On Wed, 2014-08-27 at 13:06 -0600, Eric Blake wrote:
> On 08/27/2014 10:15 AM, Pádraig Brady wrote:
> > On 08/27/2014 03:08 PM, Fridolin Pokorny wrote:
> >> diff --git a/lib/mountlist.c b/lib/mountlist.c
> >
> > Cool, this fits well.
> > It would be good to mention the functionality and
> > performance benefits in the changelog.
> >
> >> +#ifdef MOUNTED_PROC_MOUNTINFO
> >> +static const char *
> >> +mountinfo_path (void) {
> >> + static char filename[sizeof ("/proc//mountinfo") + 13]; /* 13 to hold a
> >> PID */
>
> The magic number 13 is gross, compared to using <intprops.h> from gnulib
> and using INT_STRLEN_BOUND(pid_t) (which should evaluate to 13) instead.
The magic 13 is from the kernel, I didn't know about
INT_STRLEN_BOUND(), thanks for suggestion. It is far better solution.
Anyway, it might be better to use /proc/self instead of /proc/<PID> as
suggested. Modified patch attached (also ChangeLog was modified).
Have a nice day!
Fridolin Pokorny
>From de0b7dba227f654380137c8843287f4ad32e8dc6 Mon Sep 17 00:00:00 2001
From: Fridolin Pokorny <fpoko...@redhat.com>
Date: Wed, 27 Aug 2014 15:25:30 +0200
Subject: [PATCH] mountlist: added /proc/self/mountinfo support
* mountlist: add support for libmount from util-linux
* m4/ls-mntd-fs.m4: check for libmount only when 1-argument
getmntent() is used (possible Linux)
By using libmount it is possible to propagate device ID
provided by Linux in /proc/self/mountinfo. This will give
more accurate output when using df in chroot'ed enviroments.
Device IDs are not determinated by stat() call using mountpoint,
so it is not possible to make a collision when same names are
used (e.g. /home/ and CHROOT-ROOT/home/).
---
ChangeLog | 13 +++++++++
DEPENDENCIES | 8 ++++++
lib/mountlist.c | 81 ++++++++++++++++++++++++++++++++++++++++++--------------
m4/ls-mntd-fs.m4 | 13 ++++++++-
4 files changed, 94 insertions(+), 21 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 9b3c85d..2ab46ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2014-08-27 Fridolin Pokorny <fpoko...@redhat.com>
+
+ mountlist: add support for libmount from util-linux
+ m4/ls-mntd-fs.m4: check for libmount only when 1-argument getmntent()
+ is used (possible Linux)
+ By using libmount it is possible to propagate device ID provided by
+ Linux in /proc/self/mountinfo. This will give more accurate output
+ when using df in chroot'ed enviroments. Device IDs are not
+ determinated by stat() call using mountpoint, so it is not possible to
+ make a collision when same names are used (e.g. /home/ and
+ CHROOT-ROOT/home/).
+
+
2014-07-13 Pádraig Brady <p...@draigbrady.com>
gettext: revert "update macros to version 0.19"
diff --git a/DEPENDENCIES b/DEPENDENCIES
index e19a37e..c54db82 100644
--- a/DEPENDENCIES
+++ b/DEPENDENCIES
@@ -162,3 +162,11 @@ at any time.
+ Download:
http://ftp.gnu.org/gnu/libtool/
ftp://ftp.gnu.org/gnu/libtool/
+
+* util-linux
+ + Optional.
+ Needed if you want to support /proc/self/mountinfo available on Linux.
+ This will give an ability to propagate device ID of a mounted file system.
