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cd.c revision 1.33 
      1 /*	$NetBSD: cd.c,v 1.33 2003/10/30 09:40:26 dsl 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
     38 static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
     39 #else
     40 __RCSID("$NetBSD: cd.c,v 1.33 2003/10/30 09:40:26 dsl Exp $");
     41 #endif
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <sys/stat.h>
     46 #include <stdlib.h>
     47 #include <string.h>
     48 #include <unistd.h>
     49 #include <errno.h>
     50 
     51 /*
     52  * The cd and pwd commands.
     53  */
     54 
     55 #include "shell.h"
     56 #include "var.h"
     57 #include "nodes.h"	/* for jobs.h */
     58 #include "jobs.h"
     59 #include "options.h"
     60 #include "output.h"
     61 #include "memalloc.h"
     62 #include "error.h"
     63 #include "exec.h"
     64 #include "redir.h"
     65 #include "mystring.h"
     66 #include "show.h"
     67 #include "cd.h"
     68 
     69 STATIC int docd(char *, int);
     70 STATIC char *getcomponent(void);
     71 STATIC void updatepwd(char *);
     72 STATIC char *find_pwd(int noerror);
     73 
     74 char *curdir = NULL;		/* current working directory */
     75 char *prevdir;			/* previous working directory */
     76 STATIC char *cdcomppath;
     77 
     78 int
     79 cdcmd(int argc, char **argv)
     80 {
     81 	const char *dest;
     82 	const char *path;
     83 	char *p, *d;
     84 	struct stat statb;
     85 	int print = cdprint;	/* set -cdprint to enable */
     86 
     87 	nextopt(nullstr);
     88 
     89 	/* Try (quite hard) to have 'curdir' defined, nothing has set
     90 	   it on entry to the shell, but we want 'cd fred; cd -' to work. */
     91 	getpwd(1);
     92 	dest = *argptr;
     93 	if (dest == NULL) {
     94 		dest = bltinlookup("HOME", 1);
     95 		if (dest == NULL)
     96 			error("HOME not set");
     97 	} else {
     98 		if (argptr[1]) {
     99 			/* Do 'ksh' style substitution */
    100 			if (!curdir)
    101 				error("PWD not set");
    102 			p = strstr(curdir, dest);
    103 			if (!p)
    104 				error("bad substitution");
    105 			d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
    106 			memcpy(d, curdir, p - curdir);
    107 			strcpy(d + (p - curdir), argptr[1]);
    108 			strcat(d, p + strlen(dest));
    109 			dest = d;
    110 			print = 1;
    111 		}
    112 	}
    113 
    114 	if (*dest == '\0')
    115 	        dest = ".";
    116 	if (dest[0] == '-' && dest[1] == '\0') {
    117 		dest = prevdir ? prevdir : curdir;
    118 		print = 1;
    119 		if (dest)
    120 		        print = 1;
    121 		else
    122 		        dest = ".";
    123 	}
    124 	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
    125 		path = nullstr;
    126 	while ((p = padvance(&path, dest)) != NULL) {
    127 		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
    128 			if (!print) {
    129 				/*
    130 				 * XXX - rethink
    131 				 */
    132 				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
    133 					p += 2;
    134 				print = strcmp(p, dest);
    135 			}
    136 			if (docd(p, print) >= 0)
    137 				return 0;
    138 
    139 		}
    140 	}
    141 	error("can't cd to %s", dest);
    142 	/* NOTREACHED */
    143 }
    144 
    145 
    146 /*
    147  * Actually do the chdir.  In an interactive shell, print the
    148  * directory name if "print" is nonzero.
    149  */
    150 
    151 STATIC int
    152 docd(char *dest, int print)
    153 {
    154 	char *p;
    155 	char *q;
    156 	char *component;
    157 	struct stat statb;
    158 	int first;
    159 	int badstat;
    160 
    161 	TRACE(("docd(\"%s\", %d) called\n", dest, print));
    162 
    163 	/*
    164 	 *  Check each component of the path. If we find a symlink or
    165 	 *  something we can't stat, clear curdir to force a getcwd()
    166 	 *  next time we get the value of the current directory.
