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exec.c revision 1.33
      1 /*	$NetBSD: exec.c,v 1.33 2002/09/27 18:56:50 christos 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #ifndef lint
     41 #if 0
     42 static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
     43 #else
     44 __RCSID("$NetBSD: exec.c,v 1.33 2002/09/27 18:56:50 christos Exp $");
     45 #endif
     46 #endif /* not lint */
     47 
     48 #include <sys/types.h>
     49 #include <sys/stat.h>
     50 #include <sys/wait.h>
     51 #include <unistd.h>
     52 #include <fcntl.h>
     53 #include <errno.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 
     57 /*
     58  * When commands are first encountered, they are entered in a hash table.
     59  * This ensures that a full path search will not have to be done for them
     60  * on each invocation.
     61  *
     62  * We should investigate converting to a linear search, even though that
     63  * would make the command name "hash" a misnomer.
     64  */
     65 
     66 #include "shell.h"
     67 #include "main.h"
     68 #include "nodes.h"
     69 #include "parser.h"
     70 #include "redir.h"
     71 #include "eval.h"
     72 #include "exec.h"
     73 #include "builtins.h"
     74 #include "var.h"
     75 #include "options.h"
     76 #include "input.h"
     77 #include "output.h"
     78 #include "syntax.h"
     79 #include "memalloc.h"
     80 #include "error.h"
     81 #include "init.h"
     82 #include "mystring.h"
     83 #include "show.h"
     84 #include "jobs.h"
     85 #include "alias.h"
     86 
     87 
     88 #define CMDTABLESIZE 31		/* should be prime */
     89 #define ARB 1			/* actual size determined at run time */
     90 
     91 
     92 
     93 struct tblentry {
     94 	struct tblentry *next;	/* next entry in hash chain */
     95 	union param param;	/* definition of builtin function */
     96 	short cmdtype;		/* index identifying command */
     97 	char rehash;		/* if set, cd done since entry created */
     98 	char cmdname[ARB];	/* name of command */
     99 };
    100 
    101 
    102 STATIC struct tblentry *cmdtable[CMDTABLESIZE];
    103 STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
    104 int exerrno = 0;			/* Last exec error */
    105 
    106 
    107 STATIC void tryexec __P((char *, char **, char **, int));
    108 STATIC void execinterp __P((char **, char **));
    109 STATIC void printentry __P((struct tblentry *, int));
    110 STATIC void clearcmdentry __P((int));
    111 STATIC struct tblentry *cmdlookup __P((char *, int));
    112 STATIC void delete_cmd_entry __P((void));
    113 
    114 
    115 extern char *const parsekwd[];
    116 
    117 /*
    118  * Exec a program.  Never returns.  If you change this routine, you may
    119  * have to change the find_command routine as well.
    120  */
    121 
    122 void
    123 shellexec(argv, envp, path, idx, vforked)
    124 	char **argv, **envp;
    125 	const char *path;
    126 	int idx;
    127 	int vforked;
    128 {
    129 	char *cmdname;
    130 	int e;
    131 
    132 	if (strchr(argv[0], '/') != NULL) {
    133 		tryexec(argv[0], argv, envp, vforked);
    134 		e = errno;
    135 	} else {
    136 		e = ENOENT;
    137 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
    138 			if (--idx < 0 && pathopt == NULL) {
    139 				tryexec(cmdname, argv, envp, vforked);
    140 				if (errno != ENOENT && errno != ENOTDIR)
    141 					e = errno;
    142 			}
    143 			stunalloc(cmdname);
    144 		}
    145 	}
    146 
    147 	/* Map to POSIX errors */
    148 	switch (e) {
    149 	case EACCES:
    150 		exerrno = 126;
    151 		break;
    152 	case ENOENT:
    153 		exerrno = 127;
    154 		break;
    155 	default:
    156 		exerrno = 2;
    157 		break;
    158 	}
    159 	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
    160 	/* NOTREACHED */
    161 }
    162 
    163 
    164 STATIC void
    165 tryexec(cmd, argv, envp, vforked)
    166 	char *cmd;
    167 	char **argv;
    168 	char **envp;
    169 	int vforked;
    170 	{
    171 	int e;
    172 #ifndef BSD
    173 	char *p;
    174 #endif
    175 
    176 #ifdef SYSV
    177 	do {
    178 		execve(cmd, argv, envp);
    179 	} while (errno == EINTR);
    180 #else
    181 	execve(cmd, argv, envp);
    182 #endif
    183 	e = errno;
    184 	if (e == ENOEXEC) {
    185 		if (vforked) {
    186 			/* We are currently vfork(2)ed, so raise an
    187 			 * exception, and evalcommand will try again
    188 			 * with a normal fork(2).
