替换PHP的realpath()

Question

显然，realpath非常容易出错。在PHP 5.3.1中，它会导致随机崩溃。在5.3.0及更低版本中，realpath会随机失败并返回false (当然，对于相同的字符串)，而且它总是在realpath-ing上失败两次/更多次(当然，它第一次就能工作)。

此外，它在早期的PHP版本中有很多buggy，完全无法使用。Well...it已经是了，因为它不是一致的。

不管怎样，我有什么选择呢？也许我自己重写一下？这样做可取吗？

Answer 1

感谢Sven Arduwie的代码(pointed out by Pekka)和一些修改，我构建了一个(希望)更好的实现：

/**
 * 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;
}

PHP NB：与的realpath不同，这个函数在出错时不会返回false；它会返回一个尽可能远的路径来解决这些问题。

注2:显然有些人不能正确阅读。Truepath()不适用于网络资源，包括UNC和URL。它仅适用于本地文件系统。

Answer 2

下面是修改后的代码，也支持UNC路径

static public function truepath($path)
{
    // whether $path is unix or not
    $unipath = strlen($path)==0 || $path{0}!='/';
    $unc = substr($path,0,2)=='\\\\'?true:false;
    // attempts to detect if path is relative in which case, add cwd
    if(strpos($path,':') === false && $unipath && !$unc){
        $path=getcwd().DIRECTORY_SEPARATOR.$path;
        if($path{0}=='/'){
            $unipath = false;
        }
    }

    // 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, $absolutes);
    // resolve any symlinks
    if( function_exists('readlink') && file_exists($path) && linkinfo($path)>0 ){
        $path = readlink($path);
    }
    // put initial separator that could have been lost
    $path = !$unipath ? '/'.$path : $path;
    $path = $unc ? '\\\\'.$path : $path;
    return $path;
}

Answer 3

我知道这是一个老帖子，但它真的很有帮助。

当我在phpctags中实现相对路径时，我遇到了一个奇怪的Phar::interceptFileFuncs问题，这个realpath()在phar中真的有很多buggy。

感谢这个线程给了我一些启发，下面是我基于这个线程和这个comments的christian实现的实现。

希望它能为你工作。

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;
}