    167 	 */
    168 	badstat = 0;
    169 	cdcomppath = stalloc(strlen(dest) + 1);
    170 	scopy(dest, cdcomppath);
    171 	STARTSTACKSTR(p);
    172 	if (*dest == '/') {
    173 		STPUTC('/', p);
    174 		cdcomppath++;
    175 	}
    176 	first = 1;
    177 	while ((q = getcomponent()) != NULL) {
    178 		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
    179 			continue;
    180 		if (! first)
    181 			STPUTC('/', p);
    182 		first = 0;
    183 		component = q;
    184 		while (*q)
    185 			STPUTC(*q++, p);
    186 		if (equal(component, ".."))
    187 			continue;
    188 		STACKSTRNUL(p);
    189 		if ((lstat(stackblock(), &statb) < 0)
    190 		    || (S_ISLNK(statb.st_mode)))  {
    191 			/* print = 1; */
    192 			badstat = 1;
    193 			break;
    194 		}
    195 	}
    196 
    197 	INTOFF;
    198 	if (chdir(dest) < 0) {
    199 		INTON;
    200 		return -1;
    201 	}
    202 	updatepwd(badstat ? NULL : dest);
    203 	INTON;
    204 	if (print && iflag && curdir)
    205 		out1fmt("%s\n", curdir);
    206 	return 0;
    207 }
    208 
    209 
    210 /*
    211  * Get the next component of the path name pointed to by cdcomppath.
    212  * This routine overwrites the string pointed to by cdcomppath.
    213  */
    214 
    215 STATIC char *
    216 getcomponent()
    217 {
    218 	char *p;
    219 	char *start;
    220 
    221 	if ((p = cdcomppath) == NULL)
    222 		return NULL;
    223 	start = cdcomppath;
    224 	while (*p != '/' && *p != '\0')
    225 		p++;
    226 	if (*p == '\0') {
    227 		cdcomppath = NULL;
    228 	} else {
    229 		*p++ = '\0';
    230 		cdcomppath = p;
    231 	}
    232 	return start;
    233 }
    234 
    235 
    236 
    237 /*
    238  * Update curdir (the name of the current directory) in response to a
    239  * cd command.  We also call hashcd to let the routines in exec.c know
    240  * that the current directory has changed.
    241  */
    242 
    243 STATIC void
    244 updatepwd(char *dir)
    245 {
    246 	char *new;
    247 	char *p;
    248 
    249 	hashcd();				/* update command hash table */
    250 
    251 	/*
    252 	 * If our argument is NULL, we don't know the current directory
    253 	 * any more because we traversed a symbolic link or something
    254 	 * we couldn't stat().
    255 	 */
    256 	if (dir == NULL || curdir == NULL)  {
    257 		if (prevdir)
    258 			ckfree(prevdir);
    259 		INTOFF;
    260 		prevdir = curdir;
    261 		curdir = NULL;
    262 		getpwd(1);
    263 		INTON;
    264 		if (curdir)
    265 			setvar("PWD", curdir, VEXPORT);
    266 		else
    267 			unsetvar("PWD", 0);
    268 		return;
    269 	}
    270 	cdcomppath = stalloc(strlen(dir) + 1);
    271 	scopy(dir, cdcomppath);
    272 	STARTSTACKSTR(new);
    273 	if (*dir != '/') {
    274 		p = curdir;
    275 		while (*p)
    276 			STPUTC(*p++, new);
    277 		if (p[-1] == '/')
    278 			STUNPUTC(new);
    279 	}
    280 	while ((p = getcomponent()) != NULL) {
    281 		if (equal(p, "..")) {
    282 			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
    283 		} else if (*p != '\0' && ! equal(p, ".")) {
    284 			STPUTC('/', new);
    285 			while (*p)
    286 				STPUTC(*p++, new);
    287 		}
    288 	}
    289 	if (new == stackblock())
    290 		STPUTC('/', new);
    291 	STACKSTRNUL(new);
    292 	INTOFF;
    293 	if (prevdir)
    294 		ckfree(prevdir);
    295 	prevdir = curdir;
    296 	curdir = savestr(stackblock());
    297 	setvar("PWD", curdir, VEXPORT);
    298 	INTON;
    299 }
    300 
    301 
    302 
    303 int
    304 pwdcmd(int argc, char **argv)
    305 {
    306 	int i;
    307 	char opt = 'L';
    308 	char *pwd;
    309 
    310 	while ((i = nextopt("LP")) != '\0')
    311 		opt = i;
    312 	if (*argptr)
    313 		error("unexpected argument");
    314 
    315 	if (opt == 'L') {
    316 		getpwd(0);
    317 		pwd = curdir;
    318 	} else
    319 		pwd = find_pwd(0);
    320 
    321 	out1str(pwd);
    322 	out1c('\n');
    323 	return 0;
    324 }
    325 
    326 
    327 
    328 
    329 #define MAXPWD 256
    330 
    331 /*
    332  * Find out what the current directory is. If we already know the current
    333  * directory, this routine returns immediately.
