* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
[not found] <19860.58082.277944.875401@gargle.gargle.HOWL>
@ 2011-04-01 7:46 ` Aneesh Kumar K. V
2011-04-01 8:45 ` Miklos Szeredi
2011-04-05 12:23 ` Karel Zak
0 siblings, 2 replies; 6+ messages in thread
From: Aneesh Kumar K. V @ 2011-04-01 7:46 UTC (permalink / raw)
To: victor.vde, util-linux, Miklos Szeredi, linuxram
Cc: Alexander Viro, Victor van den Elzen, Eugene J. Markow,
linux-fsdevel, linux-kernel
On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde@gmail.com wrote:
> /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> and ext3 mounts, for example:
>
> 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
>
> It seems the hyphens in the uuid confuse the parser
> mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
shouldn't the parser look for " " followed by "-" followed by " " as the
field seperator ?
I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
should be fixed ?
>
> My util-linux version is 2.19-4 Arch Linux.
>
> ~ $ findmnt -l /
> TARGET SOURCE FSTYPE OPTIONS
> / - 9756-4d84-825e-6fe999252a34 rw,noatime,ext4
>
> For reference, the commits in Linus' tree that introduced these uuids
> are:
>
> 93f1c20bc8cdb757be50566eff88d65c3b26881f vfs: Export file system uuid via /proc/<pid>/mountinfo
> 03cb5f03dcb26846fcad345d8c15aae91579a53d ext3: Copy fs UUID to superblock.
> f2fa2ffc2046fdc35f96366d1ec8675f4d578522 ext4: Copy fs UUID to superblock
-aneesh
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
2011-04-01 7:46 ` [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1 Aneesh Kumar K. V
@ 2011-04-01 8:45 ` Miklos Szeredi
2011-04-01 9:32 ` Karel Zak
2011-04-05 12:23 ` Karel Zak
1 sibling, 1 reply; 6+ messages in thread
From: Miklos Szeredi @ 2011-04-01 8:45 UTC (permalink / raw)
To: Aneesh Kumar K. V
Cc: victor.vde, util-linux, miklos, linuxram, viro, victor.vde,
ejmarkow, linux-fsdevel, linux-kernel
On Fri, 01 Apr 2011, Aneesh Kumar K. V wrote:
> On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde@gmail.com wrote:
> > /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> > and ext3 mounts, for example:
> >
> > 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
> >
> > It seems the hyphens in the uuid confuse the parser
> > mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
>
> shouldn't the parser look for " " followed by "-" followed by " " as the
> field seperator ?
>
> I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
> should be fixed ?
I think libmount should be fixed, though there is always the question
of backward compatibility.
However I don't see how the kernel could be fixed, given that libmount
doesn't seem to parse escape sequences (e.g. "\040" for space), which
it also should.
Karel?
Thanks,
Miklos
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
2011-04-01 8:45 ` Miklos Szeredi
@ 2011-04-01 9:32 ` Karel Zak
[not found] ` <20110401093240.GA11012-sHeGUpI7y9L/9pzu0YdTqQ@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Karel Zak @ 2011-04-01 9:32 UTC (permalink / raw)
To: Miklos Szeredi
Cc: Aneesh Kumar K. V, victor.vde, util-linux, linuxram, viro,
ejmarkow, linux-fsdevel, linux-kernel, Lennart Poettering
On Fri, Apr 01, 2011 at 10:45:48AM +0200, Miklos Szeredi wrote:
> On Fri, 01 Apr 2011, Aneesh Kumar K. V wrote:
> > On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde@gmail.com wrote:
> > > /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> > > and ext3 mounts, for example:
> > >
> > > 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
> > >
> > > It seems the hyphens in the uuid confuse the parser
> > > mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
> >
> > shouldn't the parser look for " " followed by "-" followed by " " as the
> > field seperator ?
> >
> > I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
> > should be fixed ?
>
> I think libmount should be fixed, though there is always the question
> of backward compatibility.
The parser uses
rc = sscanf(s, "%u " /* (1) id */
"%u " /* (2) parent */
"%u:%u " /* (3) maj:min */
"%ms " /* (4) mountroot */
"%ms " /* (5) target */
"%ms" /* (6) vfs options (fs-independent) */
"%*[^-]" /* (7) optional fields */
"- " /* (8) separator */
"%ms " /* (9) FS type */
"%ms " /* (10) source */
"%ms", /* (11) fs options (fs specific) */
note that almost the same code is in systemd.
