flock as a couple of problems.  For example it does not work reliable
on remote file systems.  In particular not with CIFS.  It does also
not work with FAT systems (i.e. vfat).  A solution to this is to use a
separate lock file and either use hardlinks or open(O_EXCL) to check
for the existence of this file.  For details see the remarks in dotlock.c.

The implementation uses a portable implementation named dotlock.c
which is in its basic form in use for more than a decade.  It was
recently enhanced to properly detect file systems without hardlink
support and then fallback to a O_EXCL style locking.  It has been
tested on ext3, ufs, nfs, cifs and on vfat.

To keep the changes simple the implementation creates and locks
immediately and does not separate lock file template creation from
actual locking.  This can be improved by either using hacks in
dotlock.c to re-use existing lock file templates or by integrating it
closer into the gnome2-store.

https://bugzilla.gnome.org...