    334  */
    335 void
    336 getpwd(int noerror)
    337 {
    338 	char *pwd;
    339 	struct stat stdot, stpwd;
    340 	static int first = 1;
    341 
    342 	if (curdir)
    343 		return;
    344 
    345 	if (first) {
    346 		first = 0;
    347 		pwd = getenv("PWD");
    348 		if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
    349 		    stat(pwd, &stpwd) != -1 &&
    350 		    stdot.st_dev == stpwd.st_dev &&
    351 		    stdot.st_ino == stpwd.st_ino) {
    352 			curdir = savestr(pwd);
    353 			return;
    354 		}
    355 	}
    356 
    357 	pwd = find_pwd(noerror);
    358 
    359 	if (pwd != NULL)
    360 		curdir = savestr(pwd);
    361 	return;
    362 }
    363 
    364 STATIC char *
    365 find_pwd(int noerror)
    366 {
    367 	int i;
    368 	char *pwd;
    369 
    370 	/*
    371 	 * Things are a bit complicated here; we could have just used
    372 	 * getcwd, but traditionally getcwd is implemented using popen
    373 	 * to /bin/pwd. This creates a problem for us, since we cannot
    374 	 * keep track of the job if it is being ran behind our backs.
    375 	 * So we re-implement getcwd(), and we suppress interrupts
    376 	 * throughout the process. This is not completely safe, since
    377 	 * the user can still break out of it by killing the pwd program.
    378 	 * We still try to use getcwd for systems that we know have a
    379 	 * c implementation of getcwd, that does not open a pipe to
    380 	 * /bin/pwd.
    381 	 */
    382 #if defined(__NetBSD__) || defined(__SVR4)
    383 
    384 	for (i = MAXPWD;; i *= 2) {
    385 		pwd = stalloc(i);
    386 		if (getcwd(pwd, i) != NULL)
    387 			return pwd;
    388 		stunalloc(pwd);
    389 		if (errno == ERANGE)
    390 			continue;
    391 		if (!noerror)
    392 			error("getcwd() failed: %s", strerror(errno));
    393 		return NULL;
    394 	}
    395 #else
    396 	{
    397 		char *p;
    398 		int status;
    399 		struct job *jp;
    400 		int pip[2];
    401 		char *buf;
    402 
    403 		buf = stalloc(MAXPWD);
    404 		INTOFF;
    405 		if (pipe(pip) < 0)
    406 			error("Pipe call failed");
    407 		jp = makejob((union node *)NULL, 1);
    408 		if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
    409 			(void) close(pip[0]);
    410 			if (pip[1] != 1) {
    411 				close(1);
    412 				copyfd(pip[1], 1);
    413 				close(pip[1]);
    414 			}
    415 			(void) execl("/bin/pwd", "pwd", (char *)0);
    416 			error("Cannot exec /bin/pwd");
    417 		}
    418 		(void) close(pip[1]);
    419 		pip[1] = -1;
    420 		p = buf;
    421 		while ((i = read(pip[0], p, buf + MAXPWD - p)) > 0
    422 		     || (i == -1 && errno == EINTR)) {
    423 			if (i > 0)
    424 				p += i;
    425 		}
    426 		(void) close(pip[0]);
    427 		pip[0] = -1;
    428 		status = waitforjob(jp);
    429 		if (status != 0)
    430 			error((char *)0);
    431 		if (i < 0 || p == buf || p[-1] != '\n') {
    432 			if (noerror) {
    433 				INTON;
    434 				return NULL;
    435 			}
    436 			error("pwd command failed");
    437 		}
    438 		p[-1] = '\0';
    439 		INTON;
    440 		return buf;
    441 	}
    442 #endif
    443 }
    444