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/
checksums.go
133 lines (113 loc) · 2.98 KB
/
checksums.go
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package main
import (
"compress/gzip"
"errors"
"io"
"os"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/digest"
"github.com/docker/docker/layer"
"github.com/vbatts/tar-split/tar/asm"
"github.com/vbatts/tar-split/tar/storage"
)
type Mounter interface {
Mount(id string) (string, func(), error)
TarStream(id, parent string) (io.ReadCloser, error)
}
type checksums struct {
driver Mounter
}
func (c *checksums) ChecksumForGraphID(id, parent, oldTarDataPath, newTarDataPath string) (diffID layer.DiffID, size int64, err error) {
defer func() {
if err != nil {
logrus.Debugf("could not get checksum for %q with tar-split: %q. Attempting fallback.", id, err)
diffID, size, err = c.checksumForGraphIDNoTarsplit(id, parent, newTarDataPath)
}
}()
if oldTarDataPath == "" {
err = errors.New("no tar-split file")
return
}
tarDataFile, err := os.Open(oldTarDataPath)
if err != nil {
return
}
defer tarDataFile.Close()
uncompressed, err := gzip.NewReader(tarDataFile)
if err != nil {
return
}
dgst := digest.Canonical.New()
err = c.assembleTarTo(id, uncompressed, &size, dgst.Hash())
if err != nil {
return
}
diffID = layer.DiffID(dgst.Digest())
os.RemoveAll(newTarDataPath)
err = os.Link(oldTarDataPath, newTarDataPath)
return
}
func (c *checksums) assembleTarTo(graphID string, metadata io.ReadCloser, size *int64, w io.Writer) error {
defer metadata.Close()
// get our relative path to the container
fsPath, release, err := c.driver.Mount(graphID)
if err != nil {
return err
}
if release != nil {
defer release()
}
metaUnpacker := storage.NewJSONUnpacker(metadata)
upackerCounter := &unpackSizeCounter{metaUnpacker, size}
fileGetter := storage.NewPathFileGetter(fsPath)
logrus.Debugf("Assembling tar data for %s from %s", graphID, fsPath)
return asm.WriteOutputTarStream(fileGetter, upackerCounter, w)
}
func (c *checksums) checksumForGraphIDNoTarsplit(id, parent, newTarDataPath string) (diffID layer.DiffID, size int64, err error) {
rawarchive, err := c.driver.TarStream(id, parent)
if err != nil {
return
}
defer rawarchive.Close()
f, err := os.Create(newTarDataPath)
if err != nil {
return
}
defer f.Close()
mfz := gzip.NewWriter(f)
defer mfz.Close()
metaPacker := storage.NewJSONPacker(mfz)
packerCounter := &packSizeCounter{metaPacker, &size}
archive, err := asm.NewInputTarStream(rawarchive, packerCounter, nil)
if err != nil {
return
}
dgst, err := digest.FromReader(archive)
if err != nil {
return
}
diffID = layer.DiffID(dgst)
return
}
type unpackSizeCounter struct {
unpacker storage.Unpacker
size *int64
}
func (u *unpackSizeCounter) Next() (*storage.Entry, error) {
e, err := u.unpacker.Next()
if err == nil && u.size != nil {
*u.size += e.Size
}
return e, err
}
type packSizeCounter struct {
packer storage.Packer
size *int64
}
func (p *packSizeCounter) AddEntry(e storage.Entry) (int, error) {
n, err := p.packer.AddEntry(e)
if err == nil && p.size != nil {
*p.size += e.Size
}
return n, err
}