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exec.c revision 1.34
      1 /*	$NetBSD: exec.c,v 1.34 2002/11/24 22:35:39 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 1.34 2002/11/24 22:35:39 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(char *, char **, char **, int);
    108 STATIC void execinterp(char **, char **);
    109 STATIC void printentry(struct tblentry *, int);
    110 STATIC void clearcmdentry(int);
    111 STATIC struct tblentry *cmdlookup(const char *, int);
    112 STATIC void delete_cmd_entry(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(char **argv, char **envp, const char *path, int idx, int vforked)
    124 {
    125 	char *cmdname;
    126 	int e;
    127 
    128 	if (strchr(argv[0], '/') != NULL) {
    129 		tryexec(argv[0], argv, envp, vforked);
    130 		e = errno;
    131 	} else {
    132 		e = ENOENT;
    133 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
    134 			if (--idx < 0 && pathopt == NULL) {
    135 				tryexec(cmdname, argv, envp, vforked);
    136 				if (errno != ENOENT && errno != ENOTDIR)
    137 					e = errno;
    138 			}
    139 			stunalloc(cmdname);
    140 		}
    141 	}
    142 
    143 	/* Map to POSIX errors */
    144 	switch (e) {
    145 	case EACCES:
    146 		exerrno = 126;
    147 		break;
    148 	case ENOENT:
    149 		exerrno = 127;
    150 		break;
    151 	default:
    152 		exerrno = 2;
    153 		break;
    154 	}
    155 	TRACE(("shellexec failed for %s, errno %d, vforked %d, suppressint %d\n",
    156 		argv[0], e, vforked, suppressint ));
    157 	exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC));
    158 	/* NOTREACHED */
    159 }
    160 
    161 
    162 STATIC void
    163 tryexec(char *cmd, char **argv, char **envp, int vforked)
    164 {
    165 	int e;
    166 #ifndef BSD
    167 	char *p;
    168 #endif
    169 
    170 #ifdef SYSV
    171 	do {
    172 		execve(cmd, argv, envp);
    173 	} while (errno == EINTR);
    174 #else
    175 	execve(cmd, argv, envp);
    176 #endif
    177 	e = errno;
    178 	if (e == ENOEXEC) {
    179 		if (vforked) {
    180 			/* We are currently vfork(2)ed, so raise an
    181 			 * exception, and evalcommand will try again
    182 			 * with a normal fork(2).
    183 			 */
    184 			exraise(EXSHELLPROC);
    185 		}
    186 		initshellproc();
    187 		setinputfile(cmd, 0);
    188 		commandname = arg0 = savestr(argv[0]);
    189 #ifndef BSD
    190 		pgetc(); pungetc();		/* fill up input buffer */
    191 		p = parsenextc;
    192 		if (parsenleft > 2 && p[0] == '#' && p[1] == '!') {
    193 			argv[0] = cmd;
    194 			execinterp(argv, envp);
    195 		}
    196 #endif
    197 		setparam(argv + 1);
    198 		exraise(EXSHELLPROC);
    199 	}
    200 	errno = e;
    201 }
    202 
    203 
    204 #ifndef BSD
    205 /*
    206  * Execute an interpreter introduced by "#!", for systems where this
    207  * feature has not been built into the kernel.  If the interpreter is
    208  * the shell, return (effectively ignoring the "#!").  If the execution
    209  * of the interpreter fails, exit.
    210  *
    211  * This code peeks inside the input buffer in order to avoid actually
    212  * reading any input.  It would benefit from a rewrite.
