Index: includes/module.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/module.inc,v
retrieving revision 1.207
diff -u -p -r1.207 module.inc
--- includes/module.inc	24 Nov 2010 16:47:44 -0000	1.207
+++ includes/module.inc	25 Nov 2010 23:30:27 -0000
@@ -596,6 +596,66 @@ function module_hook($module, $hook) {
 }
 
 /**
+ * Finds the file path of a hook implementation.
+ */
+function module_hook_implementation($module, $hook) {
+  $includes = array();
+  $function = $module . '_' . $hook;
+  $hook_info = module_hook_info();
+  $module_path = drupal_get_path('module', $module);
+  // First, look in a file for the hook's group.
+  if (isset($hook_info[$hook]['group'])) {
+    $includes[$module . '.' . $hook_info[$hook]['group'] . '.inc'] = TRUE;
+  }
+  // Add other potential locations for the hook.
+  if (function_exists('system_get_info')) {
+    $info = system_get_info('module', $module);
+    foreach ($info['files'] as $file) {
+      if (pathinfo($file, PATHINFO_EXTENSION) == 'inc') {
+        $includes[$file] = TRUE;
+      }
+    }
+  }
+  $includes = array_keys($includes);
+  while (!($exists = function_exists($function)) && ($file = array_shift($includes))) {
+    $path = DRUPAL_ROOT . '/' . $module_path . '/' . $file;
+    if (is_file($path)) {
+      require_once $path;
+    }
+  }
+  if ($exists) {
+    $function_meta = new ReflectionFunction($function);
+    // @todo: Make this string replacement more accurate.
+    return str_replace(DRUPAL_ROOT . '/', '', $function_meta->getFileName());
+  }
+
+  return FALSE;
+}
+
+/**
  * Determine which modules are implementing a hook.
  *
  * @param $hook