> However I don't see how the kernel could be fixed, given that libmount
> doesn't seem to parse escape sequences (e.g. "\040" for space), which
> it also should.
It calls unmangle_string() for all fields, so all sequences should be
decoded.
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
[not found] ` <20110401093240.GA11012-sHeGUpI7y9L/9pzu0YdTqQ@public.gmane.org>
@ 2011-04-01 10:12 ` Miklos Szeredi
2011-04-01 10:38 ` Karel Zak
0 siblings, 1 reply; 6+ messages in thread
From: Miklos Szeredi @ 2011-04-01 10:12 UTC (permalink / raw)
To: Karel Zak
Cc: miklos-sUDqSbJrdHQHWmgEVkV9KA,
aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8,
victor.vde-Re5JQEeQqe8AvxtiuMwx3w,
util-linux-u79uwXL29TY76Z2rM5mHXA,
linuxram-r/Jw6+rmf7HQT0dZR+AlfA,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn,
ejmarkow-/E1597aS9LQAvxtiuMwx3w,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA,
lennart-mdGvqq1h2p+GdvJs77BJ7Q
On Fri, 1 Apr 2011, Karel Zak wrote:
> On Fri, Apr 01, 2011 at 10:45:48AM +0200, Miklos Szeredi wrote:
> > On Fri, 01 Apr 2011, Aneesh Kumar K. V wrote:
> > > On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> > > > /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> > > > and ext3 mounts, for example:
> > > >
> > > > 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
> > > >
> > > > It seems the hyphens in the uuid confuse the parser
> > > > mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
> > >
> > > shouldn't the parser look for " " followed by "-" followed by " " as the
> > > field seperator ?
> > >
> > > I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
> > > should be fixed ?
> >
> > I think libmount should be fixed, though there is always the question
> > of backward compatibility.
>
> The parser uses
>
> rc = sscanf(s, "%u " /* (1) id */
> "%u " /* (2) parent */
> "%u:%u " /* (3) maj:min */
> "%ms " /* (4) mountroot */
> "%ms " /* (5) target */
> "%ms" /* (6) vfs options (fs-independent) */
> "%*[^-]" /* (7) optional fields */
So this says, "skip everything up to the first hyphen", even though
the rule might be better expressed as "skip all space delimited words
up to the first standalone hyphen". I guess that's not possible to
express with a scanf expression, though.
> "- " /* (8) separator */
> "%ms " /* (9) FS type */
> "%ms " /* (10) source */
> "%ms", /* (11) fs options (fs specific) */
>
> note that almost the same code is in systemd.
>
> > However I don't see how the kernel could be fixed, given that libmount
> > doesn't seem to parse escape sequences (e.g. "\040" for space), which
> > it also should.
>
> It calls unmangle_string() for all fields, so all sequences should be
> decoded.
Okay, so the kernel can simply escape the troublesome hyphens, which
would make the human parsing of /proc/pid/mountinfo more difficult but
at least would fix compatibility with util-linux's parser.
Thanks,
Miklos
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
2011-04-01 10:12 ` Miklos Szeredi
@ 2011-04-01 10:38 ` Karel Zak
0 siblings, 0 replies; 6+ messages in thread
From: Karel Zak @ 2011-04-01 10:38 UTC (permalink / raw)
To: Miklos Szeredi
Cc: aneesh.kumar, victor.vde, util-linux, linuxram, viro, ejmarkow,
linux-fsdevel, linux-kernel, lennart
On Fri, Apr 01, 2011 at 12:12:34PM +0200, Miklos Szeredi wrote:
> On Fri, 1 Apr 2011, Karel Zak wrote:
> > On Fri, Apr 01, 2011 at 10:45:48AM +0200, Miklos Szeredi wrote:
> > > On Fri, 01 Apr 2011, Aneesh Kumar K. V wrote:
> > > > On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde@gmail.com wrote:
> > > > > /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> > > > > and ext3 mounts, for example:
> > > > >
> > > > > 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
> > > > >
> > > > > It seems the hyphens in the uuid confuse the parser
> > > > > mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
> > > >
> > > > shouldn't the parser look for " " followed by "-" followed by " " as the
> > > > field seperator ?
