1/*	$NetBSD: cd.c,v 1.43 2011/06/18 21:18:46 christos 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 1.43 2011/06/18 21:18:46 christos 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 "builtins.h"
61#include "output.h"
62#include "memalloc.h"
63#include "error.h"
64#include "exec.h"
65#include "redir.h"
66#include "mystring.h"
67#include "show.h"
68#include "cd.h"
69
70STATIC int docd(const char *, int);
71STATIC char *getcomponent(void);
72STATIC void updatepwd(const char *);
73STATIC void find_curdir(int noerror);
74
75char *curdir = NULL;		/* current working directory */
76char *prevdir;			/* previous working directory */
77STATIC char *cdcomppath;
78
79int
80cdcmd(int argc, char **argv)
81{
82	const char *dest;
83	const char *path, *p;
84	char *d;
85	struct stat statb;
86	int print = cdprint;	/* set -cdprint to enable */
87
88	while (nextopt("P") != '\0')
89		;
90
91	/*
92	 * Try (quite hard) to have 'curdir' defined, nothing has set
93	 * it on entry to the shell, but we want 'cd fred; cd -' to work.
94	 */
95	getpwd(1);
96	dest = *argptr;
97	if (dest == NULL) {
98		dest = bltinlookup("HOME", 1);
99		if (dest == NULL)
100			error("HOME not set");
101	} else {
102		if (argptr[1]) {
103			/* Do 'ksh' style substitution */
104			if (!curdir)
105				error("PWD not set");
106			p = strstr(curdir, dest);
107			if (!p)
108				error("bad substitution");
109			d = stalloc(strlen(curdir) + strlen(argptr[1]) + 1);
110			memcpy(d, curdir, p - curdir);
111			strcpy(d + (p - curdir), argptr[1]);
112			strcat(d, p + strlen(dest));
113			dest = d;
114			print = 1;
115		}
116	}
117
118	if (dest[0] == '-' && dest[1] == '\0') {
119		dest = prevdir ? prevdir : curdir;
120		print = 1;
121	}
122	if (*dest == '\0')
123	        dest = ".";
124	p = dest;
125	if (*p == '.' && *++p == '.')
126	    p++;
127	if (*p == 0 || *p == '/' || (path = bltinlookup("CDPATH", 1)) == NULL)
128		path = nullstr;
129	while ((p = padvance(&path, dest)) != NULL) {
130		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
131			if (!print) {
132				/*
133				 * XXX - rethink
134				 */
135				if (p[0] == '.' && p[1] == '/' && p[2] != '\0')
136					print = strcmp(p + 2, dest);
137				else
138					print = strcmp(p, dest);
139			}
140			if (docd(p, print) >= 0)
141				return 0;
142
143		}
144	}
145	error("can't cd to %s", dest);
146	/* NOTREACHED */
147}
148
149
150/*
151 * Actually do the chdir.  In an interactive shell, print the
152 * directory name if "print" is nonzero.
153 */
154
155STATIC int
156docd(const char *dest, int print)
157{
158	char *p;
159	char *q;
160	char *component;
161	struct stat statb;
162	int first;
163	int badstat;
164
165	TRACE(("docd(\"%s\", %d) called\n", dest, print));
166
167	/*
168	 *  Check each component of the path. If we find a symlink or
169	 *  something we can't stat, clear curdir to force a getcwd()
170	 *  next time we get the value of the current directory.
171	 */
172	badstat = 0;
173	cdcomppath = stalloc(strlen(dest) + 1);
174	scopy(dest, cdcomppath);
175	STARTSTACKSTR(p);
176	if (*dest == '/') {
177		STPUTC('/', p);
178		cdcomppath++;
179	}
180	first = 1;
181	while ((q = getcomponent()) != NULL) {
182		if (q[0] == '\0' || (q[0] == '.' && q[1] == '\0'))
183			continue;
184		if (! first)
185			STPUTC('/', p);
186		first = 0;
187		component = q;
188		while (*q)
189			STPUTC(*q++, p);
190		if (equal(component, ".."))
