112 lines
2.8 KiB
Go
112 lines
2.8 KiB
Go
package content
|
|
|
|
import (
|
|
"log"
|
|
"os"
|
|
"path/filepath"
|
|
|
|
"github.com/docker/distribution/digest"
|
|
"github.com/nightlyone/lockfile"
|
|
"github.com/pkg/errors"
|
|
)
|
|
|
|
// ContentWriter represents a write transaction against the blob store.
|
|
//
|
|
//
|
|
type ContentWriter struct {
|
|
cs *ContentStore
|
|
fp *os.File // opened data file
|
|
lock lockfile.Lockfile
|
|
path string // path to writer dir
|
|
offset int64
|
|
digester digest.Digester
|
|
}
|
|
|
|
// Write p to the transaction.
|
|
//
|
|
// Note that writes are unbuffered to the backing file. When writing, it is
|
|
// recommended to wrap in a bufio.Writer or, preferrably, use io.CopyBuffer.
|
|
func (cw *ContentWriter) Write(p []byte) (n int, err error) {
|
|
n, err = cw.fp.Write(p)
|
|
cw.digester.Hash().Write(p[:n])
|
|
return n, err
|
|
}
|
|
|
|
func (cw *ContentWriter) Commit(size int64, expected digest.Digest) error {
|
|
if err := cw.fp.Sync(); err != nil {
|
|
return errors.Wrap(err, "sync failed")
|
|
}
|
|
|
|
fi, err := cw.fp.Stat()
|
|
if err != nil {
|
|
return errors.Wrap(err, "stat on ingest file failed")
|
|
}
|
|
|
|
// change to readonly, more important for read, but provides _some_
|
|
// protection from this point on. We use the existing perms with a mask
|
|
// only allowing reads honoring the umask on creation.
|
|
//
|
|
// This removes write and exec, only allowing read per the creation umask.
|
|
if err := cw.fp.Chmod((fi.Mode() & os.ModePerm) &^ 0333); err != nil {
|
|
return errors.Wrap(err, "failed to change ingest file permissions")
|
|
}
|
|
|
|
if size != fi.Size() {
|
|
return errors.Errorf("failed size validation: %v != %v", fi.Size(), size)
|
|
}
|
|
|
|
if err := cw.fp.Close(); err != nil {
|
|
return errors.Wrap(err, "failed closing ingest")
|
|
}
|
|
|
|
dgst := cw.digester.Digest()
|
|
// TODO(stevvooe): Correctly handle missing expected digest or allow no
|
|
// expected digest at commit time.
|
|
if expected != "" && expected != dgst {
|
|
return errors.Errorf("unexpected digest: %v != %v", dgst, expected)
|
|
}
|
|
|
|
apath := filepath.Join(cw.cs.root, "blobs", dgst.Algorithm().String())
|
|
if err := os.MkdirAll(apath, 0755); err != nil {
|
|
return err
|
|
}
|
|
|
|
var (
|
|
ingest = filepath.Join(cw.path, "data")
|
|
target = filepath.Join(apath, dgst.Hex())
|
|
)
|
|
|
|
// clean up!!
|
|
defer os.RemoveAll(cw.path)
|
|
if err := os.Rename(ingest, target); err != nil {
|
|
if os.IsExist(err) {
|
|
// collision with the target file!
|
|
return nil
|
|
}
|
|
return err
|
|
}
|
|
|
|
unlock(cw.lock)
|
|
cw.fp = nil
|
|
return nil
|
|
}
|
|
|
|
// Close the writer, flushing any unwritten data and leaving the progress in
|
|
// tact.
|
|
//
|
|
// If one needs to resume the transaction, a new writer can be obtained from
|
|
// `ContentStore.Resume` using the same key. The write can then be continued
|
|
// from it was left off.
|
|
func (cw *ContentWriter) Close() (err error) {
|
|
if err := unlock(cw.lock); err != nil {
|
|
log.Printf("unlock failed: %v", err)
|
|
}
|
|
|
|
if cw.fp != nil {
|
|
cw.fp.Sync()
|
|
return cw.fp.Close()
|
|
}
|
|
|
|
return nil
|
|
}
|