path - Replace PHP's realpath()

Question

Apparently, realpath is very buggy. In PHP 5.3.1, it causes random crashes. In 5.3.0 and less, realpath randomly fails and returns false (for the same string of course), plus it always fails on realpath-ing the same string twice/more (and of course, it works the first time).

Also, it is so buggy in earlier PHP versions, that it is completely unusable. Well...it already is, since it's not consistent.

Anyhow, what options do I have? Maybe rewrite it by myself? Is this advisable?

Answer 1

Thanks to Sven Arduwie's code (pointed out by Pekka) and some modification, I've built a (hopefully) better implementation:

/**
 * This function is to replace PHP's extremely buggy realpath().
 * @param string The original path, can be relative etc.
 * @return string The resolved path, it might not exist.
 */
function truepath($path){
    // whether $path is unix or not
    $unipath=strlen($path)==0 || $path{0}!='/';
    // attempts to detect if path is relative in which case, add cwd
    if(strpos($path,':')===false && $unipath)
        $path=getcwd().DIRECTORY_SEPARATOR.$path;
    // resolve path parts (single dot, double dot and double delimiters)
    $path = str_replace(array('/', '\'), DIRECTORY_SEPARATOR, $path);
    $parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
    $absolutes = array();
    foreach ($parts as $part) {
        if ('.'  == $part) continue;
        if ('..' == $part) {
            array_pop($absolutes);
        } else {
            $absolutes[] = $part;
        }
    }
    $path=implode(DIRECTORY_SEPARATOR, $absolutes);
    // resolve any symlinks
    if(file_exists($path) && linkinfo($path)>0)$path=readlink($path);
    // put initial separator that could have been lost
    $path=!$unipath ? '/'.$path : $path;
    return $path;
}

NB: Unlike PHP's realpath, this function does not return false on error; it returns a path which is as far as it could to resolving these quirks.

Note 2: Apparently some people can't read properly. Truepath() does not work on network resources including UNC and URLs. It works for the local file system only.