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exec.c revision 1.28
      1 /*	$NetBSD: exec.c,v 1.28 2000/05/13 20:50:14 elric 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 1.28 2000/05/13 20:50:14 elric 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 
    116 /*
    117  * Exec a program.  Never returns.  If you change this routine, you may
    118  * have to change the find_command routine as well.
    119  */
    120 
    121 void
    122 shellexec(argv, envp, path, idx, vforked)
    123 	char **argv, **envp;
    124 	const char *path;
    125 	int idx;
    126 	int vforked;
    127 {
    128 	char *cmdname;
    129 	int e;
    130 
    131 	if (strchr(argv[0], '/') != NULL) {
    132 		tryexec(argv[0], argv, envp, vforked);
    133 		e = errno;
    134 	} else {
    135 		e = ENOENT;
    136 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
    137 			if (--idx < 0 && pathopt == NULL) {
    138 				tryexec(cmdname, argv, envp, vforked);
    139 				if (errno != ENOENT && errno != ENOTDIR)
    140 					e = errno;
    141 			}
    142 			stunalloc(cmdname);
    143 		}
    144 	}
    145 
    146 	/* Map to POSIX errors */
    147 	switch (e) {
    148 	case EACCES:
    149 		exerrno = 126;
    150 		break;
    151 	case ENOENT:
    152 		exerrno = 127;
    153 		break;
    154 	default:
    155 		exerrno = 2;
    156 		break;
    157 	}
    158 	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
    159 	/* NOTREACHED */
    160 }
    161 
    162 
    163 STATIC void
    164 tryexec(cmd, argv, envp, vforked)
    165 	char *cmd;
    166 	char **argv;
    167 	char **envp;
    168 	int vforked;
    169 	{
    170 	int e;
    171 #ifndef BSD
    172 	char *p;
    173 #endif
    174 
    175 #ifdef SYSV
    176 	do {
    177 		execve(cmd, argv, envp);
    178 	} while (errno == EINTR);
    179 #else
    180 	execve(cmd, argv, envp);
    181 #endif
    182 	e = errno;
    183 	if (e == ENOEXEC) {
    184 		if (vforked) {
    185 			/* We are currently vfork(2)ed, so raise an
    186 			 * exception, and evalcommand will try again
    187 			 * with a normal fork(2).
    188 			 */
    189 			exraise(EXSHELLPROC);
    190 		}
    191 		initshellproc();
    192 		setinputfile(cmd, 0);
    193 		commandname = arg0 = savestr(argv[0]);
    194 #ifndef BSD
    195 		pgetc(); pungetc();		/* fill up input buffer */
    196 		p = parsenextc;
    197 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
    198 			argv[0] = cmd;
    199 			execinterp(argv, envp);
    200 		}
    201 #endif
    202 		setparam(argv + 1);
    203 		exraise(EXSHELLPROC);
    204 	}
    205 	errno = e;
    206 }
    207 
    208 
    209 #ifndef BSD
    210 /*
    211  * Execute an interpreter introduced by "#!", for systems where this
    212  * feature has not been built into the kernel.  If the interpreter is
    213  * the shell, return (effectively ignoring the "#!").  If the execution
    214  * of the interpreter fails, exit.
    215  *
    216  * This code peeks inside the input buffer in order to avoid actually
    217  * reading any input.  It would benefit from a rewrite.
