查找PHP应用程序的安装目录

Question

PHP $_SERVER['...'] variables such as for 'PHP_SELF', 'SCRIPT_NAME', 'REQUEST_URI' have me somewhat confused. I've seen (at least some) previous questions about these and can do some testing in some environments, but I've run into environments where unexpected things happen.

I write apps that must be installable in any subdirectory below the document root. For example, suppose that the document root is /var/www/html and that the app is installed in /var/www/html/sub/dir . I need to require() files in /var/www/html/sub/dir (or subdirectories to that) and link to files in www.example.com://sub/dir . Call '/sub/dir' SUB_DIR. I also want rewrite rules for friendly urls such as www.example.com/sub/dir/route/key1/val1/key2/val2 .

I have an .htaccess for Apache and a web.config for IIS to do my rewrites to send everything through /var/www/html/sub/dir/index.php. I have not run into a need to figure out nginx or others.

I've been doing something like following but with more care about off by one issues and about Windows v. real world directory separators.

$docRoot = $_SERVER['DOCUMENT_ROOT'];
$reqUrl = $_SERVER['REQUEST_URI'];
$pwd = __DIR__;  /* Occuring in www.example.com/sub/dir/index.php) */
/* Expected example value for $pwd: /var/www/html/sub/dir */
$appLinkDir = substr($pwd, strlen(docRoot));
/* Expected example value for $appLinkDir: /sub/dir */
$workingRequest = substr($_SERVER['REQUEST_URI'], strlen(appLinkDir));
/* Expected example value for $workingRequest: /route/key1/val1/key2/val2 */

I ran into an environment where $pwd is /var/www/html instead of /var/www/html/sub/dir . My guess is that the app was installed in /var/www/html (not /var/www/html/sub/dir) but was they were doing global rewrites from /sub/dir/index.php (or something). At any rate, the unexpected value of $pwd gave me unexpected values for $appLinkDir and $workingRequest .

The problematic environment was from a third party code reviewer who may have assumed my app expected to be installed in /var/www/html/sub/dir when it in fact was expecting to discover where it was installed.

Any good (or even bad) ideas on how I can get correct values for $appLinkDir and $workingRequest ?

Answer 1

__DIR__ gives you the directory path where the php file is located on disk.

It won't change unless you move the php file on disk.

So if the file is placed under /var/html/sub/another/dir/index.php __DIR__ would be /var/html/sub/another/dir/.

Always use __DIR__ for including other php resources.

Now for the URL rewriting part:

I ran in a similar problem and what I've done is just passing the whole request URI to my php script and do the parsing there.

For example:

<?php
echo $_SERVER['REQUEST_URI'];

With a rewrite (for lighttpd as a reference):

url.rewrite-once = (
    # I don't want to route PNG, CSS files with PHP..
    "^/_assets/(.*)$" => "/_assets/$1", 
    "/(.*)$" => "index.php?$1"
)

If you access /test/blub/blab/ the php script gets invoked and prints the full URI:

/test/blub/blab/