    189 			 */
    190 			exraise(EXSHELLPROC);
    191 		}
    192 		initshellproc();
    193 		setinputfile(cmd, 0);
    194 		commandname = arg0 = savestr(argv[0]);
    195 #ifndef BSD
    196 		pgetc(); pungetc();		/* fill up input buffer */
    197 		p = parsenextc;
    198 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
    199 			argv[0] = cmd;
    200 			execinterp(argv, envp);
    201 		}
    202 #endif
    203 		setparam(argv + 1);
    204 		exraise(EXSHELLPROC);
    205 	}
    206 	errno = e;
    207 }
    208 
    209 
    210 #ifndef BSD
    211 /*
    212  * Execute an interpreter introduced by "#!", for systems where this
    213  * feature has not been built into the kernel.  If the interpreter is
    214  * the shell, return (effectively ignoring the "#!").  If the execution
    215  * of the interpreter fails, exit.
    216  *
    217  * This code peeks inside the input buffer in order to avoid actually
    218  * reading any input.  It would benefit from a rewrite.
    219  */
    220 
    221 #define NEWARGS 5
    222 
    223 STATIC void
    224 execinterp(argv, envp)
    225 	char **argv, **envp;
    226 	{
    227 	int n;
    228 	char *inp;
    229 	char *outp;
    230 	char c;
    231 	char *p;
    232 	char **ap;
    233 	char *newargs[NEWARGS];
    234 	int i;
    235 	char **ap2;
    236 	char **new;
    237 
    238 	n = parsenleft - 2;
    239 	inp = parsenextc + 2;
    240 	ap = newargs;
    241 	for (;;) {
    242 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
    243 			inp++;
    244 		if (n < 0)
    245 			goto bad;
    246 		if ((c = *inp++) == '\n')
    247 			break;
    248 		if (ap == &newargs[NEWARGS])
    249 bad:		  error("Bad #! line");
    250 		STARTSTACKSTR(outp);
    251 		do {
    252 			STPUTC(c, outp);
    253 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
    254 		STPUTC('\0', outp);
    255 		n++, inp--;
    256 		*ap++ = grabstackstr(outp);
    257 	}
    258 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
    259 		p = newargs[0];
    260 		for (;;) {
    261 			if (equal(p, "sh") || equal(p, "ash")) {
    262 				return;
    263 			}
    264 			while (*p != '/') {
    265 				if (*p == '\0')
    266 					goto break2;
    267 				p++;
    268 			}
    269 			p++;
    270 		}
    271 break2:;
    272 	}
    273 	i = (char *)ap - (char *)newargs;		/* size in bytes */
    274 	if (i == 0)
    275 		error("Bad #! line");
    276 	for (ap2 = argv ; *ap2++ != NULL ; );
    277 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
    278 	ap = newargs, ap2 = new;
    279 	while ((i -= sizeof (char **)) >= 0)
    280 		*ap2++ = *ap++;
    281 	ap = argv;
    282 	while (*ap2++ = *ap++);
    283 	shellexec(new, envp, pathval(), 0);
    284 	/* NOTREACHED */
    285 }
    286 #endif
    287 
    288 
    289 
    290 /*
    291  * Do a path search.  The variable path (passed by reference) should be
    292  * set to the start of the path before the first call; padvance will update
    293  * this value as it proceeds.  Successive calls to padvance will return
    294  * the possible path expansions in sequence.  If an option (indicated by
    295  * a percent sign) appears in the path entry then the global variable
    296  * pathopt will be set to point to it; otherwise pathopt will be set to
    297  * NULL.
