Question

PHP has a nice realpath() function, which can convert something like /dir1/dir2/../dir3/filename to /dir1/dir3/filename. The “problem” with this function is that in case /dir1/dir3/filename is not an actual file but merely a link to another file, PHP would follow that link and return the real path of the actual file.

However, I actually need to get the real path of the link itself. All I need is to resolve complexities like /dir/.. in the path. How can I do it?

Answer 1

I was hoping to find an existing PHP function that does that, or else something simple along the lines of xdazz’s answer (but that would actually work the way I want it to). Having failed to find such an answer, I’ve written my own dirty function. I’d be happy to hear your comments and suggestions for improvement!

// return the contracted path (e.g. '/dir1/dir2/../dir3/filename' => '/dir1/dir3/filename')
// $path: an absolute or relative path
// $rel: the base $path is given relatively to - if $path is a relative path; NULL would take the current working directory as base
// return: the contracted path, or FALSE if $path is invalid
function contract_path($path, $rel = NULL) {
  if($path == '') return FALSE;
  if($path == '/') return '/';
  if($path[strlen($path) - 1] == '/') $path = substr($path, 0, strlen($path) - 1); // strip trailing slash
  if($path[0] != '/') { // if $path is a relative path
    if(is_null($rel)) $rel = getcwd();
    if($rel[strlen($rel) - 1] != '/') $rel .= '/';
    $path = $rel . $path;
  }
  $comps = explode('/', substr($path, 1)); // strip initial slash and extract path components
  $res = Array();
  foreach($comps as $comp) {
    if($comp == '') return FALSE; // double slash - invalid path
    if($comp == '..') {
      if(count($res) == 0) return FALSE; // parent directory of root - invalid path
      array_pop($res);
    }
    elseif($comp != '.') $res[] = $comp;
  }
  return '/' . implode('/', $res);
}