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 _GL_INLINE_HEADER_BEGIN
28 # define SAVEWD_INLINE _GL_INLINE
31 /* A saved working directory. The member names and constants defined
32 by this structure are private to the savewd module. */
35 /* The state of this object. */
38 /* This object has been created but does not yet represent
39 the working directory. */
42 /* val.fd is the original working directory's file descriptor.
43 It is still the working directory. */
46 /* Like FD_STATE, but the working directory has changed, so
47 restoring it will require a fchdir. */
50 /* Fork and let the subprocess do the work. val.child is 0 in a
51 child, negative in a childless parent, and the child process
52 ID in a parent with a child. */
55 /* A serious problem argues against further efforts. val.errnum
56 contains the error number (e.g., EIO). */
59 /* savewd_finish has been called, so the application no longer
60 cares whether the working directory is saved, and there is no
65 /* The object's value. */
74 /* Initialize a saved working directory object. */
76 savewd_init (struct savewd *wd)
78 wd->state = INITIAL_STATE;
82 /* Options for savewd_chdir. */
85 /* Do not follow symbolic links, if supported. */
86 SAVEWD_CHDIR_NOFOLLOW = 1,
88 /* The directory should be readable, so fail if it happens to be
89 discovered that the directory is not readable. (Unreadable
90 directories are not necessarily diagnosed, though.) */
91 SAVEWD_CHDIR_READABLE = 2,
93 /* Do not chdir if the directory is readable; simply succeed
94 without invoking chdir if the directory was opened. */
95 SAVEWD_CHDIR_SKIP_READABLE = 4
98 /* Change the directory, and if successful, record into *WD the fact
99 that the process chdired into DIR. A process using this module
100 should use savewd_chdir rather than chdir or fchdir. Obey the
101 options specified in OPTIONS.
103 If OPEN_RESULT is not null, store into OPEN_RESULT[0] a file
104 descriptor that accesses DIR if a file descriptor is successfully
105 obtained. Store -1 otherwise, setting OPEN_RESULT[1] to the error
106 number. Store through OPEN_RESULT regardless of whether the chdir
107 is successful. However, when -2 is returned, the contents of
108 OPEN_RESULT are indeterminate since the file descriptor is closed
111 Return -2 if a subprocess was spun off to do the real work, -1
112 (setting errno) if unsuccessful, 0 if successful. */
113 int savewd_chdir (struct savewd *wd, char const *dir, int options,
116 /* Restore the working directory from *WD. STATUS indicates the exit
117 status corresponding to the work done since the last save; this is
118 used when the caller is in a subprocess. Return 0 if successful,
119 -1 (setting errno) on our failure, a positive subprocess exit
120 status if the working directory was restored in the parent but the
121 subprocess failed. */
122 int savewd_restore (struct savewd *wd, int status);
124 /* Return WD's error number, or 0 if WD is not in an error state. */
126 savewd_errno (struct savewd const *wd)
128 return (wd->state == ERROR_STATE ? wd->val.errnum : 0);
131 /* Deallocate any resources associated with WD. A program that chdirs
132 should restore before finishing. */
133 void savewd_finish (struct savewd *wd);
135 /* Process N_FILES file names, FILE[0] through FILE[N_FILES - 1].
136 For each file name F, call ACT (F, WD, OPTIONS); ACT should invoke
137 savewd_chdir as needed, and should return an exit status. WD
138 represents the working directory; it may be in an error state when
141 Save and restore the working directory as needed by the file name
142 vector; assume that ACT does not require access to any relative
143 file names other than its first argument, and that it is OK if the
144 working directory is changed when this function returns. Some
145 actions may be applied in a subprocess.
147 Return the maximum exit status that any call to ACT returned, or
148 EXIT_SUCCESS (i.e., 0) if no calls were made. */
149 int savewd_process_files (int n_files, char **file,
150 int (*act) (char *, struct savewd *, void *),
153 _GL_INLINE_HEADER_END