fix(image): parallel Range-fetch guards + splitRanges test

cmd/image/oci.go

@@ -17,6 +17,8 @@ import (
 	"oras.land/oras-go/v2/registry/remote"
 	"oras.land/oras-go/v2/registry/remote/auth"
 	"oras.land/oras-go/v2/registry/remote/credentials"
+
+	"github.com/cocoonstack/cocoon/utils"
 )
 
 // pullConns is the number of parallel HTTP Range connections used to fetch a blob; ghcr throttles a
@@ -100,17 +102,9 @@ func rangeSupported(ctx context.Context, client *auth.Client, url string) bool {
 
 // fetchParallel downloads [0,size) in pullConns chunks concurrently, each writing at its offset.
 func fetchParallel(ctx context.Context, client *auth.Client, url string, size int64, f *os.File) error {
-	chunk := (size + pullConns - 1) / pullConns
 	g, gctx := errgroup.WithContext(ctx)
-	for i := range int64(pullConns) {
-		start := i * chunk
-		if start >= size {
-			break
-		}
-		end := start + chunk - 1
-		if end >= size {
-			end = size - 1
-		}
+	for _, r := range utils.SplitRanges(size, pullConns) {
+		start, end := r[0], r[1]
 		g.Go(func() error { return fetchRange(gctx, client, url, start, end, f) })
 	}
 	return g.Wait()
@@ -127,12 +121,7 @@ func fetchRange(ctx context.Context, client *auth.Client, url string, start, end
 		return err
 	}
 	defer func() { _ = resp.Body.Close() }()
-	if resp.StatusCode != http.StatusPartialContent {
-		return fmt.Errorf("range %d-%d: unexpected status %s", start, end, resp.Status)
-	}
-	// each chunk owns a disjoint region, so concurrent WriteAt via the offset writer never overlaps
-	_, err = io.Copy(io.NewOffsetWriter(f, start), resp.Body)
-	return err
+	return utils.CopyRangeBody(resp, io.NewOffsetWriter(f, start), start, end)
 }
 
 // fetchSingle streams the blob in one connection (fallback when Range isn't supported).

go.mod

@@ -3,7 +3,7 @@ module github.com/cocoonstack/cocoon-macos
 go 1.26.4
 
 require (
-	github.com/cocoonstack/cocoon v0.4.5
+	github.com/cocoonstack/cocoon v0.4.6-0.20260704025747-d9fa4dfb5105
 	github.com/docker/go-units v0.5.0
 	github.com/opencontainers/image-spec v1.1.1
 	github.com/projecteru2/core v0.0.0-20241016125006-ff909eefe04c

go.sum

@@ -8,8 +8,8 @@ github.com/cockroachdb/logtags v0.0.0-20230118201751-21c54148d20b h1:r6VH0faHjZe
 github.com/cockroachdb/logtags v0.0.0-20230118201751-21c54148d20b/go.mod h1:Vz9DsVWQQhf3vs21MhPMZpMGSht7O/2vFW2xusFUVOs=
 github.com/cockroachdb/redact v1.1.5 h1:u1PMllDkdFfPWaNGMyLD1+so+aq3uUItthCFqzwPJ30=
 github.com/cockroachdb/redact v1.1.5/go.mod h1:BVNblN9mBWFyMyqK1k3AAiSxhvhfK2oOZZ2lK+dpvRg=
-github.com/cocoonstack/cocoon v0.4.5 h1:FoLgZhXdfKFvTJcF1ijb6A3C4n22NDOtwT2FDsoJbgM=
-github.com/cocoonstack/cocoon v0.4.5/go.mod h1:LOFTBWiRXYsZJtNIF6UctDO0gThKCaG5+NOQ+ahGgv8=
+github.com/cocoonstack/cocoon v0.4.6-0.20260704025747-d9fa4dfb5105 h1:kY2QEEK+RiJflgTGRfvRZJvN4X87d36dkrneyOZiAMI=
+github.com/cocoonstack/cocoon v0.4.6-0.20260704025747-d9fa4dfb5105/go.mod h1:Rl/SAzj1RbyL8XJaIyWiHdT96yK2D1e0xCr8flVqIcA=
 github.com/containernetworking/cni v1.3.0 h1:v6EpN8RznAZj9765HhXQrtXgX+ECGebEYEmnuFjskwo=
 github.com/containernetworking/cni v1.3.0/go.mod h1:Bs8glZjjFfGPHMw6hQu82RUgEPNGEaBb9KS5KtNMnJ4=
 github.com/containernetworking/plugins v1.9.0 h1:Mg3SXBdRGkdXyFC4lcwr6u2ZB2SDeL6LC3U+QrEANuQ=

home/home.go

@@ -43,7 +43,7 @@ func VMDir(cmd *cobra.Command, name string) string {
 // command context alongside it.
 func OpenStore(cmd *cobra.Command) (context.Context, *cloudimg.CloudImg, error) {
 	ctx := cliutil.CommandContext(cmd)
-	s, err := cloudimg.New(ctx, Dir(cmd))
+	s, err := cloudimg.New(ctx, Dir(cmd), 0) // 0 = cloudimg's default pull connections
 	if err != nil {
 		return ctx, nil, fmt.Errorf("init cloudimg store: %w", err)
 	}