fix: windows free

Author: mworzala

build.gradle.kts

@@ -147,11 +147,14 @@ signing {
 }
 
 task<JExtractTask>("jextractLuacode") {
-    header = file("native/luau/Compiler/include/luacode.h")
+    // Note: we use the header from the build directory here because we need to catch "luau_ext_free" which is added
+    // by native/build.gradle.kts
+    header = file("native/build/root/luau/Compiler/include/luacode.h")
     targetPackage = "net.hollowcube.luau.internal.compiler"
     extraArgs = listOf(
         "--define-macro", "LUA_API=\"extern \\\"C\\\"\"",
         "--include-function", "luau_compile",
+        "--include-function", "luau_ext_free",
         "--include-struct", "lua_CompileOptions",
     )
 }

native/build.gradle.kts

@@ -22,22 +22,35 @@ task<Copy>("copyForModification") {
     into(buildProjectDir)
 }
 
+fun edit(file: File, edit: (String) -> String) {
+    val originalText = file.readText()
+    val modifiedText = edit(originalText)
+    if (originalText != modifiedText) {
+        file.writeText(modifiedText)
+    }
+}
+
 task("luauStaticToShared") {
     description = "Make Luau.Compiler and Luau.VM compile as shared libraries"
     dependsOn("copyForModification")
 
-    val targetFile = buildProjectDir.resolve("luau/CMakeLists.txt")
-    inputs.file(targetFile)
-    outputs.file(targetFile)
+    val cmakeLists = buildProjectDir.resolve("luau/CMakeLists.txt")
+    val luacodeHeader = buildProjectDir.resolve("luau/Compiler/include/luacode.h")
+    val luacodeSource = buildProjectDir.resolve("luau/Compiler/src/lcode.cpp")
+    inputs.files(cmakeLists, luacodeHeader, luacodeSource)
+    outputs.files(cmakeLists, luacodeHeader, luacodeSource)
 
     doLast {
-        val originalText = targetFile.readText()
-        val modifiedText = originalText
-            .replace("add_library(Luau.Compiler STATIC)", "add_library(Luau.Compiler SHARED)")
-            .replace("add_library(Luau.VM STATIC)", "add_library(Luau.VM SHARED)")
-
-        if (originalText != modifiedText) {
-            targetFile.writeText(modifiedText)
+        edit(cmakeLists) {
+            return@edit it
+                .replace("add_library(Luau.Compiler STATIC)", "add_library(Luau.Compiler SHARED)")
+                .replace("add_library(Luau.VM STATIC)", "add_library(Luau.VM SHARED)")
+        }
+        edit(luacodeHeader) {
+            return@edit "$it\n\nLUACODE_API void luau_ext_free(char *bytecode);"
+        }
+        edit(luacodeSource) {
+            return@edit "$it\n\nvoid luau_ext_free(char *bytecode) {\n    free(bytecode);\n}"
         }
     }
 }

src/generated/java/net/hollowcube/luau/internal/compiler/luacode_h.java

@@ -129,5 +129,62 @@ public static MemorySegment luau_compile(MemorySegment source, long size, Memory
            throw new AssertionError("should not reach here", ex$);
         }
     }
+
+    private static class luau_ext_free {
+        public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+            luacode_h.C_POINTER
+        );
+
+        public static final MemorySegment ADDR = luacode_h.findOrThrow("luau_ext_free");
+
+        public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    }
+
+    /**
+     * Function descriptor for:
+     * {@snippet lang=c :
+     * extern void luau_ext_free(char *bytecode)
+     * }
+     */
+    public static FunctionDescriptor luau_ext_free$descriptor() {
+        return luau_ext_free.DESC;
+    }
+
+    /**
+     * Downcall method handle for:
+     * {@snippet lang=c :
+     * extern void luau_ext_free(char *bytecode)
+     * }
+     */
+    public static MethodHandle luau_ext_free$handle() {
+        return luau_ext_free.HANDLE;
+    }
+
+    /**
+     * Address for:
+     * {@snippet lang=c :
+     * extern void luau_ext_free(char *bytecode)
+     * }
+     */
+    public static MemorySegment luau_ext_free$address() {
+        return luau_ext_free.ADDR;
+    }
+
+    /**
+     * {@snippet lang=c :
+     * extern void luau_ext_free(char *bytecode)
+     * }
+     */
+    public static void luau_ext_free(MemorySegment bytecode) {
+        var mh$ = luau_ext_free.HANDLE;
+        try {
+            if (TRACE_DOWNCALLS) {
+                traceDowncall("luau_ext_free", bytecode);
+            }
+            mh$.invokeExact(bytecode);
+        } catch (Throwable ex$) {
+           throw new AssertionError("should not reach here", ex$);
+        }
+    }
 }
 