    218  */
    219 
    220 #define NEWARGS 5
    221 
    222 STATIC void
    223 execinterp(argv, envp)
    224 	char **argv, **envp;
    225 	{
    226 	int n;
    227 	char *inp;
    228 	char *outp;
    229 	char c;
    230 	char *p;
    231 	char **ap;
    232 	char *newargs[NEWARGS];
    233 	int i;
    234 	char **ap2;
    235 	char **new;
    236 
    237 	n = parsenleft - 2;
    238 	inp = parsenextc + 2;
    239 	ap = newargs;
    240 	for (;;) {
    241 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
    242 			inp++;
    243 		if (n < 0)
    244 			goto bad;
    245 		if ((c = *inp++) == '\n')
    246 			break;
    247 		if (ap == &newargs[NEWARGS])
    248 bad:		  error("Bad #! line");
    249 		STARTSTACKSTR(outp);
    250 		do {
    251 			STPUTC(c, outp);
    252 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
    253 		STPUTC('\0', outp);
    254 		n++, inp--;
    255 		*ap++ = grabstackstr(outp);
    256 	}
    257 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
    258 		p = newargs[0];
    259 		for (;;) {
    260 			if (equal(p, "sh") || equal(p, "ash")) {
    261 				return;
    262 			}
    263 			while (*p != '/') {
    264 				if (*p == '\0')
    265 					goto break2;
    266 				p++;
    267 			}
    268 			p++;
    269 		}
    270 break2:;
    271 	}
    272 	i = (char *)ap - (char *)newargs;		/* size in bytes */
    273 	if (i == 0)
    274 		error("Bad #! line");
    275 	for (ap2 = argv ; *ap2++ != NULL ; );
    276 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
    277 	ap = newargs, ap2 = new;
    278 	while ((i -= sizeof (char **)) >= 0)
    279 		*ap2++ = *ap++;
    280 	ap = argv;
    281 	while (*ap2++ = *ap++);
    282 	shellexec(new, envp, pathval(), 0);
    283 	/* NOTREACHED */
    284 }
    285 #endif
    286 
    287 
    288 
    289 /*
    290  * Do a path search.  The variable path (passed by reference) should be
    291  * set to the start of the path before the first call; padvance will update
    292  * this value as it proceeds.  Successive calls to padvance will return
    293  * the possible path expansions in sequence.  If an option (indicated by
    294  * a percent sign) appears in the path entry then the global variable
    295  * pathopt will be set to point to it; otherwise pathopt will be set to
    296  * NULL.
    297  */
    298 
    299 const char *pathopt;
    300 
    301 char *
    302 padvance(path, name)
    303 	const char **path;
    304 	const char *name;
    305 	{
    306 	const char *p;
    307 	char *q;
    308 	const char *start;
    309 	int len;
    310 
    311 	if (*path == NULL)
    312 		return NULL;
    313 	start = *path;
    314 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
    315 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
    316 	while (stackblocksize() < len)
    317 		growstackblock();
    318 	q = stackblock();
    319 	if (p != start) {
    320 		memcpy(q, start, p - start);
    321 		q += p - start;
    322 		*q++ = '/';
    323 	}
    324 	strcpy(q, name);
    325 	pathopt = NULL;
    326 	if (*p == '%') {
    327 		pathopt = ++p;
    328 		while (*p && *p != ':')  p++;
    329 	}
    330 	if (*p == ':')
    331 		*path = p + 1;
    332 	else
    333 		*path = NULL;
    334 	return stalloc(len);
    335 }
    336 
    337 
    338 
    339 /*** Command hashing code ***/
    340 
    341 
    342 int
    343 hashcmd(argc, argv)
    344 	int argc;
    345 	char **argv;
    346 {
    347 	struct tblentry **pp;
    348 	struct tblentry *cmdp;
    349 	int c;
    350 	int verbose;
    351 	struct cmdentry entry;
    352 	char *name;
    353 
    354 	verbose = 0;
    355 	while ((c = nextopt("rv")) != '\0') {
    356 		if (c == 'r') {
    357 			clearcmdentry(0);
    358 		} else if (c == 'v') {
    359 			verbose++;
    360 		}
