Anyone have an equivalent function?

Question

PHP

Does anyone have a smarter analog of the function:

// _path
  // возвращает полный путь к файлу или директории, даже если таковая не существует
  if (!function_exists("_path")):
    function _path($_path) {
      $path = strval($_path);

      // errors
      if (preg_match("#[*?\"<>|+]#", $path)) return false; // [*?"<>|+]
      if (preg_match("#[.]{3,}#", $path)) return false; // ...
      if (preg_match("#[^/][.]{2,}#", $path)) return false; // a..
      if (preg_match("#[.]{2,}[^/]#", $path)) return false; // ..a
      if (preg_match("#(.{2,}|[^.]+)\.$#", $path)) return false; //ab.[end] or ..[end]

      $path = preg_replace("#[\\\/]#", "/", trim($path));
      $path = preg_replace("#/+#", "/", $path);
      $path = preg_replace("#^([^/.])#", ($_SERVER["DOCUMENT_ROOT"] . "/$1"), $path);
      $path = preg_replace("#^/#", realpath("/"), $path);
      $path = preg_replace("#^\.{2}[/]?#", (dirname($_SERVER["DOCUMENT_ROOT"]) . "/"), $path);
      $path = preg_replace("#^\./#", ($_SERVER["DOCUMENT_ROOT"] . "/"), $path);

      while (($pos = mb_strpos($path, "../")) !== FALSE):
        $var = realpath($tmp = mb_substr($path, 0, $pos) . "../");
        $left = mb_substr($path, $pos + 3) ?: null;
        if ($var):
          $path = rtrim($var, DIRECTORY_SEPARATOR) . "/" . $left;
          continue;
        endif;
        break;
      endwhile;

      $path = preg_replace("#^\.$#", $_SERVER["DOCUMENT_ROOT"] . "/", $path);
      $path = $path ?: ($_SERVER["DOCUMENT_ROOT"] . "/");
      $path = preg_replace("#[\\\/]#", "/", $path);

      return $path;
    }
  endif;

Tests:

array(
  "" => "D:/OpenServer/domains/test.wrap/test.loc/",
  ".." => "D:/OpenServer/domains/test.wrap/",
  "/.." => false,
  "/../" => "D:/",
  "a.." => false,
  "a/.." => false,
  "a/../" => "D:/OpenServer/domains/test.wrap/test.loc/a/../",
  "..a" => false,
  "/..a" => false,
  "/../a" => "D:/a",
  "a..a" => false,
  "a/..a" => false,
  "a/../a" => "D:/OpenServer/domains/test.wrap/test.loc/a/../a",
  "...." => false,
  "../.." => false,
  "../../" => "D:/OpenServer/domains/",
  "..a.." => false,
  "..a/.." => false,
  "..a/../" => false,
  "....a" => false,
  "../..a" => false,
  "../../a" => "D:/OpenServer/domains/a",
  "..a..a" => false,
  "..a/..a" => false,
  "..a/../a" => false,
  "/...." => false,
  "/../.." => false,
  "/../../" => "D:/",
  "/..a.." => false,
  "/..a/.." => false,
  "/..a/../" => false,
  "/....a" => false,
  "/../..a" => false,
  "/../../a" => "D:/a",
  "/..a..a" => false,
  "/..a/..a" => false,
  "/..a/../a" => false,
  "/..//.." => false,
  "/..//../" => "D:/",
  "/../a.." => false,
  "/../a/.." => false,
  "/../a/../" => "D:/a/../",
  "/..//..a" => false,
  "/..//../a" => "D:/a",
  "/../a..a" => false,
  "/../a/..a" => false,
  "/../a/../a" => "D:/a/../a",
  "a...." => false,
  "a../.." => false,
  "a../../" => false,
  "a..a.." => false,
  "a..a/.." => false,
  "a..a/../" => false,
  "a....a" => false,
  "a../..a" => false,
  "a../../a" => false,
  "a..a..a" => false,
  "a..a/..a" => false,
  "a..a/../a" => false,
  "a/...." => false,
  "a/../.." => false,
  "a/../../" => "D:/OpenServer/domains/test.wrap/test.loc/a/../../",
  "a/..a.." => false,
  "a/..a/.." => false,
  "a/..a/../" => false,
  "a/....a" => false,
  "a/../..a" => false,
  "a/../../a" => "D:/OpenServer/domains/test.wrap/test.loc/a/../../a",
  "a/..a..a" => false,
  "a/..a/..a" => false,
  "a/..a/../a" => false,
  "a/..//.." => false,
  "a/..//../" => "D:/OpenServer/domains/test.wrap/test.loc/a/../../",
  "a/../a.." => false,
  "a/../a/.." => false,
  "a/../a/../" => "D:/OpenServer/domains/test.wrap/test.loc/a/../a/../",
  "a/..//..a" => false,
  "a/..//../a" => "D:/OpenServer/domains/test.wrap/test.loc/a/../../a",
  "a/../a..a" => false,
  "a/../a/..a" => false,
  "a/../a/../a" => "D:/OpenServer/domains/test.wrap/test.loc/a/../a/../a",
  "..aa.." => false,
  "..aa/.." => false,
  "..aa/../" => false,
  "..aa..a" => false,
  "..aa/..a" => false,
  "..aa/../a" => false,
  "/..aa.." => false,
  "/..aa/.." => false,
  "/..aa/../" => false,
  "/..aa..a" => false,
  "/..aa/..a" => false,
  "/..aa/../a" => false,
  "/../aa.." => false,
  "/../aa/.." => false,
  "/../aa/../" => "D:/aa/../",
  "/../aa..a" => false,
  "/../aa/..a" => false,
  "/../aa/../a" => "D:/aa/../a",
  "a..aa.." => false,
  "a..aa/.." => false,
  "a..aa/../" => false,
  "a..aa..a" => false,
  "a..aa/..a" => false,
  "a..aa/../a" => false,
  "a/..aa.." => false,
  "a/..aa/.." => false,
  "a/..aa/../" => false,
  "a/..aa..a" => false,
  "a/..aa/..a" => false,
  "a/..aa/../a" => false,
  "a/../aa.." => false,
  "a/../aa/.." => false,
  "a/../aa/../" => "D:/OpenServer/domains/test.wrap/test.loc/a/../aa/../",
  "a/../aa..a" => false,
  "a/../aa/..a" => false,
  "a/../aa/../a" => "D:/OpenServer/domains/test.wrap/test.loc/a/../aa/../a"
)

Or will she fit?

Answer 1

Any bot with such functions will overwhelm you (server) ...
What are you protecting yourself from?