Fixed EXIF parser bug.

chrome/browser/resources/file_manager/js/exif_parser.js

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 const EXIF_MARK_SOI = 0xffd8;  // Start of image data.
 const EXIF_MARK_SOS = 0xffda;  // Start of "stream" (the actual image data).
 const EXIF_MARK_SOF = 0xffc0;  // Start of "frame"
 const EXIF_MARK_EXIF = 0xffe1;  // Start of exif block.
 
 const EXIF_ALIGN_LITTLE = 0x4949;  // Indicates little endian exif data.
 const EXIF_ALIGN_BIG = 0x4d4d;  // Indicates big endian exif data.
@@ skipping 76 matching lines @@
         if (filePos + br.tell() + markLength > file.size) {
           throw new Error(
               'Invalid section length @' + (filePos + br.tell() - 2));
         }
         reread(-4, markLength + 4);
         return;
       }
 
       if (mark == EXIF_MARK_EXIF) {
         this.parseExifSection(metadata, buf, br);
-      } else if ((mark & ~0xF) == EXIF_MARK_SOF) {
+      } else if (ExifParser.isSOF_(mark)) {
         // The most reliable size information is encoded in the SOF section.
-        // There are 16 variants of the SOF format distinguished by the last
-        // hex digit of the mark, but the part we want is always the same.
         br.seek(1, ByteReader.SEEK_CUR); // Skip the precision byte.
         var height = br.readScalar(2);
         var width = br.readScalar(2);
         ExifParser.setImageSize(metadata, width, height);
         callback(metadata);  // We are done!
         return;
       }
 
       br.seek(nextSectionStart, ByteReader.SEEK_BEG);
     }
   } catch (e) {
     errorCallback(e.toString());
   }
 };
 
+ExifParser.isSOF_ = function(mark) {
+  // There are 13 variants of SOF fragment format distinguished by the last
+  // hex digit of the mark, but the part we want is always the same.
+  if ((mark & ~0xF) != EXIF_MARK_SOF) return false;
+
+  // If the last digit is 4, 8 or 12 it is not really a SOF.
+  var type = mark & 0xF;
+  return (type != 4 && type != 8 && type != 12);
+};
+
 ExifParser.prototype.parseExifSection = function(metadata, buf, br) {
   var magic = br.readString(6);
   if (magic != 'Exif\0\0') {
     // Some JPEG files may have sections marked with EXIF_MARK_EXIF
     // but containing something else (e.g. XML text). Ignore such sections.
     this.vlog('Invalid EXIF magic: ' + magic + br.readString(100));
     return;
   }
 
   // Offsets inside the EXIF block are based after the magic string.
@@ skipping 221 matching lines @@
     return {
       scaleX: ExifParser.SCALEX[index],
       scaleY: ExifParser.SCALEY[index],
       rotate90: ExifParser.ROTATE90[index]
     }
   }
   return null;
 };
 
 MetadataDispatcher.registerParserClass(ExifParser);