udf: fix memory leak for libsql_wasm_engine_new

.gitignore

@@ -59,3 +59,4 @@ test/rust_suite/Cargo.lock
 testfixture
 libsql
 src/rust/libsql-shell/target/
+src/rust/wasmtime-bindings/Cargo.lock

ext/udf/wasm_bindings.h

@@ -48,6 +48,7 @@ void libsql_free_wasm_module(void *module);
 ** Creates a new wasm engine
 */
 libsql_wasm_engine_t *libsql_wasm_engine_new();
+void libsql_wasm_engine_free(libsql_wasm_engine_t *);
 
 #endif //LIBSQL_WASM_BINDINGS_H
 #endif //LIBSQL_ENABLE_WASM_RUNTIME

ext/udf/wasmedge_bindings.c

@@ -175,6 +175,9 @@ libsql_wasm_engine_t *libsql_wasm_engine_new() {
   return NULL;
 }
 
+void libsql_wasm_engine_free(libsql_wasm_engine_t *eng) {
+}
+
 libsql_wasm_module_t *libsql_compile_wasm_module(libsql_wasm_engine_t* engine, const char *pSrcBody, int nBody,
     void *(*alloc_err_buf)(unsigned long long), char **err_msg_buf) {
 

src/main.c

@@ -1266,6 +1266,11 @@ static int sqlite3Close(sqlite3 *db, int forceZombie){
   /* Convert the connection into a zombie and then close it.
   */
   db->eOpenState = SQLITE_STATE_ZOMBIE;
+#ifdef LIBSQL_ENABLE_WASM_RUNTIME
+  if (db->wasm.engine) {
+    libsql_wasm_engine_free(db->wasm.engine);
+  }
+#endif
   sqlite3LeaveMutexAndCloseZombie(db);
   return SQLITE_OK;
 }

src/rust/wasmtime-bindings/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "libsql-wasmtime-bindings"
-version = "0.2.0"
+version = "0.2.1"
 edition = "2021"
 license = "Apache-2.0"
 description = "Wasmtime bindings for libSQL user-defined functions"

src/rust/wasmtime-bindings/src/lib.rs

@@ -85,10 +85,12 @@ pub fn libsql_wasm_engine_new() -> *const c_void {
         Err(_) => return std::ptr::null() as *const c_void,
     };
 
-    let engine = Box::new(engine);
-    let engine_ptr = &*engine as *const Engine as *const c_void;
-    std::mem::forget(engine);
-    engine_ptr
+    Box::into_raw(Box::new(engine)) as *const c_void
+}
+
+#[no_mangle]
+pub fn libsql_wasm_engine_free(engine: *mut c_void) {
+    unsafe { Box::from_raw(engine as *mut Engine) };
 }
 
 #[repr(C)]