unsafe helpers

unsafe/strings.go

@@ -0,0 +1,27 @@
+// +build !appengine
+
+package unsafe
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// ByteSlice returns s as a byte slice without copying,
+// any attempt to modifythe resulting slice might end all life as we know.
+func ByteSlice(s *string) []byte {
+	sh := (*reflect.SliceHeader)(unsafe.Pointer(s))
+	sh.Cap = sh.Len
+	return *(*[]byte)(unsafe.Pointer(sh))
+}
+
+// VoidToBytes is a helper function to convert a void* buffer from a cgo call
+// to a byte slice
+func VoidToBytes(p unsafe.Pointer, ln int) []byte {
+	sh := &reflect.SliceHeader{
+		Data: uintptr(p),
+		Len:  ln,
+		Cap:  ln,
+	}
+	return *(*[]byte)(unsafe.Pointer(sh))
+}