    213  */
    214 
    215 #define NEWARGS 5
    216 
    217 STATIC void
    218 execinterp(char **argv, char **envp)
    219 {
    220 	int n;
    221 	char *inp;
    222 	char *outp;
    223 	char c;
    224 	char *p;
    225 	char **ap;
    226 	char *newargs[NEWARGS];
    227 	int i;
    228 	char **ap2;
    229 	char **new;
    230 
    231 	n = parsenleft - 2;
    232 	inp = parsenextc + 2;
    233 	ap = newargs;
    234 	for (;;) {
    235 		while (--n >= 0 && (*inp == ' ' || *inp == '\t'))
    236 			inp++;
    237 		if (n < 0)
    238 			goto bad;
    239 		if ((c = *inp++) == '\n')
    240 			break;
    241 		if (ap == &newargs[NEWARGS])
    242 bad:		  error("Bad #! line");
    243 		STARTSTACKSTR(outp);
    244 		do {
    245 			STPUTC(c, outp);
    246 		} while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n');
    247 		STPUTC('\0', outp);
    248 		n++, inp--;
    249 		*ap++ = grabstackstr(outp);
    250 	}
    251 	if (ap == newargs + 1) {	/* if no args, maybe no exec is needed */
    252 		p = newargs[0];
    253 		for (;;) {
    254 			if (equal(p, "sh") || equal(p, "ash")) {
    255 				return;
    256 			}
    257 			while (*p != '/') {
    258 				if (*p == '\0')
    259 					goto break2;
    260 				p++;
    261 			}
    262 			p++;
    263 		}
    264 break2:;
    265 	}
    266 	i = (char *)ap - (char *)newargs;		/* size in bytes */
    267 	if (i == 0)
    268 		error("Bad #! line");
    269 	for (ap2 = argv ; *ap2++ != NULL ; );
    270 	new = ckmalloc(i + ((char *)ap2 - (char *)argv));
    271 	ap = newargs, ap2 = new;
    272 	while ((i -= sizeof (char **)) >= 0)
    273 		*ap2++ = *ap++;
    274 	ap = argv;
    275 	while (*ap2++ = *ap++);
    276 	shellexec(new, envp, pathval(), 0);
    277 	/* NOTREACHED */
    278 }
    279 #endif
    280 
    281 
    282 
    283 /*
    284  * Do a path search.  The variable path (passed by reference) should be
    285  * set to the start of the path before the first call; padvance will update
    286  * this value as it proceeds.  Successive calls to padvance will return
    287  * the possible path expansions in sequence.  If an option (indicated by
    288  * a percent sign) appears in the path entry then the global variable
    289  * pathopt will be set to point to it; otherwise pathopt will be set to
    290  * NULL.
    291  */
    292 
    293 const char *pathopt;
    294 
    295 char *
    296 padvance(const char **path, const char *name)
    297 {
    298 	const char *p;
    299 	char *q;
    300 	const char *start;
    301 	int len;
    302 
    303 	if (*path == NULL)
    304 		return NULL;
    305 	start = *path;
    306 	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
    307 	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
    308 	while (stackblocksize() < len)
    309 		growstackblock();
    310 	q = stackblock();
    311 	if (p != start) {
    312 		memcpy(q, start, p - start);
    313 		q += p - start;
    314 		*q++ = '/';
    315 	}
    316 	strcpy(q, name);
    317 	pathopt = NULL;
    318 	if (*p == '%') {
    319 		pathopt = ++p;
    320 		while (*p && *p != ':')  p++;
    321 	}
    322 	if (*p == ':')
    323 		*path = p + 1;
    324 	else
    325 		*path = NULL;
    326 	return stalloc(len);
    327 }
    328 
    329 
    330 
    331 /*** Command hashing code ***/
    332 
    333 
    334 int
    335 hashcmd(int argc, char **argv)
    336 {
    337 	struct tblentry **pp;
    338 	struct tblentry *cmdp;
