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
38 static 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
69 STATIC int docd(char *, int);
70 STATIC char *getcomponent(void);
71 STATIC void updatepwd(char *);
72 STATIC void find_curdir(int noerror);
73
74 char *curdir = NULL; /* current working directory */
75 char *prevdir; /* previous working directory */
76 STATIC char *cdcomppath;
77
78 int
cdcmd(int argc,char ** argv)79 cdcmd(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
149 STATIC int
docd(char * dest,int print)150 docd(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
213 STATIC char *
getcomponent()214 getcomponent()
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
241 STATIC void
updatepwd(char * dir)242 updatepwd(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
307 int
pwdcmd(int argc,char ** argv)308 pwdcmd(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 */
338 void
getpwd(int noerror)339 getpwd(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
365 STATIC void
find_curdir(int noerror)366 find_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