RFR: 8355561: [macos] Build failure with Xcode 16.3

[Sergey Bylokhov]

On Mon, 28 Apr 2025 19:47:03 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> Multiple similar issues detected in PLATFORM_API_MacOSX_Ports.cpp more info about https://github.com/llvm/llvm-project/issues/62836
> 
> jdk/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:127:39: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
>   127 | AudioDeviceID devices[count];
>       | ^~~~~
> jdk/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:127:39: note: read of non-const variable 'count' is not allowed in a constant expression
> jdk/src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp:126:21: note: declared here
>   126 | int count = size/sizeof(AudioDeviceID);
> 
> The usage of VLA has been replaced with malloc/calloc and free, which are already used in this file.
> 
> Note that while this patch adds some validation, I am pretty sure it is still possible to crash these code paths if they are executed concurrently. Access to the native pointers being passed around is not properly synchronized.

src/java.desktop/macosx/native/libjsound/PLATFORM_API_MacOSX_Ports.cpp line 242:

> 240:     if (!mixer) {
> 241:         return nullptr;
> 242:     }

This is a pre-existing bug; the caller code is already prepared to handle null.

https://github.com/openjdk/jdk/blob/62d165d0e4e5ab1bcef35d5031554a354052c6d5/src/java.desktop/share/classes/com/sun/media/sound/PortMixer.java#L76 -> https://github.com/openjdk/jdk/blob/62d165d0e4e5ab1bcef35d5031554a354052c6d5/src/java.desktop/share/native/libjsound/PortMixer.c#L45 -> PORT_Open

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PR Review Comment: https://git.openjdk.org/jdk/pull/24937#discussion_r2064842332