cd.c revision 216622 
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
35static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
36#endif
37#endif /* not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: head/bin/sh/cd.c 216622 2010-12-21 20:47:06Z jilles $");
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
67static int cdlogical(char *);
68static int cdphysical(char *);
69static int docd(char *, int, int);
70static char *getcomponent(void);
71static char *findcwd(char *);
72static void updatepwd(char *);
73static char *getpwd(void);
74static char *getpwd2(void);
75
76static char *curdir = NULL;	/* current working directory */
77static char *prevdir;		/* previous working directory */
78static char *cdcomppath;
79
80int
81cdcmd(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 */
148static int
149docd(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
164static int
165cdlogical(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
215static int
216cdphysical(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 */
237static char *
238getcomponent(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
258static char *
259findcwd(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 */
298static void
299updatepwd(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
311int
312pwdcmd(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 */
354static char *
355getpwd(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 */
374static char *
375getpwd2(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 */
396void
397pwd_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