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stat: add %m to output the mount point for a file

* src/find-mount-point.c: A new file refactoring
find_mount_point() out from df.c
* src/find-mount-point.h: Likewise.
* src/df.c: Use the new find-mount-point module.
* src/stat.c (print_stat): Handle the new %m format.
(find_bind_mount): A new function to
return the bind mount for a file if any.
(out_mount_mount): Print the bind mount for a file, or else
the standard mount point given by the find-mount-point module.
(usage): Document the %m format directive.
* src/Makefile.am: Reference the refactored find-mount-point.c
* po/POTFILES.in: Add find_mount_point.c to the translation list
* doc/coreutils.texi (stat invocation): Document %m,
and how it may differ from the mount point that df outputs.
* test/misc/stat-mount: A new test to correlate mount points
output from df and stat.
* tests/Makefile.am: Reference the new test.
* NEWS: Mention the new feature
* THANKS: Add the author

Signed-off-by: Pádraig Brady <P@draigBrady.com>
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1 parent 872f6bb commit ddf6fb8686b1ed6a26d5f1c76a642d0fb5fe7ba7 @dajoker dajoker committed with pixelb Jul 16, 2010
Showing with 284 additions and 90 deletions.
  1. +3 −0 NEWS
  2. +1 −0 THANKS
  3. +18 −0 doc/coreutils.texi
  4. +1 −0 po/POTFILES.in
  5. +4 −0 src/Makefile.am
  6. +1 −90 src/df.c
  7. +113 −0 src/find-mount-point.c
  8. +17 −0 src/find-mount-point.h
  9. +94 −0 src/stat.c
  10. +1 −0 tests/Makefile.am
  11. +31 −0 tests/misc/stat-mount
View
@@ -24,6 +24,9 @@ GNU coreutils NEWS -*- outline -*-
sort now supports -d, -f, -i, -R, and -V in any combination.
+ stat now accepts the %m format directive to output
+ the mount point for a file.
+
** Changes in behavior
df now consistently prints the device name for a bind mounted file,
View
@@ -8,6 +8,7 @@ the bug-report mailing list (as seen on last line of e.g., cp --help).
??? kytek@cybercomm.net
A Costa agcosta@gis.net
+Aaron Burgemeister dajoker@gmail.com
Aaron Hawley ashawley@uvm.edu
Achim Blumensath blume@corona.oche.de
Adam Jimerson vendion@charter.net
View
@@ -8487,6 +8487,7 @@ removal is requested. Equivalent to @option{-I}.
When removing a hierarchy recursively, skip any directory that is on a
file system different from that of the corresponding command line argument.
+@cindex bind mount
This option is useful when removing a build ``chroot'' hierarchy,
which normally contains no valuable data. However, it is not uncommon
to bind-mount @file{/home} into such a hierarchy, to make it easier to
@@ -10685,6 +10686,7 @@ The valid @var{format} directives for files with @option{--format} and
@item %G - Group name of owner
@item %h - Number of hard links
@item %i - Inode number
+@item %m - Mount point (See note below)
@item %n - File name
@item %N - Quoted file name with dereference if symbolic link
@item %o - I/O block size
@@ -10701,6 +10703,22 @@ The valid @var{format} directives for files with @option{--format} and
@item %Z - Time of last change as seconds since Epoch
@end itemize
+The mount point printed by @samp{%m} is similar to that output
+by @command{df}, except that:
+@itemize @bullet
+@item
+stat does not dereference symlinks by default
+(unless @option{-L} is specified)
+@item
+stat does not search for specified device nodes in the
+file system list, instead operating on them directly
+@item
+@cindex bind mount
+stat outputs the alias for a bind mounted file,
+rather than its backing device. One can recursively call stat
+until there is no change in output, to get the base mount point
+@end itemize
+
When listing file system information (@option{--file-system} (@option{-f})),
you must use a different set of @var{format} directives:
View
@@ -61,6 +61,7 @@ src/expand.c
src/expr.c
src/factor.c
src/false.c
+src/find-mount-point.c
src/fmt.c
src/fold.c
src/getlimits.c
View
@@ -145,6 +145,7 @@ noinst_HEADERS = \
copy.h \
cp-hash.h \
dircolors.h \
+ find-mount-point.h \
fs.h \
group-list.h \
ls.h \
@@ -478,6 +479,9 @@ rm_SOURCES = rm.c remove.c
mkdir_SOURCES = mkdir.c prog-fprintf.c
rmdir_SOURCES = rmdir.c prog-fprintf.c
+df_SOURCES = df.c find-mount-point.c
+stat_SOURCES = stat.c find-mount-point.c
+
uname_SOURCES = uname.c uname-uname.c
arch_SOURCES = uname.c uname-arch.c
nproc_SOURCES = nproc.c
View
@@ -29,8 +29,7 @@
#include "human.h"
#include "mountlist.h"
#include "quote.h"
-#include "save-cwd.h"
-#include "xgetcwd.h"
+#include "find-mount-point.h"
/* The official name of this program (e.g., no `g' prefix). */
#define PROGRAM_NAME "df"
@@ -522,94 +521,6 @@ show_dev (char const *disk, char const *mount_point,
putchar ('\n');
}
-/* Return the root mountpoint of the file system on which FILE exists, in
- malloced storage. FILE_STAT should be the result of stating FILE.
- Give a diagnostic and return NULL if unable to determine the mount point.
