+++ /dev/null
-/* Save and restore the working directory, possibly using a child process.
-
- Copyright (C) 2006, 2007 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. */
-
-#include <config.h>
-
-#include "savewd.h"
-
-#include <assert.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-#include "dirname.h"
-#include "fcntl-safer.h"
-
-
-/* Save the working directory into *WD, if it hasn't been saved
- already. Return true if a child has been forked to do the real
- work. */
-static bool
-savewd_save (struct savewd *wd)
-{
- switch (wd->state)
- {
- case INITIAL_STATE:
- /* Save the working directory, or prepare to fall back if possible. */
- {
- int fd = open_safer (".", O_RDONLY);
- if (0 <= fd)
- {
- wd->state = FD_STATE;
- wd->val.fd = fd;
- break;
- }
- if (errno != EACCES && errno != ESTALE)
- {
- wd->state = ERROR_STATE;
- wd->val.errnum = errno;
- break;
- }
- }
- wd->state = FORKING_STATE;
- wd->val.child = -1;
- /* Fall through. */
- case FORKING_STATE:
- if (wd->val.child < 0)
- {
- /* "Save" the initial working directory by forking a new
- subprocess that will attempt all the work from the chdir
- until until the next savewd_restore. */
- wd->val.child = fork ();
- if (wd->val.child != 0)
- {
- if (0 < wd->val.child)
- return true;
- wd->state = ERROR_STATE;
- wd->val.errnum = errno;
- }
- }
- break;
-
- case FD_STATE:
- case FD_POST_CHDIR_STATE:
- case ERROR_STATE:
- case FINAL_STATE:
- break;
-
- default:
- assert (false);
- }
-
- return false;
-}
-
-int
-savewd_chdir (struct savewd *wd, char const *dir, int options,
- int open_result[2])
-{
- int fd = -1;
- int result = 0;
-
- /* Open the directory if requested, or if avoiding a race condition
- is requested and possible. */
- if (open_result
- || (options & (HAVE_WORKING_O_NOFOLLOW ? SAVEWD_CHDIR_NOFOLLOW : 0)))
- {
- fd = open (dir,
- (O_RDONLY | O_DIRECTORY | O_NOCTTY | O_NONBLOCK
- | (options & SAVEWD_CHDIR_NOFOLLOW ? O_NOFOLLOW : 0)));
-
- if (open_result)
- {
- open_result[0] = fd;
- open_result[1] = errno;
- }
-
- if (fd < 0 && ((errno != EACCES && errno != ESTALE)
- || (options & SAVEWD_CHDIR_READABLE)))
- result = -1;
- }
-
- if (result == 0 && ! (0 <= fd && options & SAVEWD_CHDIR_SKIP_READABLE))
- {
- if (savewd_save (wd))
- {
- open_result = NULL;
- result = -2;
- }
- else
- {
- result = (fd < 0 ? chdir (dir) : fchdir (fd));
-
- if (result == 0)
- switch (wd->state)
- {
- case FD_STATE:
- wd->state = FD_POST_CHDIR_STATE;
- break;
-
- case ERROR_STATE:
- case FD_POST_CHDIR_STATE:
- case FINAL_STATE:
- break;
-
- case FORKING_STATE:
- assert (wd->val.child == 0);
- break;
-
- default:
- assert (false);
- }
- }
- }
-
- if (0 <= fd && ! open_result)
- {
- int e = errno;
- close (fd);
- errno = e;
- }
-
- return result;
-}
-
-int
-savewd_restore (struct savewd *wd, int status)
-{
- switch (wd->state)
- {
- case INITIAL_STATE:
- case FD_STATE:
- /* The working directory is the desired directory, so there's no
- work to do. */
- break;
-
- case FD_POST_CHDIR_STATE:
- /* Restore the working directory using fchdir. */
- if (fchdir (wd->val.fd) == 0)
- {
- wd->state = FD_STATE;
- break;
- }
- else
- {
- int chdir_errno = errno;
- close (wd->val.fd);
- wd->state = ERROR_STATE;
- wd->val.errnum = chdir_errno;
- }
- /* Fall through. */
- case ERROR_STATE:
- /* Report an error if asked to restore the working directory. */
- errno = wd->val.errnum;
- return -1;
-
- case FORKING_STATE:
- /* "Restore" the working directory by waiting for the subprocess
- to finish. */
- {
- pid_t child = wd->val.child;
- if (child == 0)
- _exit (status);
- if (0 < child)
- {
- int child_status;
- while (waitpid (child, &child_status, 0) < 0)
- assert (errno == EINTR);
- wd->val.child = -1;
- if (! WIFEXITED (child_status))
- raise (WTERMSIG (child_status));
- return WEXITSTATUS (child_status);
- }
- }
- break;
-
- default:
- assert (false);
- }
-
- return 0;
-}
-
-void
-savewd_finish (struct savewd *wd)
-{
- switch (wd->state)
- {
- case INITIAL_STATE:
- case ERROR_STATE:
- break;
-
- case FD_STATE:
- case FD_POST_CHDIR_STATE:
- close (wd->val.fd);
- break;
-
- case FORKING_STATE:
- assert (wd->val.child < 0);
- break;
-
- default:
- assert (false);
- }
-
- wd->state = FINAL_STATE;
-}
-
-/* Return true if the actual work is currently being done by a
- subprocess.
-
- A true return means that the caller and the subprocess should
- resynchronize later with savewd_restore, using only their own
- memory to decide when to resynchronize; they should not consult the
- file system to decide, because that might lead to race conditions.
- This is why savewd_chdir is broken out into another function;
- savewd_chdir's callers _can_ inspect the file system to decide
- whether to call savewd_chdir. */
-static inline bool
-savewd_delegating (struct savewd const *wd)
-{
- return wd->state == FORKING_STATE && 0 < wd->val.child;
-}
-
-int
-savewd_process_files (int n_files, char **file,
- int (*act) (char *, struct savewd *, void *),
- void *options)
-{
- int i = 0;
- int last_relative;
- int exit_status = EXIT_SUCCESS;
- struct savewd wd;
- savewd_init (&wd);
-
- for (last_relative = n_files - 1; 0 <= last_relative; last_relative--)
- if (! IS_ABSOLUTE_FILE_NAME (file[last_relative]))
- break;
-
- for (; i < last_relative; i++)
- {
- if (! savewd_delegating (&wd))
- {
- int s = act (file[i], &wd, options);
- if (exit_status < s)
- exit_status = s;
- }
-
- if (! IS_ABSOLUTE_FILE_NAME (file[i + 1]))
- {
- int r = savewd_restore (&wd, exit_status);
- if (exit_status < r)
- exit_status = r;
- }
- }
-
- savewd_finish (&wd);
-
- for (; i < n_files; i++)
- {
- int s = act (file[i], &wd, options);
- if (exit_status < s)
- exit_status = s;
- }
-
- return exit_status;
-}
projects / thirdparty / coreutils.git / commitdiff
