Merge pull request #2674 from MichaelEischer/prune-strict-checks

prune: Stricter error checks

internal/repository/repack.go

@@ -2,8 +2,6 @@ package repository
 
 import (
 	"context"
-	"fmt"
-	"os"
 
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/errors"
@@ -59,8 +57,7 @@ func Repack(ctx context.Context, repo restic.Repository, packs restic.IDSet, kee
 
 			debug.Log("  process blob %v", h)
 
-			buf = buf[:]
-			if uint(len(buf)) < entry.Length {
+			if uint(cap(buf)) < entry.Length {
 				buf = make([]byte, entry.Length)
 			}
 			buf = buf[:entry.Length]
@@ -85,7 +82,7 @@ func Repack(ctx context.Context, repo restic.Repository, packs restic.IDSet, kee
 			if !id.Equal(entry.ID) {
 				debug.Log("read blob %v/%v from %v: wrong data returned, hash is %v",
 					h.Type, h.ID, tempfile.Name(), id)
-				fmt.Fprintf(os.Stderr, "read blob %v from %v: wrong data returned, hash is %v",
+				return nil, errors.Errorf("read blob %v from %v: wrong data returned, hash is %v",
 					h, tempfile.Name(), id)
 			}
 

internal/repository/repack_test.go

@@ -54,6 +54,24 @@ func createRandomBlobs(t testing.TB, repo restic.Repository, blobs int, pData fl
 	}
 }
 
+func createRandomWrongBlob(t testing.TB, repo restic.Repository) {
+	length := randomSize(10*1024, 1024*1024) // 10KiB to 1MiB of data
+	buf := make([]byte, length)
+	rand.Read(buf)
+	id := restic.Hash(buf)
+	// invert first data byte
+	buf[0] ^= 0xff
+
+	_, _, err := repo.SaveBlob(context.TODO(), restic.DataBlob, buf, id, false)
+	if err != nil {
+		t.Fatalf("SaveFrom() error %v", err)
+	}
+
+	if err := repo.Flush(context.Background()); err != nil {
+		t.Fatalf("repo.Flush() returned error %v", err)
+	}
+}
+
 // selectBlobs splits the list of all blobs randomly into two lists. A blob
 // will be contained in the firstone ith probability p.
 func selectBlobs(t *testing.T, repo restic.Repository, p float32) (list1, list2 restic.BlobSet) {
@@ -239,3 +257,25 @@ func TestRepack(t *testing.T) {
 		}
 	}
 }
+
+func TestRepackWrongBlob(t *testing.T) {
+	repo, cleanup := repository.TestRepository(t)
+	defer cleanup()
+
+	seed := rand.Int63()
+	rand.Seed(seed)
+	t.Logf("rand seed is %v", seed)
+
+	createRandomBlobs(t, repo, 5, 0.7)
+	createRandomWrongBlob(t, repo)
+
+	// just keep all blobs, but also rewrite every pack
+	_, keepBlobs := selectBlobs(t, repo, 0)
+	rewritePacks := findPacksForBlobs(t, repo, keepBlobs)
+
+	_, err := repository.Repack(context.TODO(), repo, rewritePacks, keepBlobs, nil)
+	if err == nil {
+		t.Fatal("expected repack to fail but got no error")
+	}
+	t.Log(err)
+}