purego: enumerate types that can be returned from callbacks (#58)

explicitly enumerates which types can be returned from a callback. It also adds support for returning reflect.Pointer and reflect.UnsafePointer

1 file · +16 -2

M syscall_darwin.go +16 -2


@@ -75,8 +75,18 @@ func compileCallback(fn interface{}) uintptr {
75	75		panic("purego: unsupported argument type: " + in.Kind().String())
76	76		}
77	77		}
78		-	if ty.NumOut() > 1 \|\| ty.NumOut() == 1 && ty.Out(0).Size() != ptrSize {
79		-	panic("purego: callbacks can only have one pointer-sized return")
	78	+	output:
	79	+	switch {
	80	+	case ty.NumOut() == 1:
	81	+	switch ty.Out(0).Kind() {
	82	+	case reflect.Pointer, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
	83	+	reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
	84	+	reflect.Bool, reflect.UnsafePointer:
	85	+	break output
	86	+	}
	87	+	panic("purego: unsupported return type: " + ty.String())
	88	+	case ty.NumOut() > 1:
	89	+	panic("purego: callbacks can only have one return")
80	90		}
81	91		cbs.lock.Lock()
82	92		defer cbs.lock.Unlock()

@@ -121,6 +131,10 @@ func callbackWrap(a *callbackArgs) {
121	131		} else {
122	132		a.result = 0
123	133		}
	134	+	case reflect.Pointer:
	135	+	a.result = ret[0].Pointer()
	136	+	case reflect.UnsafePointer:
	137	+	a.result = ret[0].Pointer()
124	138		default:
125	139		panic("purego: unsupported kind: " + k.String())
126	140		}

 			panic("purego: unsupported argument type: " + in.Kind().String())
 		}
 	}
-	if ty.NumOut() > 1 || ty.NumOut() == 1 && ty.Out(0).Size() != ptrSize {
+output:
-		panic("purego: callbacks can only have one pointer-sized return")
+	switch {
+	case ty.NumOut() == 1:
+		switch ty.Out(0).Kind() {
+		case reflect.Pointer, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
+			reflect.Bool, reflect.UnsafePointer:
+			break output
+		}
+		panic("purego: unsupported return type: " + ty.String())
+	case ty.NumOut() > 1:
+		panic("purego: callbacks can only have one return")
 	}
 	cbs.lock.Lock()
 	defer cbs.lock.Unlock()
 			} else {
 				a.result = 0
 			}
+		case reflect.Pointer:
+			a.result = ret[0].Pointer()
+		case reflect.UnsafePointer:
+			a.result = ret[0].Pointer()
 		default:
 			panic("purego: unsupported kind: " + k.String())
 		}