There might be the case that `fopen($file, 'r')` returns false and thus ownCloud might believe that the config file is empty and thus potentially leading to an overwrite of the config file.
This changeset introduces `file_exists` again which was used in ownCloud 5 where no such problems where reported and should not be affected by such problems.
Ref https://github.com/owncloud/core/issues/12785#issuecomment-71548720
The permissions are already catched properly on the installation so we just have to check whether the file is readable to prevent fatal errors from happening.
Fixes https://github.com/owncloud/core/issues/12135
This adds a file lock to the config in hope that this prevents race conditions as reported in https://github.com/owncloud/core/issues/11070
Testplan:
- [ ] Delete config.php and make it read-only => Error is thrown that it is not writeable
- [ ] Installation still works
- [ ] Changing config settings works (i.e. using the SMTP config switches in the administration menu)
- [ ] Your PC didn't blow up
- [ ] Installing the news app and the "Disable AppCode checker" app did not destroy your installation
Only skip the main config
Otherwise read only additional configs might not be processed
Test on tmpdir
Lukas Reschke
Joas Schilling
Morris Jobke
Robin McCorkell
Volkan Gezer
kondou
Scrutinizer Auto-Fixer
Bart Visscher
Robin Appelman
Thomas Müller