Merge pull request moby#3618 from tonistiigi/gha-offset

gha: avoid range requests with too big offset

Author: AkihiroSuda

cache/remotecache/gha/gha.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"sync"
 	"time"
@@ -371,6 +372,13 @@ type readerAt struct {
 	desc ocispecs.Descriptor
 }
 
+func (r *readerAt) ReadAt(p []byte, off int64) (int, error) {
+	if off >= r.desc.Size {
+		return 0, io.EOF
+	}
+	return r.ReaderAtCloser.ReadAt(p, off)
+}
+
 func (r *readerAt) Size() int64 {
 	return r.desc.Size
 }