+ + Download:
+ http://www.kernel.org/pub/linux/utils/util-linux/
+
diff --git a/lib/mountlist.c b/lib/mountlist.c
index b3be011..5195d56 100644
--- a/lib/mountlist.c
+++ b/lib/mountlist.c
@@ -128,6 +128,12 @@
# include <sys/mntent.h>
#endif
+#ifdef MOUNTED_PROC_MOUNTINFO
+/* Use /proc/self/mountinfo instead of /proc/self/mounts (/etc/mtab)
+ * on Linux, if available */
+# include <libmount/libmount.h>
+#endif
+
#ifndef HAVE_HASMNTOPT
# define hasmntopt(mnt, opt) ((char *) 0)
#endif
@@ -429,32 +435,67 @@ read_file_system_list (bool need_fs_type)
#ifdef MOUNTED_GETMNTENT1 /* GNU/Linux, 4.3BSD, SunOS, HP-UX, Dynix, Irix. */
{
- struct mntent *mnt;
- char const *table = MOUNTED;
- FILE *fp;
+#ifdef MOUNTED_PROC_MOUNTINFO
+ struct libmnt_table *fstable = NULL;
- fp = setmntent (table, "r");
- if (fp == NULL)
- return NULL;
+ fstable = mnt_new_table_from_file ("/proc/self/mountinfo");
- while ((mnt = getmntent (fp)))
+ if (fstable != NULL)
{
- me = xmalloc (sizeof *me);
- me->me_devname = xstrdup (mnt->mnt_fsname);
- me->me_mountdir = xstrdup (mnt->mnt_dir);
- me->me_type = xstrdup (mnt->mnt_type);
- me->me_type_malloced = 1;
- me->me_dummy = ME_DUMMY (me->me_devname, me->me_type, mnt);
- me->me_remote = ME_REMOTE (me->me_devname, me->me_type);
- me->me_dev = dev_from_mount_options (mnt->mnt_opts);
+ struct libmnt_fs *fs;
+ struct libmnt_iter *iter;
- /* Add to the linked list. */
- *mtail = me;
- mtail = &me->me_next;
+ iter = mnt_new_iter (MNT_ITER_FORWARD);
+
+ while (mnt_table_next_fs (fstable, iter, &fs) == 0)
+ {
+ me = xmalloc (sizeof *me);
+
+ me->me_devname = xstrdup (mnt_fs_get_source (fs));
+ me->me_mountdir = xstrdup (mnt_fs_get_target (fs));
+ me->me_type = xstrdup (mnt_fs_get_fstype (fs));
+ me->me_type_malloced = 1;
+ me->me_dev = mnt_fs_get_devno (fs);
+ me->me_dummy = mnt_fs_is_pseudofs (fs);
+ me->me_remote = mnt_fs_is_netfs (fs);
+
+ /* Add to the linked list. */
+ *mtail = me;
+ mtail = &me->me_next;
+ }
+
+ mnt_free_table (fstable);
}
+ else /* fallback to /proc/self/mounts (/etc/mtab) if anything failed */
+#endif /* MOUNTED_PROC_MOUNTINFO */
+ {
+ FILE * fp;
+ struct mntent *mnt;
+ char const *table = MOUNTED;
- if (endmntent (fp) == 0)
- goto free_then_fail;
+ fp = setmntent (table, "r");
+ if (fp == NULL)
+ return NULL;
+
+ while ((mnt = getmntent (fp)))
+ {
+ me = xmalloc (sizeof *me);
+ me->me_devname = xstrdup (mnt->mnt_fsname);
+ me->me_mountdir = xstrdup (mnt->mnt_dir);
+ me->me_type = xstrdup (mnt->mnt_type);
+ me->me_type_malloced = 1;
+ me->me_dummy = ME_DUMMY (me->me_devname, me->me_type, mnt);
+ me->me_remote = ME_REMOTE (me->me_devname, me->me_type);
+ me->me_dev = dev_from_mount_options (mnt->mnt_opts);
+
+ /* Add to the linked list. */
+ *mtail = me;
+ mtail = &me->me_next;
+ }
+
+ if (endmntent (fp) == 0)
+ goto free_then_fail;
+ }
}
#endif /* MOUNTED_GETMNTENT1. */
diff --git a/m4/ls-mntd-fs.m4 b/m4/ls-mntd-fs.m4
index 563ed71..c89e0c9 100644
--- a/m4/ls-mntd-fs.m4
+++ b/m4/ls-mntd-fs.m4
@@ -1,4 +1,4 @@
-# serial 30
+# serial 31
# How to list mounted file systems.
# Copyright (C) 1998-2004, 2006, 2009-2014 Free Software Foundation, Inc.
@@ -152,6 +152,17 @@ if test $ac_cv_func_getmntent = yes; then
of mounted file systems, and that function takes a single argument.
(4.3BSD, SunOS, HP-UX, Dynix, Irix)])
AC_CHECK_FUNCS([hasmntopt])
+
+ # Check for libmount to support /proc/self/mountinfo on Linux
+ AC_CACHE_VAL([ac_cv_lib_libmount_mnt_table_parse_stream],
+ [AC_CHECK_LIB([mount], [mnt_new_table_from_file],
+ ac_cv_lib_mount_mnt_table_parse_stream=yes,
+ ac_cv_lib_mount_mnt_table_parse_stream=no)])
+ if test $ac_cv_lib_mount_mnt_table_parse_stream = yes; then
+ AC_DEFINE([MOUNTED_PROC_MOUNTINFO], [1],
+ [Define if want to use /proc/self/mountinfo on Linux.])
+ LIBS="-lmount $LIBS"
+ fi
fi
fi
--
1.9.3
