About

PanamaPort is a library implementing the Foreign Function & Memory API for Android 8.0+ (API level 26)

Components

This project contains 4 sublibraries:

• Core - the entire public API and implementation of the Panama project
• Unsafe - low-level implementation details and additional capabilities not provided by the original API
• LLVM - bindings to the built-in libLLVM.so Android library
• VarHandles - backport of java.lang.invoke.VarHandle which didn't exist in android 8.x

Requirements

• JDK 21+
• Gradle 9.3.1+
• Android Gradle plugin 9.1.1+
• compileSdk 37+

Using versions lower than those listed may cause compilation and runtime issues. Older versions of R8/D8 have known bugs that prevent the library from working properly

Get started

Just add this library to the list of dependencies:

dependencies {
    implementation 'io.github.vova7878.panama:Core:<version>'
}

---

Supported features

PanamaPort implements full Foreign Function & Memory API support, including:

• Downcall handles - allows Java code to call foreign functions
• Upcall stubs - allows foreign functions to call Java method handles
• Linker options such as captureCallState("errno") and even critical(allowHeapAccess: true)
• Access to native memory via VarHandles
• Management of memory segments via Arenas
• And much more

Differences from the original API

• Package java.lang.foreign moved to com.v7878.foreign package because it is a port and not part of the Java core library
• WrongThreadException class is also in the com.v7878.foreign package because it doesn't exist on android
• My implementation of VarHandle is used instead of java.lang.invoke.VarHandle

What was added

All non-standard apis added to the port are marked with @PortAPI annotation

This includes just useful methods:

• MemoryLayout.valueLayout(Class<?>, ByteOrder)
• MemoryLayout.sequenceLayout(MemoryLayout)
• MemoryLayout.paddedStructLayout(MemoryLayout...)
• MemorySegment.nativeAddress()

Android-specific linker options:

• Option.allowExceptions() and Option.JNIEnvArg(int)

Port of methods outside the java.lang.foreign package:

• FileChannelUtils.map(FileChannel, MapMode, long, long, Arena)

Interaction with jextract

Usually, to use the output of jextract, it is enough to fix package names. If something doesn't work properly, please create an issue

Examples and tests

Examples are available in this repository. The same repository is where tests are ported from the OpenJ9 and Hotspot implementations