From 4e39f0ba11ff3cbb5ca51f5ccdcf5c46c9e600d9 Mon Sep 17 00:00:00 2001
From: Gary Pendergast <gary@pento.net>
Date: Tue, 21 Apr 2015 06:58:14 +0000
Subject: [PATCH] WPDB: When deciding if a query needs extra sanity checking
 based on collation, return early when we can. Merges [32232] and [32233] to
 the 3.9 branch.

See #32029.


Built from https://develop.svn.wordpress.org/branches/3.9@32239


git-svn-id: http://core.svn.wordpress.org/branches/3.9@32210 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/wp-db.php | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index 4b86cb7381..7f5876e4ad 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -2335,20 +2335,38 @@ class wpdb {
 		if ( $this->checking_collation ) {
 			return true;
 		}
+
+		// We don't need to check the collation for queries that don't read data.
+		$query = ltrim( $query, "\r\n\t (" );
+		if ( preg_match( '/^(?:SHOW|DESCRIBE|DESC|EXPLAIN)\s/i', $query ) ) {
+			return true;
+		}
+
+		// All-ASCII queries don't need extra checking.
+		if ( $this->check_ascii( $query ) ) {
+			return true;
+		}
+
 		$table = $this->get_table_from_query( $query );
 		if ( ! $table ) {
 			return false;
 		}
 
 		$this->checking_collation = true;
-		$this->get_table_charset( $table );
+		$collation = $this->get_table_charset( $table );
 		$this->checking_collation = false;
 
+		// Tables with no collation, or latin1 only, don't need extra checking.
+		if ( false === $collation || 'latin1' === $collation ) {
+			return true;
+		}
+
 		$table = strtolower( $table );
 		if ( empty( $this->col_meta[ $table ] ) ) {
 			return false;
 		}
 
+		// If any of the columns don't have one of these collations, it needs more sanity checking.
 		foreach( $this->col_meta[ $table ] as $col ) {
 			if ( empty( $col->Collation ) ) {
 				continue;
@@ -2376,6 +2394,7 @@ class wpdb {
 	 *                        such as 'field' are retained in each value array. If we cannot
 	 *                        remove invalid characters, a {@see WP_Error} object is returned.
 	 */
+		// If any of the columns don't have one of these collations, it needs more sanity checking.
 	protected function strip_invalid_text( $data ) {
 		// Some multibyte character sets that we can check in PHP.
 		$mb_charsets = array(