    339 	int c;
    340 	int verbose;
    341 	struct cmdentry entry;
    342 	char *name;
    343 
    344 	verbose = 0;
    345 	while ((c = nextopt("rv")) != '\0') {
    346 		if (c == 'r') {
    347 			clearcmdentry(0);
    348 		} else if (c == 'v') {
    349 			verbose++;
    350 		}
    351 	}
    352 	if (*argptr == NULL) {
    353 		for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    354 			for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    355 				printentry(cmdp, verbose);
    356 			}
    357 		}
    358 		return 0;
    359 	}
    360 	while ((name = *argptr) != NULL) {
    361 		if ((cmdp = cmdlookup(name, 0)) != NULL
    362 		 && (cmdp->cmdtype == CMDNORMAL
    363 		     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)))
    364 			delete_cmd_entry();
    365 		find_command(name, &entry, DO_ERR, pathval());
    366 		if (verbose) {
    367 			if (entry.cmdtype != CMDUNKNOWN) {	/* if no error msg */
    368 				cmdp = cmdlookup(name, 0);
    369 				printentry(cmdp, verbose);
    370 			}
    371 			flushall();
    372 		}
    373 		argptr++;
    374 	}
    375 	return 0;
    376 }
    377 
    378 
    379 STATIC void
    380 printentry(struct tblentry *cmdp, int verbose)
    381 {
    382 	int idx;
    383 	const char *path;
    384 	char *name;
    385 
    386 	switch (cmdp->cmdtype) {
    387 	case CMDNORMAL:
    388 		idx = cmdp->param.index;
    389 		path = pathval();
    390 		do {
    391 			name = padvance(&path, cmdp->cmdname);
    392 			stunalloc(name);
    393 		} while (--idx >= 0);
    394 		out1str(name);
    395 		break;
    396 	case CMDSPLBLTIN:
    397 		out1fmt("special builtin %s", cmdp->cmdname);
    398 		break;
    399 	case CMDBUILTIN:
    400 		out1fmt("builtin %s", cmdp->cmdname);
    401 		break;
    402 	case CMDFUNCTION:
    403 		out1fmt("function %s", cmdp->cmdname);
    404 		if (verbose) {
    405 			struct procstat ps;
    406 			INTOFF;
    407 			commandtext(&ps, cmdp->param.func);
    408 			out1c(' ');
    409 			out1str(ps.cmd);
    410 			INTON;
    411 		}
    412 		break;
    413 	default:
    414 		error("internal error: %s cmdtype %d", cmdp->cmdname, cmdp->cmdtype);
    415 	}
    416 	if (cmdp->rehash)
    417 		out1c('*');
    418 	out1c('\n');
    419 }
    420 
    421 
    422 
    423 /*
    424  * Resolve a command name.  If you change this routine, you may have to
    425  * change the shellexec routine as well.
    426  */
    427 
    428 void
    429 find_command(char *name, struct cmdentry *entry, int act, const char *path)
    430 {
    431 	struct tblentry *cmdp;
    432 	int idx;
    433 	int prev;
    434 	char *fullname;
    435 	struct stat statb;
    436 	int e;
    437 	int (*bltin)(int,char **);
    438 
    439 	/* If name contains a slash, don't use the hash table */
    440 	if (strchr(name, '/') != NULL) {
    441 		if (act & DO_ABS) {
    442 			while (stat(name, &statb) < 0) {
    443 #ifdef SYSV
    444 				if (errno == EINTR)
    445 					continue;
    446 #endif
    447 				if (errno != ENOENT && errno != ENOTDIR)
    448 					e = errno;
    449 				entry->cmdtype = CMDUNKNOWN;
    450 				entry->u.index = -1;
    451 				return;
    452 			}
    453 			entry->cmdtype = CMDNORMAL;
    454 			entry->u.index = -1;
    455 			return;
    456 		}
    457 		entry->cmdtype = CMDNORMAL;
    458 		entry->u.index = 0;
    459 		return;
    460 	}
    461 