    298  */
    299 
    300 const char *pathopt;
    301 
    302 char *
    303 padvance(path, name)
    304 	const char **path;
    305 	const char *name;
    306 	{
    307 	const char *p;
    308 	char *q;
    309 	const char *start;
    310 	int len;
    311 
    312 	if (*path == NULL)
    313 		return NULL;
    314 	start = *path;
    315 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
    316 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
    317 	while (stackblocksize() < len)
    318 		growstackblock();
    319 	q = stackblock();
    320 	if (p != start) {
    321 		memcpy(q, start, p - start);
    322 		q += p - start;
    323 		*q++ = '/';
    324 	}
    325 	strcpy(q, name);
    326 	pathopt = NULL;
    327 	if (*p == '%') {
    328 		pathopt = ++p;
    329 		while (*p && *p != ':')  p++;
    330 	}
    331 	if (*p == ':')
    332 		*path = p + 1;
    333 	else
    334 		*path = NULL;
    335 	return stalloc(len);
    336 }
    337 
    338 
    339 
    340 /*** Command hashing code ***/
    341 
    342 
    343 int
    344 hashcmd(argc, argv)
    345 	int argc;
    346 	char **argv;
    347 {
    348 	struct tblentry **pp;
    349 	struct tblentry *cmdp;
    350 	int c;
    351 	int verbose;
    352 	struct cmdentry entry;
    353 	char *name;
    354 
    355 	verbose = 0;
    356 	while ((c = nextopt("rv")) != '\0') {
    357 		if (c == 'r') {
    358 			clearcmdentry(0);
    359 		} else if (c == 'v') {
    360 			verbose++;
    361 		}
    362 	}
    363 	if (*argptr == NULL) {
    364 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    365 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    366 				printentry(cmdp, verbose);
    367 			}
    368 		}
    369 		return 0;
    370 	}
    371 	while ((name = *argptr) != NULL) {
    372 		if ((cmdp = cmdlookup(name, 0)) != NULL
    373 		 && (cmdp->cmdtype == CMDNORMAL
    374 		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
    375 			delete_cmd_entry();
    376 		find_command(name, &entry, DO_ERR, pathval());
    377 		if (verbose) {
    378 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
    379 				cmdp = cmdlookup(name, 0);
    380 				printentry(cmdp, verbose);
    381 			}
    382 			flushall();
    383 		}
    384 		argptr++;
    385 	}
    386 	return 0;
    387 }
    388 
    389 
    390 STATIC void
    391 printentry(cmdp, verbose)
    392 	struct tblentry *cmdp;
    393 	int verbose;
    394 	{
    395 	int idx;
    396 	const char *path;
    397 	char *name;
    398 
    399 	if (cmdp->cmdtype == CMDNORMAL) {
    400 		idx = cmdp->param.index;
    401 		path = pathval();
    402 		do {
    403 			name = padvance(&path, cmdp->cmdname);
    404 			stunalloc(name);
    405 		} while (--idx >= 0);
    406 		out1str(name);
    407 	} else if (cmdp->cmdtype == CMDBUILTIN) {
    408 		out1fmt("builtin %s", cmdp->cmdname);
    409 	} else if (cmdp->cmdtype == CMDFUNCTION) {
    410 		out1fmt("function %s", cmdp->cmdname);
    411 		if (verbose) {
    412 			INTOFF;
    413 			name = commandtext(cmdp->param.func);
    414 			out1c(' ');
    415 			out1str(name);
    416 			ckfree(name);
    417 			INTON;
    418 		}
    419 #ifdef DEBUG
    420 	} else {
    421 		error("internal error: cmdtype %d", cmdp->cmdtype);
    422 #endif
    423 	}
    424 	if (cmdp->rehash)
    425 		out1c('*');
    426 	out1c('\n');
    427 }
    428 
    429 
    430 
    431 /*
    432  * Resolve a command name.  If you change this routine, you may have to
    433  * change the shellexec routine as well.
