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cd.c revision 1.23 
      1 /*	$NetBSD: cd.c,v 1.23 1997/07/04 20:59:40 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[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
     43 #else
     44 __RCSID("$NetBSD: cd.c,v 1.23 1997/07/04 20:59:40 christos Exp $");
     45 #endif
     46 #endif /* not lint */
     47 
     48 #include <sys/types.h>
     49 #include <sys/stat.h>
     50 #include <stdlib.h>
     51 #include <string.h>
     52 #include <unistd.h>
     53 #include <errno.h>
     54 
     55 /*
     56  * The cd and pwd commands.
     57  */
     58 
     59 #include "shell.h"
     60 #include "var.h"
     61 #include "nodes.h"	/* for jobs.h */
     62 #include "jobs.h"
     63 #include "options.h"
     64 #include "output.h"
     65 #include "memalloc.h"
     66 #include "error.h"
     67 #include "exec.h"
     68 #include "redir.h"
     69 #include "mystring.h"
     70 #include "show.h"
     71 #include "cd.h"
     72 
     73 STATIC int docd __P((char *, int));
     74 STATIC char *getcomponent __P((void));
     75 STATIC void updatepwd __P((char *));
     76 
     77 char *curdir = NULL;		/* current working directory */
     78 char *prevdir;			/* previous working directory */
     79 STATIC char *cdcomppath;
     80 
     81 int
     82 cdcmd(argc, argv)
     83 	int argc;
     84 	char **argv;
     85 {
     86 	char *dest;
     87 	char *path;
     88 	char *p;
     89 	struct stat statb;
     90 	int print = 0;
     91 
     92 	nextopt(nullstr);
     93 	if ((dest = *argptr) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
     94 		error("HOME not set");
     95 	if (*dest == '\0')
     96 	        dest = ".";
     97 	if (dest[0] == '-' && dest[1] == '\0') {
     98 		dest = prevdir ? prevdir : curdir;
     99 		print = 1;
    100 		if (dest)
    101 		        print = 1;
    102 		else
    103 		        dest = ".";
    104 	}
    105 	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
    106 		path = nullstr;
    107 	while ((p = padvance(&path, dest)) != NULL) {
    108 		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
    109 			if (!print) {
    110 				/*
    111 				 * XXX - rethink
    112 				 */
    113 				if (p[0] == '.' && p[1] == '/')
    114 					p += 2;
    115 				print = strcmp(p, dest);
    116 			}
    117 			if (docd(p, print) >= 0)
    118 				return 0;
    119 
    120 		}
    121 	}
    122 	error("can't cd to %s", dest);
    123 	/*NOTREACHED*/
    124 	return 0;
    125 }
    126 
    127 
    128 /*
    129  * Actually do the chdir.  In an interactive shell, print the
    130  * directory name if "print" is nonzero.
    131  */
    132 
    133 STATIC int
    134 docd(dest, print)
    135 	char *dest;
    136 	int print;
    137 {
    138 	char *p;
    139 	char *q;
    140 	char *component;
    141 	struct stat statb;
    142 	int first;
    143 	int badstat;
    144 
    145 	TRACE(("docd(\"%s\", %d) called\n", dest, print));
    146 
    147 	/*
    148 	 *  Check each component of the path. If we find a symlink or
    149 	 *  something we can't stat, clear curdir to force a getcwd()
    150 	 *  next time we get the value of the current directory.
    151 	 */
    152 	badstat = 0;
    153 	cdcomppath = stalloc(strlen(dest) + 1);
    154 	scopy(dest, cdcomppath);
    155 	STARTSTACKSTR(p);
    156 	if (*dest == '/') {
    157 		STPUTC('/', p);
    158 		cdcomppath++;
    159 	}
    160 	first = 1;
    161 	while ((q = getcomponent()) != NULL) {
    162 		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
    163 			continue;
    164 		if (! first)
    165 			STPUTC('/', p);
    166 		first = 0;
    167 		component = q;
    168 		while (*q)
    169 			STPUTC(*q++, p);
    170 		if (equal(component, ".."))
    171 			continue;
    172 		STACKSTRNUL(p);
    173 		if ((lstat(stackblock(), &statb) < 0)
    174 		    || (S_ISLNK(statb.st_mode)))  {
    175 			/* print = 1; */
    176 			badstat = 1;
    177 			break;
    178 		}
    179 	}
    180 
    181 	INTOFF;
    182 	if (chdir(dest) < 0) {
    183 		INTON;
    184 		return -1;
    185 	}
    186 	updatepwd(badstat ? NULL : dest);
    187 	INTON;
    188 	if (print && iflag && curdir)
    189 		out1fmt("%s\n", curdir);
    190 	return 0;
    191 }
    192 
    193 
    194 /*
    195  * Get the next component of the path name pointed to by cdcomppath.
    196  * This routine overwrites the string pointed to by cdcomppath.
    197  */
    198 
    199 STATIC char *
    200 getcomponent() {
    201 	char *p;
    202 	char *start;
    203 
    204 	if ((p = cdcomppath) == NULL)
    205 		return NULL;
    206 	start = cdcomppath;
    207 	while (*p != '/' && *p != '\0')
    208 		p++;
    209 	if (*p == '\0') {
    210 		cdcomppath = NULL;
    211 	} else {
    212 		*p++ = '\0';
    213 		cdcomppath = p;
    214 	}
    215 	return start;
    216 }
    217 
    218 
    219 
    220 /*
    221  * Update curdir (the name of the current directory) in response to a
    222  * cd command.  We also call hashcd to let the routines in exec.c know
    223  * that the current directory has changed.
