Fix nil tx bug (#124)

* add test for non-seekable packfiles

* packfile: do not throw away the newly created transactioner

Author: alcortesm

plumbing/format/packfile/decoder.go

@@ -121,15 +121,15 @@ func (d *Decoder) readObjectsWithObjectStorer(count int) error {
 }
 
 func (d *Decoder) readObjectsWithObjectStorerTx(count int) error {
-	tx := d.o.(storer.Transactioner).Begin()
+	d.tx = d.o.(storer.Transactioner).Begin()
 
 	for i := 0; i < count; i++ {
 		obj, err := d.ReadObject()
 		if err != nil {
 			return err
 		}
 
-		if _, err := tx.SetObject(obj); err != nil {
+		if _, err := d.tx.SetObject(obj); err != nil {
 			if rerr := d.tx.Rollback(); rerr != nil {
 				return ErrRollback.AddDetails(
 					"error: %s, during tx.Set error: %s", rerr, err,
@@ -141,7 +141,7 @@ func (d *Decoder) readObjectsWithObjectStorerTx(count int) error {
 
 	}
 
-	return tx.Commit()
+	return d.tx.Commit()
 }
 
 // ReadObject reads a object from the stream and return it

plumbing/format/packfile/decoder_test.go

@@ -57,6 +57,34 @@ func (s *ReaderSuite) TestDecodeInMemory(c *C) {
 	})
 }
 
+type nonSeekableReader struct {
+	r io.Reader
+}
+
+func (nsr nonSeekableReader) Read(b []byte) (int, error) {
+	return nsr.r.Read(b)
+}
+
+func (s *ReaderSuite) TestDecodeNoSeekable(c *C) {
+	fixtures.Basic().ByTag("packfile").Test(c, func(f *fixtures.Fixture) {
+		reader := nonSeekableReader{
+			r: f.Packfile(),
+		}
+
+		scanner := NewScanner(reader)
+		storage := memory.NewStorage()
+		d, err := NewDecoder(scanner, storage)
+		c.Assert(err, IsNil)
+		defer d.Close()
+
+		ch, err := d.Decode()
+		c.Assert(err, IsNil)
+		c.Assert(ch, Equals, f.PackfileHash)
+
+		assertObjects(c, storage, expectedHashes)
+	})
+}
+
 var expectedHashes = []string{
 	"918c48b83bd081e863dbe1b80f8998f058cd8294",
 	"af2d6a6954d532f8ffb47615169c8fdf9d383a1a",