    434  */
    435 
    436 void
    437 find_command(name, entry, act, path)
    438 	char *name;
    439 	struct cmdentry *entry;
    440 	int act;
    441 	const char *path;
    442 {
    443 	struct tblentry *cmdp;
    444 	int idx;
    445 	int prev;
    446 	char *fullname;
    447 	struct stat statb;
    448 	int e;
    449 	int i;
    450 
    451 	/* If name contains a slash, don't use the hash table */
    452 	if (strchr(name, '/') != NULL) {
    453 		if (act & DO_ABS) {
    454 			while (stat(name, &statb) < 0) {
    455 	#ifdef SYSV
    456 				if (errno == EINTR)
    457 					continue;
    458 	#endif
    459 				if (errno != ENOENT && errno != ENOTDIR)
    460 					e = errno;
    461 				entry->cmdtype = CMDUNKNOWN;
    462 				entry->u.index = -1;
    463 				return;
    464 			}
    465 			entry->cmdtype = CMDNORMAL;
    466 			entry->u.index = -1;
    467 			return;
    468 		}
    469 		entry->cmdtype = CMDNORMAL;
    470 		entry->u.index = 0;
    471 		return;
    472 	}
    473 
    474 	/* If name is in the table, and not invalidated by cd, we're done */
    475 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
    476 		goto success;
    477 
    478 	/* If %builtin not in path, check for builtin next */
    479 	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
    480 		INTOFF;
    481 		cmdp = cmdlookup(name, 1);
    482 		cmdp->cmdtype = CMDBUILTIN;
    483 		cmdp->param.index = i;
    484 		INTON;
    485 		goto success;
    486 	}
    487 
    488 	/* We have to search path. */
    489 	prev = -1;		/* where to start */
    490 	if (cmdp) {		/* doing a rehash */
    491 		if (cmdp->cmdtype == CMDBUILTIN)
    492 			prev = builtinloc;
    493 		else
    494 			prev = cmdp->param.index;
    495 	}
    496 
    497 	e = ENOENT;
    498 	idx = -1;
    499 loop:
    500 	while ((fullname = padvance(&path, name)) != NULL) {
    501 		stunalloc(fullname);
    502 		idx++;
    503 		if (pathopt) {
    504 			if (prefix("builtin", pathopt)) {
    505 				if ((i = find_builtin(name)) < 0)
    506 					goto loop;
    507 				INTOFF;
    508 				cmdp = cmdlookup(name, 1);
    509 				cmdp->cmdtype = CMDBUILTIN;
    510 				cmdp->param.index = i;
    511 				INTON;
    512 				goto success;
    513 			} else if (prefix("func", pathopt)) {
    514 				/* handled below */
    515 			} else {
    516 				goto loop;	/* ignore unimplemented options */
    517 			}
    518 		}
    519 		/* if rehash, don't redo absolute path names */
    520 		if (fullname[0] == '/' && idx <= prev) {
    521 			if (idx < prev)
    522 				goto loop;
    523 			TRACE(("searchexec \"%s\": no change\n", name));
    524 			goto success;
    525 		}
    526 		while (stat(fullname, &statb) < 0) {
    527 #ifdef SYSV
    528 			if (errno == EINTR)
    529 				continue;
    530 #endif
    531 			if (errno != ENOENT && errno != ENOTDIR)
    532 				e = errno;
    533 			goto loop;
    534 		}
    535 		e = EACCES;	/* if we fail, this will be the error */
    536 		if (!S_ISREG(statb.st_mode))
    537 			goto loop;
    538 		if (pathopt) {		/* this is a %func directory */
    539 			stalloc(strlen(fullname) + 1);
    540 			readcmdfile(fullname);
    541 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
    542 				error("%s not defined in %s", name, fullname);
    543 			stunalloc(fullname);
    544 			goto success;
    545 		}
    546 #ifdef notdef