    224  */
    225 
    226 STATIC void
    227 updatepwd(dir)
    228 	char *dir;
    229 	{
    230 	char *new;
    231 	char *p;
    232 
    233 	hashcd();				/* update command hash table */
    234 
    235 	/*
    236 	 * If our argument is NULL, we don't know the current directory
    237 	 * any more because we traversed a symbolic link or something
    238 	 * we couldn't stat().
    239 	 */
    240 	if (dir == NULL)  {
    241 		if (prevdir)
    242 			ckfree(prevdir);
    243 		INTOFF;
    244 		prevdir = curdir;
    245 		curdir = NULL;
    246 		getpwd();
    247 		INTON;
    248 		return;
    249 	}
    250 
    251 	cdcomppath = stalloc(strlen(dir) + 1);
    252 	scopy(dir, cdcomppath);
    253 	STARTSTACKSTR(new);
    254 	if (*dir != '/') {
    255 		if (curdir == NULL)
    256 			return;
    257 		p = curdir;
    258 		while (*p)
    259 			STPUTC(*p++, new);
    260 		if (p[-1] == '/')
    261 			STUNPUTC(new);
    262 	}
    263 	while ((p = getcomponent()) != NULL) {
    264 		if (equal(p, "..")) {
    265 			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
    266 		} else if (*p != '\0' && ! equal(p, ".")) {
    267 			STPUTC('/', new);
    268 			while (*p)
    269 				STPUTC(*p++, new);
    270 		}
    271 	}
    272 	if (new == stackblock())
    273 		STPUTC('/', new);
    274 	STACKSTRNUL(new);
    275 	INTOFF;
    276 	if (prevdir)
    277 		ckfree(prevdir);
    278 	prevdir = curdir;
    279 	curdir = savestr(stackblock());
    280 	setvar("PWD", curdir, VEXPORT|VTEXTFIXED);
    281 	INTON;
    282 }
    283 
    284 
    285 
    286 int
    287 pwdcmd(argc, argv)
    288 	int argc;
    289 	char **argv;
    290 {
    291 	getpwd();
    292 	out1str(curdir);
    293 	out1c('\n');
    294 	return 0;
    295 }
    296 
    297 
    298 
    299 
    300 #define MAXPWD 256
    301 
    302 /*
    303  * Find out what the current directory is. If we already know the current
    304  * directory, this routine returns immediately.
    305  */
    306 void
    307 getpwd()
    308 {
    309 	char buf[MAXPWD];
    310 
    311 	if (curdir)
    312 		return;
    313 	/*
    314 	 * Things are a bit complicated here; we could have just used
    315 	 * getcwd, but traditionally getcwd is implemented using popen
    316 	 * to /bin/pwd. This creates a problem for us, since we cannot
    317 	 * keep track of the job if it is being ran behind our backs.
    318 	 * So we re-implement getcwd(), and we suppress interrupts
    319 	 * throughout the process. This is not completely safe, since
    320 	 * the user can still break out of it by killing the pwd program.
    321 	 * We still try to use getcwd for systems that we know have a
    322 	 * c implementation of getcwd, that does not open a pipe to
    323 	 * /bin/pwd.
    324 	 */
    325 #if defined(__NetBSD__) || defined(__SVR4)
    326 
    327 	if (getcwd(buf, sizeof(buf)) == NULL) {
    328 		char *pwd = getenv("PWD");
    329 		struct stat stdot, stpwd;
    330 
    331 		if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
    332 		    stat(pwd, &stpwd) != -1 &&
    333 		    stdot.st_dev == stpwd.st_dev &&
    334 		    stdot.st_ino == stpwd.st_ino) {
    335 			curdir = savestr(pwd);
    336 			return;
    337 		}
    338 		error("getcwd() failed: %s", strerror(errno));
    339 	}
    340 	curdir = savestr(buf);
    341 #else
    342 	{
    343 		char *p;
    344 		int i;
    345 		int status;
    346 		struct job *jp;
    347 		int pip[2];
    348 
    349 		INTOFF;
    350 		if (pipe(pip) < 0)
    351 			error("Pipe call failed");
    352 		jp = makejob((union node *)NULL, 1);
    353 		if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
    354 			(void) close(pip[0]);
    355 			if (pip[1] != 1) {
    356 				close(1);
    357 				copyfd(pip[1], 1);
    358 				close(pip[1]);
    359 			}
    360 			(void) execl("/bin/pwd", "pwd", (char *)0);
    361 			error("Cannot exec /bin/pwd");
    362 		}
    363 		(void) close(pip[1]);
    364 		pip[1] = -1;
    365 		p = buf;
    366 		while ((i = read(pip[0], p, buf + MAXPWD - p)) > 0
    367 		     || (i == -1 && errno == EINTR)) {
    368 			if (i > 0)
    369 				p += i;
    370 		}
    371 		(void) close(pip[0]);
    372 		pip[0] = -1;
    373 		status = waitforjob(jp);
    374 		if (status != 0)
    375 			error((char *)0);
    376 		if (i < 0 || p == buf || p[-1] != '\n')
    377 			error("pwd command failed");
    378 		p[-1] = '\0';
    379 	}
    380 	curdir = savestr(buf);
    381 	INTON;
    382 #endif
    383 }
    384