RFR: 8074211: javax.sound.midi: Error with send System Exclusive messages of different length [v5]
Phil Race
prr at openjdk.org
Thu Nov 16 19:10:39 UTC 2023
On Wed, 15 Nov 2023 16:26:56 GMT, Alec Su <duke at openjdk.org> wrote:
>> JVM attempts to reuse the buffer for sending MIDI out data when the buffer size is enough. It use `dwBytesRecorded` in `MIDIHDR` structure to indicate the actual size of the data. However, `midiOutLongMsg()` ignores `dwBytesRecorded`, although it did not mentioned in the documentation. I've tested on Windows 7, 10 and 11. All of them have the same behavior.
>>
>> The bug cannot be easily reproduced because some MIDI drivers filter out any malformed MIDI data. The example code below create a special case to make sure all MIDI data are legally when the bug is triggered.
>>
>>
>> import javax.sound.midi.*;
>>
>> public class MidiTest {
>> public static class RawMidiMessage extends MidiMessage {
>> public RawMidiMessage(byte[] data) {
>> super(data);
>> }
>>
>> @Override
>> public Object clone() {
>> return new RawMidiMessage(this.getMessage());
>> }
>> }
>>
>> public static void main(String[] args) {
>> var deviceInfos = MidiSystem.getMidiDeviceInfo();
>> for (var info : deviceInfos) {
>> try (MidiDevice device = MidiSystem.getMidiDevice(info)) {
>> if (device.getMaxReceivers() != 0) {
>> System.out.println("Open MIDI port: " + info.getName());
>> device.open();
>> Receiver receiver = device.getReceiver();
>> // Send two sysex messages at once
>> receiver.send(new RawMidiMessage(new byte[]{
>> (byte) 0xF0, 0x7D, 0x01, (byte) 0xF7,
>> (byte) 0xF0, 0x7D, 0x02, (byte) 0xF7
>> }), -1);
>> // Send another sysex message
>> receiver.send(new RawMidiMessage(new byte[]{(byte) 0xF0, 0x7D, 0x03, (byte) 0xF7}), -1);
>> }
>> } catch (MidiUnavailableException e) {
>> e.printStackTrace();
>> }
>> }
>> }
>> }
>>
>>
>> The expected messages received should be the following three messages
>>
>> F0 7D 01 F7
>> F0 7D 02 F7
>> F0 7D 03 F7
>>
>>
>> But acually four messages was received with the second message repeated twice.
>>
>> F0 7D 01 F7
>> F0 7D 02 F7
>> F0 7D 03 F7
>> F0 7D 02 F7
>>
>>
>> To resolve the issue, I add a new variable to backup the actual buffer size and set `dwBufferLength` of `MIDIHDR` structure to the size of MIDI data. After calling `midiOutLongMsg()`, I restore the original buffer size if the buf...
>
> Alec Su has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>
> - Remove the testcase and reuse the testcase added in #16477
> - Merge branch 'master' into sysex-win
> - Remove OS check in the test
> - Code cleanup
> - Add a testcase for the buffer issue on Windows
> - Resolve the message size issue when sending SysexMessage on Windows
I ran this change through our CI testing system and it all looks good.
-------------
Marked as reviewed by prr (Reviewer).
PR Review: https://git.openjdk.org/jdk/pull/16399#pullrequestreview-1735250581
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