1 /* Save and restore the working directory, possibly using a subprocess.
3 Copyright (C) 2006, 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. */
24 #include <sys/types.h>
26 #ifndef _GL_INLINE_HEADER_BEGIN
27 #error "Please include config.h first."
29 _GL_INLINE_HEADER_BEGIN
31 # define SAVEWD_INLINE _GL_INLINE
34 /* A saved working directory. The member names and constants defined
35 by this structure are private to the savewd module. */
38 /* The state of this object. */
41 /* This object has been created but does not yet represent
42 the working directory. */
45 /* val.fd is the original working directory's file descriptor.
46 It is still the working directory. */
49 /* Like FD_STATE, but the working directory has changed, so
50 restoring it will require a fchdir. */
53 /* Fork and let the subprocess do the work. val.child is 0 in a
54 child, negative in a childless parent, and the child process
55 ID in a parent with a child. */
58 /* A serious problem argues against further efforts. val.errnum
59 contains the error number (e.g., EIO). */
62 /* savewd_finish has been called, so the application no longer
63 cares whether the working directory is saved, and there is no
68 /* The object's value. */
77 /* Initialize a saved working directory object. */
79 savewd_init (struct savewd *wd)
81 wd->state = INITIAL_STATE;
85 /* Options for savewd_chdir. */
88 /* Do not follow symbolic links, if supported. */
89 SAVEWD_CHDIR_NOFOLLOW = 1,
91 /* The directory should be readable, so fail if it happens to be
92 discovered that the directory is not readable. (Unreadable
93 directories are not necessarily diagnosed, though.) */
94 SAVEWD_CHDIR_READABLE = 2,
96 /* Do not chdir if the directory is readable; simply succeed
97 without invoking chdir if the directory was opened. */
98 SAVEWD_CHDIR_SKIP_READABLE = 4
101 /* Change the directory, and if successful, record into *WD the fact
102 that the process chdired into DIR. A process using this module
103 should use savewd_chdir rather than chdir or fchdir. Obey the
104 options specified in OPTIONS.
106 If OPEN_RESULT is not null, store into OPEN_RESULT[0] a file
107 descriptor that accesses DIR if a file descriptor is successfully
108 obtained. Store -1 otherwise, setting OPEN_RESULT[1] to the error
109 number. Store through OPEN_RESULT regardless of whether the chdir
110 is successful. However, when -2 is returned, the contents of
111 OPEN_RESULT are indeterminate since the file descriptor is closed
114 Return -2 if a subprocess was spun off to do the real work, -1
115 (setting errno) if unsuccessful, 0 if successful. */
116 int savewd_chdir (struct savewd *wd, char const *dir, int options,
119 /* Restore the working directory from *WD. STATUS indicates the exit
120 status corresponding to the work done since the last save; this is
121 used when the caller is in a subprocess. Return 0 if successful,
122 -1 (setting errno) on our failure, a positive subprocess exit
123 status if the working directory was restored in the parent but the
124 subprocess failed. */
125 int savewd_restore (struct savewd *wd, int status);
127 /* Return WD's error number, or 0 if WD is not in an error state. */
129 savewd_errno (struct savewd const *wd)
131 return (wd->state == ERROR_STATE ? wd->val.errnum : 0);
134 /* Deallocate any resources associated with WD. A program that chdirs
135 should restore before finishing. */
136 void savewd_finish (struct savewd *wd);
138 /* Process N_FILES file names, FILE[0] through FILE[N_FILES - 1].
139 For each file name F, call ACT (F, WD, OPTIONS); ACT should invoke
140 savewd_chdir as needed, and should return an exit status. WD
141 represents the working directory; it may be in an error state when
144 Save and restore the working directory as needed by the file name
145 vector; assume that ACT does not require access to any relative
146 file names other than its first argument, and that it is OK if the
147 working directory is changed when this function returns. Some
148 actions may be applied in a subprocess.
150 Return the maximum exit status that any call to ACT returned, or
151 EXIT_SUCCESS (i.e., 0) if no calls were made. */
152 int savewd_process_files (int n_files, char **file,
153 int (*act) (char *, struct savewd *, void *),
156 _GL_INLINE_HEADER_END