Use "w+" mode for opening/creating the unoconv lock file

[jensschuppe]

If I understand correctly, attempting a file lock for the unoconv lock file should create it if it doesn't exist. However, fopen() uses r+ which doesn't create the file if it's missing.

systopia-reference: 23962

[jofranz]

If I remember correctly it was intentionally set as read-only as it seems to be created by a touch() command here. Debatable if this is a good place tho

[jensschuppe]

Well, r+ is for reading and writing, just as w+ while the latter also truncates the file. I'm not sure that's what we want, but w and w+ creates the file if it doesn't exist, while r+ does not do that, which is the actual problem here …

[bjendres]

I don't see any harm in the change, provided it was successfully tested on a local and on the typical client's setup.

[jensschuppe]

provided it was successfully tested on […] the typical client's setup.

Not yet, so this will have to wait …

[jensschuppe]

This has been tested by @svenow on another environment, so this is ready to merge now.