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cd.c revision 1.37 
      1 /*	$NetBSD: cd.c,v 1.37 2005/10/10 21:14:42 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. 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 1.37 2005/10/10 21:14:42 christos 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(const char *, int);
     70 STATIC char *getcomponent(void);
     71 STATIC void updatepwd(const char *);
     72 STATIC void find_curdir(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, *p;
     83 	char *d;
     84 	struct stat statb;
     85 	int print = cdprint;	/* set -cdprint to enable */
     86 
     87 	nextopt(nullstr);
     88 
     89 	/*
     90 	 * Try (quite hard) to have 'curdir' defined, nothing has set
     91 	 * it on entry to the shell, but we want 'cd fred; cd -' to work.
     92 	 */
     93 	getpwd(1);
     94 	dest = *argptr;
     95 	if (dest == NULL) {
     96 		dest = bltinlookup("HOME", 1);
     97 		if (dest == NULL)
     98 			error("HOME not set");
     99 	} else {
    100 		if (argptr[1]) {
    101 			/* Do 'ksh' style substitution */
    102 			if (!curdir)
    103 				error("PWD not set");
    104 			p = strstr(curdir, dest);
    105 			if (!p)
    106 				error("bad substitution");
    107 			d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
    108 			memcpy(d, curdir, p - curdir);
    109 			strcpy(d + (p - curdir), argptr[1]);
    110 			strcat(d, p + strlen(dest));
    111 			dest = d;
    112 			print = 1;
    113 		}
    114 	}
    115 
    116 	if (dest[0] == '-' && dest[1] == '\0') {
    117 		dest = prevdir ? prevdir : curdir;
    118 		print = 1;
    119 	}
    120 	if (*dest == '\0')
    121 	        dest = ".";
    122 	p = dest;
    123 	if (*p == '.' && *++p == '.')
    124 	    p++;
    125 	if (*p == 0 || *p == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
    126 		path = nullstr;
    127 	while ((p = padvance(&path, dest)) != NULL) {
    128 		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
    129 			if (!print) {
    130 				/*
    131 				 * XXX - rethink
    132 				 */
    133 				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
    134 					p += 2;
    135 				print = strcmp(p, dest);
    136 			}
    137 			if (docd(p, print) >= 0)
    138 				return 0;
    139 
    140 		}
    141 	}
    142 	error("can't cd to %s", dest);
    143 	/* NOTREACHED */
    144 }
    145 
    146 
    147 /*
    148  * Actually do the chdir.  In an interactive shell, print the
    149  * directory name if "print" is nonzero.
    150  */
    151 
    152 STATIC int
    153 docd(const char *dest, int print)
    154 {
    155 	char *p;
    156 	char *q;
    157 	char *component;
    158 	struct stat statb;
    159 	int first;
    160 	int badstat;
    161 
    162 	TRACE(("docd(\"%s\", %d) called\n", dest, print));
    163 
    164 	/*
    165 	 *  Check each component of the path. If we find a symlink or
    166 	 *  something we can't stat, clear curdir to force a getcwd()
    167 	 *  next time we get the value of the current directory.
    168 	 */
    169 	badstat = 0;
    170 	cdcomppath = stalloc(strlen(dest) + 1);
    171 	scopy(dest, cdcomppath);
    172 	STARTSTACKSTR(p);
    173 	if (*dest == '/') {
    174 		STPUTC('/', p);
    175 		cdcomppath++;
    176 	}
    177 	first = 1;
    178 	while ((q = getcomponent()) != NULL) {
    179 		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
    180 			continue;
    181 		if (! first)
    182 			STPUTC('/', p);
    183 		first = 0;
    184 		component = q;
    185 		while (*q)
    186 			STPUTC(*q++, p);
    187 		if (equal(component, ".."))
