aellerton / japng Goto Github PK

http://i4.tietuku.com/462f043ee14a698e.png

https://www.dropbox.com/s/o30vium13e3buxc/ct10e.png?dl=0

this image is not transparent, but it was decoded to transparent black in BasicArgb8888Director#receiveDefaultImage().

https://mastodon.juggler.jp/system/custom_emojis/images/000/000/422/original/3eb47339da4d1e7a.png

D/SubwayTooter: APNGFrames: java.lang.NullPointerException: Attempt to read from field 'int[] net.ellerton.japng.argb8888.Argb8888Palette.argbArray' on a null object reference
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.argb8888.Argb8888Processors$IndexedColour8.processScanline(Argb8888Processors.java:168)
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.PngScanlineBuffer.decompress(PngScanlineBuffer.java:112)
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.argb8888.Argb8888Processor.processFrameImageData(Argb8888Processor.java:151)
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.reader.DefaultPngChunkReader.readImageDataChunk(DefaultPngChunkReader.java:175)
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.reader.DefaultPngChunkReader.readChunk(DefaultPngChunkReader.java:66)
D/SubwayTooter: APNGFrames: 	at net.ellerton.japng.reader.PngReadHelper.read(PngReadHelper.java:63)
D/SubwayTooter: APNGFrames: 	at jp.juggler.subwaytooter.util.APNGFrames.parseAPNG(APNGFrames.java:458)
D/SubwayTooter: APNGFrames: 	at jp.juggler.subwaytooter.util.CustomEmojiCache$Worker.decodeAPNG(CustomEmojiCache.java:244)
D/SubwayTooter: APNGFrames: 	at jp.juggler.subwaytooter.util.CustomEmojiCache$Worker.run(CustomEmojiCache.java:156)
D/SubwayTooter: CustomEmojiCache: PNG decode failed. https://mastodon.juggler.jp/system/custom_emojis/images/000/000/422/original/3eb47339da4d1e7a.png?1506079832 

https://mastodon.juggler.jp/system/custom_emojis/images/000/000/021/original/tama2.png

PngFeatureException Interlaced images are not yet supported

Hi Andrew

I just wanted to make you aware of my own java APNG library of the same name: https://www.reto-hoehener.ch/japng/.

It doesn't bother me too much, but it might be confusing...

Cheers
Reto

I've try your test task on your master branch.
./gradlew test returns error about net.ellerton.japng.util.AsciiBitmapProcessor .
it used in

• api\src\test\java\net\ellerton\japng\ReadMonochromeTest.java:18
• api\src\test\java\net\ellerton\japng\ReadMonochromeTest.java:219

When there is a large ignored chunk, it crashes in production, but not when loaded with PngInfo.java

Analysis of the cause:
The offending chunk starts decoding in DefaultPngChunkReader.readChunk(). It calls DefaultPngChunkReader.readOtherChunk() which eventually calls (via the filter input stream) BufferedInputStream.skip().

From the Javadoc of skip():

Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.

And indeed, it skips up to available() bytes, which is just under 8192 because the current pointer is still small and that's the buffer's size.

PngInfo.java doesn't wrap the input stream in a BufferedInputStream so it doesn't expose the bug.

Test image: iTXt chunk (3rd ignored chunk) of this (NSFW) image (navigate to the "Original" link in the left column!)