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@xxxxxxxxx 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 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