src/main/java/net/hollowcube/luau/LuaStateImpl.java

@@ -382,6 +382,7 @@ public Object toLightUserDataTagged(int index) {
     @Override
     public Object toUserData(int index) {
         final MemorySegment ud = lua_touserdata(L, index);
+        //todo NULL can be returned. //todo this call is not valid against userDataInt ud values. We need to include some metadata in
         return GlobalRef.get(ud.get(ValueLayout.JAVA_LONG, 0));
     }
 

src/main/java/net/hollowcube/luau/compiler/LuauCompilerImpl.java

@@ -6,11 +6,14 @@
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.lang.foreign.*;
-import java.lang.invoke.MethodHandle;
+import java.lang.foreign.Arena;
+import java.lang.foreign.MemorySegment;
+import java.lang.foreign.ValueLayout;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
 
+import static net.hollowcube.luau.internal.compiler.luacode_h.luau_ext_free;
+
 @SuppressWarnings("preview")
 record LuauCompilerImpl(
         @NotNull OptimizationLevel optimizationLevel,
@@ -27,19 +30,6 @@ record LuauCompilerImpl(
         NativeLibraryLoader.loadLibrary("compiler");
     }
 
-    private static final MethodHandle FREE_HANDLE;
-
-    static {
-        // This is basically just a manually inlined version of what jextract would generate for `free`.
-
-        final SymbolLookup symbolLookup = SymbolLookup.loaderLookup().or(Linker.nativeLinker().defaultLookup());
-        final MemorySegment freeAddr = symbolLookup.find("free")
-                .orElseThrow(() -> new UnsatisfiedLinkError("unresolved symbol: free"));
-        final FunctionDescriptor freeDesc = FunctionDescriptor.ofVoid(ValueLayout.ADDRESS);
-
-        FREE_HANDLE = Linker.nativeLinker().downcallHandle(freeAddr, freeDesc);
-    }
-
     @Override
     public byte[] compile(byte @NotNull [] source) throws LuauCompileException {
         try (Arena arena = Arena.ofConfined()) {
@@ -50,7 +40,7 @@ public byte[] compile(byte @NotNull [] source) throws LuauCompileException {
             final MemorySegment result = luacode_h.luau_compile(sourceStr, source.length, compileOpts, bytecodeSize);
             final long length = bytecodeSize.get(ValueLayout.JAVA_LONG, 0);
             final byte[] bytecode = result.asSlice(0, length).toArray(ValueLayout.JAVA_BYTE);
-            free(result);
+            luau_ext_free(result);
 
             // Bytecode now contains either an error or valid luau bytecode.
             // A zero in the first byte indicates that the rest is an error.
@@ -93,14 +83,6 @@ public byte[] compile(byte @NotNull [] source) throws LuauCompileException {
         return opts;
     }
 
-    private void free(@NotNull MemorySegment segment) {
-        try {
-            FREE_HANDLE.invokeExact(segment);
-        } catch (Throwable ex) {
-            throw new AssertionError("should not reach here", ex);
-        }
-    }
-
     static final class BuilderImpl implements Builder {
         private OptimizationLevel optimizationLevel = OptimizationLevel.BASELINE;
         private DebugLevel debugLevel = DebugLevel.BACKTRACE;