xref: /freebsd/bin/sh/cd.c (revision 10b9d77bf1ccf2f3affafa6261692cb92cf7e992)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Kenneth Almquist.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #ifndef lint
34 #if 0
35 static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
36 #endif
37 #endif /* not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40 
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include <errno.h>
47 #include <limits.h>
48 
49 /*
50  * The cd and pwd commands.
51  */
52 
53 #include "shell.h"
54 #include "var.h"
55 #include "nodes.h"	/* for jobs.h */
56 #include "jobs.h"
57 #include "options.h"
58 #include "output.h"
59 #include "memalloc.h"
60 #include "error.h"
61 #include "exec.h"
62 #include "redir.h"
63 #include "mystring.h"
64 #include "show.h"
65 #include "cd.h"
66 
67 static int cdlogical(char *);
68 static int cdphysical(char *);
69 static int docd(char *, int, int);
70 static char *getcomponent(void);
71 static char *findcwd(char *);
72 static void updatepwd(char *);
73 static char *getpwd(void);
74 static char *getpwd2(void);
75 
76 static char *curdir = NULL;	/* current working directory */
77 static char *prevdir;		/* previous working directory */
78 static char *cdcomppath;
79 
80 int
81 cdcmd(int argc, char **argv)
82 {
83 	const char *dest;
84 	const char *path;
85 	char *p;
86 	struct stat statb;
87 	int ch, phys, print = 0;
88 
89 	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
90 	phys = Pflag;
91 	while ((ch = getopt(argc, argv, "LP")) != -1) {
92 		switch (ch) {
93 		case 'L':
94 			phys = 0;
95 			break;
96 		case 'P':
97 			phys = 1;
98 			break;
99 		default:
100 			error("unknown option: -%c", optopt);
101 			break;
102 		}
103 	}
104 	argc -= optind;
105 	argv += optind;
106 
107 	if (argc > 1)
108 		error("too many arguments");
109 
110 	if ((dest = *argv) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
111 		error("HOME not set");
112 	if (*dest == '\0')
113 		dest = ".";
114 	if (dest[0] == '-' && dest[1] == '\0') {
115 		dest = prevdir ? prevdir : curdir;
116 		if (dest)
117 			print = 1;
118 		else
119 			dest = ".";
120 	}
121 	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
122 		path = nullstr;
123 	while ((p = padvance(&path, dest)) != NULL) {
124 		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
125 			if (!print) {
126 				/*
127 				 * XXX - rethink
128 				 */
129 				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
130 					print = strcmp(p + 2, dest);
131 				else
132 					print = strcmp(p, dest);
133 			}
134 			if (docd(p, print, phys) >= 0)
135 				return 0;
136 		}
137 	}
138 	error("can't cd to %s", dest);
139 	/*NOTREACHED*/
140 	return 0;
141 }
142 
143 
144 /*
145  * Actually change the directory.  In an interactive shell, print the
146  * directory name if "print" is nonzero.
147  */
148 static int
149 docd(char *dest, int print, int phys)
150 {
151 
152 	TRACE(("docd(\"%s\", %d, %d) called\n", dest, print, phys));
153 
154 	/* If logical cd fails, fall back to physical. */
155 	if ((phys || cdlogical(dest) < 0) && cdphysical(dest) < 0)
156 		return (-1);
157 
158 	if (print && iflag && curdir)
159 		out1fmt("%s\n", curdir);
160 
161 	return 0;
162 }
163 
164 static int
165 cdlogical(char *dest)
166 {
167 	char *p;
168 	char *q;
169 	char *component;
170 	struct stat statb;
171 	int first;
172 	int badstat;
173 
174 	/*
175 	 *  Check each component of the path. If we find a symlink or
176 	 *  something we can't stat, clear curdir to force a getcwd()
177 	 *  next time we get the value of the current directory.
178 	 */
179 	badstat = 0;
180 	cdcomppath = stalloc(strlen(dest) + 1);
181 	scopy(dest, cdcomppath);
182 	STARTSTACKSTR(p);
183 	if (*dest == '/') {
184 		STPUTC('/', p);
185 		cdcomppath++;
186 	}
187 	first = 1;
188 	while ((q = getcomponent()) != NULL) {
189 		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
190 			continue;
191 		if (! first)
192 			STPUTC('/', p);
193 		first = 0;
194 		component = q;
195 		STPUTS(q, p);
196 		if (equal(component, ".."))
197 			continue;
198 		STACKSTRNUL(p);
199 		if (lstat(stackblock(), &statb) < 0) {
200 			badstat = 1;
201 			break;
202 		}
203 	}
204 
205 	INTOFF;
206 	if ((p = findcwd(badstat ? NULL : dest)) == NULL || chdir(p) < 0) {
207 		INTON;
208 		return (-1);
209 	}
210 	updatepwd(p);
211 	INTON;
212 	return (0);
213 }
214 
215 static int
216 cdphysical(char *dest)
217 {
218 	char *p;
219 
220 	INTOFF;
221 	if (chdir(dest) < 0) {
222 		INTON;
223 		return (-1);
224 	}
225 	p = findcwd(NULL);
226 	if (p == NULL)
227 		warning("warning: failed to get name of current directory");
228 	updatepwd(p);
229 	INTON;
230 	return (0);
231 }
232 
233 /*
234  * Get the next component of the path name pointed to by cdcomppath.