    547 		if (statb.st_uid == geteuid()) {
    548 			if ((statb.st_mode & 0100) == 0)
    549 				goto loop;
    550 		} else if (statb.st_gid == getegid()) {
    551 			if ((statb.st_mode & 010) == 0)
    552 				goto loop;
    553 		} else {
    554 			if ((statb.st_mode & 01) == 0)
    555 				goto loop;
    556 		}
    557 #endif
    558 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
    559 		INTOFF;
    560 		cmdp = cmdlookup(name, 1);
    561 		cmdp->cmdtype = CMDNORMAL;
    562 		cmdp->param.index = idx;
    563 		INTON;
    564 		goto success;
    565 	}
    566 
    567 	/* We failed.  If there was an entry for this command, delete it */
    568 	if (cmdp)
    569 		delete_cmd_entry();
    570 	if (act & DO_ERR)
    571 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
    572 	entry->cmdtype = CMDUNKNOWN;
    573 	return;
    574 
    575 success:
    576 	cmdp->rehash = 0;
    577 	entry->cmdtype = cmdp->cmdtype;
    578 	entry->u = cmdp->param;
    579 }
    580 
    581 
    582 
    583 /*
    584  * Search the table of builtin commands.
    585  */
    586 
    587 int
    588 find_builtin(name)
    589 	char *name;
    590 {
    591 	const struct builtincmd *bp;
    592 
    593 	for (bp = builtincmd ; bp->name ; bp++) {
    594 		if (*bp->name == *name && equal(bp->name, name))
    595 			return bp->code;
    596 	}
    597 	return -1;
    598 }
    599 
    600 
    601 
    602 /*
    603  * Called when a cd is done.  Marks all commands so the next time they
    604  * are executed they will be rehashed.
    605  */
    606 
    607 void
    608 hashcd() {
    609 	struct tblentry **pp;
    610 	struct tblentry *cmdp;
    611 
    612 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    613 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    614 			if (cmdp->cmdtype == CMDNORMAL
    615 			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
    616 				cmdp->rehash = 1;
    617 		}
    618 	}
    619 }
    620 
    621 
    622 
    623 /*
    624  * Called before PATH is changed.  The argument is the new value of PATH;
    625  * pathval() still returns the old value at this point.  Called with
    626  * interrupts off.
    627  */
    628 
    629 void
    630 changepath(newval)
    631 	const char *newval;
    632 {
    633 	const char *old, *new;
    634 	int idx;
    635 	int firstchange;
    636 	int bltin;
    637 
    638 	old = pathval();
    639 	new = newval;
    640 	firstchange = 9999;	/* assume no change */
    641 	idx = 0;
    642 	bltin = -1;
    643 	for (;;) {
    644 		if (*old != *new) {
    645 			firstchange = idx;
    646 			if ((*old == '\0' && *new == ':')
    647 			 || (*old == ':' && *new == '\0'))
    648 				firstchange++;
    649 			old = new;	/* ignore subsequent differences */
    650 		}
    651 		if (*new == '\0')
    652 			break;
    653 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
    654 			bltin = idx;
    655 		if (*new == ':') {
    656 			idx++;
    657 		}
    658 		new++, old++;
    659 	}
    660 	if (builtinloc < 0 && bltin >= 0)
    661 		builtinloc = bltin;		/* zap builtins */
    662 	if (builtinloc >= 0 && bltin < 0)
    663 		firstchange = 0;
    664 	clearcmdentry(firstchange);
    665 	builtinloc = bltin;
    666 }
    667 
    668 
    669 /*
    670  * Clear out command entries.  The argument specifies the first entry in
    671  * PATH which has changed.
