Merge pull request #425 from restic/fix-loadall

backend.LoadAll: return nil on expected error

backend/test/tests.go

@@ -245,6 +245,17 @@ func TestLoad(t testing.TB) {
 		}
 	}
 
+	// load with a too-large buffer, this should return io.ErrUnexpectedEOF
+	buf := make([]byte, length+100)
+	n, err := b.Load(handle, buf, 0)
+	if n != length {
+		t.Errorf("wrong length for larger buffer returned, want %d, got %d", length, n)
+	}
+
+	if err != io.ErrUnexpectedEOF {
+		t.Errorf("wrong error returned for larger buffer: want io.ErrUnexpectedEOF, got %#v", err)
+	}
+
 	OK(t, b.Remove(backend.Data, id.String()))
 }
 

backend/utils.go

@@ -1,7 +1,11 @@
 package backend
 
+import "io"
+
 // LoadAll reads all data stored in the backend for the handle. The buffer buf
-// is resized to accomodate all data in the blob.
+// is resized to accomodate all data in the blob. Errors returned by be.Load()
+// are passed on, except io.ErrUnexpectedEOF is silenced and nil returned
+// instead, since it means this function is working properly.
 func LoadAll(be Backend, h Handle, buf []byte) ([]byte, error) {
 	fi, err := be.Stat(h)
 	if err != nil {
@@ -13,6 +17,9 @@ func LoadAll(be Backend, h Handle, buf []byte) ([]byte, error) {
 	}
 
 	n, err := be.Load(h, buf, 0)
+	if err == io.ErrUnexpectedEOF {
+		err = nil
+	}
 	buf = buf[:n]
 	return buf, err
 }

backend/utils_test.go

@@ -37,3 +37,55 @@ func TestLoadAll(t *testing.T) {
 		}
 	}
 }
+
+func TestLoadSmallBuffer(t *testing.T) {
+	b := mem.New()
+
+	for i := 0; i < 20; i++ {
+		data := Random(23+i, rand.Intn(MiB)+500*KiB)
+
+		id := backend.Hash(data)
+		err := b.Save(backend.Handle{Name: id.String(), Type: backend.Data}, data)
+		OK(t, err)
+
+		buf := make([]byte, len(data)-23)
+		buf, err = backend.LoadAll(b, backend.Handle{Type: backend.Data, Name: id.String()}, buf)
+		OK(t, err)
+
+		if len(buf) != len(data) {
+			t.Errorf("length of returned buffer does not match, want %d, got %d", len(data), len(buf))
+			continue
+		}
+
+		if !bytes.Equal(buf, data) {
+			t.Errorf("wrong data returned")
+			continue
+		}
+	}
+}
+
+func TestLoadLargeBuffer(t *testing.T) {
+	b := mem.New()
+
+	for i := 0; i < 20; i++ {
+		data := Random(23+i, rand.Intn(MiB)+500*KiB)
+
+		id := backend.Hash(data)
+		err := b.Save(backend.Handle{Name: id.String(), Type: backend.Data}, data)
+		OK(t, err)
+
+		buf := make([]byte, len(data)+100)
+		buf, err = backend.LoadAll(b, backend.Handle{Type: backend.Data, Name: id.String()}, buf)
+		OK(t, err)
+
+		if len(buf) != len(data) {
+			t.Errorf("length of returned buffer does not match, want %d, got %d", len(data), len(buf))
+			continue
+		}
+
+		if !bytes.Equal(buf, data) {
+			t.Errorf("wrong data returned")
+			continue
+		}
+	}
+}