PHP奇怪的DOCUMENT_ROOT

基本上，我正在编写一个框架，作为其功能的一部分，它应该为最终开发人员提供一组完善的 URI/路径。

其中两条路径利用$_SERVER['DOCUMENT_ROOT']:

/**
 * Absolute filesystem path to web root install (aka docroot).
 * @example "C:/wamp/www" OR "/home/visitgoz/public_html/"
 */
CFG::set('ABS_WWW',
    str_replace(
        $tmpseps,
        DIRECTORY_SEPARATOR,
        truepath($_SERVER['DOCUMENT_ROOT']).'/'
    )
);

/**
 * K2F path relative to web root.
 * @example /K2F/
 */
CFG::set('REL_K2F',
    str_replace(
        array('//','\\'),
        '/',
        str_replace(CFG::get('ABS_WWW'),'/',CFG::get('ABS_K2F'))
    )
);

该代码经过微调，可以在 Linux 和 Windows 上运行。显然，它有效mostLinux 上的时间，事实上在 VPS 上相当无缝。

然而，最近，我在一个HG 经销商帐户 http://www.hostgator.com/resellers.shtml（共享主机）一切都破裂了。 我已在有问题的机器上打印出 $_SERVER 内的数据：

Array
(
**  [DOCUMENT_ROOT] => /usr/local/apache/htdocs
    [GATEWAY_INTERFACE] => CGI/1.1
    [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9;q=0.8
    [HTTP_ACCEPT_CHARSET] => ISO-8859-1,utf-8;q=0.7,*;q=0.7
    [HTTP_ACCEPT_ENCODING] => gzip,deflate
    [HTTP_ACCEPT_LANGUAGE] => en-gb,en;q=0.5
    [HTTP_CONNECTION] => keep-alive
    [HTTP_COOKIE] => <snip>
    [HTTP_HOST] => <snip>
    [HTTP_KEEP_ALIVE] => 115
    [HTTP_USER_AGENT] => <snip>
    [PATH] => /bin:/usr/bin
    [QUERY_STRING] => 
    [REDIRECT_STATUS] => 200
    [REMOTE_ADDR] => <snip>
    [REMOTE_PORT] => 49262
    [REQUEST_METHOD] => GET
    [REQUEST_URI] => /~sitename/
**  [SCRIPT_FILENAME] => /home/sitename/public_html/index.php
    [SCRIPT_NAME] => /~sitename/index.php
    [SERVER_ADDR] => <snip>
    [SERVER_ADMIN] => <snip>
    [SERVER_NAME] => <snip>
    [SERVER_PORT] => 80
    [SERVER_PROTOCOL] => HTTP/1.1
    [SERVER_SIGNATURE] => 
Apache mod_fcgid/2.3.5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at <snip> Port 80


    [SERVER_SOFTWARE] => Apache mod_fcgid/2.3.5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635
    [UNIQUE_ID] => TVox-Eo1Z8IAAG1kAh4AAAEZ
    [PHP_SELF] => /~sitename/index.php
    [REQUEST_TIME] => 1297756668
    [argv] => Array
        (
        )

    [argc] => 0
)

还有我的机器：

Array
(
    [HTTP_AUTHORIZATION] => 
    [HTTP_HOST] => <snip>
    [HTTP_USER_AGENT] => <snip>
    [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9;q=0.8
    [HTTP_ACCEPT_LANGUAGE] => en-gb,en;q=0.5
    [HTTP_ACCEPT_ENCODING] => gzip,deflate
    [HTTP_ACCEPT_CHARSET] => ISO-8859-1,utf-8;q=0.7,*;q=0.7
    [HTTP_KEEP_ALIVE] => 115
    [HTTP_CONNECTION] => keep-alive
    [PATH] => <snip>
    [SystemRoot] => C:\Windows
    [COMSPEC] => C:\Windows\system32\cmd.exe
    [PATHEXT] => .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
    [WINDIR] => C:\Windows
    [SERVER_SIGNATURE] => 
    [SERVER_SOFTWARE] => Apache/2.2.11 (Win32) PHP/5.3.1
    [SERVER_NAME] => <snip>
    [SERVER_ADDR] => <snip>
    [SERVER_PORT] => 80
    [REMOTE_ADDR] => <snip>
**  [DOCUMENT_ROOT] => C:/wamp/www/
    [SERVER_ADMIN] => admin@localhost
**  [SCRIPT_FILENAME] => C:/wamp/www/K2F/cms/cms-joomla-1.5/index.php
    [REMOTE_PORT] => 49947
    [GATEWAY_INTERFACE] => CGI/1.1
    [SERVER_PROTOCOL] => HTTP/1.1
    [REQUEST_METHOD] => GET
    [QUERY_STRING] => 
    [REQUEST_URI] => /K2F/cms/cms-joomla-1.5/
    [SCRIPT_NAME] => /K2F/cms/cms-joomla-1.5/index.php
    [PHP_SELF] => /K2F/cms/cms-joomla-1.5/index.php
    [REQUEST_TIME] => 1297758541
)

** 你应该读出的部分应该完美地解释我的问题。

所以基本上，预期的DOCUMENT_ROOT is /home/sitename/public_html/，但我却得到了/usr/local/apache/htdocs.

哦，抱歉，如果我有点太冗长了；）

Edit:

getcwd() => /home/visitgoz/public_html

__FILE__ => /home/visitgoz/public_html/K2F/config.php

那些（便宜的）大众主机经常会使用一些 Apache URL 重写技巧 - 这基本上使他们的生活变得更轻松，因为只有一台 Apache V 主机，所有共享网站都有一个文档根。

在这种情况下要找到“真实”文档根：

• 从左到右比较 DOCUMENT_ROOT 和 SCRIPT_FILENAME。如果没有匹配的路径组件，则它是共享主机。
• 如果是这样的共享主机，请从示例中的 SCRIPT_NAME => "index.php" 中删除 REQUEST_URI。
• 然后：从 SCRIPT_FILENAME => 你的 DOCUMENT_ROOT (/home/sitename/public_html/) 末尾删除上面的结果

编辑（克里斯蒂安·西贝拉斯）：这是正确的答案，但它缺少代码，无论如何我都必须编写代码，所以这里是：

if(strpos($_SERVER['SCRIPT_FILENAME'],$_SERVER['DOCUMENT_ROOT'])===false){
    // how it works on reseller accounts...
    $path=str_common(getcwd(),__FILE__);
}else{
    // how it normally works...
    $path=truepath($_SERVER['DOCUMENT_ROOT']).'/';
}