grow() resets permissions

[Aaron Wright <Aaron_Wright@…>]

I need to create shared memory with unrestricted permissions (0666). This works fine. When I attempt to grow the shared memory, using the grow() function, the permissions get reset to 0644.

I followed the code a bit and saw that it was using ftruncate. Checking the man page for ftruncate reveals, "the set-user-ID and set-group-ID permission bits may be cleared." Not sure what affects the "may" clause, but it did it every time for me. Umask was set to 0000.

Obviously this only effects systems using ftruncate. Windows works correctly.

Not sure on what versions may be needed, but: libc6 - 2.11.1 libglib2.0 - 2.24.1 gcc - 4.4.3