Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Avoid reading unused bytes from PNG streams #535

Merged
merged 4 commits into from
May 4, 2021
Merged

Avoid reading unused bytes from PNG streams #535

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
b28f43f
Comparing PNG chunk size to available bytes in buffer
Draczech Apr 28, 2021
e116370
Only copying chunk data for specified chunk types
Draczech May 3, 2021
c588b95
Fixing diamond operator for Java 1.6 compatibility
Draczech May 3, 2021
6247ec7
Removed tests with corrupted image as it should be placed into image …
Draczech May 4, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 13 additions & 1 deletion Source/com/drew/imaging/png/PngChunkReader.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,12 @@ public Iterable<PngChunk> extract(@NotNull final SequentialReader reader, @Nulla
// Miscellaneous information: bKGD, hIST, pHYs, sPLT
// Time information: tIME
//
// CHUNK READING
//
// Only chunk data for types specified in desiredChunkTypes is extracted.
// For empty chunk type list NO data is copied from source stream.
// For null chunk type list ALL data is copied from source stream.
//

reader.setMotorolaByteOrder(true); // network byte order

Expand All @@ -93,7 +99,13 @@ public Iterable<PngChunk> extract(@NotNull final SequentialReader reader, @Nulla

boolean willStoreChunk = desiredChunkTypes == null || desiredChunkTypes.contains(chunkType);

byte[] chunkData = reader.getBytes(chunkDataLength);
byte[] chunkData;
if (willStoreChunk) {
chunkData = reader.getBytes(chunkDataLength);
} else {
chunkData = null; // To satisfy the compiler
reader.skip(chunkDataLength);
}

// Skip the CRC bytes at the end of the chunk
// TODO consider verifying the CRC value to determine if we're processing bad data
Expand Down