pkg_name calculated incorrectly

[Jamie Strandboge]

get_app_pkg_name() parses the value of /proc/self/attr/current to determine the value to use for the cache directory, but it has an off by one error as seen with this apparmor denial:
Oct 4 14:47:00 localhost kernel: [ 2456.617111] type=1400 audit(1380916020.878:369): apparmor="DENIED" operation="mkdir" parent=3324 profile="net.launchpad.ubuntu-security.ubuntu-sdk-1310-api-demos_ubuntu-sdk-1310-api-demos_0.6" name="/home/jamie/.cache/net.launchpad.ubuntu-security.ubuntu-sdk-1310-api-demo/" pid=15749 comm="qmlscene" requested_mask="c" denied_mask="c" fsuid=1000 ouid=1000

The app's apparmor label is "net.launchpad.ubuntu-security.ubuntu-sdk-1310-api-demos_ubuntu-sdk-1310-api-demos_0.6" so it should use:
/home/jamie/.cache/net.launchpad.ubuntu-security.ubuntu-sdk-1310-api-demos

however is actually uses:
/home/jamie/.cache/net.launchpad.ubuntu-security.ubuntu-sdk-1310-api-demo

This can perhaps be seen more clearly with the attached test program. Steps to reproduce:
$ cat > /tmp/bug.profile <<EOM
#include <tunables/global>
profile test_me {
  file,
}
EOM
$ sudo apparmor_parser -r /tmp/bug.profile
$ g++ /tmp/bug.cpp -o /tmp/bug
$ aa-exec -p test_me -- /tmp/bug
/proc/self/attr/current=test_me (enforce)
app_pkg_name=tes
$

In addition to the above, get_app_pkg_name() is not careful enough in determining the package name. It should throw an error if the value of /proc/self/attr/current doesn't match the following regex:
 ^[a-z0-9][a-z0-9+.-]+_[a-zA-Z0-9+.-]+_[0-9][a-zA-Z0-9.+:~-]*$

(see https://wiki.ubuntu.com/AppStore/Interfaces/ApplicationId for details). To consider why, consider the following valid profile names:
  /usr/bin/lsb_release
  /usr/lib/lightdm/lightdm/lightdm-guest-session-wrapper//chromium_browser
  /opt/foo/_bar

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:thumbnailer at revision 54, scheduled for release in thumbnailer, milestone Unknown

[Launchpad Janitor (janitor)]

This bug was fixed in the package thumbnailer - 1.0+13.10.20131008-0ubuntu1

---------------
thumbnailer (1.0+13.10.20131008-0ubuntu1) saucy; urgency=low

  [ Jussi Pakkanen ]
  * Fix off by one error. (LP: #1235444)
  * Disable use of in-process GStreamer because we use 1.0, which
    clashes with 0.10. (LP: #1235484)

  [ Ubuntu daily release ]
  * Automatic snapshot from revision 55
 -- Ubuntu daily release <email address hidden> Tue, 08 Oct 2013 12:49:51 +0000

[Jussi Pakkanen (jpakkane)]

The regex bit is actually not yet implemented.