- Exit if unable to restore current working directory. */
-static char *
-find_mount_point (const char *file, const struct stat *file_stat)
-{
- struct saved_cwd cwd;
- struct stat last_stat;
- char *mp = NULL; /* The malloced mount point. */
-
- if (save_cwd (&cwd) != 0)
- {
- error (0, errno, _("cannot get current directory"));
- return NULL;
- }
-
- if (S_ISDIR (file_stat->st_mode))
- /* FILE is a directory, so just chdir there directly. */
- {
- last_stat = *file_stat;
- if (chdir (file) < 0)
- {
- error (0, errno, _("cannot change to directory %s"), quote (file));
- return NULL;
- }
- }
- else
- /* FILE is some other kind of file; use its directory. */
- {
- char *xdir = dir_name (file);
- char *dir;
- ASSIGN_STRDUPA (dir, xdir);
- free (xdir);
-
- if (chdir (dir) < 0)
- {
- error (0, errno, _("cannot change to directory %s"), quote (dir));
- return NULL;
- }
-
- if (stat (".", &last_stat) < 0)
- {
- error (0, errno, _("cannot stat current directory (now %s)"),
- quote (dir));
- goto done;
- }
- }
-
- /* Now walk up FILE's parents until we find another file system or /,
- chdiring as we go. LAST_STAT holds stat information for the last place
- we visited. */
- while (true)
- {
- struct stat st;
- if (stat ("..", &st) < 0)
- {
- error (0, errno, _("cannot stat %s"), quote (".."));
- goto done;
- }
- if (st.st_dev != last_stat.st_dev || st.st_ino == last_stat.st_ino)
- /* cwd is the mount point. */
- break;
- if (chdir ("..") < 0)
- {
- error (0, errno, _("cannot change to directory %s"), quote (".."));
- goto done;
- }
- last_stat = st;
- }
-
- /* Finally reached a mount point, see what it's called. */
- mp = xgetcwd ();
-
-done:
- /* Restore the original cwd. */
- {
- int save_errno = errno;
- if (restore_cwd (&cwd) != 0)
- error (EXIT_FAILURE, errno,
- _("failed to return to initial working directory"));
- free_cwd (&cwd);
- errno = save_errno;
- }
-
- return mp;
-}
-
/* If DISK corresponds to a mount point, show its usage
and return true. Otherwise, return false. */
static bool
View
@@ -0,0 +1,113 @@
+/* find-mount-point.c -- find the root mount point for a file.
+ Copyright (C) 2010 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include <sys/types.h>
+
+#include "system.h"
+#include "error.h"
+#include "quote.h"
+#include "save-cwd.h"
+#include "xgetcwd.h"
+#include "find-mount-point.h"
+
+/* Return the root mountpoint of the file system on which FILE exists, in
+ malloced storage. FILE_STAT should be the result of stating FILE.
+ Give a diagnostic and return NULL if unable to determine the mount point.
+ Exit if unable to restore current working directory. */
+extern char *
+find_mount_point (const char *file, const struct stat *file_stat)
+{
+ struct saved_cwd cwd;
+ struct stat last_stat;
+ char *mp = NULL; /* The malloced mount point. */
+
+ if (save_cwd (&cwd) != 0)
+ {
+ error (0, errno, _("cannot get current directory"));
+ return NULL;
+ }
+
+ if (S_ISDIR (file_stat->st_mode))
+ /* FILE is a directory, so just chdir there directly. */
+ {
+ last_stat = *file_stat;
+ if (chdir (file) < 0)
+ {
+ error (0, errno, _("cannot change to directory %s"), quote (file));
+ return NULL;
+ }
+ }
+ else
+ /* FILE is some other kind of file; use its directory. */
+ {
+ char *xdir = dir_name (file);
+ char *dir;
+ ASSIGN_STRDUPA (dir, xdir);
+ free (xdir);
+
+ if (chdir (dir) < 0)
+ {
+ error (0, errno, _("cannot change to directory %s"), quote (dir));
+ return NULL;
+ }
+
+ if (stat (".", &last_stat) < 0)
+ {
+ error (0, errno, _("cannot stat current directory (now %s)"),
+ quote (dir));
+ goto done;
+ }
+ }
+
+ /* Now walk up FILE's parents until we find another file system or /,
+ chdiring as we go. LAST_STAT holds stat information for the last place
+ we visited. */
+ while (true)
+ {
+ struct stat st;
+ if (stat ("..", &st) < 0)
+ {
+ error (0, errno, _("cannot stat %s"), quote (".."));
+ goto done;
+ }
+ if (st.st_dev != last_stat.st_dev || st.st_ino == last_stat.st_ino)
+ /* cwd is the mount point. */
+ break;
+ if (chdir ("..") < 0)
+ {
+ error (0, errno, _("cannot change to directory %s"), quote (".."));
+ goto done;
+ }
+ last_stat = st;
+ }
+
+ /* Finally reached a mount point, see what it's called. */
+ mp = xgetcwd ();
+
+done:
+ /* Restore the original cwd. */
+ {
+ int save_errno = errno;
+ if (restore_cwd (&cwd) != 0)
+ error (EXIT_FAILURE, errno,
+ _("failed to return to initial working directory"));
+ free_cwd (&cwd);
+ errno = save_errno;
+ }
+
+ return mp;
+}
@@ -0,0 +1,17 @@
+/* find-mount-point.h -- find the root mount point for a file.
+ Copyright (C) 2010 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
+
+extern char* find_mount_point (const char *, const struct stat *);
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