191			continue;
192		STACKSTRNUL(p);
193		if ((lstat(stackblock(), &statb) < 0)
194		    || (S_ISLNK(statb.st_mode)))  {
195			/* print = 1; */
196			badstat = 1;
197			break;
198		}
199	}
200
201	INTOFF;
202	if (chdir(dest) < 0) {
203		INTON;
204		return -1;
205	}
206	updatepwd(badstat ? NULL : dest);
207	INTON;
208	if (print && iflag == 1 && curdir)
209		out1fmt("%s\n", curdir);
210	return 0;
211}
212
213
214/*
215 * Get the next component of the path name pointed to by cdcomppath.
216 * This routine overwrites the string pointed to by cdcomppath.
217 */
218
219STATIC char *
220getcomponent(void)
221{
222	char *p;
223	char *start;
224
225	if ((p = cdcomppath) == NULL)
226		return NULL;
227	start = cdcomppath;
228	while (*p != '/' && *p != '\0')
229		p++;
230	if (*p == '\0') {
231		cdcomppath = NULL;
232	} else {
233		*p++ = '\0';
234		cdcomppath = p;
235	}
236	return start;
237}
238
239
240
241/*
242 * Update curdir (the name of the current directory) in response to a
243 * cd command.  We also call hashcd to let the routines in exec.c know
244 * that the current directory has changed.
245 */
246
247STATIC void
248updatepwd(const char *dir)
249{
250	char *new;
251	char *p;
252
253	hashcd();				/* update command hash table */
254
255	/*
256	 * If our argument is NULL, we don't know the current directory
257	 * any more because we traversed a symbolic link or something
258	 * we couldn't stat().
259	 */
260	if (dir == NULL || curdir == NULL)  {
261		if (prevdir)
262			ckfree(prevdir);
263		INTOFF;
264		prevdir = curdir;
265		curdir = NULL;
266		getpwd(1);
267		INTON;
268		if (curdir) {
269			setvar("OLDPWD", prevdir, VEXPORT);
270			setvar("PWD", curdir, VEXPORT);
271		} else
272			unsetvar("PWD", 0);
273		return;
274	}
275	cdcomppath = stalloc(strlen(dir) + 1);
276	scopy(dir, cdcomppath);
277	STARTSTACKSTR(new);
278	if (*dir != '/') {
279		p = curdir;
280		while (*p)
281			STPUTC(*p++, new);
282		if (p[-1] == '/')
283			STUNPUTC(new);
284	}
285	while ((p = getcomponent()) != NULL) {
286		if (equal(p, "..")) {
287			while (new > stackblock() && (STUNPUTC(new), *new) != '/');
288		} else if (*p != '\0' && ! equal(p, ".")) {
289			STPUTC('/', new);
290			while (*p)
291				STPUTC(*p++, new);
292		}
293	}
294	if (new == stackblock())
295		STPUTC('/', new);
296	STACKSTRNUL(new);
297	INTOFF;
298	if (prevdir)
299		ckfree(prevdir);
300	prevdir = curdir;
301	curdir = savestr(stackblock());
302	setvar("OLDPWD", prevdir, VEXPORT);
303	setvar("PWD", curdir, VEXPORT);
304	INTON;
305}
306
307/*
308 * Posix says the default should be 'pwd -L' (as below), however
309 * the 'cd' command (above) does something much nearer to the
310 * posix 'cd -P' (not the posix default of 'cd -L').
311 * If 'cd' is changed to support -P/L then the default here
312 * needs to be revisited if the historic behaviour is to be kept.
