cd.c revision 223060 
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 223060 2011-06-13 21:03:27Z 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#include "builtins.h"
67
68static int cdlogical(char *);
69static int cdphysical(char *);
70static int docd(char *, int, int);
71static char *getcomponent(void);
72static char *findcwd(char *);
73static void updatepwd(char *);
74static char *getpwd(void);
75static char *getpwd2(void);
76
77static char *curdir = NULL;	/* current working directory */
78static char *prevdir;		/* previous working directory */
79static char *cdcomppath;
80
81int
82cdcmd(int argc, char **argv)
83{
84	const char *dest;
85	const char *path;
86	char *p;
87	struct stat statb;
88	int ch, phys, print = 0, getcwderr = 0;
89	int rc;
90	int errno1 = ENOENT;
91
92	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
93	phys = Pflag;
94	while ((ch = getopt(argc, argv, "eLP")) != -1) {
95		switch (ch) {
96		case 'e':
97			getcwderr = 1;
98			break;
99		case 'L':
100			phys = 0;
101			break;
102		case 'P':
103			phys = 1;
104			break;
105		default:
106			error("unknown option: -%c", optopt);
107			break;
108		}
109	}
110	argc -= optind;
111	argv += optind;
112
113	if (argc > 1)
114		error("too many arguments");
115
116	if ((dest = *argv) == NULL && (dest = bltinlookup("HOME", 1)) == NULL)
117		error("HOME not set");
118	if (*dest == '\0')
119		dest = ".";
120	if (dest[0] == '-' && dest[1] == '\0') {
121		dest = prevdir ? prevdir : curdir;
122		if (dest)
123			print = 1;
124		else
125			dest = ".";
126	}
127	if (dest[0] == '/' ||
128	    (dest[0] == '.' && (dest[1] == '/' || dest[1] == '\0')) ||
129	    (dest[0] == '.' && dest[1] == '.' && (dest[2] == '/' || dest[2] == '\0')) ||
130	    (path = bltinlookup("CDPATH", 1)) == NULL)
131		path = nullstr;
132	while ((p = padvance(&path, dest)) != NULL) {
133		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
134			if (!print) {
135				/*
136				 * XXX - rethink
137				 */
138				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
139					print = strcmp(p + 2, dest);
140				else
141					print = strcmp(p, dest);
142			}
143			rc = docd(p, print, phys);
144			if (rc >= 0)
145				return getcwderr ? rc : 0;
146			if (errno != ENOENT)
147				errno1 = errno;
148		}
149	}
150	error("%s: %s", dest, strerror(errno1));
151	/*NOTREACHED*/
152	return 0;
153}
154
155
156/*
157 * Actually change the directory.  In an interactive shell, print the
158 * directory name if "print" is nonzero.
159 */
160static int
161docd(char *dest, int print, int phys)
162{
163	int rc;
164
165	TRACE(("docd(\"%s\", %d, %d) called\n", dest, print, phys));
166
167	/* If logical cd fails, fall back to physical. */
168	if ((phys || (rc = cdlogical(dest)) < 0) && (rc = cdphysical(dest)) < 0)
169		return (-1);
170
171	if (print && iflag && curdir)
172		out1fmt("%s\n", curdir);
173
174	return (rc);
175}
176
177static int
178cdlogical(char *dest)
179{
180	char *p;
181	char *q;
182	char *component;
183	struct stat statb;
184	int first;
185	int badstat;
186
187	/*
188	 *  Check each component of the path. If we find a symlink or
189	 *  something we can't stat, clear curdir to force a getcwd()
190	 *  next time we get the value of the current directory.
191	 */
192	badstat = 0;
193	cdcomppath = stalloc(strlen(dest) + 1);
194	scopy(dest, cdcomppath);
195	STARTSTACKSTR(p);
196	if (*dest == '/') {
197		STPUTC('/', p);
198		cdcomppath++;
199	}
200	first = 1;
201	while ((q = getcomponent()) != NULL) {
202		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
203			continue;
204		if (! first)
205			STPUTC('/', p);
206		first = 0;
207		component = q;
208		STPUTS(q, p);
209		if (equal(component, ".."))
210			continue;
211		STACKSTRNUL(p);
212		if (lstat(stackblock(), &statb) < 0) {
213			badstat = 1;
214			break;
215		}
216	}
217
218	INTOFF;
219	if ((p = findcwd(badstat ? NULL : dest)) == NULL || chdir(p) < 0) {
220		INTON;
221		return (-1);
222	}
223	updatepwd(p);
224	INTON;
225	return (0);
226}
227
228static int
229cdphysical(char *dest)
230{
231	char *p;
232	int rc = 0;
233
234	INTOFF;
235	if (chdir(dest) < 0) {
236		INTON;
237		return (-1);
238	}
239	p = findcwd(NULL);
240	if (p == NULL) {
241		warning("warning: failed to get name of current directory");
242		rc = 1;
243	}
244	updatepwd(p);
245	INTON;
246	return (rc);
247}
248
249/*
250 * Get the next component of the path name pointed to by cdcomppath.
