containerd/services/content/provider.go

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package content
import (
"context"
"io"
contentapi "github.com/docker/containerd/api/services/content"
"github.com/docker/containerd/content"
digest "github.com/opencontainers/go-digest"
)
func NewProviderFromClient(client contentapi.ContentClient) content.Provider {
return &remoteProvider{
client: client,
}
}
type remoteProvider struct {
client contentapi.ContentClient
}
func (rp *remoteProvider) Reader(ctx context.Context, dgst digest.Digest) (io.ReadCloser, error) {
client, err := rp.client.Read(ctx, &contentapi.ReadRequest{Digest: dgst})
if err != nil {
return nil, err
}
return &remoteReader{
client: client,
}, nil
}
type remoteReader struct {
client contentapi.Content_ReadClient
extra []byte
}
func (rr *remoteReader) Read(p []byte) (n int, err error) {
n += copy(p, rr.extra)
if n >= len(p) {
if n <= len(rr.extra) {
rr.extra = rr.extra[n:]
} else {
rr.extra = rr.extra[:0]
}
return
}
p = p[n:]
for len(p) > 0 {
var resp *contentapi.ReadResponse
// fill our buffer up until we can fill p.
resp, err = rr.client.Recv()
if err != nil {
return
}
copied := copy(p, resp.Data)
n += copied
p = p[copied:]
if copied < len(p) {
continue
}
rr.extra = append(rr.extra, resp.Data[copied:]...)
}
return
}
// TODO(stevvooe): Implemente io.ReaderAt.
func (rr *remoteReader) Close() error {
return rr.client.CloseSend()
}