The monitor supports utab only (as documented). It's application
responsibility to use libmount in the right way. It's overkill to
check for valid environment during monitor initialization.
For example systemd checks for regular mtab during boot, it's better
than try to be smart later in libmount monitor when system is already
running.
Signed-off-by: Karel Zak <kzak@redhat.com>
Based on patch from Kees Cook, he wrote:
> The kernel's maximum path length is PATH_MAX (4096). The use of BUFSIZ
> (8192) would seem sufficient for reading mountinfo files, but it's
> not. Paths may contain escaped characters (requiring 4x as many bytes
> to read), and filesystem options are of unknown length. To avoid
> mounts being either intentionally or unintentionally hidden from
> libmount and its users, we must accept arbitrary length lines when
> parsing.
>
> Long valid entries are currently ignored, with warnings like this:
> mount: /proc/self/mountinfo: parse error: ignore entry at line 11.
> mount: /proc/self/mountinfo: parse error: ignore entry at line 12.
>
> Instead of using a malloc on every line parsed from mount files, do it
> once per mount file context, growing it as needed. The general case
> will never grow it.
I have moved the parser stuff to the new struct libmnt_parser, maybe
we can move more things (e.g. libmnt_table->fmt) to this struct later.
Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Karel Zak <kzak@redhat.com>
sys-utils/zramctl.c: In function 'get_mm_stat':
sys-utils/zramctl.c:276:58: warning: declaration of 'inbytes' shadows a global declaration [-Wshadow]
static char *get_mm_stat(struct zram *z, size_t idx, int inbytes)
sys-utils/zramctl.c:119:39: note: shadowed declaration is here
static unsigned int raw, no_headings, inbytes;
libmount/src/tab.c: In function 'mnt_table_get_fs_root':
libmount/src/tab.c:1221:22: warning: declaration of 'fs' shadows a parameter [-Wshadow]
struct libmnt_fs *fs = mnt_table_find_mountpoint(tb,
libmount/src/tab.c:1197:24: note: shadowed declaration is here
struct libmnt_fs *fs,
disk-utils/fsck.minix.c: In function 'main':
disk-utils/fsck.minix.c:1364:17: warning: declaration of 'i' shadows a previous local [-Wshadow]
unsigned long i, free;
disk-utils/fsck.minix.c:1250:6: note: shadowed declaration is here
int i;
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Now it's necessary t use two mount(8) calls to create a read-only
mount:
mount /foo /bar -o bind
mount /bar -o remount,ro,bind
This patch allows to specify "bind,ro" and the remount is done
automatically by libmount by additional mount(2) syscall. It's not
atomic of course.
Signed-off-by: Karel Zak <kzak@redhat.com>
The mnt_free_filesystems() relies on NULL as the last item in the
filesystems array. It's necessary to keep NULL there after failed
strdup() too, because we call mnt_free_filesystems() to deallocate
after error.
Signed-off-by: Karel Zak <kzak@redhat.com>
The current implementation calls mkdir and open(O_CREATE) to
initialize /run/mount/utab.lock before it starts to monitor the file.
Unfortunately it makes the monitor useless for non-root processes
(e.g. systemd --user).
The new implementation adds inotify watch for the last existing
component in the path (/run/mount/utab.lock) and re-initialize
after a change. It makes the monitor robust enough for mkdir/rmdir
when monitor is already active.
Signed-off-by: Karel Zak <kzak@redhat.com>
The umount.<type> helpers does not support --fake option and it does
not make sense to call the helpers at all. All we need is to remove
mtab/utab entries.
Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1172297
Signed-off-by: Karel Zak <kzak@redhat.com>
We have to call epoll to drain mountinfo events too. The problem is
visible if the monitor epoll FD is within another (top-level) epoll.
Signed-off-by: Karel Zak <kzak@redhat.com>
The overlay filesystem does not provide usable st_dev (in traditional
UNIX way). It's necessary to search in /proc/self/mountinfo to detect
which path element is mountpoint.
