--- /dev/null
+/* Save and restore the working directory, possibly using a subprocess.
+
+ Copyright (C) 2006 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Written by Paul Eggert. */
+
+#ifndef SAVEWD_H
+# define SAVEWD_H 1
+
+#include <stdbool.h>
+#include <sys/types.h>
+
+/* A saved working directory. The member names and constants defined
+ by this structure are private to the savewd module. */
+struct savewd
+{
+ /* The state of this object. */
+ enum
+ {
+ /* This object has been created but does not yet represent
+ the working directory. */
+ INITIAL_STATE,
+
+ /* val.fd is the original working directory's file descriptor.
+ It is still the working directory. */
+ FD_STATE,
+
+ /* Like FD_STATE, but the working directory has changed, so
+ restoring it will require a fchdir. */
+ FD_POST_CHDIR_STATE,
+
+ /* Fork and let the subprocess do the work. val.child is 0 in a
+ child, negative in a childless parent, and the child process
+ ID in a parent with a child. */
+ FORKING_STATE,
+
+ /* A serious problem argues against further efforts. val.errnum
+ contains the error number (e.g., EIO). */
+ ERROR_STATE,
+
+ /* savewd_finish has been called, so the application no longer
+ cares whether the working directory is saved, and there is no
+ more work to do. */
+ FINAL_STATE
+ } state;
+
+ /* The object's value. */
+ union
+ {
+ int fd;
+ int errnum;
+ pid_t child;
+ } val;
+};
+
+/* Initialize a saved working directory object. */
+static inline void
+savewd_init (struct savewd *wd)
+{
+ wd->state = INITIAL_STATE;
+}
+
+
+/* Options for savewd_chdir. */
+enum
+ {
+ /* Do not follow symbolic links, if supported. */
+ SAVEWD_CHDIR_NOFOLLOW = 1,
+
+ /* The directory should be readable, so fail if it happens to be
+ discovered that the directory is not readable. (Unreadable
+ directories are not necessarily diagnosed, though.) */
+ SAVEWD_CHDIR_READABLE = 2,
+
+ /* Do not chdir if the directory is readable; simply succeed
+ without invoking chdir if the directory was opened. */
+ SAVEWD_CHDIR_SKIP_READABLE = 4
+ };
+
+/* Change the directory, and if successful, record into *WD the fact
+ that the process chdired into DIR. A process using this module
+ should use savewd_chdir rather than chdir or fchdir. Obey the
+ options specified in OPTIONS.
+
+ If OPEN_RESULT is not null, store into OPEN_RESULT[0] a file
+ descriptor that accesses DIR if a file descriptor is successfully
+ obtained. Store -1 otherwise, setting OPEN_RESULT[1] to the error
+ number. Store through OPEN_RESULT regardless of whether the chdir
+ is successful. However, when -2 is returned, the contents of
+ OPEN_RESULT are indeterminate since the file descriptor is closed
+ in the parent.
+
+ Return -2 if a subprocess was spun off to do the real work, -1
+ (setting errno) if unsuccessful, 0 if successful. */
+int savewd_chdir (struct savewd *wd, char const *dir, int options,
+ int open_result[2]);
+
+/* Restore the working directory from *WD. STATUS indicates the exit
+ status corresponding to the work done since the last save; this is
+ used when the caller is in a subprocess. Return 0 if successful,
+ -1 (setting errno) on our failure, a positive subprocess exit
+ status if the working directory was restored in the parent but the
+ subprocess failed. */
+int savewd_restore (struct savewd *wd, int status);
+
+/* Return WD's error number, or 0 if WD is not in an error state. */
+static inline int
+savewd_errno (struct savewd const *wd)
+{
+ return (wd->state == ERROR_STATE ? wd->val.errnum : 0);
+}
+
+/* Deallocate any resources associated with WD. A program that chdirs
+ should restore before finishing. */
+void savewd_finish (struct savewd *wd);
+
+/* Process N_FILES file names, FILE[0] through FILE[N_FILES - 1].
+ For each file name F, call ACT (F, WD, OPTIONS); ACT should invoke
+ savewd_chdir as needed, and should return an exit status. WD
+ represents thw working directory; it may be in an error state when
+ ACT is called.
+
+ Save and restore the working directory as needed by the file name
+ vector; assume that ACT does not require access to any relative
+ file names other than its first argument, and that it is OK if the
+ working directory is changed when this function returns. Some
+ actions may be applied in a subprocess.
+
+ Return the maximum exit status that any call to ACT returned, or
+ EXIT_SUCCESS (i.e., 0) if no calls were made. */
+int savewd_process_files (int n_files, char **file,
+ int (*act) (char *, struct savewd *, void *),
+ void *options);
+
+#endif
projects / gnulib.git / blobdiff