Reduce dependency stack of rewrite map script to prevent hangs

This moves the logic for cache misses to a separate script,
rewrite_miss.php, which will process the rewrite and return
the correct route. The rewrite_miss.php script includes a
time limit to prevent hang-ups from occurring.
Closes #424

rewrite.php

 #!/usr/bin/php
 <?php
 
-define('DRUPAL_ROOT', getcwd());
-
-require_once DRUPAL_ROOT . '/includes/unl_bootstrap.inc';
-require_once DRUPAL_ROOT . '/includes/bootstrap.inc';
-
 $stdin = fopen('php://stdin', 'r');
 $cache = new RewriteCache();
 
@@ -16,41 +11,21 @@ while ($line = fgets($stdin)) {
   
   // Check for this result in the cache
   if (!($output = $cache->get($line))) {
-  
-    // Parse the 3 fields.
-    list($host, $uri, $path) = explode(';delim;', $line);
-    
-    // Get the base path of the drupal install
-    $base_path = substr($uri, 0, strlen($uri) - strlen($path));
-    
-    // Set up some _SERVER variables as if this was a HTTP request.
-    $_SERVER['SCRIPT_NAME'] = $base_path . 'index.php';
-    $_SERVER['SCRIPT_FILENAME'] = DRUPAL_ROOT . '/index.php';
-    $_SERVER['REQUEST_URI'] = $uri;
-    $_SERVER['HTTP_HOST'] = $host;
-    
-    // Call the UNL bootstrap to fix conf_path and SCRIPT_NAME
-    unl_bootstrap();
-    $site_dir = conf_path();
-    $base_path = substr($_SERVER['SCRIPT_NAME'], 0, -9);
-    // Now we fix the drupal path.
-    $drupal_path = substr($uri, strlen($base_path));
-    
-    // Finally, generate the path to the file we might be accessing
-    $file_path = $site_dir . '/files/' . $drupal_path;
-    
-    // If that file exists, return the correct path to it, otherwise, return what we were given. 
-    if (is_file($file_path)) {
-      $output = $file_path;
-    }
-    else {
-      $output = 'NULL';
+
+    exec('/usr/bin/php ' . __DIR__ . '/rewrite_miss.php ' . escapeshellarg($line), $output, $return_var);
+
+    // Set default route
+    $route = 'NULL';
+
+    if (!$return_var && isset($output[0])) {
+      //Success! a route was found
+      $route = $output[0];
     }
     
-    $cache->set($line, $output);
+    $cache->set($line, $route);
   }
   
-  echo $output . PHP_EOL;
+  echo $route . PHP_EOL;
 }
 
 

rewrite_miss.php

+<?php
+
+if (!isset($argv, $argv[1])) {
+  echo 'NULL';
+  exit(1);
+}
+
+$line = $argv[1];
+
+set_time_limit(5);
+
+define('DRUPAL_ROOT', __DIR__);
+
+require_once DRUPAL_ROOT . '/includes/unl_bootstrap.inc';
+require_once DRUPAL_ROOT . '/includes/bootstrap.inc';
+
+// Parse the 3 fields.
+list($host, $uri, $path) = explode(';delim;', $line);
+
+// Get the base path of the drupal install
+$base_path = substr($uri, 0, strlen($uri) - strlen($path));
+
+// Set up some _SERVER variables as if this was a HTTP request.
+$_SERVER['SCRIPT_NAME'] = $base_path . 'index.php';
+$_SERVER['SCRIPT_FILENAME'] = DRUPAL_ROOT . '/index.php';
+$_SERVER['REQUEST_URI'] = $uri;
+$_SERVER['HTTP_HOST'] = $host;
+
+// Call the UNL bootstrap to fix conf_path and SCRIPT_NAME
+unl_bootstrap();
+$site_dir = conf_path();
+$base_path = substr($_SERVER['SCRIPT_NAME'], 0, -9);
+// Now we fix the drupal path.
+$drupal_path = substr($uri, strlen($base_path));
+
+// Finally, generate the path to the file we might be accessing
+$file_path = $site_dir . '/files/' . $drupal_path;
+
+// If that file exists, return the correct path to it, otherwise, return what we were given. 
+if (is_file($file_path)) {
+  $output = $file_path;
+}
+else {
+  $output = 'NULL';
+}
+
+echo $output;
+