    361 	}
    362 	if (*argptr == NULL) {
    363 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    364 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    365 				printentry(cmdp, verbose);
    366 			}
    367 		}
    368 		return 0;
    369 	}
    370 	while ((name = *argptr) != NULL) {
    371 		if ((cmdp = cmdlookup(name, 0)) != NULL
    372 		 && (cmdp->cmdtype == CMDNORMAL
    373 		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
    374 			delete_cmd_entry();
    375 		find_command(name, &entry, DO_ERR, pathval());
    376 		if (verbose) {
    377 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
    378 				cmdp = cmdlookup(name, 0);
    379 				printentry(cmdp, verbose);
    380 			}
    381 			flushall();
    382 		}
    383 		argptr++;
    384 	}
    385 	return 0;
    386 }
    387 
    388 
    389 STATIC void
    390 printentry(cmdp, verbose)
    391 	struct tblentry *cmdp;
    392 	int verbose;
    393 	{
    394 	int idx;
    395 	const char *path;
    396 	char *name;
    397 
    398 	if (cmdp->cmdtype == CMDNORMAL) {
    399 		idx = cmdp->param.index;
    400 		path = pathval();
    401 		do {
    402 			name = padvance(&path, cmdp->cmdname);
    403 			stunalloc(name);
    404 		} while (--idx >= 0);
    405 		out1str(name);
    406 	} else if (cmdp->cmdtype == CMDBUILTIN) {
    407 		out1fmt("builtin %s", cmdp->cmdname);
    408 	} else if (cmdp->cmdtype == CMDFUNCTION) {
    409 		out1fmt("function %s", cmdp->cmdname);
    410 		if (verbose) {
    411 			INTOFF;
    412 			name = commandtext(cmdp->param.func);
    413 			out1c(' ');
    414 			out1str(name);
    415 			ckfree(name);
    416 			INTON;
    417 		}
    418 #ifdef DEBUG
    419 	} else {
    420 		error("internal error: cmdtype %d", cmdp->cmdtype);
    421 #endif
    422 	}
    423 	if (cmdp->rehash)
    424 		out1c('*');
    425 	out1c('\n');
    426 }
    427 
    428 
    429 
    430 /*
    431  * Resolve a command name.  If you change this routine, you may have to
    432  * change the shellexec routine as well.
    433  */
    434 
    435 void
    436 find_command(name, entry, act, path)
    437 	char *name;
    438 	struct cmdentry *entry;
    439 	int act;
    440 	const char *path;
    441 {
    442 	struct tblentry *cmdp;
    443 	int idx;
    444 	int prev;
    445 	char *fullname;
    446 	struct stat statb;
    447 	int e;
    448 	int i;
    449 
    450 	/* If name contains a slash, don't use the hash table */
    451 	if (strchr(name, '/') != NULL) {
    452 		if (act & DO_ABS) {
    453 			while (stat(name, &statb) < 0) {
    454 	#ifdef SYSV
    455 				if (errno == EINTR)
    456 					continue;
    457 	#endif
    458 				if (errno != ENOENT && errno != ENOTDIR)
    459 					e = errno;
    460 				entry->cmdtype = CMDUNKNOWN;
    461 				entry->u.index = -1;
    462 				return;
    463 			}
    464 			entry->cmdtype = CMDNORMAL;
    465 			entry->u.index = -1;
    466 			return;
    467 		}
    468 		entry->cmdtype = CMDNORMAL;
    469 		entry->u.index = 0;
    470 		return;
    471 	}
    472 
    473 	/* If name is in the table, and not invalidated by cd, we're done */
    474 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
    475 		goto success;
    476 
    477 	/* If %builtin not in path, check for builtin next */
    478 	if (builtinloc < 0 && (i = find_builtin(name)) >= 0) {
    479 		INTOFF;
    480 		cmdp = cmdlookup(name, 1);
    481 		cmdp->cmdtype = CMDBUILTIN;
    482 		cmdp->param.index = i;
    483 		INTON;
    484 		goto success;
    485 	}
    486 
    487 	/* We have to search path. */
    488 	prev = -1;		/* where to start */
    489 	if (cmdp) {		/* doing a rehash */
    490 		if (cmdp->cmdtype == CMDBUILTIN)
    491 			prev = builtinloc;
    492 		else
    493 			prev = cmdp->param.index;
    494 	}
    495 
