Merge pull request #52 from ursachec/master

Support for git_odb_hash.

odb.go

@@ -79,6 +79,22 @@ func (v *Odb) ForEach() chan *Oid {
 	return ch
 }
 
+// Hash determines the object-ID (sha1) of a data buffer.
+func (v *Odb) Hash(data []byte, otype ObjectType) (oid *Oid, err error) {
+	oid = new(Oid)
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
+	ptr := unsafe.Pointer(header.Data)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_odb_hash(oid.toC(), ptr, C.size_t(header.Len), C.git_otype(otype));
+	if ret < 0 {
+		err = LastError()
+	}
+	return
+}
+
 // NewReadStream opens a read stream from the ODB. Reading from it will give you the
 // contents of the object.
 func (v *Odb) NewReadStream(id *Oid) (*OdbReadStream, error) {

odb_test.go

@@ -33,3 +33,30 @@ func TestOdbStream(t *testing.T) {
 		t.Fatal("Wrong data written")
 	}
 }
+
+func TestOdbHash(t *testing.T) {
+
+    repo := createTestRepo(t)
+	defer os.RemoveAll(repo.Workdir())
+	_, _ = seedTestRepo(t, repo)
+
+	odb, error := repo.Odb()
+	checkFatal(t, error)
+
+	str := `tree 115fcae49287c82eb55bb275cbbd4556fbed72b7
+parent 66e1c476199ebcd3e304659992233132c5a52c6c
+author John Doe <john@doe.com> 1390682018 +0000
+committer John Doe <john@doe.com> 1390682018 +0000
+
+Initial commit.`;
+
+	oid, error := odb.Hash([]byte(str), ObjectCommit)
+	checkFatal(t, error)
+
+	coid, error := odb.Write([]byte(str), ObjectCommit)
+	checkFatal(t, error)
+
+	if oid.Cmp(coid) != 0 {
+		t.Fatal("Hash and write Oids are different")
+	}
+}