    462 	/* If name is in the table, and not invalidated by cd, we're done */
    463 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0)
    464 		goto success;
    465 
    466 	/* If %builtin not in path, check for builtin next */
    467 	if (builtinloc < 0 && (bltin = find_builtin(name)) != 0) {
    468 		INTOFF;
    469 		cmdp = cmdlookup(name, 1);
    470 		cmdp->cmdtype = CMDBUILTIN;
    471 		cmdp->param.bltin = bltin;
    472 		INTON;
    473 		goto success;
    474 	}
    475 
    476 	/* We have to search path. */
    477 	prev = -1;		/* where to start */
    478 	if (cmdp) {		/* doing a rehash */
    479 		if (cmdp->cmdtype == CMDBUILTIN)
    480 			prev = builtinloc;
    481 		else
    482 			prev = cmdp->param.index;
    483 	}
    484 
    485 	e = ENOENT;
    486 	idx = -1;
    487 loop:
    488 	while ((fullname = padvance(&path, name)) != NULL) {
    489 		stunalloc(fullname);
    490 		idx++;
    491 		if (pathopt) {
    492 			if (prefix("builtin", pathopt)) {
    493 				if ((bltin = find_builtin(name)) == 0)
    494 					goto loop;
    495 				INTOFF;
    496 				cmdp = cmdlookup(name, 1);
    497 				cmdp->cmdtype = CMDBUILTIN;
    498 				cmdp->param.bltin = bltin;
    499 				INTON;
    500 				goto success;
    501 			} else if (prefix("func", pathopt)) {
    502 				/* handled below */
    503 			} else {
    504 				goto loop;	/* ignore unimplemented options */
    505 			}
    506 		}
    507 		/* if rehash, don't redo absolute path names */
    508 		if (fullname[0] == '/' && idx <= prev) {
    509 			if (idx < prev)
    510 				goto loop;
    511 			TRACE(("searchexec \"%s\": no change\n", name));
    512 			goto success;
    513 		}
    514 		while (stat(fullname, &statb) < 0) {
    515 #ifdef SYSV
    516 			if (errno == EINTR)
    517 				continue;
    518 #endif
    519 			if (errno != ENOENT && errno != ENOTDIR)
    520 				e = errno;
    521 			goto loop;
    522 		}
    523 		e = EACCES;	/* if we fail, this will be the error */
    524 		if (!S_ISREG(statb.st_mode))
    525 			goto loop;
    526 		if (pathopt) {		/* this is a %func directory */
    527 			stalloc(strlen(fullname) + 1);
    528 			readcmdfile(fullname);
    529 			if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION)
    530 				error("%s not defined in %s", name, fullname);
    531 			stunalloc(fullname);
    532 			goto success;
    533 		}
    534 #ifdef notdef
    535 		if (statb.st_uid == geteuid()) {
    536 			if ((statb.st_mode & 0100) == 0)
    537 				goto loop;
    538 		} else if (statb.st_gid == getegid()) {
    539 			if ((statb.st_mode & 010) == 0)
    540 				goto loop;
    541 		} else {
    542 			if ((statb.st_mode & 01) == 0)
    543 				goto loop;
    544 		}
    545 #endif
    546 		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
    547 		INTOFF;
    548 		cmdp = cmdlookup(name, 1);
    549 		cmdp->cmdtype = CMDNORMAL;
    550 		cmdp->param.index = idx;
    551 		INTON;
    552 		goto success;
    553 	}
    554 
    555 	/* We failed.  If there was an entry for this command, delete it */
    556 	if (cmdp)
    557 		delete_cmd_entry();
    558 	if (act & DO_ERR)
    559 		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
    560 	entry->cmdtype = CMDUNKNOWN;
    561 	return;
    562 
    563 success:
    564 	cmdp->rehash = 0;
    565 	entry->cmdtype = cmdp->cmdtype;
    566 	entry->u = cmdp->param;
    567 }
    568 
    569 
    570 
    571 /*
    572  * Search the table of builtin commands.