    496 	e = ENOENT;
    497 	idx = -1;
    498 loop:
    499 	while ((fullname = padvance(&path, name)) != NULL) {
    500 		stunalloc(fullname);
    501 		idx++;
    502 		if (pathopt) {
    503 			if (prefix("builtin", pathopt)) {
    504 				if ((i = find_builtin(name)) < 0)
    505 					goto loop;
    506 				INTOFF;
    507 				cmdp = cmdlookup(name, 1);
    508 				cmdp->cmdtype = CMDBUILTIN;
    509 				cmdp->param.index = i;
    510 				INTON;
    511 				goto success;
    512 			} else if (prefix("func", pathopt)) {
    513 				/* handled below */
    514 			} else {
    515 				goto loop;	/* ignore unimplemented options */
    516 			}
    517 		}
    518 		/* if rehash, don't redo absolute path names */
    519 		if (fullname[0] == '/' && idx <= prev) {
    520 			if (idx < prev)
    521 				goto loop;
    522 			TRACE(("searchexec \"%s\": no change\n", name));
    523 			goto success;
    524 		}
    525 		while (stat(fullname, &statb) < 0) {
    526 #ifdef SYSV
    527 			if (errno == EINTR)
    528 				continue;
    529 #endif
    530 			if (errno != ENOENT && errno != ENOTDIR)
    531 				e = errno;
    532 			goto loop;
    533 		}
    534 		e = EACCES;	/* if we fail, this will be the error */
    535 		if (!S_ISREG(statb.st_mode))
    536 			goto loop;
    537 		if (pathopt) {		/* this is a %func directory */
    538 			stalloc(strlen(fullname) + 1);
    539 			readcmdfile(fullname);
    540 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
    541 				error("%s not defined in %s", name, fullname);
    542 			stunalloc(fullname);
    543 			goto success;
    544 		}
    545 #ifdef notdef
    546 		if (statb.st_uid == geteuid()) {
    547 			if ((statb.st_mode & 0100) == 0)
    548 				goto loop;
    549 		} else if (statb.st_gid == getegid()) {
    550 			if ((statb.st_mode & 010) == 0)
    551 				goto loop;
    552 		} else {
    553 			if ((statb.st_mode & 01) == 0)
    554 				goto loop;
    555 		}
    556 #endif
    557 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
    558 		INTOFF;
    559 		cmdp = cmdlookup(name, 1);
    560 		cmdp->cmdtype = CMDNORMAL;
    561 		cmdp->param.index = idx;
    562 		INTON;
    563 		goto success;
    564 	}
    565 
    566 	/* We failed.  If there was an entry for this command, delete it */
    567 	if (cmdp)
    568 		delete_cmd_entry();
    569 	if (act & DO_ERR)
    570 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
    571 	entry->cmdtype = CMDUNKNOWN;
    572 	return;
    573 
    574 success:
    575 	cmdp->rehash = 0;
    576 	entry->cmdtype = cmdp->cmdtype;
    577 	entry->u = cmdp->param;
    578 }
    579 
    580 
    581 
    582 /*
    583  * Search the table of builtin commands.
    584  */
    585 
    586 int
    587 find_builtin(name)
    588 	char *name;
    589 {
    590 	const struct builtincmd *bp;
    591 
    592 	for (bp = builtincmd ; bp->name ; bp++) {
    593 		if (*bp->name == *name && equal(bp->name, name))
    594 			return bp->code;
    595 	}
    596 	return -1;
    597 }
    598 
    599 
    600 
    601 /*
    602  * Called when a cd is done.  Marks all commands so the next time they
    603  * are executed they will be rehashed.
    604  */
    605 
    606 void
    607 hashcd() {
    608 	struct tblentry **pp;
    609 	struct tblentry *cmdp;
    610 
    611 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    612 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    613 			if (cmdp->cmdtype == CMDNORMAL
    614 			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
    615 				cmdp->rehash = 1;
    616 		}
    617 	}
    618 }
    619 
    620 
    621 
    622 /*
    623  * Called before PATH is changed.  The argument is the new value of PATH;
    624  * pathval() still returns the old value at this point.  Called with
    625  * interrupts off.
