Error reporting for filesystem matters

[joshtrichards]

For an improved user experience (and the reduction of invalid bug reports) we should add better interpretation (i.e. errno to readable hints) and reporting of underlying errors (at least as reported to us by the underlying OS) in the following steps/areas:

• createBackup()
• downloadUpdate()
• extractDownload()
• verifyIntegrity()
• moveNewVersionInPlace()
• deleteOldFiles()

[joshtrichards]

• ZipArchive::open() - used in extractDownload - returns a number of detailed error codes that we can translate into human readable form (not all of them are on the PHP docs page but they can be found in the PHP source code and/or in the comments in the manual)
  • https://www.php.net/manual/en/ziparchive.open.php
  • they can be handled here:

    updater/index.php

    Lines 764 to 766 in 4d660d8

    	} else {
    	throw new \Exception("Can't handle ZIP file. Error code is: ".print_r($zipState, true));
    	}

• https://github.com/nih-at/libzip/blob/cf7bf43ba2f85f936705231903aa0d5cfb2fdf11/lib/zip.h#L120-L156