str(" is a shell function\n");
1037			else
1038				out1fmt("%s\n", arg);
1039			break;
1040
1041		case CMDBUILTIN:
1042			if (!v_flag)
1043				out1str(" is a shell builtin\n");
1044			else
1045				out1fmt("%s\n", arg);
1046			break;
1047
1048		case CMDSPLBLTIN:
1049			if (!v_flag)
1050				out1str(" is a special shell builtin\n");
1051			else
1052				out1fmt("%s\n", arg);
1053			break;
1054
1055		default:
1056			if (!v_flag)
1057				out1str(": not found\n");
1058			err = 127;
1059			break;
1060		}
1061	}
1062	return err;
1063}
1064