1 files changed, 11 insertions, 4 deletions

diff --git a/patch.go b/patch.go
index 561786e..f2016c4 100644
--- a/patch.go
+++ b/patch.go
@@ -12,7 +12,7 @@ type Patch struct {
 	ptr *C.git_patch
 }
 
-func newPatch(ptr *C.git_patch) *Patch {
+func newPatchFromC(ptr *C.git_patch) *Patch {
 	if ptr == nil {
 		return nil
 	}
@@ -25,13 +25,20 @@ func newPatch(ptr *C.git_patch) *Patch {
 	return patch
 }
 
-func (patch *Patch) Free() {
+func (patch *Patch) Free() error {
+	if patch.ptr == nil {
+		return ErrInvalid
+	}
 	runtime.SetFinalizer(patch, nil)
 	C.git_patch_free(patch.ptr)
+	return nil
 }
 
-func (patch *Patch) String() string {
+func (patch *Patch) String() (string, error) {
+	if diff.ptr != nil {
+		return "", ErrInvalid
+	}
 	var cptr *C.char
 	C.git_patch_to_str(&cptr, patch.ptr)
-	return C.GoString(cptr)
+	return C.GoString(cptr), nil
 }