IssueTracker

The <?php $_SERVER['SCRIPT_NAME'] ?> implementation differs from Apache mod_php implementation (and most likely others) which can cause issues with a variety of PHP applications. The variable matches the HTTP spec and not the filesystem when called through Apache.

For example a script named foo.php contains the following.

<?php
var_dump($_SERVER['SCRIPT_NAME']);
?>
When executed from command line here are the results.

$ php foo.php
string(7) "foo.php"
 
$ php ./foo.php
string(9) "./foo.php"

When invoked through Apache like http://example.com/foo.php.

string(8) "/foo.php"

The documentation does not talk about this behavior (although many comments demonstrated the expected Apache behavior [matching style of HTTP request]), but it is definitely depended on.

On app engine the when called like http://example.com/foo.php.

string(8) "foo.php"

additionally when redirected to a subfolder using routers in app.yaml the SCRIPT_NAME contains the path even though that is not present in the external request.

On app engine the when called like http://example.com/foo.php while file is located in mydir/foo.php.

string(8) "mydir/foo.php"

The difference causes Drupal to format invalid URLs.

example.com.foo.css (instead of ...com/foo.css)
example.comsubdir/foo.css (instead of ...com/subdir/foo.css)
Drupal derives the URL from <?php dirname() ?> of <?php $_SERVER['SCRIPT_NAME'] ?> which will return . if no slashes or just / for something like /index.php.

Obviously this is something that can be handled within PHP applications, but seems like the value should be altered to match the HTTP spec as is generally expected by PHP applications.