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moby--moby/builder/tarsum.go

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package builder
import (
"fmt"
"io"
"os"
"path/filepath"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/chrootarchive"
"github.com/docker/docker/pkg/ioutils"
"github.com/docker/docker/pkg/symlink"
"github.com/docker/docker/pkg/tarsum"
)
type tarSumContext struct {
root string
sums tarsum.FileInfoSums
}
func (c *tarSumContext) Close() error {
return os.RemoveAll(c.root)
}
func convertPathError(err error, cleanpath string) error {
if err, ok := err.(*os.PathError); ok {
err.Path = cleanpath
return err
}
return err
}
func (c *tarSumContext) Open(path string) (io.ReadCloser, error) {
cleanpath, fullpath, err := c.normalize(path)
if err != nil {
return nil, err
}
r, err := os.Open(fullpath)
if err != nil {
return nil, convertPathError(err, cleanpath)
}
return r, nil
}
func (c *tarSumContext) Stat(path string) (string, FileInfo, error) {
cleanpath, fullpath, err := c.normalize(path)
if err != nil {
return "", nil, err
}
st, err := os.Lstat(fullpath)
if err != nil {
return "", nil, convertPathError(err, cleanpath)
}
rel, err := filepath.Rel(c.root, fullpath)
if err != nil {
return "", nil, convertPathError(err, cleanpath)
}
// We set sum to path by default for the case where GetFile returns nil.
// The usual case is if relative path is empty.
sum := path
// Use the checksum of the followed path(not the possible symlink) because
// this is the file that is actually copied.
if tsInfo := c.sums.GetFile(rel); tsInfo != nil {
sum = tsInfo.Sum()
}
fi := &HashedFileInfo{PathFileInfo{st, fullpath, filepath.Base(cleanpath)}, sum}
return rel, fi, nil
}
// MakeTarSumContext returns a build Context from a tar stream.
//
// It extracts the tar stream to a temporary folder that is deleted as soon as
// the Context is closed.
// As the extraction happens, a tarsum is calculated for every file, and the set of
// all those sums then becomes the source of truth for all operations on this Context.
//
// Closing tarStream has to be done by the caller.
func MakeTarSumContext(tarStream io.Reader) (ModifiableContext, error) {
root, err := ioutils.TempDir("", "docker-builder")
if err != nil {
return nil, err
}
tsc := &tarSumContext{root: root}
// Make sure we clean-up upon error. In the happy case the caller
// is expected to manage the clean-up
defer func() {
if err != nil {
tsc.Close()
}
}()
decompressedStream, err := archive.DecompressStream(tarStream)
if err != nil {
return nil, err
}
sum, err := tarsum.NewTarSum(decompressedStream, true, tarsum.Version1)
if err != nil {
return nil, err
}
if err := chrootarchive.Untar(sum, root, nil); err != nil {
return nil, err
}
tsc.sums = sum.GetSums()
return tsc, nil
}
func (c *tarSumContext) normalize(path string) (cleanpath, fullpath string, err error) {
cleanpath = filepath.Clean(string(os.PathSeparator) + path)[1:]
fullpath, err = symlink.FollowSymlinkInScope(filepath.Join(c.root, path), c.root)
if err != nil {
return "", "", fmt.Errorf("Forbidden path outside the build context: %s (%s)", path, fullpath)
}
_, err = os.Lstat(fullpath)
if err != nil {
return "", "", convertPathError(err, path)
}
return
}
func (c *tarSumContext) Walk(root string, walkFn WalkFunc) error {
root = filepath.Join(c.root, filepath.Join(string(filepath.Separator), root))
return filepath.Walk(root, func(fullpath string, info os.FileInfo, err error) error {
rel, err := filepath.Rel(c.root, fullpath)
if err != nil {
return err
}
if rel == "." {
return nil
}
sum := rel
if tsInfo := c.sums.GetFile(filepath.ToSlash(rel)); tsInfo != nil {
sum = tsInfo.Sum()
}
fi := &HashedFileInfo{PathFileInfo{FileInfo: info, FilePath: fullpath}, sum}
if err := walkFn(rel, fi, nil); err != nil {
return err
}
return nil
})
}
func (c *tarSumContext) Remove(path string) error {
_, fullpath, err := c.normalize(path)
if err != nil {
return err
}
return os.RemoveAll(fullpath)
}