Normalize drive letter in paths

[Rarst]

Windows platform mostly treats paths as case-insensitive. However WordPress tends to use case-sensitive comparisons for paths.

Introduction of wp_normalize_path() gave an API way to deal with slashes consistently.

Another issue it could handle is consistent case of drive letter.

Due to varied possible sources of paths (PHP, web server, user configuration) mismatch in case of drive letter is relatively common (anecdotally I have encountered it multiple times in different contexts), ruins case-sensitive paths comparisons, and is hard to notice and debug.

I would suggest to uppercase drive letter in wp_normalize_path().

Upper case would be consistent with PHP constants (such as __FILE__) and historical Windows conventions (as far as I am aware there is no formal rule which is "correct" case).

[dd32]

I'm of two minds here

• All paths are case-insensitive on windows systems, only upper-casing the drive letter seems like altering 1 character of many
• Drive letters are uppercase by convention, paths are usually lower-case (unless a system path), leaving the drive letter as the only character that needs upper-casing.

Due to the PHP constants always returning uppercase drive letters, I'm inclined to go that way through.

33265.diff​ implements that, still not 100% sure which way though.

[SergeyBiryukov]

33265.diff​ looks good to me.

[tyxla]

Looks like this is a great moment to add general tests for wp_normalize_path() in addition to a test for the uppercase drive letters. Patch with tests coming up.

[tyxla]

Adding tests for wp_normalize_path(): general and uppercase drive letter cases included.

[tyxla]

And by the way, I suggest using ucfirst() for capitalizing the drive letter. It seems to be a more efficient and short way to do that IMHO. Patch coming up for that as well.

[tyxla]

Improved @dd32's patch by making the drive letter capitalization shorter and more efficient.

[dd32]

@tyxla Good calls!

[dd32]

In 34104:

When running on windows systems, normalise the capitalisation of the drive letter for more reliable string comparisons.

Props tyxla
Fixes #33265

[bobbingwide]

Could be even quicker if you don't bother to check for the colon.
just do ucfirst()

Assumption is that on nix systems the first letter is a '/' which doesn't get changed.

Are there cases where the $path does validly start with a letter that's not a drive letter
and should therefore not be uppercased.

[dd32]

While it's a good suggestion, I'm personally worried that people will be passing relative-paths somewhere, for example, $file = ABSPATH . wp_normalize_path( $file );