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fix: handle 0x00E1 / 0x00E0 segments from Pixel phones #84

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merged 3 commits into from Jan 11, 2021
Merged

fix: handle 0x00E1 / 0x00E0 segments from Pixel phones #84

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29ef731
add unit test to reproduce https://github.com/eugeneware/jpeg-js/issu…
hisham Jan 6, 2021
771a0f1
Added new case to deal with e0 and e1 unused byte markers
AT41 Jan 8, 2021
4e7d056
Popular invalid filemarkers now treated as exceptions
AT41 Jan 11, 2021
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5 changes: 4 additions & 1 deletion lib/decoder.js
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Expand Up @@ -813,7 +813,10 @@ var JpegImage = (function jpegImage() {
offset--;
}
break;

case 0xE0:
case 0xE1: // Unused bytes
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what about moving this into default block and something like...

// Recover from malformed APP1 markers popular in some phone models.
// See https://github.com/eugeneware/jpeg-js/issues/82
if (data[offset - 2] === 0x00 && data[offset - 1] === 0xE1) {
  const nextOffset = readUint16();
  if (data[nextOffset] === 0xFF) {
    offset = nextOffset;
    break;
  }
}

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Totally agree with you. In hindsight I should have seen that some of the files contained more than 1 0xFFE1 segment header and concluded that they aren't unique. Headers should also always start with 0xFF according to the JFIF standards, so you make a good point that 0x00E1 is definitely an error.

I've implemented the changes and added a new error that specifies the locations of 2 malformed headers like 0x00E1. Let me know if there's anything else that can be improved!

offset += readUint16()
break;
default:
if (data[offset - 3] == 0xFF &&
data[offset - 2] >= 0xC0 && data[offset - 2] <= 0xFE) {
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Binary file added test/fixtures/table-with-bad-e1.jpg
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Binary file added test/fixtures/table-with-good-e1.jpg
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8 changes: 8 additions & 0 deletions test/index.js
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Expand Up @@ -12,6 +12,14 @@ const SUPER_LARGE_JPEG_BASE64 =

const SUPER_LARGE_JPEG_BUFFER = Buffer.from(SUPER_LARGE_JPEG_BASE64, 'base64');

it('should be able read image with a bad e1 marker not preceeded by ff', function () {
var jpegData = fixture('table-with-bad-e1.jpg');
var rawImageData = jpeg.decode(jpegData);
var expected = fixture('table-with-good-e1.jpg');
var rawExpectedImageData = jpeg.decode(expected);
expect(rawImageData.data).toEqual(rawExpectedImageData.data);
});

it('should be able to decode a JPEG', function () {
var jpegData = fixture('grumpycat.jpg');
var rawImageData = jpeg.decode(jpegData);
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