| Subject: | undocumented file locking in File::Temp |
Dear File::Temp maintainer,
In Perl v5.8.8, File::Lock::tempfile obtains an exclusive lock on the
temporary file only on systems that support the O_EXLOCK sysopen flag.
On systems that do not support O_EXLOCK, no lock is obtained by
File::Lock::tempfile. This behavior is not documented in "perldoc
File::Lock", and no way is provided to suppress the acquisition of the lock.
For an example of the problem caused by this behavior, see:
http://rt.cpan.org/Ticket/Display.html?id=28373
In this example, Brackup's test code wishes to create a database in a
temporary file. So it creates a temporary file using
File::Lock::tempfile, and tries to create a database in it using
DBD::SQLite. When DBD::SQLite attempts to lock the file, the test fails
because it blocks indefinitely on FreeBSD systems (which support
O_EXLOCK) because the file has already been locked. But the test passes
on Linux systems where O_EXLOCK is unsupported.
Rather than documenting this behavior, I would prefer eliminating it.
There is little value in automatically obtaining an exclusive lock only
on the systems that support O_EXLOCK, and since the behavior is
undocumented nobody should be depending on it. Attached is a patch which
removes the use of EXLOCK from File::Temp 0.18.
Thanks,
Matt