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authorJim Meyering <meyering@redhat.com>2011-12-29 14:49:00 +0100
committerJim Meyering <meyering@redhat.com>2012-01-03 16:55:58 +0100
commit1e18d8416f9ef43bf08982cabe54220587061a08 (patch)
tree7d5d10b59ce3e81508e3bd2114f17d69d321914c
parent520b69ce36a71f83772e7d2bfeed7aefd1bc4f6f (diff)
downloadcoreutils-1e18d8416f9ef43bf08982cabe54220587061a08.tar.xz
df: work around long-named /dev/disk/by-uuid/... symlinks
On systems with recent kernel/tools, a symlink from /etc/mtab to /proc/mounts, and a by-UUID mount (i.e., soon, nearly everyone), you will see something like the following when running "df -hT": (this has been truncated to fit in a width-limited ChangeLog file) Filesystem Type Siz... rootfs rootfs 11G udev devtmpfs 3.8G tmpfs tmpfs 774M /dev/disk/by-uuid/828fc648-9f30-43d8-a0b1-f7096a2edb66 ext4 11G tmpfs tmpfs 1.6G /dev/sda2 ext3 494M /dev/sda5 ext4 12G /dev/sda6 ext4 9.9G Contrast that with what we're used to seeing (modulo the two entries mounted on "/", which is a separate problem): Filesystem Type Size Used Avail Use% Mounted on rootfs rootfs 11G 1.9G 8.0G 19% / udev devtmpfs 3.8G 0 3.8G 0% /dev tmpfs tmpfs 774M 376K 774M 1% /run /dev/sda3 ext4 11G 1.9G 8.0G 19% / tmpfs tmpfs 1.6G 8.0K 1.6G 1% /run/shm /dev/sda2 ext3 494M 78M 392M 17% /boot /dev/sda5 ext4 12G 7.6G 3.7G 68% /usr /dev/sda6 ext4 9.9G 6.6G 2.8G 71% /var When that long /dev/disk/by-uuid/... name is merely a symlink to a much shorter (and often more useful) device name like "/dev/sda3", and when it's part of a listing of all file systems, I would much prefer to see only the latter. Similarly, when using an encrypted root file system, you would see a name like /dev/mapper/luks-828fc648-9f30-43d8-a0b1-f7196a2edb66 pointing to say, /dev/dm-0, I prefer the shorter name. I.e., if I explicitly run "df -hT /dev/disk/by-uuid/828fc648-9f30-43d8-a0b1-f7096a2edb66", then, it's fine -- and expected -- to print to the long name. It was explicitly given. However, with no non-option argument, df should print the shorter name. Note that performing this translation at a lower level (via a change to gnulib's mountlist.c) would make it impossible to distinguish those two cases. * src/df.c: Include "canonicalize.h". (get_dev): Add a parameter, telling when we're in process-all- mount-points mode; update all callers. When true, resolve UUID-suffixed symlinks. * NEWS (Changes in behavior): Mention it. Reported by Dan Jacobson in http://bugs.gnu.org/10363
-rw-r--r--NEWS5
-rw-r--r--src/df.c49
2 files changed, 46 insertions, 8 deletions
diff --git a/NEWS b/NEWS
index 78a90b672..bc5a0a91c 100644
--- a/NEWS
+++ b/NEWS
@@ -36,6 +36,11 @@ GNU coreutils NEWS -*- outline -*-
** Changes in behavior
+ df, with no non-option argument and recent enough kernel/tools, would
+ print a long UUID-including file system name, pushing second and subsequent
+ columns far to the right. Now, when that long name refers to a symlink,
+ df prints the usually-short referent instead.
+
tail -f now uses polling (not inotify) when any of its file arguments
resides on a file system of unknown type. In addition, for each such
argument, tail -f prints a warning with the FS type magic number and a
diff --git a/src/df.c b/src/df.c
index 967768799..fae32cd93 100644
--- a/src/df.c
+++ b/src/df.c
@@ -25,6 +25,7 @@
#include <assert.h>
#include "system.h"
+#include "canonicalize.h"
#include "error.h"
#include "fsusage.h"
#include "human.h"
@@ -417,6 +418,17 @@ add_uint_with_neg_flag (uintmax_t *dest, bool *dest_neg,
*dest = -*dest;
}
+/* Return true if S ends in a string that may be a 36-byte UUID,
+ i.e., of the form HHHHHHHH-HHHH-HHHH-HHHH-HHHHHHHHHHHH, where
+ each H is an upper or lower case hexadecimal digit. */
+static bool _GL_ATTRIBUTE_PURE
+has_uuid_suffix (char const *s)
+{
+ size_t len = strlen (s);
+ return (36 < len
+ && strspn (s + len - 36, "-0123456789abcdefABCDEF") == 36);
+}
+
/* Obtain a space listing for the disk device with absolute file name DISK.