    573  */
    574 
    575 int
    576 (*find_builtin(name))(int, char **)
    577 	char *name;
    578 {
    579 	const struct builtincmd *bp;
    580 
    581 	for (bp = builtincmd ; bp->name ; bp++) {
    582 		if (*bp->name == *name && equal(bp->name, name))
    583 			return bp->builtin;
    584 	}
    585 	return 0;
    586 }
    587 
    588 int
    589 (*find_splbltin(name))(int, char **)
    590 	char *name;
    591 {
    592 	const struct builtincmd *bp;
    593 
    594 	for (bp = splbltincmd ; bp->name ; bp++) {
    595 		if (*bp->name == *name && equal(bp->name, name))
    596 			return bp->builtin;
    597 	}
    598 	return 0;
    599 }
    600 
    601 /*
    602  * At shell startup put special builtins into hash table.
    603  * ensures they are executed first (see posix).
    604  * We stop functions being added with the same name
    605  * (as they are impossible to call)
    606  */
    607 
    608 void
    609 hash_special_builtins(void)
    610 {
    611 	const struct builtincmd *bp;
    612 	struct tblentry *cmdp;
    613 
    614 	for (bp = splbltincmd ; bp->name ; bp++) {
    615 		cmdp = cmdlookup(bp->name, 1);
    616 		cmdp->cmdtype = CMDSPLBLTIN;
    617 		cmdp->param.bltin = bp->builtin;
    618 	}
    619 }
    620 
    621 
    622 
    623 /*
    624  * Called when a cd is done.  Marks all commands so the next time they
    625  * are executed they will be rehashed.
    626  */
    627 
    628 void
    629 hashcd(void)
    630 {
    631 	struct tblentry **pp;
    632 	struct tblentry *cmdp;
    633 
    634 	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
    635 		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    636 			if (cmdp->cmdtype == CMDNORMAL
    637 			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
    638 				cmdp->rehash = 1;
    639 		}
    640 	}
    641 }
    642 
    643 
    644 
    645 /*
    646  * Called before PATH is changed.  The argument is the new value of PATH;
    647  * pathval() still returns the old value at this point.  Called with
    648  * interrupts off.
    649  */
    650 
    651 void
    652 changepath(const char *newval)
    653 {
    654 	const char *old, *new;
    655 	int idx;
    656 	int firstchange;
    657 	int bltin;
    658 
    659 	old = pathval();
    660 	new = newval;
    661 	firstchange = 9999;	/* assume no change */
    662 	idx = 0;
    663 	bltin = -1;
    664 	for (;;) {
    665 		if (*old != *new) {
    666 			firstchange = idx;
    667 			if ((*old == '\0' && *new == ':')
    668 			 || (*old == ':' && *new == '\0'))
    669 				firstchange++;
    670 			old = new;	/* ignore subsequent differences */
    671 		}
    672 		if (*new == '\0')
    673 			break;
    674 		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
    675 			bltin = idx;
    676 		if (*new == ':') {
    677 			idx++;
    678 		}
    679 		new++, old++;
    680 	}
    681 	if (builtinloc < 0 && bltin >= 0)
    682 		builtinloc = bltin;		/* zap builtins */
    683 	if (builtinloc >= 0 && bltin < 0)
    684 		firstchange = 0;
    685 	clearcmdentry(firstchange);
    686 	builtinloc = bltin;
    687 }
    688 
    689 
    690 /*
    691  * Clear out command entries.  The argument specifies the first entry in
    692  * PATH which has changed.
    693  */
    694 
    695 STATIC void
    696 clearcmdentry(int firstchange)
    697 {
    698 	struct tblentry **tblp;
    699 	struct tblentry **pp;
    700 	struct tblentry *cmdp;
    701 
    702 	INTOFF;
    703 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
    704 		pp = tblp;
    705 		while ((cmdp = *pp) != NULL) {
    706 			if ((cmdp->cmdtype == CMDNORMAL &&
    707 			     cmdp->param.index >= firstchange)
    708 			 || (cmdp->cmdtype == CMDBUILTIN &&
    709 			     builtinloc >= firstchange)) {
    710 				*pp = cmdp->next;
    711 				ckfree(cmdp);
    712 			} else {
    713 				pp = &cmdp->next;
    714 			}
    715 		}
    716 	}
    717 	INTON;
    718 }
    719 
    720 
    721 /*
    722  * Delete all functions.
