cd.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0 
1/*	$NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl 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. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#ifndef lint
37#if 0
38static char sccsid[] = "@(#)cd.c	8.2 (Berkeley) 5/4/95";
39#else
40__RCSID("$NetBSD: cd.c,v 1.34 2003/11/14 20:00:28 dsl Exp $");
41#endif
42#endif /* not lint */
43
44#include <sys/types.h>
45#include <sys/stat.h>
46#include <stdlib.h>
47#include <string.h>
48#include <unistd.h>
49#include <errno.h>
50
51/*
52 * The cd and pwd commands.
53 */
54
55#include "shell.h"
56#include "var.h"
57#include "nodes.h"	/* for jobs.h */
58#include "jobs.h"
59#include "options.h"
60#include "output.h"
61#include "memalloc.h"
62#include "error.h"
63#include "exec.h"
64#include "redir.h"
65#include "mystring.h"
66#include "show.h"
67#include "cd.h"
68
69STATIC int docd(char *, int);
70STATIC char *getcomponent(void);
71STATIC void updatepwd(char *);
72STATIC void find_curdir(int noerror);
73
74char *curdir = NULL;		/* current working directory */
75char *prevdir;			/* previous working directory */
76STATIC char *cdcomppath;
77
78int
79cdcmd(int argc, char **argv)
80{
81	const char *dest;
82	const char *path;
83	char *p, *d;
84	struct stat statb;
85	int print = cdprint;	/* set -cdprint to enable */
86
87	nextopt(nullstr);
88
89	/*
90	 * Try (quite hard) to have 'curdir' defined, nothing has set
91	 * it on entry to the shell, but we want 'cd fred; cd -' to work.
92	 */
93	getpwd(1);
94	dest = *argptr;
95	if (dest == NULL) {
96		dest = bltinlookup("HOME", 1);
97		if (dest == NULL)
98			error("HOME not set");
99	} else {
100		if (argptr[1]) {
101			/* Do 'ksh' style substitution */
102			if (!curdir)
103				error("PWD not set");
104			p = strstr(curdir, dest);
105			if (!p)
106				error("bad substitution");
107			d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
108			memcpy(d, curdir, p - curdir);
109			strcpy(d + (p - curdir), argptr[1]);
110			strcat(d, p + strlen(dest));
111			dest = d;
112			print = 1;
113		}
114	}
115
116	if (dest[0] == '-' && dest[1] == '\0') {
117		dest = prevdir ? prevdir : curdir;
118		print = 1;
119	}
120	if (*dest == '\0')
121	        dest = ".";
122	if (*dest == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
123		path = nullstr;
124	while ((p = padvance(&path, dest)) != NULL) {
125		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
126			if (!print) {
127				/*
128				 * XXX - rethink
129				 */
130				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
131					p += 2;
132				print = strcmp(p, dest);
133			}
134			if (docd(p, print) >= 0)
135				return 0;
136
137		}
138	}
139	error("can't cd to %s", dest);
140	/* NOTREACHED */
141}
142
143
144/*
145 * Actually do the chdir.  In an interactive shell, print the
146 * directory name if "print" is nonzero.
147 */
148
149STATIC int
150docd(char *dest, int print)
151{
152	char *p;
153	char *q;
154	char *component;
155	struct stat statb;
156	int first;
157	int badstat;
158
159	TRACE(("docd(\"%s\", %d) called\n", dest, print));
160
161	/*
162	 *  Check each component of the path. If we find a symlink or
163	 *  something we can't stat, clear curdir to force a getcwd()
164	 *  next time we get the value of the current directory.
165	 */
166	badstat = 0;
167	cdcomppath = stalloc(strlen(dest) + 1);
168	scopy(dest, cdcomppath);
169	STARTSTACKSTR(p);
170	if (*dest == '/') {
171		STPUTC('/', p);
172		cdcomppath++;
173	}
174	first = 1;
175	while ((q = getcomponent()) != NULL) {
176		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
177			continue;
178		if (! first)
179			STPUTC('/', p);
180		first = 0;
181		component = q;
182		while (*q)
183			STPUTC(*q++, p);
184		if (equal(component, ".."))
185			continue;
186		STACKSTRNUL(p);
187		if ((lstat(stackblock(), &statb) < 0)
188		    || (S_ISLNK(statb.st_mode)))  {
189			/* print = 1; */
190			badstat = 1;
191			break;
192		}
193	}
194
195	INTOFF;
196	if (chdir(dest) < 0) {
197		INTON;
198		return -1;
199	}
200	updatepwd(badstat ? NULL : dest);
201	INTON;
202	if (print && iflag && curdir)
203		out1fmt("%s\n", curdir);
204	return 0;
205}
206
207
208/*
209 * Get the next component of the path name pointed to by cdcomppath.
210 * This routine overwrites the string pointed to by cdcomppath.
211 */
212
213STATIC char *
214getcomponent()
215{
216	char *p;
217	char *start;
218
219	if ((p = cdcomppath) == NULL)
220		return NULL;
221	start = cdcomppath;
222	while (*p != '/' && *p != '\0')
223		p++;
224	if (*p == '\0') {
225		cdcomppath = NULL;
226	} else {
227		*p++ = '\0';
228		cdcomppath = p;
229	}
230	return start;
231}
232
233
234
235/*
236 * Update curdir (the name of the current directory) in response to a
237 * cd command.  We also call hashcd to let the routines in exec.c know
238 * that the current directory has changed.
