cd.c revision 201053 
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 201053 2009-12-27 18:04:05Z 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 *getpwd2(void);
74
75STATIC char *curdir = NULL;	/* current working directory */
76STATIC char *prevdir;		/* previous working directory */
77STATIC char *cdcomppath;
78
79int
80cdcmd(int argc, char **argv)
81{
82	const char *dest;
83	const char *path;
84	char *p;
85	struct stat statb;
86	int ch, phys, print = 0;
87
88	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
89	phys = Pflag;
90	while ((ch = getopt(argc, argv, "LP")) != -1) {
91		switch (ch) {
92		case 'L':
93			phys = 0;
94			break;
95		case 'P':
96			phys = 1;
97			break;
98		default:
99			error("unknown option: -%c", optopt);
100			break;
101		}
102	}
103	argc -= optind;
104	argv += optind;
105
106	if (argc > 1)
107		error("too many arguments");
108
109	if ((dest = *argv) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
110		error("HOME not set");
111	if (*dest == '\0')
112		dest = ".";
113	if (dest[0] == '-' && dest[1] == '\0') {
114		dest = prevdir ? prevdir : curdir;
115		if (dest)
116			print = 1;
117		else
118			dest = ".";
119	}
120	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
121		path = nullstr;
122	while ((p = padvance(&path, dest)) != NULL) {
123		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
124			if (!print) {
125				/*
126				 * XXX - rethink
127				 */
128				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
129					print = strcmp(p + 2, dest);
130				else
131					print = strcmp(p, dest);
132			}
133			if (docd(p, print, phys) >= 0)
134				return 0;
135		}
136	}
137	error("can't cd to %s", dest);
138	/*NOTREACHED*/
139	return 0;
140}
141
142
143/*
144 * Actually change the directory.  In an interactive shell, print the
145 * directory name if "print" is nonzero.
146 */
147STATIC int
148docd(char *dest, int print, int phys)
149{
150
151	TRACE(("docd(\"%s\", %d, %d) called\n", dest, print, phys));
152
153	/* If logical cd fails, fall back to physical. */
154	if ((phys || cdlogical(dest) < 0) && cdphysical(dest) < 0)
155		return (-1);
156
157	if (print && iflag && curdir)
158		out1fmt("%s\n", curdir);
159
160	return 0;
161}
162
163STATIC int
164cdlogical(char *dest)
165{
166	char *p;
167	char *q;
168	char *component;
169	struct stat statb;
170	int first;
171	int badstat;
172
173	/*
174	 *  Check each component of the path. If we find a symlink or
175	 *  something we can't stat, clear curdir to force a getcwd()
176	 *  next time we get the value of the current directory.
177	 */
178	badstat = 0;
179	cdcomppath = stalloc(strlen(dest) + 1);
180	scopy(dest, cdcomppath);
181	STARTSTACKSTR(p);
182	if (*dest == '/') {
183		STPUTC('/', p);
184		cdcomppath++;
185	}
186	first = 1;
187	while ((q = getcomponent()) != NULL) {
188		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
189			continue;
190		if (! first)
191			STPUTC('/', p);
192		first = 0;
193		component = q;
194		while (*q)
195			STPUTC(*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 || (p = findcwd(NULL)) == NULL) {
222		INTON;
223		return (-1);
224	}
225	updatepwd(p);
226	INTON;
227	return (0);
228}
229
230/*
231 * Get the next component of the path name pointed to by cdcomppath.
232 * This routine overwrites the string pointed to by cdcomppath.
233 */
234STATIC char *
235getcomponent(void)
236{
237	char *p;
238	char *start;
239
240	if ((p = cdcomppath) == NULL)
241		return NULL;
242	start = cdcomppath;
243	while (*p != '/' && *p != '\0')
244		p++;
245	if (*p == '\0') {
246		cdcomppath = NULL;
247	} else {
248		*p++ = '\0';
249		cdcomppath = p;
250	}
251	return start;
252}
253
254
255STATIC char *
256findcwd(char *dir)
257{
258	char *new;
259	char *p;
260
261	/*
262	 * If our argument is NULL, we don't know the current directory
263	 * any more because we traversed a symbolic link or something
264	 * we couldn't stat().
265	 */
266	if (dir == NULL || curdir == NULL)
267		return getpwd2();
268	cdcomppath = stalloc(strlen(dir) + 1);
269	scopy(dir, cdcomppath);
270	STARTSTACKSTR(new);
271	if (*dir != '/') {
272		p = curdir;
273		while (*p)
274			STPUTC(*p++, new);
275		if (p[-1] == '/')
276			STUNPUTC(new);
277	}
278	while ((p = getcomponent()) != NULL) {
279		if (equal(p, "..")) {
280			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
281		} else if (*p != '\0' && ! equal(p, ".")) {
282			STPUTC('/', new);
283			while (*p)
284				STPUTC(*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 = savestr(dir);
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 */
354char *
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	struct stat stdot, stpwd;
378	char *pwd;
379	int i;
380
381	for (i = MAXPWD;; i *= 2) {
382		pwd = stalloc(i);
383		if (getcwd(pwd, i) != NULL)
384			return pwd;
385		stunalloc(pwd);
386		if (errno != ERANGE)
387			break;
388	}
389
390	pwd = getenv("PWD");
391	if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
392	    stat(pwd, &stpwd) != -1 &&
393	    stdot.st_dev == stpwd.st_dev &&
394	    stdot.st_ino == stpwd.st_ino) {
395		return pwd;
396	}
397	return NULL;
398}
399