diff options
Diffstat (limited to 'includes/HistoryBlob.php')
| -rw-r--r-- | includes/HistoryBlob.php | 64 |
1 files changed, 53 insertions, 11 deletions
diff --git a/includes/HistoryBlob.php b/includes/HistoryBlob.php index f707b3f6..bb8ec5e3 100644 --- a/includes/HistoryBlob.php +++ b/includes/HistoryBlob.php @@ -1,5 +1,25 @@ <?php - +/** + * Efficient concatenated text storage. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * http://www.gnu.org/copyleft/gpl.html + * + * @file + */ + /** * Base class for general text storage via the "object" flag in old_flags, or * two-part external storage URLs. Used for represent efficient concatenated @@ -179,8 +199,8 @@ class HistoryBlobStub { var $mOldId, $mHash, $mRef; /** - * @param $hash Strng: the content hash of the text - * @param $oldid Integer: the old_id for the CGZ object + * @param $hash string the content hash of the text + * @param $oldid Integer the old_id for the CGZ object */ function __construct( $hash = '', $oldid = 0 ) { $this->mHash = $hash; @@ -298,7 +318,7 @@ class HistoryBlobCurStub { } /** - * @return string|false + * @return string|bool */ function getText() { $dbr = wfGetDB( DB_SLAVE ); @@ -515,13 +535,11 @@ class DiffHistoryBlob implements HistoryBlob { $header = unpack( 'Vofp/Vcsize', substr( $diff, 0, 8 ) ); - # Check the checksum if mhash is available - if ( extension_loaded( 'mhash' ) ) { - $ofp = mhash( MHASH_ADLER32, $base ); - if ( $ofp !== substr( $diff, 0, 4 ) ) { - wfDebug( __METHOD__. ": incorrect base checksum\n" ); - return false; - } + # Check the checksum if hash/mhash is available + $ofp = $this->xdiffAdler32( $base ); + if ( $ofp !== false && $ofp !== substr( $diff, 0, 4 ) ) { + wfDebug( __METHOD__. ": incorrect base checksum\n" ); + return false; } if ( $header['csize'] != strlen( $base ) ) { wfDebug( __METHOD__. ": incorrect base length\n" ); @@ -560,6 +578,30 @@ class DiffHistoryBlob implements HistoryBlob { return $out; } + /** + * 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 + */ + function xdiffAdler32( $s ) { + 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( $hash ); + } + function uncompress() { if ( !$this->mDiffs ) { return; |