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package libpod
import (
"archive/tar"
"io"
"github.com/containers/libpod/libpod/layers"
"github.com/containers/storage/pkg/archive"
"github.com/pkg/errors"
)
var containerMounts = map[string]bool{
"/dev": true,
"/etc/hostname": true,
"/etc/hosts": true,
"/etc/resolv.conf": true,
"/proc": true,
"/run": true,
"/run/.containerenv": true,
"/run/secrets": true,
"/sys": true,
}
// GetDiff returns the differences between the two images, layers, or containers
func (r *Runtime) GetDiff(from, to string) ([]archive.Change, error) {
toLayer, err := r.getLayerID(to)
if err != nil {
return nil, err
}
fromLayer := ""
if from != "" {
fromLayer, err = r.getLayerID(from)
if err != nil {
return nil, err
}
}
var rchanges []archive.Change
changes, err := r.store.Changes(fromLayer, toLayer)
if err == nil {
for _, c := range changes {
if containerMounts[c.Path] {
continue
}
rchanges = append(rchanges, c)
}
}
return rchanges, err
}
// skipFileInTarAchive is an archive.TarModifierFunc function
// which tells archive.ReplaceFileTarWrapper to skip files
// from the tarstream
func skipFileInTarAchive(path string, header *tar.Header, content io.Reader) (*tar.Header, []byte, error) {
return nil, nil, nil
}
// GetDiffTarStream returns the differences between the two images, layers, or containers.
// It is the same functionality as GetDiff() except that it returns a tarstream
func (r *Runtime) GetDiffTarStream(from, to string) (io.ReadCloser, error) {
toLayer, err := r.getLayerID(to)
if err != nil {
return nil, err
}
fromLayer := ""
if from != "" {
fromLayer, err = r.getLayerID(from)
if err != nil {
return nil, err
}
}
rc, err := r.store.Diff(fromLayer, toLayer, nil)
if err != nil {
return nil, err
}
// Skip files in the tar archive which are listed
// in containerMounts map. Just as in the GetDiff()
// function from above
filterMap := make(map[string]archive.TarModifierFunc)
for key := range containerMounts {
filterMap[key[1:]] = skipFileInTarAchive
// In the tarstream directories always include a trailing '/'.
// For simplicity this duplicates every entry from
// containerMounts with a trailing '/', as containerMounts
// does not use trailing '/' for directories.
filterMap[key[1:]+"/"] = skipFileInTarAchive
}
filteredTarStream := archive.ReplaceFileTarWrapper(rc, filterMap)
return filteredTarStream, nil
}
// ApplyDiffTarStream applies the changes stored in 'diff' to the layer 'to'
func (r *Runtime) ApplyDiffTarStream(to string, diff io.Reader) error {
toLayer, err := r.getLayerID(to)
if err != nil {
return err
}
_, err = r.store.ApplyDiff(toLayer, diff)
return err
}
// GetLayerID gets a full layer id given a full or partial id
// If the id matches a container or image, the id of the top layer is returned
// If the id matches a layer, the top layer id is returned
func (r *Runtime) getLayerID(id string) (string, error) {
var toLayer string
toImage, err := r.imageRuntime.NewFromLocal(id)
if err != nil {
toCtr, err := r.store.Container(id)
if err != nil {
toLayer, err = layers.FullID(r.store, id)
if err != nil {
return "", errors.Errorf("layer, image, or container %s does not exist", id)
}
} else {
toLayer = toCtr.LayerID
}
} else {
toLayer = toImage.TopLayer()
}
return toLayer, nil
}
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