On Mon, Apr 30, 2007 at 03:24:43PM -0400, Mike Frysinger wrote:
> On Tuesday 24 April 2007, Karel Zak wrote:
> > On Fri, Apr 13, 2007 at 07:28:25AM -0400, Mike Frysinger wrote:
> > > ---
> > > mount/mount.c | 2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/mount/mount.c b/mount/mount.c
> > > index 8e850b0..ea5ddc9 100644
> > > --- a/mount/mount.c
> > > +++ b/mount/mount.c
> > > @@ -759,7 +759,7 @@ update_mtab_entry(const char *spec, const char *node,
> > > const char *type, print_one (&mnt);
> > >
> > > if (!nomtab && mtab_is_writable()) {
> > > - if (flags & MS_REMOUNT)
> > > + if (fake || (flags & MS_REMOUNT))
> > > update_mtab (mnt.mnt_dir, &mnt);
> > > else {
> > > mntFILE *mfp;
> >
> > Sorry, NAK.
> >
> > man mount (about -f):
> > Causes everything to be done except for the actual system call;
> >
> >
> > there is nothing about any other exception. It's root's mistake when
> > add to mtab duplicate entry. The mount command prevents duplicate
> > mounts for "mount -a" or MS_USER/MS_USERS only. I don't think that we
> > need an exception for fake mounts. The fake mount has to work exactly
> > like normal mount otherwise it's nonsense.
>
> well, the reason for the change was because of the usage in the man page you
> also referred to:
>
> Causes everything to be done except for the actual system call; if it's not
> obvious, this fakes'' mounting the file system. This option is useful in
> conjunction with the -v flag to determine what the mount command is trying to
> do. It can also be used to add entries for devices that were mounted earlier
> with the -n option.
>
> that description (last sentence) indicates that the process should be a lot
> more safe than it actually is ... if the change i proposed above is NACKed,
Well, I'm not so stubborn ... but I'd like to add there a check for
duplicate entries rather than hide the problem and update the mtab
for fake mounts in a other way than for normal mounts (as was proposed
by your patch). See the patch below.
Karel
diff --git a/mount/mount.8 b/mount/mount.8
index 2d7c218..6cd1abc 100644
--- a/mount/mount.8
+++ b/mount/mount.8
@@ -341,7 +341,9 @@ conjunction with the
flag to determine what the
.B mount
command is trying to do. It can also be used to add entries for devices
-that were mounted earlier with the -n option.
+that were mounted earlier with the -n option. It also checks for duplicate
+entries, because for normal non-fake mounts it's kernel that avoid duplicate
+mounts.
.TP
.B \-i
Don't call the /sbin/mount.<filesystem> helper even if it exists.
diff --git a/mount/mount.c b/mount/mount.c
index 1526f26..9eb7f3b 100644
--- a/mount/mount.c
+++ b/mount/mount.c
@@ -190,6 +190,8 @@ static const struct opt_map opt_map[] = {
static const char *opt_loopdev, *opt_vfstype, *opt_offset, *opt_encryption,
*opt_speed, *opt_comment, *opt_uhelper;
+static int mounted (const char *spec0, const char *node0);
+
static struct string_opt_map {
char *tag;
int skip;
@@ -861,6 +863,14 @@ try_mount_one (const char *spec0, const char *node0, const char *types0,
suid_check(spec, node, &flags, &user);
+ /* To avoid duplicate entries in mtab -- for normal non-fake mounts
+ * it's kernel that checks duplicates.
+ */
+ if (fake && mounted (spec, node))
+ die(EX_USAGE, _("mount: according to mtab, "
+ "%s is already mounted on %s\n"),
+ spec, node);
+
mount_opts = extra_opts;
if (opt_speed)
-
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