    188 			continue;
    189 		STACKSTRNUL(p);
    190 		if ((lstat(stackblock(), &statb) < 0)
    191 		    || (S_ISLNK(statb.st_mode)))  {
    192 			/* print = 1; */
    193 			badstat = 1;
    194 			break;
    195 		}
    196 	}
    197 
    198 	INTOFF;
    199 	if (chdir(dest) < 0) {
    200 		INTON;
    201 		return -1;
    202 	}
    203 	updatepwd(badstat ? NULL : dest);
    204 	INTON;
    205 	if (print && iflag == 1 && curdir)
    206 		out1fmt("%s\n", curdir);
    207 	return 0;
    208 }
    209 
    210 
    211 /*
    212  * Get the next component of the path name pointed to by cdcomppath.
    213  * This routine overwrites the string pointed to by cdcomppath.
    214  */
    215 
    216 STATIC char *
    217 getcomponent(void)
    218 {
    219 	char *p;
    220 	char *start;
    221 
    222 	if ((p = cdcomppath) == NULL)
    223 		return NULL;
    224 	start = cdcomppath;
    225 	while (*p != '/' && *p != '\0')
    226 		p++;
    227 	if (*p == '\0') {
    228 		cdcomppath = NULL;
    229 	} else {
    230 		*p++ = '\0';
    231 		cdcomppath = p;
    232 	}
    233 	return start;
    234 }
    235 
    236 
    237 
    238 /*
    239  * Update curdir (the name of the current directory) in response to a
    240  * cd command.  We also call hashcd to let the routines in exec.c know
    241  * that the current directory has changed.
    242  */
    243 
    244 STATIC void
    245 updatepwd(const char *dir)
    246 {
    247 	char *new;
    248 	char *p;
    249 
    250 	hashcd();				/* update command hash table */
    251 
    252 	/*
    253 	 * If our argument is NULL, we don't know the current directory
    254 	 * any more because we traversed a symbolic link or something
    255 	 * we couldn't stat().
    256 	 */
    257 	if (dir == NULL || curdir == NULL)  {
    258 		if (prevdir)
    259 			ckfree(prevdir);
    260 		INTOFF;
    261 		prevdir = curdir;
    262 		curdir = NULL;
    263 		getpwd(1);
    264 		INTON;
    265 		if (curdir)
    266 			setvar("PWD", curdir, VEXPORT);
    267 		else
    268 			unsetvar("PWD", 0);
    269 		return;
    270 	}
    271 	cdcomppath = stalloc(strlen(dir) + 1);
    272 	scopy(dir, cdcomppath);
    273 	STARTSTACKSTR(new);
    274 	if (*dir != '/') {
    275 		p = curdir;
    276 		while (*p)
    277 			STPUTC(*p++, new);
    278 		if (p[-1] == '/')
    279 			STUNPUTC(new);
    280 	}
    281 	while ((p = getcomponent()) != NULL) {
    282 		if (equal(p, "..")) {
    283 			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
    284 		} else if (*p != '\0' && ! equal(p, ".")) {
    285 			STPUTC('/', new);
    286 			while (*p)
    287 				STPUTC(*p++, new);
    288 		}
    289 	}
    290 	if (new == stackblock())
    291 		STPUTC('/', new);
    292 	STACKSTRNUL(new);
    293 	INTOFF;
    294 	if (prevdir)
    295 		ckfree(prevdir);
    296 	prevdir = curdir;
    297 	curdir = savestr(stackblock());
    298 	setvar("PWD", curdir, VEXPORT);
    299 	INTON;
    300 }
    301 
    302 /*
    303  * Posix says the default should be 'pwd -L' (as below), however
    304  * the 'cd' command (above) does something much nearer to the
    305  * posix 'cd -P' (not the posix default of 'cd -L').
    306  * If 'cd' is changed to support -P/L then the default here
    307  * needs to be revisited if the historic behaviour is to be kept.
