Ensure accurate JPEG offset retrieval by accounting for the length of SOF marker segments

[robinbisping]

JPEG images can include additional marker segments after SOF marker segments. ExifReader failed to detect these because it did not account for the length of SOF marker segments.

Here is the binary representation of such an image:

I highlighted the markers with red.

• Byte 216: SOF2
• Byte 235: DHT
• Byte 264: DHT
• Byte 291: IPTC

Because ExifReader did not reassign the fieldLength for SOF segments, it reapplied the length of the previous marker segment. As a result, appMarkerPosition was out of sync and did not detect the following marker segments.

[mattiasw]

Thanks! Do you have one or a couple of example images where this happens?

[robinbisping]

I sent you an email.

[mattiasw]

Published as version 4.21.1. Thanks for the contribution! I actually had one test file with this issue. I was just on the wrong branch in your fork when testing. 🤦 😄

[robinbisping]

Thank you for looking into this so quickly. 🙏