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/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package proxy
import (
"context"
contentapi "github.com/containerd/containerd/api/services/content/v1"
digest "github.com/opencontainers/go-digest"
)
type remoteReaderAt struct {
ctx context.Context
digest digest.Digest
size int64
client contentapi.TTRPCContentClient
}
func (ra *remoteReaderAt) Size() int64 {
return ra.size
}
func (ra *remoteReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
rr := &contentapi.ReadContentRequest{
Digest: ra.digest.String(),
Offset: off,
Size: int64(len(p)),
}
// we need a child context with cancel, or the eventually called
// grpc.NewStream will leak the goroutine until the whole thing is cleared.
// See comment at https://godoc.org/google.golang.org/grpc#ClientConn.NewStream
childCtx, cancel := context.WithCancel(ra.ctx)
// we MUST cancel the child context; see comment above
defer cancel()
rc, err := ra.client.Read(childCtx, rr)
if err != nil {
return 0, err
}
for len(p) > 0 {
var resp *contentapi.ReadContentResponse
// fill our buffer up until we can fill p.
resp, err = rc.Recv()
if err != nil {
return n, err
}
copied := copy(p, resp.Data)
n += copied
p = p[copied:]
}
return n, nil
}
func (ra *remoteReaderAt) Close() error {
return nil
}
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