> > > >
> > > > I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
> > > > should be fixed ?
> > >
> > > I think libmount should be fixed, though there is always the question
> > > of backward compatibility.
> >
> > The parser uses
> >
> > rc = sscanf(s, "%u " /* (1) id */
> > "%u " /* (2) parent */
> > "%u:%u " /* (3) maj:min */
> > "%ms " /* (4) mountroot */
> > "%ms " /* (5) target */
> > "%ms" /* (6) vfs options (fs-independent) */
> > "%*[^-]" /* (7) optional fields */
>
> So this says, "skip everything up to the first hyphen", even though
> the rule might be better expressed as "skip all space delimited words
> up to the first standalone hyphen". I guess that's not possible to
> express with a scanf expression, though.
Yes, I'll probably use two sscanf(), %n and strstr(), something like:
rc = sscanf(s, "%u " /* (1) id */
"%u " /* (2) parent */
"%u:%u " /* (3) maj:min */
"%ms " /* (4) mountroot */
"%ms " /* (5) target */
"%ms" /* (6) vfs options (fs-independent) */
"%n",
&id,
&parent,
&maj, &min,
&root,
&target,
&vfs_optstr,
&end);
s += end;
/* (7) optional fields, terminated by " - " */
p = strstr(s, " - ");
if (p)
s = p + 3;
rc += sscanf(s, "%ms " /* (8) FS type */
"%ms " /* (9) source */
"%ms", /* (10) fs options (fs specific) */
&fstype,
&src,
&fs_optstr);
...or anyone has a better idea?
> > It calls unmangle_string() for all fields, so all sequences should be
> > decoded.
>
> Okay, so the kernel can simply escape the troublesome hyphens, which
> would make the human parsing of /proc/pid/mountinfo more difficult but
> at least would fix compatibility with util-linux's parser.
Hmm.. IMHO it will be better to fix the parsers in libmount and systemd. The
both projects are young, nobody will be surprised with bugs :-)
I think the example in Documentation/filesystems/proc.txt is pretty
obvious, the separator is an extra field with " - ".
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1
2011-04-01 7:46 ` [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1 Aneesh Kumar K. V
2011-04-01 8:45 ` Miklos Szeredi
@ 2011-04-05 12:23 ` Karel Zak
1 sibling, 0 replies; 6+ messages in thread
From: Karel Zak @ 2011-04-05 12:23 UTC (permalink / raw)
To: Aneesh Kumar K. V
Cc: victor.vde, util-linux, Miklos Szeredi, linuxram, Alexander Viro,
Eugene J. Markow, linux-fsdevel, linux-kernel
On Fri, Apr 01, 2011 at 01:16:23PM +0530, Aneesh Kumar K. V wrote:
> On Thu, 31 Mar 2011 22:24:01 +0200, victor.vde@gmail.com wrote:
> > /proc/self/mountinfo on Linux v2.6.39-rc1 includes the UUID of ext4
> > and ext3 mounts, for example:
> >
> > 15 1 8:3 / / rw,noatime uuid:c645234d-9756-4d84-825e-6fe999252a34 - ext4 /dev/sda3 rw,user_xattr,acl,barrier=1,data=ordered
> >
> > It seems the hyphens in the uuid confuse the parser
> > mnt_parse_mountinfo_line in tab_parse.c of libmount in util-linux.
>
> shouldn't the parser look for " " followed by "-" followed by " " as the
> field seperator ?
>
> I am adding Miklos and Ram Pai to CC to check whether the kernel or the libmount
> should be fixed ?
The libmount (in util-linux git tree) should be fixed now. Thanks for
the report!
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
^ permalink raw reply [flat|nested] 6+ messages in thread
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2011-04-01 7:46 ` [BUG] libmount misparses mountinfo on Linux v2.6.39-rc1 Aneesh Kumar K. V
2011-04-01 8:45 ` Miklos Szeredi
2011-04-01 9:32 ` Karel Zak
[not found] ` <20110401093240.GA11012-sHeGUpI7y9L/9pzu0YdTqQ@public.gmane.org>
2011-04-01 10:12 ` Miklos Szeredi
2011-04-01 10:38 ` Karel Zak
2011-04-05 12:23 ` Karel Zak
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