ericonr
/
util-linux
mirror of https://github.com/ericonr/util-linux.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

libmount: (mountinfo) parse empty strings in source 

The source of a mount in /proc/self/mountinfo can unfortunately be an
empty string. Before this patch, 'mount' and 'mountpoint' fail as
following:

  $ sudo mount -t tmpfs "" /tmp/bb
  $ mount
  mount: /proc/self/mountinfo: parse error at line 64 -- ignored
  $ mountpoint /tmp/bb
  /tmp/bb is not a mountpoint

This patch fixes the parsing. It is unfortunately more complex because
sscanf() does not handle fields with empty strings easily.

Other projects have their own parser for mountinfo and have similar
issues. I know of runc and runtime-tools (I'll send a patch for those
two) but there are probably others.

Signed-off-by: Alban Crequy <alban@kinvolk.io>
This commit is contained in:
Alban Crequy 2018-06-22 13:54:25 +02:00 committed by Karel Zak
parent 66638b0b70
commit 18a52a5094
1 changed files with 28 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
libmount/src/tab_parse.c
View File

@ -173,13 +173,36 @@ static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, char *s)
fs->opt_fields = strndup(s + 1, p - s - 1);
s = p + 3;
rc += sscanf(s, UL_SCNsA" " /* (8) FS type */
UL_SCNsA" " /* (9) source */
UL_SCNsA, /* (10) fs options (fs specific) */
end = 0;
rc += sscanf(s, UL_SCNsA"%n", /* (8) FS type */
&fstype,
&src,
&fs->fs_optstr);
&end);
if (rc >= 8 && end > 0)
s += end;
if (s[0] == ' ')
s++;
/* (9) source can unfortunately be an empty string "" and scanf does
* not work well with empty string. Test with:
* $ sudo mount -t tmpfs "" /tmp/bb
* $ mountpoint /tmp/bb
* */
if (s[0] == ' ') {
src = strdup("");
s++;
rc++;
rc += sscanf(s, UL_SCNsA, /* (10) fs options (fs specific) */
&fs->fs_optstr);
} else {
rc += sscanf(s, UL_SCNsA" " /* (9) source */
UL_SCNsA, /* (10) fs options (fs specific) */
&src,
&fs->fs_optstr);
}
if (rc >= 10) {
size_t sz;