diskpacked: don't append duplicate blobs.

Change-Id: I3adce39641458a67a3cdee09bb66411dd1111acd

pkg/blobserver/diskpacked/diskpacked.go

@@ -417,7 +417,18 @@ func (s *storage) ReceiveBlob(br blob.Ref, source io.Reader) (sbr blob.SizedRef,
 	if err != nil {
 		return
 	}
+
 	sbr = blob.SizedRef{Ref: br, Size: n}
+
+	// Check if it's a dup. Still accept it if the pack file on disk seems to be corrupt
+	// or truncated.
+	if m, err := s.meta(br); err == nil {
+		fi, err := os.Stat(s.filename(m.file))
+		if err == nil && fi.Size() >= m.offset+m.size {
+			return sbr, nil
+		}
+	}
+
 	err = s.append(sbr, &b)
 	return
 }

pkg/blobserver/diskpacked/diskpacked_test.go

@@ -19,10 +19,12 @@ package diskpacked
 import (
 	"io/ioutil"
 	"os"
+	"strings"
 	"testing"
 
 	"camlistore.org/pkg/blobserver"
 	"camlistore.org/pkg/blobserver/storagetest"
+	"camlistore.org/pkg/test"
 )
 
 func newTempDiskpacked(t *testing.T) (sto blobserver.Storage, cleanup func()) {
@@ -44,3 +46,49 @@ func newTempDiskpacked(t *testing.T) (sto blobserver.Storage, cleanup func()) {
 func TestDiskpacked(t *testing.T) {
 	storagetest.Test(t, newTempDiskpacked)
 }
+
+func TestDoubleReceive(t *testing.T) {
+	sto, cleanup := newTempDiskpacked(t)
+	defer cleanup()
+
+	size := func(n int) int64 {
+		path := sto.(*storage).filename(n)
+		fi, err := os.Stat(path)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return fi.Size()
+	}
+
+	const blobSize = 5 << 10
+	b := &test.Blob{Contents: strings.Repeat("a", blobSize)}
+	br := b.BlobRef()
+
+	_, err := blobserver.Receive(sto, br, b.Reader())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if size(0) < blobSize {
+		t.Fatalf("size = %d; want at least %d", size(0), blobSize)
+	}
+	sto.(*storage).nextPack()
+
+	_, err = blobserver.Receive(sto, br, b.Reader())
+	if err != nil {
+		t.Fatal(err)
+	}
+	sizePostDup := size(1)
+	if sizePostDup >= blobSize {
+		t.Fatalf("size(pack1) = %d; appeared to double-write.", sizePostDup)
+	}
+
+	os.Remove(sto.(*storage).filename(0))
+	_, err = blobserver.Receive(sto, br, b.Reader())
+	if err != nil {
+		t.Fatal(err)
+	}
+	sizePostDelete := size(1)
+	if sizePostDelete < blobSize {
+		t.Fatalf("after packfile delete + reupload, not big enough. want size of a blob")
+	}
+}