DiffHistoryBlob: don't check for mhash extension

Checking for the mhash extension is pointless in PHP 5.3+ because
it only exists as B/C functions that are part of the hash extension.

From ext/hash/config.m4:

    if test "$PHP_MHASH" != "no"; then
      if test "$PHP_HASH" = "no"; then
        PHP_HASH="yes"
      fi

      AC_DEFINE(PHP_MHASH_BC, 1, [ ])
    fi

So if mhash() is compiled in, hash() must also be compiled in.

Change-Id: Ic376f4c438aaf701ebb4f1394ab6e4c1803fb8b8

diff --git a/includes/HistoryBlob.php b/includes/HistoryBlob.php
index 46cf238..31aa0f8 100644 (file)
--- a/includes/HistoryBlob.php
+++ b/includes/HistoryBlob.php
@@ -530,7 +530,7 @@ class DiffHistoryBlob implements HistoryBlob {
 
                $header = unpack( 'Vofp/Vcsize', substr( $diff, 0, 8 ) );
 
-               # Check the checksum if hash/mhash is available
+               # Check the checksum if hash extension is available
                $ofp = $this->xdiffAdler32( $base );
                if ( $ofp !== false && $ofp !== substr( $diff, 0, 4 ) ) {
                        wfDebug( __METHOD__ . ": incorrect base checksum\n" );
@@ -577,24 +577,23 @@ class DiffHistoryBlob implements HistoryBlob {
         * Compute a binary "Adler-32" checksum as defined by LibXDiff, i.e. with
         * the bytes backwards and initialised with 0 instead of 1. See bug 34428.
         *
-        * Returns false if no hashing library is available
+        * @param string $s
+        * @return string|bool: false if the hash extension is not available
         */
        function xdiffAdler32( $s ) {
+               if ( !function_exists( 'hash' ) ) {
+                       return false;
+               }
+
                static $init;
                if ( $init === null ) {
                        $init = str_repeat( "\xf0", 205 ) . "\xee" . str_repeat( "\xf0", 67 ) . "\x02";
                }
+
                // The real Adler-32 checksum of $init is zero, so it initialises the
                // state to zero, as it is at the start of LibXDiff's checksum
                // algorithm. Appending the subject string then simulates LibXDiff.
-               if ( function_exists( 'hash' ) ) {
-                       $hash = hash( 'adler32', $init . $s, true );
-               } elseif ( function_exists( 'mhash' ) ) {
-                       $hash = mhash( MHASH_ADLER32, $init . $s );
-               } else {
-                       return false;
-               }
-               return strrev( $hash );
+               return strrev( hash( 'adler32', $init . $s, true ) );
        }
 
        function uncompress() {

diff --git a/tests/phpunit/includes/DiffHistoryBlobTest.php b/tests/phpunit/includes/DiffHistoryBlobTest.php
index 53f33d9..d927b7a 100644 (file)
--- a/tests/phpunit/includes/DiffHistoryBlobTest.php
+++ b/tests/phpunit/includes/DiffHistoryBlobTest.php
@@ -12,8 +12,8 @@ class DiffHistoryBlobTest extends MediaWikiTestCase {
 
                        return;
                }
-               if ( !extension_loaded( 'hash' ) && !extension_loaded( 'mhash' ) ) {
-                       $this->markTestSkipped( 'Neither the hash nor mhash extension is available' );
+               if ( !extension_loaded( 'hash' ) ) {
+                       $this->markTestSkipped( 'The hash extension is not available' );
 
                        return;
                }