** Description changed:
[Impact]
System lock unrefing is broken, off-by-one error. Locking twice opens a
second fd for the lock file, and the old fd gets lost and remains open for the
remaining duration of the program
[Test case]
- TODO
+
+ Executing the following script should show one lock file in the first
+ line, and none in the last line.
+
+ def maybe_readlink(path):
+ try:
+ return os.readlink("/proc/self/fd/" + p)
+ except:
+ return "<deleted>"
+
+ import os, apt_pkg
+ apt_pkg.init()
+ apt_pkg.pkgsystem_lock()
+ apt_pkg.pkgsystem_lock()
+ apt_pkg.pkgsystem_unlock()
+ apt_pkg.pkgsystem_unlock()
+ print([(p, maybe_readlink("/proc/self/fd/" + p)) for p in
os.listdir("/proc/self/fd")])
+
+
+ [Test output]
+ good, cosmic:
+ [('0', '/dev/pts/2'), ('1', '/dev/pts/2'), ('2', '/dev/pts/2'), ('3',
'/var/lib/dpkg/lock'), ('4', '<deleted>')]
+ [('0', '/dev/pts/2'), ('1', '/dev/pts/2'), ('2', '/dev/pts/2'), ('3',
'<deleted>')]
+
+ bad, bionic:
+ [('0', '/dev/pts/0'), ('1', '/dev/pts/0'), ('2', '/dev/pts/0'), ('3',
'pipe:[40889331]'), ('4', '/var/lib/dpkg/lock'), ('5', '/var/lib/dpkg/lock'),
('6', '<deleted>'), ('17', 'socket:[53931]')]
+ [('0', '/dev/pts/0'), ('1', '/dev/pts/0'), ('2', '/dev/pts/0'), ('3',
'pipe:[40889331]'), ('4', '/var/lib/dpkg/lock'), ('5', '<deleted>'), ('17',
'socket:[53931]')]
+
[Regression potential]
- TODO
+ A locking change can potentially break locking, but this one seems like an
obvious off-by-one error.
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https://bugs.launchpad.net/bugs/1778547
Title:
Broken system lock counting
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