[wp-trac] [WordPress Trac] #54582: Problem with deleting old files at the end of a core update when the filesystem is case-insensitive

[WordPress Trac]

#54582: Problem with deleting old files at the end of a core update when the
filesystem is case-insensitive
---------------------------------------+---------------------
 Reporter:  pbiron                     |       Owner:  (none)
     Type:  defect (bug)               |      Status:  new
 Priority:  high                       |   Milestone:  5.9
Component:  Upgrade/Install            |     Version:
 Severity:  major                      |  Resolution:
 Keywords:  needs-patch needs-testing  |     Focuses:
---------------------------------------+---------------------

Comment (by pbiron):

 Here's what I currently have for the check whether the filesystem is case-
 insensitive.  I'm thing this could be added as a method to
 `WP_Filesystem_Direct`:

 {{{
 #!php
 function is_filesystem_case_insenstive() {
         $temp_dir = get_temp_dir();
         if ( ! is_dir( $temp_dir) ) {
                 mkdir( $temp_dir );
         }

         $mixed_case_filename = tempnam( $temp_dir, 'MixedCase' );
         $lower_case_filename = strtolower( $mixed_case_filename );
         touch( $lower_case_filename );

         $mixed_case_stat = stat( $mixed_case_filename );
         $lower_case_stat = stat( $lower_case_filename );

         // Compare the Inodes returned by the 2 stat calls: if their the
 same, then filesystem is case-insensitive.
         $filesystem_case_insensitive = $mixed_case_stat['ino'] ===
 $lower_case_stat['ino'];

         unlink( $mixed_case_filename );
         if ( ! $filesystem_case_insensitive ) {
                 unlink( $lower_case_filename );
         }

         return $filesystem_case_insensitive;
 }
 }}}

 It seems to work as expected, but needs some error checking added (e.g.,
 test that `tempnam()` and `stat()` succeed).  Not yet sure what to do if
 those fail, i.e., what should it return in that case.

 My thought with comparing the `Inodes` is that is more foolproof than
 doing something like a `glob()` and counting the number of results
 returned...but I could certainly overthinking it.  Would love feedback on
 that.

 I've tested this in Windows and 2 different linux environments (centos a
 public server and centos running within WSL on Windows) and it reports
 correctly in all 3 cases.  Would love to have someone test in MacOS (both
 case-sensitive and case-insensitive configs).

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Ticket URL: <https://core.trac.wordpress.org/ticket/54582#comment:2>
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