    672  */
    673 
    674 STATIC void
    675 clearcmdentry(firstchange)
    676 	int firstchange;
    677 {
    678 	struct tblentry **tblp;
    679 	struct tblentry **pp;
    680 	struct tblentry *cmdp;
    681 
    682 	INTOFF;
    683 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
    684 		pp = tblp;
    685 		while ((cmdp = *pp) != NULL) {
    686 			if ((cmdp->cmdtype == CMDNORMAL &&
    687 			     cmdp->param.index >= firstchange)
    688 			 || (cmdp->cmdtype == CMDBUILTIN &&
    689 			     builtinloc >= firstchange)) {
    690 				*pp = cmdp->next;
    691 				ckfree(cmdp);
    692 			} else {
    693 				pp = &cmdp->next;
    694 			}
    695 		}
    696 	}
    697 	INTON;
    698 }
    699 
    700 
    701 /*
    702  * Delete all functions.
    703  */
    704 
    705 #ifdef mkinit
    706 MKINIT void deletefuncs __P((void));
    707 
    708 SHELLPROC {
    709 	deletefuncs();
    710 }
    711 #endif
    712 
    713 void
    714 deletefuncs() {
    715 	struct tblentry **tblp;
    716 	struct tblentry **pp;
    717 	struct tblentry *cmdp;
    718 
    719 	INTOFF;
    720 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
    721 		pp = tblp;
    722 		while ((cmdp = *pp) != NULL) {
    723 			if (cmdp->cmdtype == CMDFUNCTION) {
    724 				*pp = cmdp->next;
    725 				freefunc(cmdp->param.func);
    726 				ckfree(cmdp);
    727 			} else {
    728 				pp = &cmdp->next;
    729 			}
    730 		}
    731 	}
    732 	INTON;
    733 }
    734 
    735 
    736 
    737 /*
    738  * Locate a command in the command hash table.  If "add" is nonzero,
    739  * add the command to the table if it is not already present.  The
    740  * variable "lastcmdentry" is set to point to the address of the link
    741  * pointing to the entry, so that delete_cmd_entry can delete the
    742  * entry.
    743  */
    744 
    745 struct tblentry **lastcmdentry;
    746 
    747 
    748 STATIC struct tblentry *
    749 cmdlookup(name, add)
    750 	char *name;
    751 	int add;
    752 {
    753 	int hashval;
    754 	char *p;
    755 	struct tblentry *cmdp;
    756 	struct tblentry **pp;
    757 
    758 	p = name;
    759 	hashval = *p << 4;
    760 	while (*p)
    761 		hashval += *p++;
    762 	hashval &= 0x7FFF;
    763 	pp = &cmdtable[hashval % CMDTABLESIZE];
    764 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    765 		if (equal(cmdp->cmdname, name))
    766 			break;
    767 		pp = &cmdp->next;
    768 	}
    769 	if (add && cmdp == NULL) {
    770 		INTOFF;
    771 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
    772 					+ strlen(name) + 1);
    773 		cmdp->next = NULL;
    774 		cmdp->cmdtype = CMDUNKNOWN;
    775 		cmdp->rehash = 0;
    776 		strcpy(cmdp->cmdname, name);
    777 		INTON;
    778 	}
    779 	lastcmdentry = pp;
    780 	return cmdp;
    781 }
    782 
    783 /*
    784  * Delete the command entry returned on the last lookup.
    785  */
    786 
    787 STATIC void
    788 delete_cmd_entry() {
    789 	struct tblentry *cmdp;
    790 
    791 	INTOFF;
    792 	cmdp = *lastcmdentry;
    793 	*lastcmdentry = cmdp->next;
    794 	ckfree(cmdp);
    795 	INTON;
    796 }
    797 
    798 
    799 
    800 #ifdef notdef
    801 void
    802 getcmdentry(name, entry)
    803 	char *name;
    804 	struct cmdentry *entry;
    805 	{
    806 	struct tblentry *cmdp = cmdlookup(name, 0);
    807 
    808 	if (cmdp) {
    809 		entry->u = cmdp->param;
    810 		entry->cmdtype = cmdp->cmdtype;
    811 	} else {
    812 		entry->cmdtype = CMDUNKNOWN;
    813 		entry->u.index = 0;
    814 	}
    815 }
    816 #endif
    817 
    818 
    819 /*
    820  * Add a new command entry, replacing any existing command entry for
    821  * the same name.