251 * This routine overwrites the string pointed to by cdcomppath.
252 */
253static char *
254getcomponent(void)
255{
256	char *p;
257	char *start;
258
259	if ((p = cdcomppath) == NULL)
260		return NULL;
261	start = cdcomppath;
262	while (*p != '/' && *p != '\0')
263		p++;
264	if (*p == '\0') {
265		cdcomppath = NULL;
266	} else {
267		*p++ = '\0';
268		cdcomppath = p;
269	}
270	return start;
271}
272
273
274static char *
275findcwd(char *dir)
276{
277	char *new;
278	char *p;
279
280	/*
281	 * If our argument is NULL, we don't know the current directory
282	 * any more because we traversed a symbolic link or something
283	 * we couldn't stat().
284	 */
285	if (dir == NULL || curdir == NULL)
286		return getpwd2();
287	cdcomppath = stalloc(strlen(dir) + 1);
288	scopy(dir, cdcomppath);
289	STARTSTACKSTR(new);
290	if (*dir != '/') {
291		STPUTS(curdir, new);
292		if (STTOPC(new) == '/')
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			STPUTS(p, new);
301		}
302	}
303	if (new == stackblock())
304		STPUTC('/', new);
305	STACKSTRNUL(new);
306	return stackblock();
307}
308
309/*
310 * Update curdir (the name of the current directory) in response to a
311 * cd command.  We also call hashcd to let the routines in exec.c know
312 * that the current directory has changed.
313 */
314static void
315updatepwd(char *dir)
316{
317	hashcd();				/* update command hash table */
318
319	if (prevdir)
320		ckfree(prevdir);
321	prevdir = curdir;
322	curdir = dir ? savestr(dir) : NULL;
323	setvar("PWD", curdir, VEXPORT);
324	setvar("OLDPWD", prevdir, VEXPORT);
325}
326
327int
328pwdcmd(int argc, char **argv)
329{
330	char *p;
331	int ch, phys;
332
333	optreset = 1; optind = 1; opterr = 0; /* initialize getopt */
334	phys = Pflag;
335	while ((ch = getopt(argc, argv, "LP")) != -1) {
336		switch (ch) {
337		case 'L':
338			phys = 0;
339			break;
340		case 'P':
341			phys = 1;
342			break;
343		default:
344			error("unknown option: -%c", optopt);
345			break;
346		}
347	}
348	argc -= optind;
349	argv += optind;
350
351	if (argc != 0)
352		error("too many arguments");
353
354	if (!phys && getpwd()) {
355		out1str(curdir);
356		out1c('\n');
357	} else {
358		if ((p = getpwd2()) == NULL)
359			error(".: %s", strerror(errno));
360		out1str(p);
361		out1c('\n');
362	}
363
364	return 0;
365}
366
367/*
368 * Get the current directory and cache the result in curdir.
369 */
370static char *
371getpwd(void)
372{
373	char *p;
374
375	if (curdir)
376		return curdir;
377
378	p = getpwd2();
379	if (p != NULL)
380		curdir = savestr(p);
381
382	return curdir;
383}
384
385#define MAXPWD 256
386
387/*
388 * Return the current directory.
389 */
390static char *
391getpwd2(void)
392{
393	char *pwd;
394	int i;
395
396	for (i = MAXPWD;; i *= 2) {
397		pwd = stalloc(i);
398		if (getcwd(pwd, i) != NULL)
399			return pwd;
400		stunalloc(pwd);
401		if (errno != ERANGE)
402			break;
403	}
404
405	return NULL;
406}
407
408/*
409 * Initialize PWD in a new shell.
410 * If the shell is interactive, we need to warn if this fails.
411 */
412void
413pwd_init(int warn)
414{
415	char *pwd;
416	struct stat stdot, stpwd;
417
418	pwd = lookupvar("PWD");
419	if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
420	    stat(pwd, &stpwd) != -1 &&
421	    stdot.st_dev == stpwd.st_dev &&
422	    stdot.st_ino == stpwd.st_ino) {
423		if (curdir)
424			ckfree(curdir);
425		curdir = savestr(pwd);
426	}
427	if (getpwd() == NULL && warn)
428		out2fmt_flush("sh: cannot determine working directory\n");
429	setvar("PWD", curdir, VEXPORT);
430}
431