ffi: migrate to jffi which will provide a path for struct support

ffi/build.gradle.kts

@@ -7,4 +7,6 @@ dependencies {
   api(project(":evaluator"))
 
   implementation(project(":common"))
+  implementation("com.github.jnr:jffi:1.3.12")
+  implementation("com.github.jnr:jffi:1.3.12:native")
 }

ffi/src/main/kotlin/gay/pizza/pork/ffi/FfiAddress.kt

@@ -0,0 +1,7 @@
+package gay.pizza.pork.ffi
+
+data class FfiAddress(val location: Long) {
+  companion object {
+    val Null = FfiAddress(0L)
+  }
+}

ffi/src/main/kotlin/gay/pizza/pork/ffi/FfiNativeProvider.kt

@@ -1,10 +1,11 @@
 package gay.pizza.pork.ffi
 
-import gay.pizza.pork.ast.ArgumentSpec
+import com.kenai.jffi.*
+import com.kenai.jffi.Function
+import gay.pizza.pork.ast.gen.ArgumentSpec
 import gay.pizza.pork.evaluator.CallableFunction
 import gay.pizza.pork.evaluator.NativeProvider
 import gay.pizza.pork.evaluator.None
-import java.lang.foreign.*
 import java.nio.file.Path
 import kotlin.io.path.Path
 import kotlin.io.path.absolutePathString
@@ -15,7 +16,6 @@ class FfiNativeProvider : NativeProvider {
 
   override fun provideNativeFunction(definitions: List<String>, arguments: List<ArgumentSpec>): CallableFunction {
     val functionDefinition = FfiFunctionDefinition.parse(definitions[0], definitions[1])
-    val linker = Linker.nativeLinker()
     val functionAddress = lookupSymbol(functionDefinition)
 
     val parameters = functionDefinition.parameters.map { id ->
@@ -25,47 +25,72 @@ class FfiNativeProvider : NativeProvider {
     val returnTypeId = functionDefinition.returnType
     val returnType = ffiTypeRegistry.lookup(returnTypeId) ?:
       throw RuntimeException("Unknown ffi return type: $returnTypeId")
-    val parameterArray = parameters.map { typeAsLayout(it) }.toTypedArray()
-    val descriptor = if (returnType == FfiPrimitiveType.Void)
-      FunctionDescriptor.ofVoid(*parameterArray)
-    else FunctionDescriptor.of(typeAsLayout(returnType), *parameterArray)
-    val handle = linker.downcallHandle(functionAddress, descriptor)
+    val returnTypeFfi = typeConversion(returnType)
+    val parameterArray = parameters.map { typeConversion(it) }.toTypedArray()
+    val function = Function(functionAddress, returnTypeFfi, *parameterArray)
+    val context = function.callContext
+    val invoker = Invoker.getInstance()
     return CallableFunction { functionArguments, _ ->
-      Arena.ofConfined().use { arena ->
-        handle.invokeWithArguments(functionArguments.map { valueAsFfi(it, arena) }) ?: None
+      val buffer = HeapInvocationBuffer(context)
+      val freeStringList = mutableListOf<FfiStringWrapper>()
+      for ((index, spec) in arguments.withIndex()) {
+        val ffiType = ffiTypeRegistry.lookup(functionDefinition.parameters[index]) ?:
+          throw RuntimeException("Unknown ffi type: ${functionDefinition.parameters[index]}")
+        if (spec.multiple) {
+          val variableArguments = functionArguments
+            .subList(index, functionArguments.size)
+          variableArguments.forEach {
+            var value = it
+            if (value is String) {
+              value = FfiStringWrapper(value)
+              freeStringList.add(value)
+            }
+            put(buffer, value)
+          }
+          break
+        } else {
+          val converted = convert(ffiType, functionArguments[index])
+          if (converted is FfiStringWrapper) {
+            freeStringList.add(converted)
+          }
+          put(buffer, converted)
+        }
       }
-    }
-  }
 
