On Mon, 9 Nov 2020 20:17:44 GMT, Sergey Bylokhov <s...@openjdk.org> wrote:
> The JavaSound supports the special system exclusive message(SysexMessage).
>
> An important part of the spec:
>
>> Data of a system exclusive message should be stored in the data array of a
>> {@code SysexMessage} as follows: the system exclusive message status byte
>> (0xF0 or 0xF7), all message data bytes, and finally the end-of-exclusive
>> flag (0xF7):
>>
>> The first {@code SysexMessage} object containing data for a particular system
>> exclusive message should have the status value 0xF0. If this message contains
>> all the system exclusive data for the message, it should end with the status
>> byte 0xF7 (EOX). Otherwise, additional system exclusive data should be sent
>> in one or more {@code SysexMessages} with a status value of 0xF7. The
>> {@code SysexMessage} containing the last of the data for the system exclusive
>> message should end with the value 0xF7 (EOX) to mark the end of the system
>> exclusive message.
>
> In short, the text above can be represented by these examples:
> 1. SImple case: `SysexMessage{0xF0, some_data, 0xF7}`
> 2. "Continuation" sysex messages: `SysexMessage{0xF0,some_data},
> SysexMessage{0xF7,some_data}, SysexMessage{0xF7,some_data},
> SysexMessage{0xF7,some_data, 0xF7}.`
>
>
> Note that the second case above the "SysexMessage{0xF7,some_data}" is named
> as a "continuation" sysex messages.
> Usually, when a create a sysex message we carefully calculate the size of the
> message before sending it to the native code, but the "continuation" sysex
> messages were implemented in 2003 directly in native after all checks are
> done, and it just skips the status byte and tries to push nonexistent data to
> the native device.
>
> So the culprit is in the message like this:
> `SysexMessage{0xF0,some_data}, SysexMessage{0xF7}.`
>
> The code assumes that the second message is "continuation", but it does not,
> it just ends the previous message.
>
> After the fix, we will not consider the 0xF7 as a continuation if there are
> no data after.
Marked as reviewed by kizune (Reviewer).
-------------
PR: https://git.openjdk.java.net/jdk/pull/1135
