1 /* Save and restore the working directory, possibly using a child process.
3 Copyright (C) 2006-2007, 2009-2013 Free Software Foundation, Inc.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert. */
22 #define SAVEWD_INLINE _GL_EXTERN_INLINE
32 #include <sys/types.h>
37 #include "fcntl-safer.h"
39 /* Save the working directory into *WD, if it hasn't been saved
40 already. Return true if a child has been forked to do the real
43 savewd_save (struct savewd *wd)
48 /* Save the working directory, or prepare to fall back if possible. */
50 int fd = open_safer (".", O_SEARCH);
57 if (errno != EACCES && errno != ESTALE)
59 wd->state = ERROR_STATE;
60 wd->val.errnum = errno;
64 wd->state = FORKING_STATE;
68 if (wd->val.child < 0)
70 /* "Save" the initial working directory by forking a new
71 subprocess that will attempt all the work from the chdir
72 until until the next savewd_restore. */
73 wd->val.child = fork ();
74 if (wd->val.child != 0)
76 if (0 < wd->val.child)
78 wd->state = ERROR_STATE;
79 wd->val.errnum = errno;
85 case FD_POST_CHDIR_STATE:
98 savewd_chdir (struct savewd *wd, char const *dir, int options,
104 /* Open the directory if requested, or if avoiding a race condition
105 is requested and possible. */
107 || (options & (HAVE_WORKING_O_NOFOLLOW ? SAVEWD_CHDIR_NOFOLLOW : 0)))
110 (O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK
111 | (options & SAVEWD_CHDIR_NOFOLLOW ? O_NOFOLLOW : 0)));
116 open_result[1] = errno;
119 if (fd < 0 && (errno != EACCES || (options & SAVEWD_CHDIR_READABLE)))
123 if (result == 0 && ! (0 <= fd && options & SAVEWD_CHDIR_SKIP_READABLE))
125 if (savewd_save (wd))
132 result = (fd < 0 ? chdir (dir) : fchdir (fd));
138 wd->state = FD_POST_CHDIR_STATE;
142 case FD_POST_CHDIR_STATE:
147 assert (wd->val.child == 0);
156 if (0 <= fd && ! open_result)
167 savewd_restore (struct savewd *wd, int status)
173 /* The working directory is the desired directory, so there's no
177 case FD_POST_CHDIR_STATE:
178 /* Restore the working directory using fchdir. */
179 if (fchdir (wd->val.fd) == 0)
181 wd->state = FD_STATE;
186 int chdir_errno = errno;
188 wd->state = ERROR_STATE;
189 wd->val.errnum = chdir_errno;
193 /* Report an error if asked to restore the working directory. */
194 errno = wd->val.errnum;
198 /* "Restore" the working directory by waiting for the subprocess
201 pid_t child = wd->val.child;
207 while (waitpid (child, &child_status, 0) < 0)
208 assert (errno == EINTR);
210 if (! WIFEXITED (child_status))
211 raise (WTERMSIG (child_status));
212 return WEXITSTATUS (child_status);
225 savewd_finish (struct savewd *wd)
234 case FD_POST_CHDIR_STATE:
239 assert (wd->val.child < 0);
246 wd->state = FINAL_STATE;
249 /* Return true if the actual work is currently being done by a
252 A true return means that the caller and the subprocess should
253 resynchronize later with savewd_restore, using only their own
254 memory to decide when to resynchronize; they should not consult the
255 file system to decide, because that might lead to race conditions.
256 This is why savewd_chdir is broken out into another function;
257 savewd_chdir's callers _can_ inspect the file system to decide
258 whether to call savewd_chdir. */
260 savewd_delegating (struct savewd const *wd)
262 return wd->state == FORKING_STATE && 0 < wd->val.child;
266 savewd_process_files (int n_files, char **file,
267 int (*act) (char *, struct savewd *, void *),
272 int exit_status = EXIT_SUCCESS;
276 for (last_relative = n_files - 1; 0 <= last_relative; last_relative--)
277 if (! IS_ABSOLUTE_FILE_NAME (file[last_relative]))
280 for (; i < last_relative; i++)
282 if (! savewd_delegating (&wd))
284 int s = act (file[i], &wd, options);
289 if (! IS_ABSOLUTE_FILE_NAME (file[i + 1]))
291 int r = savewd_restore (&wd, exit_status);
299 for (; i < n_files; i++)
301 int s = act (file[i], &wd, options);