    626  */
    627 
    628 void
    629 changepath(newval)
    630 	const char *newval;
    631 {
    632 	const char *old, *new;
    633 	int idx;
    634 	int firstchange;
    635 	int bltin;
    636 
    637 	old = pathval();
    638 	new = newval;
    639 	firstchange = 9999;	/* assume no change */
    640 	idx = 0;
    641 	bltin = -1;
    642 	for (;;) {
    643 		if (*old != *new) {
    644 			firstchange = idx;
    645 			if ((*old == '\0' && *new == ':')
    646 			 || (*old == ':' && *new == '\0'))
    647 				firstchange++;
    648 			old = new;	/* ignore subsequent differences */
    649 		}
    650 		if (*new == '\0')
    651 			break;
    652 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
    653 			bltin = idx;
    654 		if (*new == ':') {
    655 			idx++;
    656 		}
    657 		new++, old++;
    658 	}
    659 	if (builtinloc < 0 && bltin >= 0)
    660 		builtinloc = bltin;		/* zap builtins */
    661 	if (builtinloc >= 0 && bltin < 0)
    662 		firstchange = 0;
    663 	clearcmdentry(firstchange);
    664 	builtinloc = bltin;
    665 }
    666 
    667 
    668 /*
    669  * Clear out command entries.  The argument specifies the first entry in
    670  * PATH which has changed.
    671  */
    672 
    673 STATIC void
    674 clearcmdentry(firstchange)
    675 	int firstchange;
    676 {
    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 == CMDNORMAL &&
    686 			     cmdp->param.index >= firstchange)
    687 			 || (cmdp->cmdtype == CMDBUILTIN &&
    688 			     builtinloc >= firstchange)) {
    689 				*pp = cmdp->next;
    690 				ckfree(cmdp);
    691 			} else {
    692 				pp = &cmdp->next;
    693 			}
    694 		}
    695 	}
    696 	INTON;
    697 }
    698 
    699 
    700 /*
    701  * Delete all functions.
    702  */
    703 
    704 #ifdef mkinit
    705 MKINIT void deletefuncs __P((void));
    706 
    707 SHELLPROC {
    708 	deletefuncs();
    709 }
    710 #endif
    711 
    712 void
    713 deletefuncs() {
    714 	struct tblentry **tblp;
    715 	struct tblentry **pp;
    716 	struct tblentry *cmdp;
    717 
    718 	INTOFF;
    719 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
    720 		pp = tblp;
    721 		while ((cmdp = *pp) != NULL) {
    722 			if (cmdp->cmdtype == CMDFUNCTION) {
    723 				*pp = cmdp->next;
    724 				freefunc(cmdp->param.func);
    725 				ckfree(cmdp);
    726 			} else {
    727 				pp = &cmdp->next;
    728 			}
    729 		}
    730 	}
    731 	INTON;
    732 }
    733 
    734 
    735 
    736 /*
    737  * Locate a command in the command hash table.  If "add" is nonzero,
    738  * add the command to the table if it is not already present.  The
    739  * variable "lastcmdentry" is set to point to the address of the link
    740  * pointing to the entry, so that delete_cmd_entry can delete the
    741  * entry.
    742  */
    743 
    744 struct tblentry **lastcmdentry;
    745 
    746 
    747 STATIC struct tblentry *
    748 cmdlookup(name, add)
    749 	char *name;
    750 	int add;
    751 {
    752 	int hashval;
    753 	char *p;
    754 	struct tblentry *cmdp;
    755 	struct tblentry **pp;
    756 
    757 	p = name;
    758 	hashval = *p << 4;
    759 	while (*p)
    760 		hashval += *p++;
    761 	hashval &= 0x7FFF;
    762 	pp = &cmdtable[hashval % CMDTABLESIZE];
    763 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    764 		if (equal(cmdp->cmdname, name))
    765 			break;
    766 		pp = &cmdp->next;
    767 	}
    768 	if (add && cmdp == NULL) {
    769 		INTOFF;
    770 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
    771 					+ strlen(name) + 1);
    772 		cmdp->next = NULL;
    773 		cmdp->cmdtype = CMDUNKNOWN;
    774 		cmdp->rehash = 0;
    775 		strcpy(cmdp->cmdname, name);
    776 		INTON;
    777 	}
    778 	lastcmdentry = pp;
    779 	return cmdp;
    780 }
    781 
    782 /*
    783  * Delete the command entry returned on the last lookup.
