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cd.c revision 1.14 
      1 /*	$NetBSD: cd.c,v 1.14 1995/11/19 23:27:37 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 #ifndef lint
     40 #if 0
     41 static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
     42 #else
     43 static char rcsid[] = "$NetBSD: cd.c,v 1.14 1995/11/19 23:27:37 christos Exp $";
     44 #endif
     45 #endif /* not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/stat.h>
     49 #include <stdlib.h>
     50 #include <unistd.h>
     51 #include <errno.h>
     52 
     53 /*
     54  * The cd and pwd commands.
     55  */
     56 
     57 #include "shell.h"
     58 #include "var.h"
     59 #include "nodes.h"	/* for jobs.h */
     60 #include "jobs.h"
     61 #include "options.h"
     62 #include "output.h"
     63 #include "memalloc.h"
     64 #include "error.h"
     65 #include "redir.h"
     66 #include "mystring.h"
     67 #include "show.h"
     68 #include "cd.h"
     69 
     70 STATIC int docd __P((char *, int));
     71 STATIC char *getcomponent __P((void));
     72 STATIC void updatepwd __P((char *));
     73 
     74 char *curdir = NULL;		/* current working directory */
     75 char *prevdir;			/* previous working directory */
     76 STATIC char *cdcomppath;
     77 
     78 int
     79 cdcmd(argc, argv)
     80 	int argc;
     81 	char **argv;
     82 {
     83 	char *dest;
     84 	char *path;
     85 	char *p;
     86 	struct stat statb;
     87 	char *padvance();
     88 	int print = 0;
     89 
     90 	nextopt(nullstr);
     91 	if ((dest = *argptr) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
     92 		error("HOME not set");
     93 	if (dest[0] == '-' && dest[1] == '\0') {
     94 		dest = prevdir ? prevdir : curdir;
     95 		print = 1;
     96 	}
     97 	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
     98 		path = nullstr;
     99 	while ((p = padvance(&path, dest)) != NULL) {
    100 		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
    101 			if (!print) {
    102 				/*
    103 				 * XXX - rethink
    104 				 */
    105 				if (p[0] == '.' && p[1] == '/')
    106 					p += 2;
    107 				print = strcmp(p, dest);
    108 			}
    109 			if (docd(p, print) >= 0)
    110 				return 0;
    111 
    112 		}
    113 	}
    114 	error("can't cd to %s", dest);
    115 	/*NOTREACHED*/
    116 	return 0;
    117 }
    118 
    119 
    120 /*
    121  * Actually do the chdir.  If the name refers to symbolic links, we
    122  * compute the actual directory name before doing the cd.  In an
    123  * interactive shell, print the directory name if "print" is nonzero
    124  * or if the name refers to a symbolic link.  We also print the name
    125  * if "/u/logname" was expanded in it, since this is similar to a
    126  * symbolic link.  (The check for this breaks if the user gives the
    127  * cd command some additional, unused arguments.)
    128  */
    129 
    130 #if SYMLINKS == 0
    131 STATIC int
    132 docd(dest, print)
    133 	char *dest;
    134 	{
    135 	INTOFF;
    136 	if (chdir(dest) < 0) {
    137 		INTON;
    138 		return -1;
    139 	}
    140 	updatepwd(dest);
    141 	INTON;
    142 	if (print && iflag)
    143 		out1fmt("%s\n", stackblock());
    144 	return 0;
    145 }
    146 
    147 #else
    148 
    149 
    150 
    151 STATIC int
    152 docd(dest, print)
    153 	char *dest;
    154 	int print;
    155 {
    156 	register char *p;
    157 	register char *q;
    158 	char *symlink;
    159 	char *component;
    160 	struct stat statb;
    161 	int first;
    162 	int i;
    163 
    164 	TRACE(("docd(\"%s\", %d) called\n", dest, print));
    165 
    166 top:
    167 	cdcomppath = dest;
    168 	STARTSTACKSTR(p);
    169 	if (*dest == '/') {
    170 		STPUTC('/', p);
    171 		cdcomppath++;
    172 	}
    173 	first = 1;
    174 	while ((q = getcomponent()) != NULL) {
    175 		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
    176 			continue;
    177 		if (! first)
    178 			STPUTC('/', p);
    179 		first = 0;
    180 		component = q;
    181 		while (*q)
    182 			STPUTC(*q++, p);
    183 		if (equal(component, ".."))
    184 			continue;
    185 		STACKSTRNUL(p);
    186 		if (lstat(stackblock(), &statb) < 0)
    187 			error("lstat %s failed", stackblock());
    188 		if (!S_ISLNK(statb.st_mode))
    189 			continue;
    190 
    191 		/* Hit a symbolic link.  We have to start all over again. */
    192 		print = 1;
    193 		STPUTC('\0', p);
    194 		symlink = grabstackstr(p);
    195 		i = (int)statb.st_size + 2;		/* 2 for '/' and '\0' */
    196 		if (cdcomppath != NULL)
    197 			i += strlen(cdcomppath);
    198 		p = stalloc(i);
    199 		if (readlink(symlink, p, (int)statb.st_size) < 0) {
    200 			error("readlink %s failed", stackblock());
    201 		}
    202 		if (cdcomppath != NULL) {
    203 			p[(int)statb.st_size] = '/';
    204 			scopy(cdcomppath, p + (int)statb.st_size + 1);
    205 		} else {
    206 			p[(int)statb.st_size] = '\0';
    207 		}
    208 		if (p[0] != '/') {	/* relative path name */
    209 			char *r;
    210 			q = r = symlink;
    211 			while (*q) {
    212 				if (*q++ == '/')
    213 					r = q;
    214 			}
    215 			*r = '\0';
    216 			dest = stalloc(strlen(symlink) + strlen(p) + 1);
    217 			scopy(symlink, dest);
    218 			strcat(dest, p);
    219 		} else {
    220 			dest = p;
    221 		}
    222 		goto top;
    223 	}
    224 	STPUTC('\0', p);
    225 	p = grabstackstr(p);
    226 	INTOFF;
    227 	if (chdir(p) < 0) {
    228 		INTON;
    229 		return -1;
    230 	}
    231 	updatepwd(p);
    232 	INTON;
    233 	if (print && iflag)
    234 		out1fmt("%s\n", p);
    235 	return 0;
    236 }
    237 #endif /* SYMLINKS */
    238 
    239 
    240 
    241 /*
    242  * Get the next component of the path name pointed to by cdcomppath.
