WordPress may not return correct $home_path when installed in a subdirectory

[ptahdunbar]

I've got a local install of WordPress set within a subdirectory of the root (like all the cool kids).

Here's the file path:
/Users/ptah/Sites/vhosts/wp.dev/www/wp/

After installing and setting pretty permalinks, WordPress wasn't able to create the .htaccess file even though it had write access to the root folder.

I traced the bug down to get_home_path() where it trys to guess the WordPress directory by strpos() the script path against the relative wp path. Starting the comparison from left to right, it stopped at the first wp it found giving me the following home path:
/Users/ptah/Sites/vhosts/

Well, that's wrong. It should be:
/Users/ptah/Sites/vhosts/wp.dev/www/wp/

Patch fixes this by using strrpos() instead which stops at the last occurrence of the needle.
Given that it's matching against $_SERVER['SCRIPT_FILENAME'], it's more logical to work from the script path of WordPress than the other way around which may or may not contain duplicate matches.

[volcanicpixels]

I just tested the patch - works great.

[nacin]

Looks good to me. Unit tests might be helpful for this. Assigning to dd32.

[dd32]

A simple way to trigger this is to install into a folder of the same name as your username.

Verified, patch works.

[dd32]

In [19697]:

Fix edge case in get_home_path() where the incorrect path may be returned. Props ptahdunbar. Fixes #18768

[WraithKenny]

See #20449 fails for /wp/wp-admin/options-permalink.php since wp-admin is the last occurrence.