Sorry, few typos in the script ** 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] 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>" + try: + return os.readlink(path) + 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] A locking change can potentially break locking, but this one seems like an obvious off-by-one error. ** 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] 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(path) except: return "<deleted>" import os, apt_pkg apt_pkg.init() apt_pkg.pkgsystem_lock() apt_pkg.pkgsystem_lock() + print([(p, maybe_readlink("/proc/self/fd/" + p)) for p in os.listdir("/proc/self/fd")]) 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] A locking change can potentially break locking, but this one seems like an obvious off-by-one error. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1778547 Title: Broken system lock counting Status in apt package in Ubuntu: Fix Committed Status in apt source package in Xenial: Fix Committed Status in apt source package in Artful: Fix Committed Status in apt source package in Bionic: Fix Committed Bug description: [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] 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(path) except: return "<deleted>" import os, apt_pkg apt_pkg.init() apt_pkg.pkgsystem_lock() apt_pkg.pkgsystem_lock() print([(p, maybe_readlink("/proc/self/fd/" + p)) for p in os.listdir("/proc/self/fd")]) 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] A locking change can potentially break locking, but this one seems like an obvious off-by-one error. 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