From edb3e4582571973d04c473bf163055901995f894 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Fri, 24 Jul 2009 22:15:23 +0000
Subject: [PATCH] 64-bit host compatibility for hash function in pure-PHP
 implementation of CDB reader/writer. This fixes the problem where
 localization cache files generated under command-line and web were
 incompatible on Mac OS X when using $wgCacheDirectory instead of l10n_cache
 table in database. (Apple ships a 64-bit Apache+mod_php but only a 32-bit CLI
 php binary, and neither has the cda extension present by default.)

Confirmed hash compatibility with native cda extension by running Tim's maintenance/cdb-test.php on 32-bit and 64-bit Ubuntu installs:

32 bit before patch:
brion@bribuntu:~/src/phase3$ php maintenance/cdb-test.php
Write test...
e5d9cbbcd0137b281da400bb213820fa  php.cdb
e5d9cbbcd0137b281da400bb213820fa  dba.cdb
Read test...
Done.


32-bit after patch:
brion@bribuntu:~/src/phase3$ php maintenance/cdb-test.php
Write test...
84108f6dab5c34823333169ca05eb5c3  php.cdb
84108f6dab5c34823333169ca05eb5c3  dba.cdb
Read test...
Done.
brion@bribuntu:~/src/phase3$


64-bit before patch:
brion@bribuntu64:~/src/phase3$ php maintenance/cdb-test.php
Write test...
188d06832d321b20e88e9d0200242efc  php.cdb
14e0225466464003d21496204f12d20c  dba.cdb <- note mismatch!
Read test...
Done.


64-bit after patch:
brion@bribuntu64:~/src/phase3$ php maintenance/cdb-test.php
Write test...
d244a877c9639e27c79aa1bdbcaee3c2  php.cdb
d244a877c9639e27c79aa1bdbcaee3c2  dba.cdb <- now matches!
Read test...
Done.

YESSSS
---
 includes/Cdb_PHP.php | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/includes/Cdb_PHP.php b/includes/Cdb_PHP.php
index b2229093a6..8f1b30e6bc 100644
--- a/includes/Cdb_PHP.php
+++ b/includes/Cdb_PHP.php
@@ -17,7 +17,7 @@ class CdbFunctions {
 	 * $b must be less than 0x40000000 and greater than 0
 	 */
 	public static function unsignedMod( $a, $b ) {
-		if ( $a < 0 ) {
+		if ( $a & 0x80000000 ) {
 			$m = ( $a & 0x7fffffff ) % $b + 2 * ( 0x40000000 % $b );
 			return $m % $b;
 		} else {
@@ -32,7 +32,7 @@ class CdbFunctions {
 		if ( $b == 0 ) {
 			return $a;
 		}
-		if ( $a < 0 ) {
+		if ( $a & 0x80000000 ) {
 			return ( ( $a & 0x7fffffff ) >> $b ) | ( 0x40000000 >> ( $b - 1 ) );
 		} else {
 			return $a >> $b;
@@ -45,20 +45,21 @@ class CdbFunctions {
 	public static function hash( $s ) {
 		$h = 5381;
 		for ( $i = 0; $i < strlen( $s ); $i++ ) {
-			$h5 = $h << 5;
+			$h5 = ($h << 5) & 0xffffffff;
 			// Do a 32-bit sum
 			// Inlined here for speed
 			$sum = ($h & 0x3fffffff) + ($h5 & 0x3fffffff);
 			$h = 
 				(
 					( $sum & 0x40000000 ? 1 : 0 )
-					+ ( $h < 0 ? 2 : 0 )
+					+ ( $h & 0x80000000 ? 2 : 0 )
 					+ ( $h & 0x40000000 ? 1 : 0 )
-					+ ( $h5 < 0 ? 2 : 0 )
+					+ ( $h5 & 0x80000000 ? 2 : 0 )
 					+ ( $h5 & 0x40000000 ? 1 : 0 )
 				) << 30
 				| ( $sum & 0x3fffffff );
 			$h ^= ord( $s[$i] );
+			$h &= 0xffffffff;
 		}
 		return $h;
 	}
-- 
2.20.1