fix: don’t fail if scan contains trailing bytes (jpeg-js#66)

zed-0xff · Apr 21, 2020 · 5737c99 · 5737c99
1 parent ce5433c
commit 5737c99
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Showing 3 changed files with 21 additions and 0 deletions.
diff --git a/lib/decoder.js b/lib/decoder.js
@@ -325,6 +325,18 @@ var JpegImage = (function jpegImage() {
         }
       }
 
+      if (mcu === mcuExpected) {
+        // Skip trailing bytes at the end of the scan - until we reach the next marker
+        do {
+          if (data[offset] === 0xFF) {
+            if (data[offset + 1] !== 0x00) {
+              break;
+            }
+          }
+          offset += 1;
+        } while (offset < data.length - 2);
+      }
+
       // find marker
       bitsCount = 0;
       marker = (data[offset] << 8) | data[offset + 1];

diff --git a/test/fixtures/redbox-with-trailing-bytes.jpg b/test/fixtures/redbox-with-trailing-bytes.jpg
diff --git a/test/index.js b/test/index.js
@@ -54,6 +54,15 @@ it('should be able to decode a JPEG with RST intervals', function(t) {
   t.end();
 });
 
+it('should be able to decode a JPEG with trailing bytes', function(t) {
+  var jpegData = fixture('redbox-with-trailing-bytes.jpg');
+  var rawImageData = jpeg.decode(jpegData);
+  var expected = fixture('redbox.jpg');
+  var rawExpectedImageData = jpeg.decode(expected);
+  t.deepEqual(rawImageData.data, rawExpectedImageData.data);
+  t.end();
+});
+
 it('should be able to decode a grayscale JPEG', function(t) {
   var jpegData = fixture('apsara.jpg');
   var rawImageData = jpeg.decode(jpegData);