235  * This routine overwrites the string pointed to by cdcomppath.
236  */
237 static char *
238 getcomponent(void)
239 {
240 	char *p;
241 	char *start;
242 
243 	if ((p = cdcomppath) == NULL)
244 		return NULL;
245 	start = cdcomppath;
246 	while (*p != '/' && *p != '\0')
247 		p++;
248 	if (*p == '\0') {
249 		cdcomppath = NULL;
250 	} else {
251 		*p++ = '\0';
252 		cdcomppath = p;
253 	}
254 	return start;
255 }
256 
257 
258 static char *
259 findcwd(char *dir)
260 {
261 	char *new;
262 	char *p;
263 
264 	/*
265 	 * If our argument is NULL, we don't know the current directory
266 	 * any more because we traversed a symbolic link or something
267 	 * we couldn't stat().
268 	 */
269 	if (dir == NULL || curdir == NULL)
270 		return getpwd2();
271 	cdcomppath = stalloc(strlen(dir) + 1);
272 	scopy(dir, cdcomppath);
273 	STARTSTACKSTR(new);
274 	if (*dir != '/') {
275 		STPUTS(curdir, new);
276 		if (STTOPC(new) == '/')
277 			STUNPUTC(new);
278 	}
279 	while ((p = getcomponent()) != NULL) {
280 		if (equal(p, "..")) {
281 			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
282 		} else if (*p != '\0' && ! equal(p, ".")) {
283 			STPUTC('/', new);
284 			STPUTS(p, new);
285 		}
286 	}
287 	if (new == stackblock())
288 		STPUTC('/', new);
289 	STACKSTRNUL(new);
290 	return stackblock();
291 }
292 
293 /*
294  * Update curdir (the name of the current directory) in response to a
295  * cd command.  We also call hashcd to let the routines in exec.c know
296  * that the current directory has changed.
297  */
298 static void
299 updatepwd(char *dir)
300 {
301 	hashcd();				/* update command hash table */
302 
303 	if (prevdir)
304 		ckfree(prevdir);
305 	prevdir = curdir;
306 	curdir = dir ? savestr(dir) : NULL;
307 	setvar("PWD", curdir, VEXPORT);
308 	setvar("OLDPWD", prevdir, VEXPORT);
309 }
310 
311 int
312 pwdcmd(int argc, char **argv)
313 {
314 	char *p;
315 	int ch, phys;
316 
317 	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
318 	phys = Pflag;
319 	while ((ch = getopt(argc, argv, "LP")) != -1) {
320 		switch (ch) {
321 		case 'L':
322 			phys = 0;
323 			break;
324 		case 'P':
325 			phys = 1;
326 			break;
327 		default:
328 			error("unknown option: -%c", optopt);
329 			break;
330 		}
331 	}
332 	argc -= optind;
333 	argv += optind;
334 
335 	if (argc != 0)
336 		error("too many arguments");
337 
338 	if (!phys && getpwd()) {
339 		out1str(curdir);
340 		out1c('\n');
341 	} else {
342 		if ((p = getpwd2()) == NULL)
343 			error(".: %s", strerror(errno));
344 		out1str(p);
345 		out1c('\n');
346 	}
347 
348 	return 0;
349 }
350 
351 /*
352  * Get the current directory and cache the result in curdir.
353  */
354 static char *
355 getpwd(void)
356 {
357 	char *p;
358 
359 	if (curdir)
360 		return curdir;
361 
362 	p = getpwd2();
363 	if (p != NULL)
364 		curdir = savestr(p);
365 
366 	return curdir;
367 }
368 
369 #define MAXPWD 256
370 
371 /*
372  * Return the current directory.
373  */
374 static char *
375 getpwd2(void)
376 {
377 	char *pwd;
378 	int i;
379 
380 	for (i = MAXPWD;; i *= 2) {
381 		pwd = stalloc(i);
382 		if (getcwd(pwd, i) != NULL)
383 			return pwd;
384 		stunalloc(pwd);
385 		if (errno != ERANGE)
386 			break;
387 	}
388 
389 	return NULL;
390 }
391 
392 /*
393  * Initialize PWD in a new shell.
394  * If the shell is interactive, we need to warn if this fails.
395  */
396 void
397 pwd_init(int warn)
398 {
399 	char *pwd;
400 	struct stat stdot, stpwd;
401 
402 	pwd = lookupvar("PWD");
403 	if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
404 	    stat(pwd, &stpwd) != -1 &&
405 	    stdot.st_dev == stpwd.st_dev &&
406 	    stdot.st_ino == stpwd.st_ino) {
407 		if (curdir)
408 			ckfree(curdir);
409 		curdir = savestr(pwd);
410 	}
411 	if (getpwd() == NULL && warn)
412 		out2fmt_flush("sh: cannot determine working directory\n");
413 	setvar("PWD", curdir, VEXPORT);
414 }
415