From e19f45b912fdce106fb31fdff6dbcc7ad391db0d Mon Sep 17 00:00:00 2001
From: Alex Zhang <zhangchi0104@live.com>
Date: Sat, 14 May 2022 12:30:40 +0800
Subject: [PATCH] rewrite callback for msvc

---
 src/dart/lib/maa_core.dart |  5 +++--
 src/dart/native/callback.c | 14 +++++++-------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/dart/lib/maa_core.dart b/src/dart/lib/maa_core.dart
index 1db8bd8d8c..8ef43a58a9 100644
--- a/src/dart/lib/maa_core.dart
+++ b/src/dart/lib/maa_core.dart
@@ -36,7 +36,6 @@ class MaaCore implements MaaCoreInterface {
     final result = _asstLoadResource(strPtr);
     _resourceLoaded = _resourceLoaded || result;
   }
-
   MaaCore(String libDir, [Function(String)? callback]) {
     _loadCppLib(libDir);
     if (!_apiInited) {
@@ -65,7 +64,9 @@ class MaaCore implements MaaCoreInterface {
   void Function(dynamic) _wrapCallback(void Function(String) cb) {
     return (dynamic data) {
       // c will manage the memory for the string
-      String msg = data;
+      final Pointer<Utf8> ptr = Pointer.fromAddress(data as int);
+      String msg = ptr.toDartString();
+      malloc.free(ptr);
       cb(msg);
     };
   }
diff --git a/src/dart/native/callback.c b/src/dart/native/callback.c
index ce66b0bd0f..d9c498a5a0 100644
--- a/src/dart/native/callback.c
+++ b/src/dart/native/callback.c
@@ -1,6 +1,7 @@
 #include "dart_api_dl.h"
 #include <string.h>
 #include <stdio.h>
+#include <stdlib.h>
 void callback(int, const char *, void *);
 void init_dart_api(void *);
 void init_dart_api(void *api_data) {
@@ -19,14 +20,13 @@ void callback(int retval, const char *json_str, void *custom_arg) {
     }
     Dart_CObject obj;
     int required_len = n_digits + strlen(json_str) + 1;
-    char retstr[required_len];
-    retstr[required_len-1] = 0;
-    sprintf(retstr, "{\"retval\": %d, \"payload\": %s }", retval, json_str);
-    obj.type = Dart_CObject_kString;
-    obj.value.as_string = retstr;
-    printf("C: Sending Pointer %ld to dart through port %ld\n", (int64_t)json_str, port);
+    char* retptr = calloc(required_len, sizeof(char));
+    snprintf(retptr, required_len, "{\"retval\": %d, \"payload\": %s }", retval, json_str);
+    obj.type = Dart_CObject_kInt64;
+    obj.value.as_string = (int64_t)retptr;
+    printf("C: Sending Pointer %p to dart through port %lld\n", retptr, (int64_t) port);
     char res = Dart_PostCObject_DL(port, &obj);
     if (res == 0) {
         printf("C: Failed to send message to Dart\n");
     }
-}
\ No newline at end of file
+}