1 /* $NetBSD: cd.c,v 1.44 2011/08/31 16:24:54 plunky 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 1.44 2011/08/31 16:24:54 plunky 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
70 STATIC int docd(const char *, int);
71 STATIC char *getcomponent(void);
72 STATIC void updatepwd(const char *);
73 STATIC void find_curdir(int noerror);
74
75 char *curdir = NULL; /* current working directory */
76 char *prevdir; /* previous working directory */
77 STATIC char *cdcomppath;
78
79 int
cdcmd(int argc,char ** argv)80 cdcmd(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
155 STATIC int
docd(const char * dest,int print)156 docd(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
219 STATIC char *
getcomponent(void)220 getcomponent(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
247 STATIC void
updatepwd(const char * dir)248 updatepwd(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
315 int
pwdcmd(int argc,char ** argv)316 pwdcmd(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
340 void
initpwd(void)341 initpwd(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 */
356 void
getpwd(int noerror)357 getpwd(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
383 STATIC void
find_curdir(int noerror)384 find_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) || defined(__minix)
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