    784  */
    785 
    786 STATIC void
    787 delete_cmd_entry() {
    788 	struct tblentry *cmdp;
    789 
    790 	INTOFF;
    791 	cmdp = *lastcmdentry;
    792 	*lastcmdentry = cmdp->next;
    793 	ckfree(cmdp);
    794 	INTON;
    795 }
    796 
    797 
    798 
    799 #ifdef notdef
    800 void
    801 getcmdentry(name, entry)
    802 	char *name;
    803 	struct cmdentry *entry;
    804 	{
    805 	struct tblentry *cmdp = cmdlookup(name, 0);
    806 
    807 	if (cmdp) {
    808 		entry->u = cmdp->param;
    809 		entry->cmdtype = cmdp->cmdtype;
    810 	} else {
    811 		entry->cmdtype = CMDUNKNOWN;
    812 		entry->u.index = 0;
    813 	}
    814 }
    815 #endif
    816 
    817 
    818 /*
    819  * Add a new command entry, replacing any existing command entry for
    820  * the same name.
    821  */
    822 
    823 void
    824 addcmdentry(name, entry)
    825 	char *name;
    826 	struct cmdentry *entry;
    827 	{
    828 	struct tblentry *cmdp;
    829 
    830 	INTOFF;
    831 	cmdp = cmdlookup(name, 1);
    832 	if (cmdp->cmdtype == CMDFUNCTION) {
    833 		freefunc(cmdp->param.func);
    834 	}
    835 	cmdp->cmdtype = entry->cmdtype;
    836 	cmdp->param = entry->u;
    837 	INTON;
    838 }
    839 
    840 
    841 /*
    842  * Define a shell function.
    843  */
    844 
    845 void
    846 defun(name, func)
    847 	char *name;
    848 	union node *func;
    849 	{
    850 	struct cmdentry entry;
    851 
    852 	INTOFF;
    853 	entry.cmdtype = CMDFUNCTION;
    854 	entry.u.func = copyfunc(func);
    855 	addcmdentry(name, &entry);
    856 	INTON;
    857 }
    858 
    859 
    860 /*
    861  * Delete a function if it exists.
    862  */
    863 
    864 int
    865 unsetfunc(name)
    866 	char *name;
    867 	{
    868 	struct tblentry *cmdp;
    869 
    870 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
    871 		freefunc(cmdp->param.func);
    872 		delete_cmd_entry();
    873 		return (0);
    874 	}
    875 	return (1);
    876 }
    877 
    878 /*
    879  * Locate and print what a word is...
    880  */
    881 
    882 int
    883 typecmd(argc, argv)
    884 	int argc;
    885 	char **argv;
    886 {
    887 	struct cmdentry entry;
    888 	struct tblentry *cmdp;
    889 	char **pp;
    890 	struct alias *ap;
    891 	int i;
    892 	int err = 0;
    893 	extern char *const parsekwd[];
    894 
    895 	for (i = 1; i < argc; i++) {
    896 		out1str(argv[i]);
    897 		/* First look at the keywords */
    898 		for (pp = (char **)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 			int j = entry.u.index;
    926 			const char *path = pathval();
    927 			char *name;
    928 			if (j == -1)
    929 				name = argv[i];
    930 			else {
    931 				do {
    932 					name = padvance(&path, argv[i]);
    933 					stunalloc(name);
    934 				} while (--j >= 0);
    935 			}
    936 			out1fmt(" is%s %s\n",
    937 			    cmdp ? " a tracked alias for" : "", name);
    938 			break;
    939 		}
    940 		case CMDFUNCTION:
    941 			out1str(" is a shell function\n");
    942 			break;
    943 
    944 		case CMDBUILTIN:
    945 			out1str(" is a shell builtin\n");
    946 			break;
    947 
    948 		default:
    949 			out1str(" not found\n");
    950 			err |= 127;
    951 			break;
    952 		}
    953 	}
    954 	return err;
    955 }
    956