239 */
240
241STATIC void
242updatepwd(char *dir)
243{
244	char *new;
245	char *p;
246
247	hashcd();				/* update command hash table */
248
249	/*
250	 * If our argument is NULL, we don't know the current directory
251	 * any more because we traversed a symbolic link or something
252	 * we couldn't stat().
253	 */
254	if (dir == NULL || curdir == NULL)  {
255		if (prevdir)
256			ckfree(prevdir);
257		INTOFF;
258		prevdir = curdir;
259		curdir = NULL;
260		getpwd(1);
261		INTON;
262		if (curdir)
263			setvar("PWD", curdir, VEXPORT);
264		else
265			unsetvar("PWD", 0);
266		return;
267	}
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	INTOFF;
291	if (prevdir)
292		ckfree(prevdir);
293	prevdir = curdir;
294	curdir = savestr(stackblock());
295	setvar("PWD", curdir, VEXPORT);
296	INTON;
297}
298
299/*
300 * Posix says the default should be 'pwd -L' (as below), however
301 * the 'cd' command (above) does something much nearer to the
302 * posix 'cd -P' (not the posix default of 'cd -L').
303 * If 'cd' is changed to support -P/L then the default here
304 * needs to be revisited if the historic behaviour is to be kept.
305 */
306
307int
308pwdcmd(int argc, char **argv)
309{
310	int i;
311	char opt = 'L';
312
313	while ((i = nextopt("LP")) != '\0')
314		opt = i;
315	if (*argptr)
316		error("unexpected argument");
317
318	if (opt == 'L')
319		getpwd(0);
320	else
321		find_curdir(0);
322
323	setvar("PWD", curdir, VEXPORT);
324	out1str(curdir);
325	out1c('\n');
326	return 0;
327}
328
329
330
331
332#define MAXPWD 256
333
334/*
335 * Find out what the current directory is. If we already know the current
336 * directory, this routine returns immediately.
337 */
338void
339getpwd(int noerror)
340{
341	char *pwd;
342	struct stat stdot, stpwd;
343	static int first = 1;
344
345	if (curdir)
346		return;
347
348	if (first) {
349		first = 0;
350		pwd = getenv("PWD");
351		if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
352		    stat(pwd, &stpwd) != -1 &&
353		    stdot.st_dev == stpwd.st_dev &&
354		    stdot.st_ino == stpwd.st_ino) {
355			curdir = savestr(pwd);
356			return;
357		}
358	}
359
360	find_curdir(noerror);
361
362	return;
363}
364
365STATIC void
366find_curdir(int noerror)
367{
368	int i;
369	char *pwd;
370
371	/*
372	 * Things are a bit complicated here; we could have just used
373	 * getcwd, but traditionally getcwd is implemented using popen
374	 * to /bin/pwd. This creates a problem for us, since we cannot
375	 * keep track of the job if it is being ran behind our backs.
376	 * So we re-implement getcwd(), and we suppress interrupts
377	 * throughout the process. This is not completely safe, since
378	 * the user can still break out of it by killing the pwd program.
379	 * We still try to use getcwd for systems that we know have a
380	 * c implementation of getcwd, that does not open a pipe to
381	 * /bin/pwd.
382	 */
383#if defined(__NetBSD__) || defined(__SVR4) || defined(__linux__)
384	for (i = MAXPWD;; i *= 2) {
385		pwd = stalloc(i);
386		if (getcwd(pwd, i) != NULL) {
387			curdir = savestr(pwd);
388			return;
389		}
390		stunalloc(pwd);
391		if (errno == ERANGE)
392			continue;
393		if (!noerror)
394			error("getcwd() failed: %s", strerror(errno));
395		return;
396	}
397#else
398	{
399		char *p;
400		int status;
401		struct job *jp;
402		int pip[2];
403
404		pwd = stalloc(MAXPWD);
405		INTOFF;
406		if (pipe(pip) < 0)
407			error("Pipe call failed");
408		jp = makejob((union node *)NULL, 1);
409		if (forkshell(jp, (union node *)NULL, FORK_NOJOB) == 0) {
410			(void) close(pip[0]);
411			if (pip[1] != 1) {
412				close(1);
413				copyfd(pip[1], 1);
414				close(pip[1]);
415			}
416			(void) execl("/bin/pwd", "pwd", (char *)0);
417			sh_warn("Cannot exec /bin/pwd");
418			exit(1);
419		}
420		(void) close(pip[1]);
421		pip[1] = -1;
422		p = pwd;
423		while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
424		     || (i == -1 && errno == EINTR)) {
425			if (i > 0)
426				p += i;
427		}
428		(void) close(pip[0]);
429		pip[0] = -1;
430		status = waitforjob(jp);
431		if (status != 0)
432			error((char *)0);
433		if (i < 0 || p == pwd || p[-1] != '\n') {
434			if (noerror) {
435				INTON;
436				return;
437			}
438			error("pwd command failed");
439		}
440		p[-1] = '\0';
441		INTON;
442		curdir = savestr(pwd);
443		return;
444	}
445#endif
446}
447