If MOUNT_POINT is non-NULL, it is the name of the root of the
file system on DISK.
@@ -428,13 +440,16 @@ add_uint_with_neg_flag (uintmax_t *dest, bool *dest_neg,
If FSTYPE is non-NULL, it is the type of the file system on DISK.
If MOUNT_POINT is non-NULL, then DISK may be NULL -- certain systems may
not be able to produce statistics in this case.
- ME_DUMMY and ME_REMOTE are the mount entry flags. */
+ ME_DUMMY and ME_REMOTE are the mount entry flags.
+ Caller must set PROCESS_ALL to true when iterating over all entries, as
+ when df is invoked with no non-option argument. See below for details. */
static void
get_dev (char const *disk, char const *mount_point,
char const *stat_file, char const *fstype,
bool me_dummy, bool me_remote,
- const struct fs_usage *force_fsu)
+ const struct fs_usage *force_fsu,
+ bool process_all)
{
struct fs_usage fsu;
char buf[LONGEST_HUMAN_READABLE + 2];
@@ -488,6 +503,24 @@ get_dev (char const *disk, char const *mount_point,
if (! disk)
disk = "-"; /* unknown */
+
+ char *dev_name = xstrdup (disk);
+ char *resolved_dev;
+
+ /* On some systems, dev_name is a long-named symlink like
+ /dev/disk/by-uuid/828fc648-9f30-43d8-a0b1-f7196a2edb66 pointing to a
+ much shorter and more useful name like /dev/sda1. It may also look
+ like /dev/mapper/luks-828fc648-9f30-43d8-a0b1-f7196a2edb66 and point to
+ /dev/dm-0. When process_all is true and dev_name is a symlink whose
+ name ends with a UUID use the resolved name instead. */
+ if (process_all
+ && has_uuid_suffix (dev_name)
+ && (resolved_dev = canonicalize_filename_mode (dev_name, CAN_EXISTING)))
+ {
+ free (dev_name);
+ dev_name = resolved_dev;
+ }
+
if (! fstype)
fstype = "-"; /* unknown */
@@ -537,7 +570,7 @@ get_dev (char const *disk, char const *mount_point,
switch (field)
{
case DEV_FIELD:
- cell = xstrdup (disk);
+ cell = dev_name;
break;
case TYPE_FIELD:
@@ -648,7 +681,7 @@ get_disk (char const *disk)
{
get_dev (best_match->me_devname, best_match->me_mountdir, NULL,
best_match->me_type, best_match->me_dummy,
- best_match->me_remote, NULL);
+ best_match->me_remote, NULL, false);
return true;
}
@@ -734,7 +767,7 @@ get_point (const char *point, const struct stat *statp)
if (best_match)
get_dev (best_match->me_devname, best_match->me_mountdir, point,
best_match->me_type, best_match->me_dummy, best_match->me_remote,
- NULL);
+ NULL, false);
else
{
/* We couldn't find the mount entry corresponding to POINT. Go ahead and
@@ -745,7 +778,7 @@ get_point (const char *point, const struct stat *statp)
char *mp = find_mount_point (point, statp);
if (mp)
{
- get_dev (NULL, mp, NULL, NULL, false, false, NULL);
+ get_dev (NULL, mp, NULL, NULL, false, false, NULL, false);
free (mp);
}
}
@@ -774,7 +807,7 @@ get_all_entries (void)
for (me = mount_list; me; me = me->me_next)
get_dev (me->me_devname, me->me_mountdir, NULL, me->me_type,
- me->me_dummy, me->me_remote, NULL);
+ me->me_dummy, me->me_remote, NULL, true);
}
/* Add FSTYPE to the list of file system types to display. */
@@ -1066,7 +1099,7 @@ main (int argc, char **argv)
{
if (inode_format)
grand_fsu.fsu_blocks = 1;
- get_dev ("total", NULL, NULL, NULL, false, false, &grand_fsu);
+ get_dev ("total", NULL, NULL, NULL, false, false, &grand_fsu, false);
}
print_table ();