unify ReadAt to ReadCloser conversion

Also removes dependency from pkg/ioutils

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

solver/llbsolver/history.go

@@ -21,6 +21,7 @@ import (
 	"github.com/moby/buildkit/cmd/buildkitd/config"
 	"github.com/moby/buildkit/identity"
 	containerdsnapshot "github.com/moby/buildkit/snapshot/containerd"
+	"github.com/moby/buildkit/util/iohelper"
 	"github.com/moby/buildkit/util/leaseutil"
 	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
@@ -254,7 +255,7 @@ func (h *HistoryQueue) migrateBlobV2(ctx context.Context, id string, detectSkipL
 		return false, nil // allow skipping
 	}
 	defer ra.Close()
-	if err := content.Copy(ctx, w, &reader{ReaderAt: ra}, 0, dgst, content.WithLabels(labels)); err != nil {
+	if err := content.Copy(ctx, w, iohelper.ReadCloser(ra), 0, dgst, content.WithLabels(labels)); err != nil {
 		return false, err
 	}
 
@@ -460,9 +461,11 @@ func (h *HistoryQueue) Status(ctx context.Context, ref string, st chan<- *client
 	if err != nil {
 		return err
 	}
-	defer ra.Close()
 
-	brdr := bufio.NewReader(&reader{ReaderAt: ra})
+	rc := iohelper.ReadCloser(ra)
+	defer rc.Close()
+
+	brdr := bufio.NewReader(rc)
 
 	buf := make([]byte, 32*1024)
 
@@ -906,14 +909,3 @@ func (p *channel[T]) close() {
 		close(p.done)
 	})
 }
-
-type reader struct {
-	io.ReaderAt
-	pos int64
-}
-
-func (r *reader) Read(p []byte) (int, error) {
-	n, err := r.ReaderAt.ReadAt(p, r.pos)
-	r.pos += int64(len(p))
-	return n, err
-}

source/containerimage/ocilayout.go

@@ -12,6 +12,7 @@ import (
 	"github.com/moby/buildkit/session"
 	sessioncontent "github.com/moby/buildkit/session/content"
 	"github.com/moby/buildkit/util/imageutil"
+	"github.com/moby/buildkit/util/iohelper"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 )
@@ -51,7 +52,7 @@ func (r *ociLayoutResolver) Fetch(ctx context.Context, desc ocispecs.Descriptor)
 		if err != nil {
 			return err
 		}
-		rc = &readerAtWrapper{readerAt: readerAt}
+		rc = iohelper.ReadCloser(readerAt)
 		return nil
 	})
 	return rc, err
@@ -137,18 +138,3 @@ func (r *ociLayoutResolver) withCaller(ctx context.Context, f func(context.Conte
 		return f(ctx, caller)
 	})
 }
-
-// readerAtWrapper wraps a ReaderAt to give a Reader
-type readerAtWrapper struct {
-	offset   int64
-	readerAt content.ReaderAt
-}
-
-func (r *readerAtWrapper) Read(p []byte) (n int, err error) {
-	n, err = r.readerAt.ReadAt(p, r.offset)
-	r.offset += int64(n)
-	return
-}
-func (r *readerAtWrapper) Close() error {
-	return r.readerAt.Close()
-}

util/compression/compression.go

@@ -251,5 +251,5 @@ func decompress(ctx context.Context, cs content.Store, desc ocispecs.Descriptor)
 			return nil, err
 		}
 	}
-	return &iohelper.ReadCloser{ReadCloser: r, CloseFunc: ra.Close}, nil
+	return iohelper.WithCloser(r, ra.Close), nil
 }

util/compression/uncompressed.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/images"
-	"github.com/docker/docker/pkg/ioutils"
 	"github.com/moby/buildkit/util/iohelper"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
 )
@@ -22,8 +21,7 @@ func (c uncompressedType) Decompress(ctx context.Context, cs content.Store, desc
 	if err != nil {
 		return nil, err
 	}
-	rdr := io.NewSectionReader(ra, 0, ra.Size())
-	return ioutils.NewReadCloserWrapper(rdr, ra.Close), nil
+	return iohelper.ReadCloser(ra), nil
 }
 
 func (c uncompressedType) NeedsConversion(ctx context.Context, cs content.Store, desc ocispecs.Descriptor) (bool, error) {

util/iohelper/helper.go

@@ -15,18 +15,26 @@ func (w *NopWriteCloser) Close() error {
 	return nil
 }
 
-type ReadCloser struct {
-	io.ReadCloser
-	CloseFunc func() error
+type closeFunc func() error
+
+func (c closeFunc) Close() error {
+	return c()
 }
 
-func (rc *ReadCloser) Close() error {
-	err1 := rc.ReadCloser.Close()
-	err2 := rc.CloseFunc()
-	if err1 != nil {
-		return errors.Wrapf(err1, "failed to close: %v", err2)
+// WithCloser returns a ReadCloser with additional closer function.
+func WithCloser(r io.ReadCloser, closer func() error) io.ReadCloser {
+	var f closeFunc = func() error {
+		err1 := r.Close()
+		err2 := closer()
+		if err1 != nil {
+			return errors.Wrapf(err1, "failed to close: %v", err2)
+		}
+		return err2
+	}
+	return &readCloser{
+		Reader: r,
+		Closer: f,
 	}
-	return err2
 }
 
 type WriteCloser struct {
@@ -61,3 +69,22 @@ func (c *Counter) Size() (n int64) {
 	c.mu.Unlock()
 	return
 }
+
+type ReaderAtCloser interface {
+	io.ReaderAt
+	io.Closer
+	Size() int64
+}
+
+// ReadCloser returns a ReadCloser from ReaderAtCloser.
+func ReadCloser(in ReaderAtCloser) io.ReadCloser {
+	return &readCloser{
+		Reader: io.NewSectionReader(in, 0, in.Size()),
+		Closer: in,
+	}
+}
+
+type readCloser struct {
+	io.Reader
+	io.Closer
+}