1 /* Save and restore the working directory, possibly using a subprocess.
3 Copyright (C) 2006 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 2, or (at your option)
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, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19 /* Written by Paul Eggert. */
25 #include <sys/types.h>
27 /* A saved working directory. The member names and constants defined
28 by this structure are private to the savewd module. */
31 /* The state of this object. */
34 /* This object has been created but does not yet represent
35 the working directory. */
38 /* val.fd is the original working directory's file descriptor.
39 It is still the working directory. */
42 /* Like FD_STATE, but the working directory has changed, so
43 restoring it will require a fchdir. */
46 /* Fork and let the subprocess do the work. val.child is 0 in a
47 child, negative in a childless parent, and the child process
48 ID in a parent with a child. */
51 /* A serious problem argues against further efforts. val.errnum
52 contains the error number (e.g., EIO). */
55 /* savewd_finish has been called, so the application no longer
56 cares whether the working directory is saved, and there is no
61 /* The object's value. */
70 /* Initialize a saved working directory object. */
72 savewd_init (struct savewd *wd)
74 wd->state = INITIAL_STATE;
78 /* Options for savewd_chdir. */
81 /* Do not follow symbolic links, if supported. */
82 SAVEWD_CHDIR_NOFOLLOW = 1,
84 /* The directory should be readable, so fail if it happens to be
85 discovered that the directory is not readable. (Unreadable
86 directories are not necessarily diagnosed, though.) */
87 SAVEWD_CHDIR_READABLE = 2,
89 /* Do not chdir if the directory is readable; simply succeed
90 without invoking chdir if the directory was opened. */
91 SAVEWD_CHDIR_SKIP_READABLE = 4
94 /* Change the directory, and if successful, record into *WD the fact
95 that the process chdired into DIR. A process using this module
96 should use savewd_chdir rather than chdir or fchdir. Obey the
97 options specified in OPTIONS.
99 If OPEN_RESULT is not null, store into OPEN_RESULT[0] a file
100 descriptor that accesses DIR if a file descriptor is successfully
101 obtained. Store -1 otherwise, setting OPEN_RESULT[1] to the error
102 number. Store through OPEN_RESULT regardless of whether the chdir
103 is successful. However, when -2 is returned, the contents of
104 OPEN_RESULT are indeterminate since the file descriptor is closed
107 Return -2 if a subprocess was spun off to do the real work, -1
108 (setting errno) if unsuccessful, 0 if successful. */
109 int savewd_chdir (struct savewd *wd, char const *dir, int options,
112 /* Restore the working directory from *WD. STATUS indicates the exit
113 status corresponding to the work done since the last save; this is
114 used when the caller is in a subprocess. Return 0 if successful,
115 -1 (setting errno) on our failure, a positive subprocess exit
116 status if the working directory was restored in the parent but the
117 subprocess failed. */
118 int savewd_restore (struct savewd *wd, int status);
120 /* Return WD's error number, or 0 if WD is not in an error state. */
122 savewd_errno (struct savewd const *wd)
124 return (wd->state == ERROR_STATE ? wd->val.errnum : 0);
127 /* Deallocate any resources associated with WD. A program that chdirs
128 should restore before finishing. */
129 void savewd_finish (struct savewd *wd);
131 /* Process N_FILES file names, FILE[0] through FILE[N_FILES - 1].
132 For each file name F, call ACT (F, WD, OPTIONS); ACT should invoke
133 savewd_chdir as needed, and should return an exit status. WD
134 represents the working directory; it may be in an error state when
137 Save and restore the working directory as needed by the file name
138 vector; assume that ACT does not require access to any relative
139 file names other than its first argument, and that it is OK if the
140 working directory is changed when this function returns. Some
141 actions may be applied in a subprocess.
143 Return the maximum exit status that any call to ACT returned, or
144 EXIT_SUCCESS (i.e., 0) if no calls were made. */
145 int savewd_process_files (int n_files, char **file,
146 int (*act) (char *, struct savewd *, void *),