[b2] use HEAD instead of Range 0-1 to stat files

Fixes #71

b2/b2.go

@@ -613,8 +613,9 @@ func (discard) Write(p []byte) (int, error) {
 }
 
 func (b *Bucket) getObject(ctx context.Context, name string) (*Object, error) {
-	fr, err := b.b.downloadFileByName(ctx, name, 0, 1)
+	fr, err := b.b.downloadFileByName(ctx, name, 0, 0, true)
 	if err != nil {
+		fmt.Printf("%v: %T\n", err, err)
 		return nil, err
 	}
 	io.Copy(discard{}, fr)

b2/b2_test.go

@@ -210,7 +210,7 @@ func (t *testBucket) listUnfinishedLargeFiles(ctx context.Context, count int, co
 	return nil, "", fmt.Errorf("testBucket.listUnfinishedLargeFiles(ctx, %d, %q): not implemented", count, cont)
 }
 
-func (t *testBucket) downloadFileByName(_ context.Context, name string, offset, size int64) (b2FileReaderInterface, error) {
+func (t *testBucket) downloadFileByName(_ context.Context, name string, offset, size int64, _ bool) (b2FileReaderInterface, error) {
 	gmux.Lock()
 	defer gmux.Unlock()
 	f := t.files[name]

b2/backend.go

@@ -54,7 +54,7 @@ type beBucketInterface interface {
 	listFileNames(context.Context, int, string, string, string) ([]beFileInterface, string, error)
 	listFileVersions(context.Context, int, string, string, string, string) ([]beFileInterface, string, string, error)
 	listUnfinishedLargeFiles(context.Context, int, string) ([]beFileInterface, string, error)
-	downloadFileByName(context.Context, string, int64, int64) (beFileReaderInterface, error)
+	downloadFileByName(context.Context, string, int64, int64, bool) (beFileReaderInterface, error)
 	hideFile(context.Context, string) (beFileInterface, error)
 	getDownloadAuthorization(context.Context, string, time.Duration, string) (string, error)
 	baseURL() string
@@ -427,11 +427,11 @@ func (b *beBucket) listUnfinishedLargeFiles(ctx context.Context, count int, cont
 	return files, cont, nil
 }
 
-func (b *beBucket) downloadFileByName(ctx context.Context, name string, offset, size int64) (beFileReaderInterface, error) {
+func (b *beBucket) downloadFileByName(ctx context.Context, name string, offset, size int64, header bool) (beFileReaderInterface, error) {
 	var reader beFileReaderInterface
 	f := func() error {
 		g := func() error {
-			fr, err := b.b2bucket.downloadFileByName(ctx, name, offset, size)
+			fr, err := b.b2bucket.downloadFileByName(ctx, name, offset, size, header)
 			if err != nil {
 				return err
 			}

b2/baseline.go

@@ -50,7 +50,7 @@ type b2BucketInterface interface {
 	listFileNames(context.Context, int, string, string, string) ([]b2FileInterface, string, error)
 	listFileVersions(context.Context, int, string, string, string, string) ([]b2FileInterface, string, string, error)
 	listUnfinishedLargeFiles(context.Context, int, string) ([]b2FileInterface, string, error)
-	downloadFileByName(context.Context, string, int64, int64) (b2FileReaderInterface, error)
+	downloadFileByName(context.Context, string, int64, int64, bool) (b2FileReaderInterface, error)
 	hideFile(context.Context, string) (b2FileInterface, error)
 	getDownloadAuthorization(context.Context, string, time.Duration, string) (string, error)
 	baseURL() string
@@ -367,8 +367,8 @@ func (b *b2Bucket) listUnfinishedLargeFiles(ctx context.Context, count int, cont
 	return files, cont, nil
 }
 
-func (b *b2Bucket) downloadFileByName(ctx context.Context, name string, offset, size int64) (b2FileReaderInterface, error) {
-	fr, err := b.b.DownloadFileByName(ctx, name, offset, size)
+func (b *b2Bucket) downloadFileByName(ctx context.Context, name string, offset, size int64, header bool) (b2FileReaderInterface, error) {
+	fr, err := b.b.DownloadFileByName(ctx, name, offset, size, header)
 	if err != nil {
 		code, _ := base.Code(err)
 		switch code {

b2/integration_test.go

@@ -919,6 +919,24 @@ func TestDeleteWithoutName(t *testing.T) {
 	}
 }
 
+func TestZeroByteObject(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Minute)
+	defer cancel()
+
+	bucket, done := startLiveTest(ctx, t)
+	defer done()
+
+	_, _, err := writeFile(ctx, bucket, smallFileName, 0, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := bucket.Object(smallFileName).Delete(ctx); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestListUnfinishedLargeFiles(t *testing.T) {
 	ctx := context.Background()
 	bucket, done := startLiveTest(ctx, t)

b2/reader.go

@@ -132,7 +132,7 @@ func (r *Reader) thread() {
 			}
 			var b backoff
 		redo:
-			fr, err := r.o.b.b.downloadFileByName(r.ctx, r.name, offset, size)
+			fr, err := r.o.b.b.downloadFileByName(r.ctx, r.name, offset, size, false)
 			if err == errNoMoreContent {
 				// this read generated a 416 so we are entirely past the end of the object
 				r.readOffEnd = true

base/base.go

@@ -197,10 +197,10 @@ func logRequest(req *http.Request, args []byte) {
 	hstr := strings.Join(headers, ";")
 	method := req.Header.Get("X-Blazer-Method")
 	if args != nil {
-		blog.V(2).Infof(">> %s uri: %v headers: {%s} args: (%s)", method, req.URL, hstr, string(args))
+		blog.V(2).Infof(">> %s %v: %v headers: {%s} args: (%s)", method, req.Method, req.URL, hstr, string(args))
 		return
 	}
-	blog.V(2).Infof(">> %s uri: %v {%s} (no args)", method, req.URL, hstr)
+	blog.V(2).Infof(">> %s %v: %v {%s} (no args)", method, req.Method, req.URL, hstr)
 }
 
 var authRegexp = regexp.MustCompile(`"authorizationToken": ".[^"]*"`)
@@ -1115,9 +1115,13 @@ func mkRange(offset, size int64) string {
 }
 
 // DownloadFileByName wraps b2_download_file_by_name.
-func (b *Bucket) DownloadFileByName(ctx context.Context, name string, offset, size int64) (*FileReader, error) {
+func (b *Bucket) DownloadFileByName(ctx context.Context, name string, offset, size int64, header bool) (*FileReader, error) {
 	uri := fmt.Sprintf("%s/file/%s/%s", b.b2.downloadURI, b.Name, escape(name))
-	req, err := http.NewRequest("GET", uri, nil)
+	method := "GET"
+	if header {
+		method = "HEAD"
+	}
+	req, err := http.NewRequest(method, uri, nil)
 	if err != nil {
 		return nil, err
 	}