$ findmnt --target /mnt/merged/dir-a/foo
TARGET SOURCE FSTYPE OPTIONS
/mnt/merged overlay overlay rw,relatime,lowerdir=/mnt/low,upperdir=/mnt/high/data,workdir=/mnt/high/work
Signed-off-by: Karel Zak <kzak@redhat.com>
* check for timer_create()
* define dependence on timer_create() for flock
* rename CLOCKGETTIME_LIBS to REALTIME_LIBS
Signed-off-by: Karel Zak <kzak@redhat.com>
The default libmount mtab management depends on mtan symlink. If the
symlink exists than libmount parses /proc/self/mountinfo, otherwise it
parses regular classic /etc/mtab. This is backwardly compatible and
transparent solution.
Unfortunately, this is not robust enough because some broken init
scripts or 3-party mount helpers may remove the symlink and create
regular mtab file. This is pretty bad if initd (systemd) depends on
libmount.
Fortunately we known that mtab is absolutely unwanted on some distros,
so it's fine too ignore mtab at all and don't care about the symlink.
Reported-by: Martin Pitt <martin.pitt@ubuntu.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
Now libmount reads utab only when mtab filename is no explicitly
specified, but for example:
mnt_table_parse_mtab(tb, "/proc/self/mountinfo");
ignores utab because filename points to regular file. This is mistake,
we wnat to read utab always when we read mount table from kernel.
Reported-by: Martin Pitt <martin.pitt@ubuntu.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
Hi,
I have found out that libmount does not respect MNT_OMODE_FORCE mode.
I don't see any usage in sources and libmount does not respect this mode
when calling library functions. I'm proposing a patch to fix this.
Have a nice day!
Fridolin Pokorny
It's backwardly incompatible nonsense to prefer mtab on remount.
mount -o remount /foo
has to read mount options from fstab otherwise the remount has no
effect. (The ideal solution would be to read both mtab, then modify
the options according to fstab -- but for now more important is to be
backwardly compatible.)
References: https://bugzilla.redhat.com/show_bug.cgi?id=1182778
Signed-off-by: Karel Zak <kzak@redhat.com>
This change fixes all shadow declarations. The worth while to mention
fix is with libfdisk sun geometry. It comes from bitops.h cpu_to_be16
macro that further expands from include/bits/byteswap.h that has the
shadowing.
libfdisk/src/sun.c:961:173: warning: declaration of '__v' shadows a previous local [-Wshadow]
libfdisk/src/sun.c:961:69: warning: shadowed declaration is here [-Wshadow]
libfdisk/src/sun.c:961:178: warning: declaration of '__x' shadows a previous local [-Wshadow]
libfdisk/src/sun.c:961:74: warning: shadowed declaration is here [-Wshadow]
That could have caused earlier some unexpected results.
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
It's better than monitor utab directly. The utab is updated by
rename(2) and it's really tricky for inotify, because it's necessary
to monitor all /run/mount directory and then it's necessary to verify
that the renamed file is really "utab".
The new concept is without possible false positives and it also
triggers the change when utab update is really done.
Signed-off-by: Karel Zak <kzak@redhat.com>
We need full control on changes evaluation, so it's better to
hide all in our private epoll. This change also significantly
simplify the API.
mn = mnt_new_monitor();
mnt_monitor_enable_userapce(mn, TRUE, NULL);
mnt_monitor_enable_kenrel(mn, TRUE);
fd = mnt_monitor_get_fd(mn);
...
<use 'fd' in epoll controlled by your application>
...
while (mnt_monitor_next_changed(mn, &filename, NULL) == 0)
printf("%s: change detected\n", filename);
Signed-off-by: Karel Zak <kzak@redhat.com>
Karel Zak
Kir Kolyshkin
Sami Kerola
Ronny Chevalier
Fridolin Pokorny