-  private fun lookupSymbol(functionDefinition: FfiFunctionDefinition): MemorySegment {
-    if (functionDefinition.library == "c") {
-      return SymbolLookup.loaderLookup().find(functionDefinition.function).orElseThrow {
-        RuntimeException("Unknown function: ${functionDefinition.function}")
+      try {
+        return@CallableFunction invoke(invoker, function, buffer, returnType)
+      } finally {
+        freeStringList.forEach { it.free() }
       }
     }
+  }
+
+  private fun lookupSymbol(functionDefinition: FfiFunctionDefinition): Long {
     val actualLibraryPath = findLibraryPath(functionDefinition.library)
-    val functionAddress = FfiLibraryCache.dlsym(actualLibraryPath.absolutePathString(), functionDefinition.function)
-    if (functionAddress.address() == 0L) {
-      throw RuntimeException("Unknown function: ${functionDefinition.function} in library $actualLibraryPath")
+    val library = Library.getCachedInstance(actualLibraryPath.absolutePathString(), Library.NOW)
+      ?: throw RuntimeException("Failed to load library $actualLibraryPath")
+    val functionAddress = library.getSymbolAddress(functionDefinition.function)
+    if (functionAddress == 0L) {
+      throw RuntimeException(
+        "Failed to find symbol ${functionDefinition.function} in " +
+        "library ${actualLibraryPath.absolutePathString()}")
     }
     return functionAddress
   }
 
-  private fun typeAsLayout(type: FfiType): MemoryLayout = when (type) {
-    FfiPrimitiveType.UnsignedByte, FfiPrimitiveType.Byte -> ValueLayout.JAVA_BYTE
-    FfiPrimitiveType.UnsignedInt, FfiPrimitiveType.Int -> ValueLayout.JAVA_INT
-    FfiPrimitiveType.UnsignedShort, FfiPrimitiveType.Short -> ValueLayout.JAVA_SHORT
-    FfiPrimitiveType.UnsignedLong, FfiPrimitiveType.Long -> ValueLayout.JAVA_LONG
-    FfiPrimitiveType.String -> ValueLayout.ADDRESS
-    FfiPrimitiveType.Pointer -> ValueLayout.ADDRESS
-    FfiPrimitiveType.Void -> MemoryLayout.sequenceLayout(0, ValueLayout.JAVA_INT)
-    else -> throw RuntimeException("Unknown ffi type to convert to memory layout: $type")
-  }
-
-  private fun valueAsFfi(value: Any, allocator: SegmentAllocator): Any = when (value) {
-      is String -> allocator.allocateUtf8String(value)
-    None -> MemorySegment.NULL
-    else -> value
+  private fun typeConversion(type: FfiType): Type = when (type) {
+    FfiPrimitiveType.UnsignedByte -> Type.UINT8
+    FfiPrimitiveType.Byte -> Type.SINT8
+    FfiPrimitiveType.UnsignedInt -> Type.UINT32
+    FfiPrimitiveType.Int -> Type.SINT32
+    FfiPrimitiveType.UnsignedShort -> Type.UINT16
+    FfiPrimitiveType.Short -> Type.SINT16
+    FfiPrimitiveType.UnsignedLong -> Type.UINT64
+    FfiPrimitiveType.Long -> Type.SINT64
+    FfiPrimitiveType.String -> Type.POINTER
+    FfiPrimitiveType.Pointer -> Type.POINTER
+    FfiPrimitiveType.Void -> Type.VOID
+    else -> throw RuntimeException("Unknown ffi type: $type")
   }
 
