Mercurial > hg
changeset 17682:829919ef894a stable
lock: fixed race condition in trylock/testlock (issue3506)
Suppose the following scenario:
1. Process A takes the lock (e.g. on commit).
2. Process B wants to grab the lock. Since lock file exists
the exception is raised. In the catch block the testlock
function is called.
3. Process A releases the lock.
4. Process B tries to read the lock file as a part of testlock
function. This results in OSError (ENOENT) and since we're
not inside the exception handler function this is propagated
and aborts the whole operation.
To fix this we now check in testlock function whether lock file
actually exists and if not (i.e. if readlock fails) we just return.
| author | Tomasz Kleczek <tomasz.kleczek@fb.com> |
|---|---|
| date | Thu, 27 Sep 2012 14:38:03 -0700 |
| parents | 07d577dae285 |
| children | 6d7db5794e8c b3f0f9a39c4e |
| files | mercurial/lock.py |
| diffstat | 1 files changed, 6 insertions(+), 1 deletions(-) [+] |
line wrap: on
line diff
--- a/mercurial/lock.py Sat Sep 29 13:33:55 2012 +0200 +++ b/mercurial/lock.py Thu Sep 27 14:38:03 2012 -0700 @@ -97,7 +97,12 @@ The lock file is only deleted when None is returned. """ - locker = util.readlock(self.f) + try: + locker = util.readlock(self.f) + except OSError, why: + if why.errno == errno.ENOENT: + return None + raise try: host, pid = locker.split(":", 1) except ValueError: