don't pass go strings to c - pass char*+len, callee must call free()

main.go

@@ -31,24 +31,27 @@ func Bolt_Options_New_Readonly() ObjectReference {
 }
 
 //export Bolt_Open
-func Bolt_Open(path string, mode uint32, opts ObjectReference) (ObjectReference, string) {
+func Bolt_Open(path string, mode uint32, opts ObjectReference) (ObjectReference, *C.char, int) {
 	optsIFC, ok := gms.Get(opts)
 	if !ok {
-		return 0, ""
+		errMsg := NullObjectReference.Error()
+		return 0, C.CString(errMsg), len(errMsg)
 	}
 
 	ptrBoltOps, ok := optsIFC.(*bolt.Options)
 	if !ok {
-		return 0, ""
+		errMsg := NullObjectReference.Error()
+		return 0, C.CString(errMsg), len(errMsg)
 	}
 
 	ptrDB, err := bolt.Open(path, os.FileMode(mode), ptrBoltOps)
 	if err != nil {
-		return 0, err.Error()
+		errMsg := err.Error()
+		return 0, C.CString(errMsg), len(errMsg)
 	}
 
 	dbRef := gms.Put(ptrDB)
-	return dbRef, ""
+	return dbRef, nil, 0
 }
 
 func withBoltDBReference(b ObjectReference, fn func(db *bolt.DB) error) error {
@@ -134,28 +137,31 @@ const (
 )
 
 //export GetNext
-func GetNext(oRef ObjectReference) (int64, string) {
+func GetNext(oRef ObjectReference) (int64, *C.char, int) {
 	pNC_Iface, ok := gms.Get(oRef)
 	if !ok {
-		return ERROR_AND_STOP_CALLING, NullObjectReference.Error()
+		msg := NullObjectReference.Error()
+		return ERROR_AND_STOP_CALLING, C.CString(msg), len(msg)
 	}
 
 	pNC, ok := pNC_Iface.(*NextCall)
 	if !ok {
-		return ERROR_AND_STOP_CALLING, NullObjectReference.Error()
+		msg := NullObjectReference.Error()
+		return ERROR_AND_STOP_CALLING, C.CString(msg), len(msg)
 	}
 
 	cr, ok := <-pNC.content
 	if !ok {
 		gms.Delete(oRef)
-		return FINISHED_OK, ""
+		return FINISHED_OK, nil, 0
 	}
 
 	if cr.e != nil {
-		return ERROR_AND_KEEP_CALLING, cr.e.Error()
+		msg := cr.e.Error()
+		return ERROR_AND_KEEP_CALLING, C.CString(msg), len(msg)
 	}
 
-	return REAL_MESSAGE, cr.s
+	return REAL_MESSAGE, C.CString(cr.s), len(cr.s)
 }
 
 //export Bolt_ListBucketsAtRoot
@@ -164,17 +170,18 @@ func Bolt_ListBucketsAtRoot(b ObjectReference) ObjectReference {
 }
 
 //export Bolt_Close
-func Bolt_Close(b ObjectReference) string {
+func Bolt_Close(b ObjectReference) (*C.char, int) {
 	err := withBoltDBReference(b, func(db *bolt.DB) error {
 		return db.Close()
 	})
 
 	if err != nil {
-		return err.Error()
+		msg := err.Error()
+		return C.CString(msg), len(msg)
 	}
 
 	gms.Delete(b)
-	return ""
+	return nil, 0
 }
 
 func main() {

qbolt.h

@@ -61,7 +61,8 @@ extern GoInt64 Bolt_Options_New_Readonly();
 /* Return type for Bolt_Open */
 struct Bolt_Open_return {
 	GoInt64 r0;
-	GoString r1;
+	char* r1;
+	GoInt r2;
 };
 
 extern struct Bolt_Open_return Bolt_Open(GoString p0, GoUint32 p1, GoInt64 p2);
@@ -71,14 +72,21 @@ extern GoInt64 Bolt_ListBuckets(GoInt64 p0, GoSlice p1);
 /* Return type for GetNext */
 struct GetNext_return {
 	GoInt64 r0;
-	GoString r1;
+	char* r1;
+	GoInt r2;
 };
 
 extern struct GetNext_return GetNext(GoInt64 p0);
 
 extern GoInt64 Bolt_ListBucketsAtRoot(GoInt64 p0);
 
-extern GoString Bolt_Close(GoInt64 p0);
+/* Return type for Bolt_Close */
+struct Bolt_Close_return {
+	char* r0;
+	GoInt r1;
+};
+
+extern struct Bolt_Close_return Bolt_Close(GoInt64 p0);
 
 #ifdef __cplusplus
 }

qbolt/boltdb.cpp

@@ -13,8 +13,9 @@ BoltDB* BoltDB::createFrom(QString filePath, QString &errorOut)
     GoString filePathGS = Interop::toGoString_WeakRef(&filePathBytes);
 
     auto open_ret = ::Bolt_Open(filePathGS, 0444, opts);
-    if (open_ret.r1.n != 0) {
+    if (open_ret.r2 != 0) {
-        errorOut = QString(open_ret.r1.p);
+        errorOut = QString::fromUtf8(open_ret.r1, open_ret.r2);
+        free(open_ret.r1);
         return nullptr;
     }
 
@@ -38,11 +39,13 @@ bool BoltDB::listBucketsAtRoot(QString& errorOut, NameReciever cb)
         auto gnr = ::GetNext(listJob);
 
         if (gnr.r0 == ERROR_AND_STOP_CALLING) {
-            errorOut.append(QString(gnr.r1.p)); // log error
+            errorOut.append(QString::fromUtf8(gnr.r1, gnr.r2)); // log error
+            free(gnr.r1);
             break; // done
 
         } else if (gnr.r0 == ERROR_AND_KEEP_CALLING) {
-            errorOut.append(QString(gnr.r1.p)); // log error
+            errorOut.append(QString::fromUtf8(gnr.r1, gnr.r2)); // log error
+            free(gnr.r1);
             continue;
 
         } else if (gnr.r0 == FINISHED_OK) {
@@ -50,7 +53,8 @@ bool BoltDB::listBucketsAtRoot(QString& errorOut, NameReciever cb)
             break;
 
         } else if (gnr.r0 == REAL_MESSAGE) {
-            cb(QByteArray(gnr.r1.p, gnr.r1.n));
+            cb(QByteArray(gnr.r1, gnr.r2));
+            free(gnr.r1);
             continue;
         }
     }
@@ -60,9 +64,11 @@ bool BoltDB::listBucketsAtRoot(QString& errorOut, NameReciever cb)
 
 BoltDB::~BoltDB()
 {
-    GoString err = ::Bolt_Close(this->gmsDbRef);
+    auto err = ::Bolt_Close(this->gmsDbRef);
-    if (err.n != 0) {
+    if (err.r1 != 0) {
         // Error closing database!
         // Need to display an alert... somewhere
+
+        free(err.r0);
     }
 }