utf8mb4.patch

diff --git a/includes/database/mysql/database.inc b/includes/database/mysql/database.inc
index a96b053..43fa3d5 100644
--- a/includes/database/mysql/database.inc
+++ b/includes/database/mysql/database.inc
@@ -26,6 +26,8 @@ class DatabaseConnection_mysql extends DatabaseConnection {
     // MySQL never supports transactional DDL.
     $this->transactionalDDLSupport = FALSE;
 
+    // Allow the default charset to be overridden in settings.php.
+    $charset = (isset($connection_options['charset']) && $connection_options['charset'] === 'utf8mb4') ? 'utf8mb4' : 'utf8');
     $this->connectionOptions = $connection_options;
 
     // The DSN should use either a socket or a host/port.
@@ -39,7 +41,7 @@ class DatabaseConnection_mysql extends DatabaseConnection {
     // Character set is added to dsn to ensure PDO uses the proper character
     // set when escaping. This has security implications. See
     // https://www.drupal.org/node/1201452 for further discussion.
-    $dsn .= ';charset=utf8';
+    $dsn .= ';charset=' . $charset;
     $dsn .= ';dbname=' . $connection_options['database'];
     // Allow PDO options to be overridden.
     $connection_options += array(
@@ -63,10 +65,10 @@ class DatabaseConnection_mysql extends DatabaseConnection {
     // certain one has been set; otherwise, MySQL defaults to 'utf8_general_ci'
     // for UTF-8.
     if (!empty($connection_options['collation'])) {
-      $this->exec('SET NAMES utf8 COLLATE ' . $connection_options['collation']);
+      $this->exec('SET NAMES ' . $charset . ' COLLATE ' . $connection_options['collation']);
     }
     else {
-      $this->exec('SET NAMES utf8');
+      $this->exec('SET NAMES ' . $charset);
     }
 
     // Set MySQL init_commands if not already defined.  Default Drupal's MySQL
diff --git a/includes/database/mysql/schema.inc b/includes/database/mysql/schema.inc
index 2a2722e..7796721 100644
--- a/includes/database/mysql/schema.inc
+++ b/includes/database/mysql/schema.inc
@@ -81,7 +81,8 @@ class DatabaseSchema_mysql extends DatabaseSchema {
     // Provide defaults if needed.
     $table += array(
       'mysql_engine' => 'InnoDB',
-      'mysql_character_set' => 'utf8',
+      // Allow the default charset to be overridden in settings.php.
+      'mysql_character_set' => (isset($info['charset']) && info['charset'] === 'utf8mb4' ? 'utf8mb4' : 'utf8'),
     );
 
     $sql = "CREATE TABLE {" . $name . "} (\n";
@@ -109,6 +110,13 @@ class DatabaseSchema_mysql extends DatabaseSchema {
       $sql .= ' COLLATE ' . $info['collation'];
     }
 
+    // The row format needs to be either DYNAMIC or COMPRESSED in order to allow
+    // for the innodb_large_prefix setting to take effect, see
+    // https://dev.mysql.com/doc/refman/5.6/en/create-table.html
+    if (isset($info['charset']) && $info['charset'] === 'utf8mb4') {
+      $sql .= ' ROW_FORMAT=DYNAMIC';
+    }
+
     // Add table comment.
     if (!empty($table['description'])) {
       $sql .= ' COMMENT ' . $this->prepareComment($table['description'], self::COMMENT_MAX_TABLE);
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index 7e36a4a..2af2a23 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -126,6 +126,30 @@
  * );
  * @endcode
  *
+ * For handling full UTF-8 including multi-byte characters such as emojis, asian
+ * symbols, and mathematical symbols, you may set the collation and charset to
+ * "utf8mb4":
+ * @code
+ * $databases['default']['default']['charset'] = 'utf8mb4';
+ * $databases['default']['default']['collation'] = 'utf8mb4_general_ci';
+ * @endcode
+ * When using this setting on an existing installation, ensure that
+ * all existing tables have been converted to the utf8mb4 charset,
+ * for example by using the utf8mb4_convert contrib module, so as to prevent
+ * mixing data with different charsets.
+ * Note this should only be used when all of the following conditions are met:
+ * - In order to allow for large indexes, MySQL must be set up with the
+ *   following my.cnf settings:
+ *     [mysqld]
+ *     innodb_large_prefix=0
+ *     innodb_file_format=barracuda
+ *     innodb_file_per_table=true
+ *   These settings are available as of MySQL 5.5.14, and are defaults in
+ *   MySQL 5.7.7 and up.
+ * - The PHP MySQL driver must support the utf8mb4 charset (libmysqlclient
+     5.5.3 and up, as well as mysqlnd 5.0.9 and up).
+ * - The MySQL server must support the utf8mb4 charset (5.5.3 and up).
+ *
  * You can optionally set prefixes for some or all database table names
  * by using the 'prefix' setting. If a prefix is specified, the table
  * name will be prepended with its value. Be sure to use valid database