    723  */
    724 
    725 #ifdef mkinit
    726 MKINIT void deletefuncs(void);
    727 MKINIT void hash_special_builtins(void);
    728 
    729 INIT {
    730 	hash_special_builtins();
    731 }
    732 
    733 SHELLPROC {
    734 	deletefuncs();
    735 }
    736 #endif
    737 
    738 void
    739 deletefuncs(void)
    740 {
    741 	struct tblentry **tblp;
    742 	struct tblentry **pp;
    743 	struct tblentry *cmdp;
    744 
    745 	INTOFF;
    746 	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
    747 		pp = tblp;
    748 		while ((cmdp = *pp) != NULL) {
    749 			if (cmdp->cmdtype == CMDFUNCTION) {
    750 				*pp = cmdp->next;
    751 				freefunc(cmdp->param.func);
    752 				ckfree(cmdp);
    753 			} else {
    754 				pp = &cmdp->next;
    755 			}
    756 		}
    757 	}
    758 	INTON;
    759 }
    760 
    761 
    762 
    763 /*
    764  * Locate a command in the command hash table.  If "add" is nonzero,
    765  * add the command to the table if it is not already present.  The
    766  * variable "lastcmdentry" is set to point to the address of the link
    767  * pointing to the entry, so that delete_cmd_entry can delete the
    768  * entry.
    769  */
    770 
    771 struct tblentry **lastcmdentry;
    772 
    773 
    774 STATIC struct tblentry *
    775 cmdlookup(const char *name, int add)
    776 {
    777 	int hashval;
    778 	const char *p;
    779 	struct tblentry *cmdp;
    780 	struct tblentry **pp;
    781 
    782 	p = name;
    783 	hashval = *p << 4;
    784 	while (*p)
    785 		hashval += *p++;
    786 	hashval &= 0x7FFF;
    787 	pp = &cmdtable[hashval % CMDTABLESIZE];
    788 	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
    789 		if (equal(cmdp->cmdname, name))
    790 			break;
    791 		pp = &cmdp->next;
    792 	}
    793 	if (add && cmdp == NULL) {
    794 		INTOFF;
    795 		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
    796 					+ strlen(name) + 1);
    797 		cmdp->next = NULL;
    798 		cmdp->cmdtype = CMDUNKNOWN;
    799 		cmdp->rehash = 0;
    800 		strcpy(cmdp->cmdname, name);
    801 		INTON;
    802 	}
    803 	lastcmdentry = pp;
    804 	return cmdp;
    805 }
    806 
    807 /*
    808  * Delete the command entry returned on the last lookup.
    809  */
    810 
    811 STATIC void
    812 delete_cmd_entry(void)
    813 {
    814 	struct tblentry *cmdp;
    815 
    816 	INTOFF;
    817 	cmdp = *lastcmdentry;
    818 	*lastcmdentry = cmdp->next;
    819 	ckfree(cmdp);
    820 	INTON;
    821 }
    822 
    823 
    824 
    825 #ifdef notdef
    826 void
    827 getcmdentry(char *name, struct cmdentry *entry)
    828 {
    829 	struct tblentry *cmdp = cmdlookup(name, 0);
    830 
    831 	if (cmdp) {
    832 		entry->u = cmdp->param;
    833 		entry->cmdtype = cmdp->cmdtype;
    834 	} else {
    835 		entry->cmdtype = CMDUNKNOWN;
    836 		entry->u.index = 0;
    837 	}
    838 }
    839 #endif
    840 
    841 
    842 /*
    843  * Add a new command entry, replacing any existing command entry for
    844  * the same name - except special builtins.