313 */
314
315int
316pwdcmd(int argc, char **argv)
317{
318	int i;
319	char opt = 'L';
320
321	while ((i = nextopt("LP")) != '\0')
322		opt = i;
323	if (*argptr)
324		error("unexpected argument");
325
326	if (opt == 'L')
327		getpwd(0);
328	else
329		find_curdir(0);
330
331	setvar("OLDPWD", prevdir, VEXPORT);
332	setvar("PWD", curdir, VEXPORT);
333	out1str(curdir);
334	out1c('\n');
335	return 0;
336}
337
338
339
340void
341initpwd(void)
342{
343	getpwd(1);
344	if (curdir)
345		setvar("PWD", curdir, VEXPORT);
346	else
347		sh_warnx("Cannot determine current working directory");
348}
349
350#define MAXPWD 256
351
352/*
353 * Find out what the current directory is. If we already know the current
354 * directory, this routine returns immediately.
355 */
356void
357getpwd(int noerror)
358{
359	char *pwd;
360	struct stat stdot, stpwd;
361	static int first = 1;
362
363	if (curdir)
364		return;
365
366	if (first) {
367		first = 0;
368		pwd = getenv("PWD");
369		if (pwd && *pwd == '/' && stat(".", &stdot) != -1 &&
370		    stat(pwd, &stpwd) != -1 &&
371		    stdot.st_dev == stpwd.st_dev &&
372		    stdot.st_ino == stpwd.st_ino) {
373			curdir = savestr(pwd);
374			return;
375		}
376	}
377
378	find_curdir(noerror);
379
380	return;
381}
382
383STATIC void
384find_curdir(int noerror)
385{
386	int i;
387	char *pwd;
388
389	/*
390	 * Things are a bit complicated here; we could have just used
391	 * getcwd, but traditionally getcwd is implemented using popen
392	 * to /bin/pwd. This creates a problem for us, since we cannot
393	 * keep track of the job if it is being ran behind our backs.
394	 * So we re-implement getcwd(), and we suppress interrupts
395	 * throughout the process. This is not completely safe, since
396	 * the user can still break out of it by killing the pwd program.
397	 * We still try to use getcwd for systems that we know have a
398	 * c implementation of getcwd, that does not open a pipe to
399	 * /bin/pwd.
400	 */
401#if defined(__NetBSD__) || defined(__SVR4)
402
403	for (i = MAXPWD;; i *= 2) {
404		pwd = stalloc(i);
405		if (getcwd(pwd, i) != NULL) {
406			curdir = savestr(pwd);
407			return;
408		}
409		stunalloc(pwd);
410		if (errno == ERANGE)
411			continue;
412		if (!noerror)
413			error("getcwd() failed: %s", strerror(errno));
414		return;
415	}
416#else
417	{
418		char *p;
419		int status;
420		struct job *jp;
421		int pip[2];
422
423		pwd = stalloc(MAXPWD);
424		INTOFF;
425		if (pipe(pip) < 0)
426			error("Pipe call failed");
427		jp = makejob(NULL, 1);
428		if (forkshell(jp, NULL, FORK_NOJOB) == 0) {
429			(void) close(pip[0]);
430			if (pip[1] != 1) {
431				close(1);
432				copyfd(pip[1], 1, 1);
433				close(pip[1]);
434			}
435			(void) execl("/bin/pwd", "pwd", (char *)0);
436			error("Cannot exec /bin/pwd");
437		}
438		(void) close(pip[1]);
439		pip[1] = -1;
440		p = pwd;
441		while ((i = read(pip[0], p, pwd + MAXPWD - p)) > 0
442		     || (i == -1 && errno == EINTR)) {
443			if (i > 0)
444				p += i;
445		}
446		(void) close(pip[0]);
447		pip[0] = -1;
448		status = waitforjob(jp);
449		if (status != 0)
450			error((char *)0);
451		if (i < 0 || p == pwd || p[-1] != '\n') {
452			if (noerror) {
453				INTON;
454				return;
455			}
456			error("pwd command failed");
457		}
458		p[-1] = '\0';
459		INTON;
460		curdir = savestr(pwd);
461		return;
462	}
463#endif
464}
465