drupal-core-ajax-page-ids.patch

diff --git a/includes/common.inc b/includes/common.inc
index 8bb70df..1ca7b9c 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -3889,50 +3889,23 @@ function drupal_html_id($id) {
   // take into account IDs that are already in use on the base page.
   $seen_ids_init = &drupal_static(__FUNCTION__ . ':init');
   if (!isset($seen_ids_init)) {
-    // Ideally, Drupal would provide an API to persist state information about
-    // prior page requests in the database, and we'd be able to add this
-    // function's $seen_ids static variable to that state information in order
-    // to have it properly initialized for this page request. However, no such
-    // page state API exists, so instead, ajax.js adds all of the in-use HTML
-    // IDs to the POST data of Ajax submissions. Direct use of $_POST is
-    // normally not recommended as it could open up security risks, but because
-    // the raw POST data is cast to a number before being returned by this
-    // function, this usage is safe.
-    if (empty($_POST['ajax_html_ids'])) {
-      $seen_ids_init = array();
+    // A number of contrib modules were relying on being able to unset
+    // $_POST['ajax_html_ids'] to not trigger the unique ID functionality
+    // on AJAX requests, so we still check that variable and respond as they
+    // would expect.
+    if (empty($_POST['ajax_html_ids']) || empty($_POST['ajax_html_ids_counter'])) {
+      $seen_ids_init = 1;
     }
     else {
-      // This function ensures uniqueness by appending a counter to the base id
-      // requested by the calling function after the first occurrence of that
-      // requested id. $_POST['ajax_html_ids'] contains the ids as they were
-      // returned by this function, potentially with the appended counter, so
-      // we parse that to reconstruct the $seen_ids array.
-      if (isset($_POST['ajax_html_ids'][0]) && strpos($_POST['ajax_html_ids'][0], ',') === FALSE) {
-        $ajax_html_ids = $_POST['ajax_html_ids'];
+      if (is_numeric($_POST['ajax_html_ids_counter'])) {
+        $seen_ids_init = $_POST['ajax_html_ids_counter'];
       }
       else {
-        // jquery.form.js may send the server a comma-separated string as the
-        // first element of an array (see http://drupal.org/node/1575060), so
-        // we need to convert it to an array in that case.
-        $ajax_html_ids = explode(',', $_POST['ajax_html_ids'][0]);
-      }
-      foreach ($ajax_html_ids as $seen_id) {
-        // We rely on '--' being used solely for separating a base id from the
-        // counter, which this function ensures when returning an id.
-        $parts = explode('--', $seen_id, 2);
-        if (!empty($parts[1]) && is_numeric($parts[1])) {
-          list($seen_id, $i) = $parts;
-        }
-        else {
-          $i = 1;
-        }
-        if (!isset($seen_ids_init[$seen_id]) || ($i > $seen_ids_init[$seen_id])) {
-          $seen_ids_init[$seen_id] = $i;
-        }
+        $seen_ids_init = 1;
       }
     }
   }
-  $seen_ids = &drupal_static(__FUNCTION__, $seen_ids_init);
+  $seen_ids = &drupal_static(__FUNCTION__, array());
 
   $id = strtr(drupal_strtolower($id), array(' ' => '-', '_' => '-', '[' => '-', ']' => ''));
 
@@ -3951,11 +3924,17 @@ function drupal_html_id($id) {
   // the base ID. Requiring a unique delimiter helps ensure that we really do
   // return unique IDs and also helps us re-create the $seen_ids array during
   // Ajax requests.
+  // We use the $seen_ids_init value as a starting point for the counters,
+  // if it's non-unitary, then initialize the counters from that value.
+  if (($seen_ids_init != 1) && !isset($seen_ids[$id])) {
+    $seen_ids[$id] = $seen_ids_init;
+  }
+
   if (isset($seen_ids[$id])) {
     $id = $id . '--' . ++$seen_ids[$id];
   }
   else {
-    $seen_ids[$id] = 1;
+    $seen_ids[$id] = $seen_ids_init;
   }
 
   return $id;
diff --git a/misc/ajax.js b/misc/ajax.js
index 90c3bb8..80668fb 100644
--- a/misc/ajax.js
+++ b/misc/ajax.js
@@ -292,9 +292,17 @@ Drupal.ajax.prototype.beforeSerialize = function (element, options) {
 
   // Prevent duplicate HTML ids in the returned markup.
   // @see drupal_html_id()
-  options.data['ajax_html_ids[]'] = [];
+  options.data['ajax_html_ids[]'] = 1;
+  options.data['ajax_html_ids_counter'] = 1;
   $('[id]').each(function () {
-    options.data['ajax_html_ids[]'].push(this.id);
+    var $this = $(this);
+    // If this ID already has a counter, then ensure that the counter is at least that.
+    if ((typeof $this.attr('id') === 'string') && ($this.attr('id').indexOf('--') != -1)) {
+      var potentialCounter = this.id.substring(this.id.indexOf('--') + 2);
+      if ((typeof potentialCounter === 'number' || typeof potentialCounter === 'string') && potentialCounter !== '' && !isNaN(potentialCounter)) {
+        options.data['ajax_html_ids_counter'] = Math.max(options.data['ajax_html_ids_counter'], potentialCounter);
+      }
+    }
   });
 
   // Allow Drupal to return new JavaScript and CSS files to load without