    845  */
    846 
    847 void
    848 addcmdentry(char *name, struct cmdentry *entry)
    849 {
    850 	struct tblentry *cmdp;
    851 
    852 	INTOFF;
    853 	cmdp = cmdlookup(name, 1);
    854 	if (cmdp->cmdtype != CMDSPLBLTIN) {
    855 		if (cmdp->cmdtype == CMDFUNCTION) {
    856 			freefunc(cmdp->param.func);
    857 		}
    858 		cmdp->cmdtype = entry->cmdtype;
    859 		cmdp->param = entry->u;
    860 	}
    861 	INTON;
    862 }
    863 
    864 
    865 /*
    866  * Define a shell function.
    867  */
    868 
    869 void
    870 defun(char *name, union node *func)
    871 {
    872 	struct cmdentry entry;
    873 
    874 	INTOFF;
    875 	entry.cmdtype = CMDFUNCTION;
    876 	entry.u.func = copyfunc(func);
    877 	addcmdentry(name, &entry);
    878 	INTON;
    879 }
    880 
    881 
    882 /*
    883  * Delete a function if it exists.
    884  */
    885 
    886 int
    887 unsetfunc(char *name)
    888 {
    889 	struct tblentry *cmdp;
    890 
    891 	if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) {
    892 		freefunc(cmdp->param.func);
    893 		delete_cmd_entry();
    894 		return (0);
    895 	}
    896 	return (1);
    897 }
    898 
    899 /*
    900  * Locate and print what a word is...
    901  */
    902 
    903 int
    904 typecmd(int argc, char **argv)
    905 {
    906 	struct cmdentry entry;
    907 	struct tblentry *cmdp;
    908 	char * const *pp;
    909 	struct alias *ap;
    910 	int i;
    911 	int err = 0;
    912 
    913 	for (i = 1; i < argc; i++) {
    914 		out1str(argv[i]);
    915 		/* First look at the keywords */
    916 		for (pp = parsekwd; *pp; pp++)
    917 			if (**pp == *argv[i] && equal(*pp, argv[i]))
    918 				break;
    919 
    920 		if (*pp) {
    921 			out1str(" is a shell keyword\n");
    922 			continue;
    923 		}
    924 
    925 		/* Then look at the aliases */
    926 		if ((ap = lookupalias(argv[i], 1)) != NULL) {
    927 			out1fmt(" is an alias for %s\n", ap->val);
    928 			continue;
    929 		}
    930 
    931 		/* Then check if it is a tracked alias */
    932 		if ((cmdp = cmdlookup(argv[i], 0)) != NULL) {
    933 			entry.cmdtype = cmdp->cmdtype;
    934 			entry.u = cmdp->param;
    935 		}
    936 		else {
    937 			/* Finally use brute force */
    938 			find_command(argv[i], &entry, DO_ABS, pathval());
    939 		}
    940 
    941 		switch (entry.cmdtype) {
    942 		case CMDNORMAL: {
    943 			if (strchr(argv[i], '/') == NULL) {
    944 				const char *path = pathval();
    945 				char *name;
    946 				int j = entry.u.index;
    947 				do {
    948 					name = padvance(&path, argv[i]);
    949 					stunalloc(name);
    950 				} while (--j >= 0);
    951 				out1fmt(" is%s %s\n",
    952 				    cmdp ? " a tracked alias for" : "", name);
    953 			} else {
    954 				if (access(argv[i], X_OK) == 0)
    955 					out1fmt(" is %s\n", argv[i]);
    956 				else
    957 					out1fmt(": %s\n", strerror(errno));
    958 			}
    959  			break;
    960 		}
    961 		case CMDFUNCTION:
    962 			out1str(" is a shell function\n");
    963 			break;
    964 
    965 		case CMDBUILTIN:
    966 			out1str(" is a shell builtin\n");
    967 			break;
    968 
    969 		case CMDSPLBLTIN:
    970 			out1str(" is a special shell builtin\n");
    971 			break;
    972 
    973 		default:
    974 			out1str(": not found\n");
    975 			err |= 127;
    976 			break;
    977 		}
    978 	}
    979 	return err;
    980 }
    981