   private fun findLibraryPath(name: String): Path {
@@ -76,4 +101,69 @@ class FfiNativeProvider : NativeProvider {
     return FfiPlatforms.current.platform.findLibrary(name)
       ?: throw RuntimeException("Unable to find library: $name")
   }
+
+  private fun convert(type: FfiType, value: Any?): Any {
+    if (type !is FfiPrimitiveType) {
+      return value ?: FfiAddress.Null
+    }
+
+    if (type.numberConvert != null) {
+      return numberConvert(type.id, value, type.numberConvert)
+    }
+
+    if (type.notNullConversion != null) {
+      return notNullConvert(type.id, value, type.notNullConversion)
+    }
+
+    if (type.nullableConversion != null) {
+      return nullableConvert(value, type.nullableConversion) ?: FfiAddress.Null
+    }
+    return value ?: FfiAddress.Null
+  }
+
+  private fun <T> notNullConvert(type: String, value: Any?, into: Any.() -> T): T {
+    if (value == null) {
+      throw RuntimeException("Null values cannot be used for converting to type $type")
+    }
+    return into(value)
+  }
+
+  private fun <T> nullableConvert(value: Any?, into: Any.() -> T): T? {
+    if (value == null || value == None) {
+      return null
+    }
+    return into(value)
+  }
+
+  private fun <T> numberConvert(type: String, value: Any?, into: Number.() -> T): T {
+    if (value == null || value == None) {
+      throw RuntimeException("Null values cannot be used for converting to numeric type $type")
+    }
+
+    if (value !is Number) {
+      throw RuntimeException("Cannot convert value '$value' into type $type")
+    }
+    return into(value)
+  }
+
+  private fun put(buffer: InvocationBuffer, value: Any): Unit = when (value) {
+    is Byte -> buffer.putByte(value.toInt())
+    is Short -> buffer.putShort(value.toInt())
+    is Int -> buffer.putInt(value)
+    is Long -> buffer.putLong(value)
+    is FfiAddress -> buffer.putAddress(value.location)
+    is FfiStringWrapper -> buffer.putAddress(value.address)
+    else -> throw RuntimeException("Unknown buffer insertion: $value (${value.javaClass.name})")
+  }
+
+  private fun invoke(invoker: Invoker, function: Function, buffer: HeapInvocationBuffer, type: FfiType): Any = when (type) {
+    FfiPrimitiveType.Pointer -> invoker.invokeAddress(function, buffer)
+    FfiPrimitiveType.UnsignedInt, FfiPrimitiveType.Int -> invoker.invokeInt(function, buffer)
+    FfiPrimitiveType.Long -> invoker.invokeLong(function, buffer)
+    FfiPrimitiveType.Void -> invoker.invokeStruct(function, buffer)
+    FfiPrimitiveType.Double -> invoker.invokeDouble(function, buffer)
+    FfiPrimitiveType.Float -> invoker.invokeFloat(function, buffer)
+    FfiPrimitiveType.String -> invoker.invokeAddress(function, buffer)
+    else -> throw RuntimeException("Unsupported ffi return type: $type")
+  } ?: None
 }

ffi/src/main/kotlin/gay/pizza/pork/ffi/FfiPrimitiveType.kt

@@ -1,7 +1,6 @@
 package gay.pizza.pork.ffi
 
 import gay.pizza.pork.evaluator.None
-import java.lang.foreign.MemorySegment
 
 enum class FfiPrimitiveType(
   val id: kotlin.String,
@@ -20,13 +19,14 @@ enum class FfiPrimitiveType(
   Long("long", 8, numberConvert = { toLong() }),
   UnsignedLong("unsigned long", 8, numberConvert = { toLong() }),
   Double("double", 8, numberConvert = { toDouble() }),
-  String("char*", 8, nullableConversion = { toString() }),
+  String("char*", 8, nullableConversion = { FfiStringWrapper(toString()) }),
   Pointer("void*", 8, nullableConversion = {
-    if (this is kotlin.Long) {
-      MemorySegment.ofAddress(this)
-    } else if (this == None) {
-      MemorySegment.NULL
-    } else this as MemorySegment
+    when (this) {
+      is FfiAddress -> this
+      is None -> FfiAddress.Null
+      is Number -> FfiAddress(this.toLong())
+      else -> FfiAddress.Null
+    }
   }),
   Void("void", 0)
 }

ffi/src/main/kotlin/gay/pizza/pork/ffi/FfiStringWrapper.kt

@@ -0,0 +1,17 @@
+package gay.pizza.pork.ffi
+
+import com.kenai.jffi.MemoryIO
+
+class FfiStringWrapper(input: String) {
+  val address: Long
+
+  init {
+    val bytes = input.toByteArray()
+    address = MemoryIO.getInstance().allocateMemory((bytes.size + 1).toLong(), true)
+    MemoryIO.getInstance().putZeroTerminatedByteArray(address, bytes, 0, bytes.size)
+  }
+
+  fun free() {
+    MemoryIO.getInstance().freeMemory(address)
+  }
+}