    308  */
    309 
    310 int
    311 pwdcmd(int argc, char **argv)
    312 {
    313 	int i;
    314 	char opt = 'L';
    315 
    316 	while ((i = nextopt("LP")) != '\0')
    317 		opt = i;
    318 	if (*argptr)
    319 		error("unexpected argument");
    320 
    321 	if (opt == 'L')
    322 		getpwd(0);
    323 	else
    324 		find_curdir(0);
    325 
    326 	setvar("PWD", curdir, VEXPORT);
    327 	out1str(curdir);
    328 	out1c('\n');
    329 	return 0;
    330 }
    331 
    332 
    333 
    334 void
    335 initpwd(void)
    336 {
    337 	getpwd(0);
    338 	setvar("PWD", curdir, VEXPORT);
    339 }
    340 
    341 #define MAXPWD 256
    342 
    343 /*
    344  * Find out what the current directory is. If we already know the current
    345  * directory, this routine returns immediately.
    346  */
    347 void
    348 getpwd(int noerror)
    349 {
    350 	char *pwd;
    351 	struct stat stdot, stpwd;
    352 	static int first = 1;
    353 
    354 	if (curdir)
    355 		return;
    356 
    357 	if (first) {
    358 		first = 0;
    359 		pwd = getenv("PWD");
    360 		if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
    361 		    stat(pwd, &stpwd) != -1 &&
    362 		    stdot.st_dev == stpwd.st_dev &&
    363 		    stdot.st_ino == stpwd.st_ino) {
    364 			curdir = savestr(pwd);
    365 			return;
    366 		}
    367 	}
    368 
    369 	find_curdir(noerror);
    370 
    371 	return;
    372 }
    373 
    374 STATIC void
    375 find_curdir(int noerror)
    376 {
    377 	int i;
    378 	char *pwd;
    379 
    380 	/*
    381 	 * Things are a bit complicated here; we could have just used
    382 	 * getcwd, but traditionally getcwd is implemented using popen
    383 	 * to /bin/pwd. This creates a problem for us, since we cannot
    384 	 * keep track of the job if it is being ran behind our backs.
    385 	 * So we re-implement getcwd(), and we suppress interrupts
    386 	 * throughout the process. This is not completely safe, since
    387 	 * the user can still break out of it by killing the pwd program.
    388 	 * We still try to use getcwd for systems that we know have a
    389 	 * c implementation of getcwd, that does not open a pipe to
    390 	 * /bin/pwd.
    391 	 */
    392 #if defined(__NetBSD__) || defined(__SVR4)
    393 
    394 	for (i = MAXPWD;; i *= 2) {
    395 		pwd = stalloc(i);
    396 		if (getcwd(pwd, i) != NULL) {
    397 			curdir = savestr(pwd);
    398 			return;
    399 		}
    400 		stunalloc(pwd);
    401 		if (errno == ERANGE)
    402 			continue;
    403 		if (!noerror)
    404 			error("getcwd() failed: %s", strerror(errno));
    405 		return;
    406 	}
    407 #else
    408 	{
    409 		char *p;
    410 		int status;
    411 		struct job *jp;
    412 		int pip[2];
    413 
    414 		pwd = stalloc(MAXPWD);
    415 		INTOFF;
    416 		if (pipe(pip) < 0)
    417 			error("Pipe call failed");
    418 		jp = makejob((union node *)NULL, 1);
    419 		if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
    420 			(void) close(pip[0]);
    421 			if (pip[1] != 1) {
    422 				close(1);
    423 				copyfd(pip[1], 1);
    424 				close(pip[1]);
    425 			}
    426 			(void) execl("/bin/pwd", "pwd", (char *)0);
    427 			error("Cannot exec /bin/pwd");
    428 		}
    429 		(void) close(pip[1]);
    430 		pip[1] = -1;
    431 		p = pwd;
    432 		while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
    433 		     || (i == -1 && errno == EINTR)) {
    434 			if (i > 0)
    435 				p += i;
    436 		}
    437 		(void) close(pip[0]);
    438 		pip[0] = -1;
    439 		status = waitforjob(jp);
    440 		if (status != 0)
    441 			error((char *)0);
    442 		if (i < 0 || p == pwd || p[-1] != '\n') {
    443 			if (noerror) {
    444 				INTON;
    445 				return;
    446 			}
    447 			error("pwd command failed");
    448 		}
    449 		p[-1] = '\0';
    450 		INTON;
    451 		curdir = savestr(pwd);
    452 		return;
    453 	}
    454 #endif
    455 }
    456