get_attached_file() treats fully qualified URLs as relative

[tobiaskochsonlinenet]

If you call the function get_attached_file() of wp-include/post.php with a fully qualified URL (like "​http://www.example.com/file.ext") it will prepend the upload directory.

Checking the file's URI for :// would prevent this.

!preg_match('|^://|', $file)

[tobiaskochsonlinenet]

Oops, actually the regular expression should read:

!preg_match('|://|', $file)

[SergeyBiryukov]

Related: [8796], [9242].

[stevenlinx]

1.)
Related: 36308 patch fixes Windows paths and also makes the expression more compact.

2.)
This patch, which adds on top of the patch above, also fixes URL paths by prevent an URL from going into the relative path conditional.

[stevenlinx]

added unit test

[antpb]

It's currently possible to use the get_attached_file filter to modify the function to use full URLs. With that consideration it was agreed in a recent Media bug scrub through older issues that this is best fit for a plugin (as one of the attendees actually had an example plugin using the filter for this reason.)

Marking this wontfix to keep our open ticket list accurate to component goals.