    822  */
    823 
    824 void
    825 addcmdentry(name, entry)
    826 	char *name;
    827 	struct cmdentry *entry;
    828 	{
    829 	struct tblentry *cmdp;
    830 
    831 	INTOFF;
    832 	cmdp = cmdlookup(name, 1);
    833 	if (cmdp->cmdtype == CMDFUNCTION) {
    834 		freefunc(cmdp->param.func);
    835 	}
    836 	cmdp->cmdtype = entry->cmdtype;
    837 	cmdp->param = entry->u;
    838 	INTON;
    839 }
    840 
    841 
    842 /*
    843  * Define a shell function.
    844  */
    845 
    846 void
    847 defun(name, func)
    848 	char *name;
    849 	union node *func;
    850 	{
    851 	struct cmdentry entry;
    852 
    853 	INTOFF;
    854 	entry.cmdtype = CMDFUNCTION;
    855 	entry.u.func = copyfunc(func);
    856 	addcmdentry(name, &entry);
    857 	INTON;
    858 }
    859 
    860 
    861 /*
    862  * Delete a function if it exists.
    863  */
    864 
    865 int
    866 unsetfunc(name)
    867 	char *name;
    868 	{
    869 	struct tblentry *cmdp;
    870 
    871 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
    872 		freefunc(cmdp->param.func);
    873 		delete_cmd_entry();
    874 		return (0);
    875 	}
    876 	return (1);
    877 }
    878 
    879 /*
    880  * Locate and print what a word is...
    881  */
    882 
    883 int
    884 typecmd(argc, argv)
    885 	int argc;
    886 	char **argv;
    887 {
    888 	struct cmdentry entry;
    889 	struct tblentry *cmdp;
    890 	char * const *pp;
    891 	struct alias *ap;
    892 	int i;
    893 	int err = 0;
    894 
    895 	for (i = 1; i < argc; i++) {
    896 		out1str(argv[i]);
    897 		/* First look at the keywords */
    898 		for (pp = parsekwd; *pp; pp++)
    899 			if (**pp == *argv[i] && equal(*pp, argv[i]))
    900 				break;
    901 
    902 		if (*pp) {
    903 			out1str(" is a shell keyword\n");
    904 			continue;
    905 		}
    906 
    907 		/* Then look at the aliases */
    908 		if ((ap = lookupalias(argv[i], 1)) != NULL) {
    909 			out1fmt(" is an alias for %s\n", ap->val);
    910 			continue;
    911 		}
    912 
    913 		/* Then check if it is a tracked alias */
    914 		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
    915 			entry.cmdtype = cmdp->cmdtype;
    916 			entry.u = cmdp->param;
    917 		}
    918 		else {
    919 			/* Finally use brute force */
    920 			find_command(argv[i], &entry, DO_ABS, pathval());
    921 		}
    922 
    923 		switch (entry.cmdtype) {
    924 		case CMDNORMAL: {
    925 			if (strchr(argv[i], '/') == NULL) {
    926 				const char *path = pathval();
    927 				char *name;
    928 				int j = entry.u.index;
    929 				do {
    930 					name = padvance(&path, argv[i]);
    931 					stunalloc(name);
    932 				} while (--j >= 0);
    933 				out1fmt(" is%s %s\n",
    934 				    cmdp ? " a tracked alias for" : "", name);
    935 			} else {
    936 				if (access(argv[i], X_OK) == 0)
    937 					out1fmt(" is %s\n", argv[i]);
    938 				else
    939 					out1fmt(": %s\n", strerror(errno));
    940 			}
    941  			break;
    942 		}
    943 		case CMDFUNCTION:
    944 			out1str(" is a shell function\n");
    945 			break;
    946 
    947 		case CMDBUILTIN:
    948 			out1str(" is a shell builtin\n");
    949 			break;
    950 
    951 		default:
    952 			out1str(": not found\n");
    953 			err |= 127;
    954 			break;
    955 		}
    956 	}
    957 	return err;
    958 }
    959