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

I know this is an old thread, but it is really helpful.

I meet a weird Phar::interceptFileFuncs issue when I implemented relative path in phpctags, the realpath() is really really buggy inside phar.

Thanks this thread give me some lights, here comes with my implementation based on christian's implemenation from this thread and this comments.

Hope it works for you.

function relativePath($from, $to)
{
    $fromPath = absolutePath($from);
    $toPath = absolutePath($to);

    $fromPathParts = explode(DIRECTORY_SEPARATOR, rtrim($fromPath, DIRECTORY_SEPARATOR));
    $toPathParts = explode(DIRECTORY_SEPARATOR, rtrim($toPath, DIRECTORY_SEPARATOR));
    while(count($fromPathParts) && count($toPathParts) && ($fromPathParts[0] == $toPathParts[0]))
    {
        array_shift($fromPathParts);
        array_shift($toPathParts);
    }
    return str_pad("", count($fromPathParts)*3, '..'.DIRECTORY_SEPARATOR).implode(DIRECTORY_SEPARATOR, $toPathParts);
}

function absolutePath($path)
{
    $isEmptyPath    = (strlen($path) == 0);
    $isRelativePath = ($path{0} != '/');
    $isWindowsPath  = !(strpos($path, ':') === false);

    if (($isEmptyPath || $isRelativePath) && !$isWindowsPath)
        $path= getcwd().DIRECTORY_SEPARATOR.$path;

    // resolve path parts (single dot, double dot and double delimiters)
    $path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);
    $pathParts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
    $absolutePathParts = array();
    foreach ($pathParts as $part) {
        if ($part == '.')
            continue;

        if ($part == '..') {
            array_pop($absolutePathParts);
        } else {
            $absolutePathParts[] = $part;
        }
    }
    $path = implode(DIRECTORY_SEPARATOR, $absolutePathParts);

    // resolve any symlinks
    if (file_exists($path) && linkinfo($path)>0)
        $path = readlink($path);

    // put initial separator that could have been lost
    $path= (!$isWindowsPath ? '/'.$path : $path);

    return $path;
}