bc01f8fc05
Allows optimized copying from a local content file into another file. Signed-off-by: Derek McGowan <derek@mcg.dev>
73 lines
1.7 KiB
Go
73 lines
1.7 KiB
Go
/*
|
|
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 local
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
|
|
"github.com/containerd/containerd/content"
|
|
"github.com/containerd/containerd/errdefs"
|
|
)
|
|
|
|
// readerat implements io.ReaderAt in a completely stateless manner by opening
|
|
// the referenced file for each call to ReadAt.
|
|
type sizeReaderAt struct {
|
|
size int64
|
|
fp *os.File
|
|
}
|
|
|
|
// OpenReader creates ReaderAt from a file
|
|
func OpenReader(p string) (content.ReaderAt, error) {
|
|
fi, err := os.Stat(p)
|
|
if err != nil {
|
|
if !os.IsNotExist(err) {
|
|
return nil, err
|
|
}
|
|
|
|
return nil, fmt.Errorf("blob not found: %w", errdefs.ErrNotFound)
|
|
}
|
|
|
|
fp, err := os.Open(p)
|
|
if err != nil {
|
|
if !os.IsNotExist(err) {
|
|
return nil, err
|
|
}
|
|
|
|
return nil, fmt.Errorf("blob not found: %w", errdefs.ErrNotFound)
|
|
}
|
|
|
|
return sizeReaderAt{size: fi.Size(), fp: fp}, nil
|
|
}
|
|
|
|
func (ra sizeReaderAt) ReadAt(p []byte, offset int64) (int, error) {
|
|
return ra.fp.ReadAt(p, offset)
|
|
}
|
|
|
|
func (ra sizeReaderAt) Size() int64 {
|
|
return ra.size
|
|
}
|
|
|
|
func (ra sizeReaderAt) Close() error {
|
|
return ra.fp.Close()
|
|
}
|
|
|
|
func (ra sizeReaderAt) Reader() io.Reader {
|
|
return io.LimitReader(ra.fp, ra.size)
|
|
}
|