1 files changed, 100 insertions, 0 deletions
diff --git a/includes/libs/RiffExtractor.php b/includes/libs/RiffExtractor.php
new file mode 100644
index 00000000..f987c59d
--- /dev/null
+++ b/includes/libs/RiffExtractor.php
@@ -0,0 +1,100 @@
+<?php
+/**
+ * Extractor for the Resource Interchange File Format
+ *
+ * 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
+ * @author Bryan Tong Minh
+ * @ingroup Media
+ */
+
+class RiffExtractor {
+	public static function findChunksFromFile( $filename, $maxChunks = -1 ) {
+		$file = fopen( $filename, 'rb' );
+		$info = self::findChunks( $file, $maxChunks );
+		fclose( $file );
+		return $info;
+	}
+
+	public static function findChunks( $file, $maxChunks = -1 ) {
+		$riff = fread( $file, 4 );
+		if ( $riff !== 'RIFF' ) {
+			return false;
+		}
+
+		// Next four bytes are fileSize
+		$fileSize = fread( $file, 4 );
+		if ( !$fileSize || strlen( $fileSize ) != 4 ) {
+			return false;
+		}
+
+		// Next four bytes are the FourCC
+		$fourCC = fread( $file, 4 );
+		if ( !$fourCC || strlen( $fourCC ) != 4 ) {
+			return false;
+		}
+
+		// Create basic info structure
+		$info = array(
+			'fileSize' => self::extractUInt32( $fileSize ),
+			'fourCC' => $fourCC,
+			'chunks' => array(),
+		);
+		$numberOfChunks = 0;
+
+		// Find out the chunks
+		while ( !feof( $file ) && !( $numberOfChunks >= $maxChunks && $maxChunks >= 0 ) ) {
+			$chunkStart = ftell( $file );
+
+			$chunkFourCC = fread( $file, 4 );
+			if ( !$chunkFourCC || strlen( $chunkFourCC ) != 4 ) {
+				return $info;
+			}
+
+			$chunkSize = fread( $file, 4 );
+			if ( !$chunkSize || strlen( $chunkSize ) != 4 ) {
+				return $info;
+			}
+			$intChunkSize = self::extractUInt32( $chunkSize );
+
+			// Add chunk info to the info structure
+			$info['chunks'][] = array(
+				'fourCC' => $chunkFourCC,
+				'start' => $chunkStart,
+				'size' => $intChunkSize
+			);
+
+			// Uneven chunks have padding bytes
+			$padding = $intChunkSize % 2;
+			// Seek to the next chunk
+			fseek( $file, $intChunkSize + $padding, SEEK_CUR );
+
+		}
+
+		return $info;
+	}
+
+	/**
+	 * Extract a little-endian uint32 from a 4 byte string
+	 * @param string $string 4-byte string
+	 * @return int
+	 */
+	public static function extractUInt32( $string ) {
+		$unpacked = unpack( 'V', $string );
+		return $unpacked[1];
+	}
+};