    243  * This routine overwrites the string pointed to by cdcomppath.
    244  */
    245 
    246 STATIC char *
    247 getcomponent() {
    248 	register char *p;
    249 	char *start;
    250 
    251 	if ((p = cdcomppath) == NULL)
    252 		return NULL;
    253 	start = cdcomppath;
    254 	while (*p != '/' && *p != '\0')
    255 		p++;
    256 	if (*p == '\0') {
    257 		cdcomppath = NULL;
    258 	} else {
    259 		*p++ = '\0';
    260 		cdcomppath = p;
    261 	}
    262 	return start;
    263 }
    264 
    265 
    266 
    267 /*
    268  * Update curdir (the name of the current directory) in response to a
    269  * cd command.  We also call hashcd to let the routines in exec.c know
    270  * that the current directory has changed.
    271  */
    272 
    273 void hashcd();
    274 
    275 STATIC void
    276 updatepwd(dir)
    277 	char *dir;
    278 	{
    279 	char *new;
    280 	char *p;
    281 
    282 	hashcd();				/* update command hash table */
    283 	cdcomppath = stalloc(strlen(dir) + 1);
    284 	scopy(dir, cdcomppath);
    285 	STARTSTACKSTR(new);
    286 	if (*dir != '/') {
    287 		if (curdir == NULL)
    288 			return;
    289 		p = curdir;
    290 		while (*p)
    291 			STPUTC(*p++, new);
    292 		if (p[-1] == '/')
    293 			STUNPUTC(new);
    294 	}
    295 	while ((p = getcomponent()) != NULL) {
    296 		if (equal(p, "..")) {
    297 			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
    298 		} else if (*p != '\0' && ! equal(p, ".")) {
    299 			STPUTC('/', new);
    300 			while (*p)
    301 				STPUTC(*p++, new);
    302 		}
    303 	}
    304 	if (new == stackblock())
    305 		STPUTC('/', new);
    306 	STACKSTRNUL(new);
    307 	INTOFF;
    308 	if (prevdir)
    309 		ckfree(prevdir);
    310 	prevdir = curdir;
    311 	curdir = savestr(stackblock());
    312 	INTON;
    313 }
    314 
    315 
    316 
    317 int
    318 pwdcmd(argc, argv)
    319 	int argc;
    320 	char **argv;
    321 {
    322 	getpwd();
    323 	out1str(curdir);
    324 	out1c('\n');
    325 	return 0;
    326 }
    327 
    328 
    329 
    330 
    331 #define MAXPWD 256
    332 
    333 /*
    334  * Find out what the current directory is. If we already know the current
    335  * directory, this routine returns immediately.
    336  */
    337 void
    338 getpwd()
    339 {
    340 	char buf[MAXPWD];
    341 
    342 	if (curdir)
    343 		return;
    344 	/*
    345 	 * Things are a bit complicated here; we could have just used
    346 	 * getcwd, but traditionally getcwd is implemented using popen
    347 	 * to /bin/pwd. This creates a problem for us, since we cannot
    348 	 * keep track of the job if it is being ran behind our backs.
    349 	 * So we re-implement getcwd(), and we suppress interrupts
    350 	 * throughout the process. This is not completely safe, since
    351 	 * the user can still break out of it by killing the pwd program.
    352 	 * We still try to use getcwd for systems that we know have a
    353 	 * c implementation of getcwd, that does not open a pipe to
    354 	 * /bin/pwd.
    355 	 */
    356 #if defined(__NetBSD__) || defined(__svr4__)
    357 	if (getcwd(buf, sizeof(buf)) == NULL)
    358 		error("getcwd() failed");
    359 #else
    360 	{
    361 		char *p;
    362 		int i;
    363 		int status;
    364 		struct job *jp;
    365 		int pip[2];
    366 
    367 		INTOFF;
    368 		if (pipe(pip) < 0)
    369 			error("Pipe call failed");
    370 		jp = makejob((union node *)NULL, 1);
    371 		if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
    372 			(void) close(pip[0]);
    373 			if (pip[1] != 1) {
    374 				close(1);
    375 				copyfd(pip[1], 1);
    376 				close(pip[1]);
    377 			}
    378 			(void) execl("/bin/pwd", "pwd", (char *)0);
    379 			error("Cannot exec /bin/pwd");
    380 		}
    381 		(void) close(pip[1]);
    382 		pip[1] = -1;
    383 		p = buf;
    384 		while ((i = read(pip[0], p, buf + MAXPWD - p)) > 0
    385 		     || (i == -1 && errno == EINTR)) {
    386 			if (i > 0)
    387 				p += i;
    388 		}
    389 		(void) close(pip[0]);
    390 		pip[0] = -1;
    391 		status = waitforjob(jp);
    392 		if (status != 0)
    393 			error((char *)0);
    394 		if (i < 0 || p == buf || p[-1] != '\n')
    395 			error("pwd command failed");
    396 		p[-1] = '\0';
    397 	}
    398 #endif
    399 	curdir = savestr(buf);
    400 	INTON;
    401 }
    402