containerd/content/helpers.go
Michael Crosby 3101be93bc Load runtimes dynamically via go1.8 plugins
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

Add registration for more subsystems via plugins

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

Move content service to separate package

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
2017-02-21 16:29:46 -08:00

58 lines
1.2 KiB
Go

package content
import (
"context"
"io"
"io/ioutil"
"github.com/opencontainers/go-digest"
"github.com/pkg/errors"
)
// WriteBlob writes data with the expected digest into the content store. If
// expected already exists, the method returns immediately and the reader will
// not be consumed.
//
// This is useful when the digest and size are known beforehand.
//
// Copy is buffered, so no need to wrap reader in buffered io.
func WriteBlob(ctx context.Context, cs Ingester, r io.Reader, ref string, size int64, expected digest.Digest) error {
cw, err := cs.Writer(ctx, ref)
if err != nil {
return err
}
ws, err := cw.Status()
if err != nil {
return err
}
if ws.Offset > 0 {
// Arbitrary limitation for now. We can detect io.Seeker on r and
// resume.
return errors.Errorf("cannot resume already started write")
}
buf := BufPool.Get().([]byte)
defer BufPool.Put(buf)
nn, err := io.CopyBuffer(cw, r, buf)
if err != nil {
return err
}
if size > 0 && nn != size {
return errors.Errorf("failed size verification: %v != %v", nn, size)
}
if err := cw.Commit(size, expected); err != nil {
return err
}
return nil
}
func readFileString(path string) (string, error) {
p, err := ioutil.ReadFile(path)
return string(p), err
}