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a966dcdb69
Update to latest gnulib with new copyright year. Run "make update-copyright" and then... * gnulib: Update included in this commit as copyright years are the only change from the previous gnulib commit. * tests/init.sh: Sync with gnulib to pick up copyright year. * bootstrap: Manually update copyright year, until we fully sync with gnulib at a later stage. * tests/sample-test: Adjust to use the single most recent year.
112 lines
3.3 KiB
C
112 lines
3.3 KiB
C
/* find-mount-point.c -- find the root mount point for a file.
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Copyright (C) 2010-2024 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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#include <sys/types.h>
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#include "system.h"
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#include "save-cwd.h"
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#include "xgetcwd.h"
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#include "find-mount-point.h"
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/* Return the root mountpoint of the file system on which FILE exists, in
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malloced storage. FILE_STAT should be the result of stating FILE.
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Give a diagnostic and return nullptr if unable to determine the mount point.
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Exit if unable to restore current working directory. */
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extern char *
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find_mount_point (char const *file, struct stat const *file_stat)
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{
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struct saved_cwd cwd;
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struct stat last_stat;
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char *mp = nullptr; /* The malloc'd mount point. */
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if (save_cwd (&cwd) != 0)
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{
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error (0, errno, _("cannot get current directory"));
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return nullptr;
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}
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if (S_ISDIR (file_stat->st_mode))
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/* FILE is a directory, so just chdir there directly. */
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{
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last_stat = *file_stat;
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if (chdir (file) < 0)
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{
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error (0, errno, _("cannot change to directory %s"), quoteaf (file));
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return nullptr;
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}
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}
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else
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/* FILE is some other kind of file; use its directory. */
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{
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char *xdir = dir_name (file);
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char *dir;
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ASSIGN_STRDUPA (dir, xdir);
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free (xdir);
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if (chdir (dir) < 0)
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{
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error (0, errno, _("cannot change to directory %s"), quoteaf (dir));
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return nullptr;
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}
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if (stat (".", &last_stat) < 0)
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{
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error (0, errno, _("cannot stat current directory (now %s)"),
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quoteaf (dir));
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goto done;
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}
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}
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/* Now walk up FILE's parents until we find another file system or /,
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chdiring as we go. LAST_STAT holds stat information for the last place
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we visited. */
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while (true)
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{
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struct stat st;
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if (stat ("..", &st) < 0)
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{
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error (0, errno, _("cannot stat %s"), quoteaf (".."));
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goto done;
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}
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if (st.st_dev != last_stat.st_dev || st.st_ino == last_stat.st_ino)
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/* cwd is the mount point. */
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break;
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if (chdir ("..") < 0)
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{
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error (0, errno, _("cannot change to directory %s"), quoteaf (".."));
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goto done;
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}
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last_stat = st;
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}
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/* Finally reached a mount point, see what it's called. */
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mp = xgetcwd ();
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done:
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/* Restore the original cwd. */
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{
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int save_errno = errno;
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if (restore_cwd (&cwd) != 0)
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error (EXIT_FAILURE, errno,
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_("failed to return to initial working directory"));
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free_cwd (&cwd);
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errno = save_errno;
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}
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return mp;
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}
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