fix when multipart fetching and the server does not return content length

azr · k8s-infra-cherrypick-robot · commit 7636bd5eb252 · 2025-06-19T21:08:53.000Z
Signed-off-by: Adrien Delorme &lt;azr@users.noreply.github.com&gt;
diff --git a/core/content/helpers.go b/core/content/helpers.go
@@ -200,7 +200,7 @@ func Copy(ctx context.Context, cw Writer, or io.Reader, size int64, expected dig
 		}
 		if size != 0 && copied < size-ws.Offset {
 			// Short writes would return its own error, this indicates a read failure
-			return fmt.Errorf("failed to read expected number of bytes: %w", io.ErrUnexpectedEOF)
+			return fmt.Errorf("short read: expected %d bytes but got %d: %w", size-ws.Offset, copied, io.ErrUnexpectedEOF)
 		}
 		if err := cw.Commit(ctx, size, expected, opts...); err != nil {
 			if errors.Is(err, ErrReset) {
diff --git a/core/remotes/docker/fetcher.go b/core/remotes/docker/fetcher.go
@@ -480,6 +480,10 @@ func (r dockerFetcher) open(ctx context.Context, req *request, mediatype string,
 	})
 
 	remaining, _ := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 0)
+	if remaining <= chunkSize {
+		parallelism = 1
+	}
+
 	if parallelism > 1 {
 		// If we have a content length, we can use multiple requests to fetch
 		// the content in parallel. This will make download of bigger bodies
diff --git a/core/remotes/docker/fetcher_test.go b/core/remotes/docker/fetcher_test.go
@@ -133,6 +133,7 @@ func TestFetcherOpenParallel(t *testing.T) {
 	size := int64(3 * 1024 * 1024)
 	content := make([]byte, size)
 	rand.New(rand.NewSource(1)).Read(content)
+	sendContentLength := true
 
 	f := dockerFetcher{
 		&dockerBase{
@@ -179,12 +180,16 @@ func TestFetcherOpenParallel(t *testing.T) {
 		}
 
 		if len(rng) == 0 {
-			rw.Header().Set("content-length", strconv.Itoa(len(content)))
+			if sendContentLength {
+				rw.Header().Set("content-length", strconv.Itoa(len(content)))
+			}
 			_, _ = rw.Write(content)
 		} else {
 			b := content[rng[0].start : rng[0].start+rng[0].length]
 			rw.Header().Set("content-range", rng[0].contentRange(size))
-			rw.Header().Set("content-length", strconv.Itoa(len(b)))
+			if sendContentLength {
+				rw.Header().Set("content-length", strconv.Itoa(len(b)))
+			}
 			_, _ = rw.Write(b)
 		}
 
@@ -237,6 +242,10 @@ func TestFetcherOpenParallel(t *testing.T) {
 
 	checkReader(25)
 
+	sendContentLength = false
+	checkReader(25)
+	sendContentLength = true
+
 	ignoreContentRange = true
 	checkReader(25)
 	ignoreContentRange = false

Original file line number	Diff line number	Diff line change
`@@ -200,7 +200,7 @@ func Copy(ctx context.Context, cw Writer, or io.Reader, size int64, expected dig`
`200`	`200`	`}`
`201`	`201`	`if size != 0 && copied < size-ws.Offset {`
`202`	`202`	`// Short writes would return its own error, this indicates a read failure`
`203`		`- return fmt.Errorf("failed to read expected number of bytes: %w", io.ErrUnexpectedEOF)`
	`203`	`+ return fmt.Errorf("short read: expected %d bytes but got %d: %w", size-ws.Offset, copied, io.ErrUnexpectedEOF)`
`204`	`204`	`}`
`205`	`205`	`if err := cw.Commit(ctx, size, expected, opts...); err != nil {`
`206`	`206`	`if errors.Is(err, ErrReset) {`