IssueTracker

Does this reproduce in 1.3.7 or is it a regression in 1.4.0-alpha01?

Thanks - it looks like the original image has no Exif data, so something is going wrong with the way ExifInterface is adding Exif data. We have unit tests for this case, so there must be something different/specific about this image that is different to the images used in our tests. I haven't worked out what that difference is yet.

Dropping 001.webp into the existing testWebpWithoutExif() test causes it to fail, so there's definitely something different about this file.

I took a look at 001.webp in a hex editor and noticed that its declared file length (from the RIFF header) is 0xD4C00100, which (because it's little endian) is 114900 in decimal. This should be the length of the file from offset 8 (i.e. file should be 8 bytes longer than this) - but the file is actually 12 bytes longer than this (114912) with 4 trailing 0x04 bytes on the end.

Removing these trailing bytes and re-running the test causes it to pass.

Inspecting 001_corrupt.webp I can see the trailing 0x04 bytes at the end.

So what happens when we write out a WebP file is:

1. We add the RIFF header and placeholder for the file length
2. We synthesise a VP8X header.
3. We copy the existing VP8 chunk
4. Append the new Exif chunk
5. Copy the rest of the file (the 4 trailing 0x04 bytes).
6. Go back to the beginning and fill in the file length based on how much data we wrote in steps 2, 3, 4 & 5.
   • This ends up including the trailing 0x04 bytes in the RIFF length, but they're not a valid chunk - so the file ends up being invalid.

The issue comes from copying the whole of the input file, and assuming it should all be covered by the new RIFF header, instead of considering the RIFF length of the original file. I will send a change for review which only includes existing RIFF data and new Exif data in the new RIFF length, and then copies over any additional trailing data outside the RIFF structure.

Project: platform/frameworks/support
Branch: androidx-main
Author: Ian Baker <ibaker@google.com>
Link:      https://android-review.googlesource.com/3432668

Exclude trailing non-WebP data from length when writing new file

Exclude trailing non-WebP data from length when writing new file 
 
Some files have trailing data outside the length defined by the RIFF 
header. ExifInterface previously naively copied this data and then 
calculated a new RIFF length which included it, resulting in an invalid 
file. 
 
This change only copies RIFF-defined data from the old file before 
calculating the new RIFF length, and then appends any additional data 
after that - in order to more closely mimic the input file's structure 
without throwing away the trailing data. 
 
Test: ExifInterfaceTest 
Bug: 385766064 
 
Change-Id: I8a955cf85d229ad4af5a1e02aa891cfca0e54d60

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.exifinterface:exifinterface:1.4.0-beta01