Status Update
Comments
ib...@google.com <ib...@google.com>
ju...@gmail.com <ju...@gmail.com> #2
ib...@google.com <ib...@google.com> #3
If the width or height is greater than 8191, left-shifting causes the sign bit to be lost, turning a '1' into a '0', which results in an incorrect width or height.
I agree there's a bug here, but I'm not sure this is quite a precise description of the problem. A quick experiment suggests that the left shift (<<
) works fine (if we are just looking at bits), but the right shift (>>
) is where the problem is introduced, because >>
does "sign extension" in Java - meaning if input value is negative (the MSB of the 32-bit int is 1
), then the result will be negative too. This can be fixed by using the unsigned right shift operator (>>>
).
You can see this in jshell
:
$ jshell
| Welcome to JShell -- Version 22
| For an introduction type: /help intro
jshell> int width = 5
width ==> 5
jshell> int height = 8192
height ==> 8192
jshell> int widthAndHeight = (width << 16) | height
widthAndHeight ==> 335872
jshell> (widthAndHeight << 18) >> 18
$8 ==> -8192
jshell> (widthAndHeight << 18) >>> 18
$9 ==> 8192
That said, I also agree that your change in
ju...@gmail.com <ju...@gmail.com> #4
Thanks for your reply. So it it ok to be merged?
ap...@google.com <ap...@google.com> #5
Branch: androidx-main
commit 59e5677498b92689c2c92801c1f371f24ca7024e
Author: Ian Baker <ibaker@google.com>
Date: Thu Aug 01 16:12:27 2024
Add a test WebP image with a height of 8192px
This exercises the bug reported in
The test is disabled for now. It can be enabled as part of merging the
fix in
This image was generated using imagemagick:
$ convert webp_without_exif.webp \
-resize 6144x8192 \
webp_without_exif_height_8192px.webp
Bug: 342697059
Test: ExifInterfaceTest
Change-Id: Ib014f54fbe8d28579f95d5d2f34e302cdd569fb9
M exifinterface/exifinterface/src/androidTest/java/androidx/exifinterface/media/ExifInterfaceTest.java
A exifinterface/exifinterface/src/androidTest/res/raw/webp_without_exif_height_8192px.webp
ap...@google.com <ap...@google.com> #7
Branch: androidx-main
commit e6f75a0d1eb7fe104812ffaa108b71ed7a86b2d4
Author: Ian Baker <ibaker@google.com>
Date: Tue Aug 06 13:59:45 2024
Add missing comment to @SdkSuppress annotation
This explains why this test is skipped on API 21.
Test: ExifInterfaceTest
Bug: 342697059
Change-Id: I49b364107f52827417540e87704010cbc8f5a02e
M exifinterface/exifinterface/src/androidTest/java/androidx/exifinterface/media/ExifInterfaceTest.java
na...@google.com <na...@google.com> #8
The following release(s) address this bug.It is possible this bug has only been partially addressed:
androidx.exifinterface:exifinterface:1.4.0-alpha01
Description
Summary:
Using ExifInterface to call saveAttributes on a WebP file corrupts the WebP file, causing it to become invalid.
Steps to Reproduce:
Use ExifInterface to load a WebP file that does not contain a VP8X header. Call saveAttributes on the ExifInterface object. Attempt to open the resulting WebP file. Expected Result: The WebP file should remain valid and openable after saving attributes.
Actual Result: The WebP file becomes corrupted and cannot be opened properly.
Root Cause Analysis:
If the WebP file does not have a VP8X header, ExifInterface writes a new VP8X header.
When the WebP file's width or height is greater than 8191, the issue arises.
The following code causes the problem:
If the width or height is greater than 8191, left-shifting causes the sign bit to be lost, turning a '1' into a '0', which results in an incorrect width or height.
Environment