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moby--moby/archive/diff.go
2013-11-19 00:35:03 -08:00

95 lines
2.1 KiB
Go

package archive
import (
"os"
"path/filepath"
"strings"
"syscall"
"time"
)
// ApplyLayer parses a diff in the standard layer format from `layer`, and
// applies it to the directory `dest`.
func ApplyLayer(dest string, layer Archive) error {
// Poor man's diff applyer in 2 steps:
// Step 1: untar everything in place
if err := Untar(layer, dest, nil); err != nil {
return err
}
modifiedDirs := make(map[string]*syscall.Stat_t)
addDir := func(file string) {
d := filepath.Dir(file)
if _, exists := modifiedDirs[d]; !exists {
if s, err := os.Lstat(d); err == nil {
if sys := s.Sys(); sys != nil {
if stat, ok := sys.(*syscall.Stat_t); ok {
modifiedDirs[d] = stat
}
}
}
}
}
// Step 2: walk for whiteouts and apply them, removing them in the process
err := filepath.Walk(dest, func(fullPath string, f os.FileInfo, err error) error {
if err != nil {
if os.IsNotExist(err) {
// This happens in the case of whiteouts in parent dir removing a directory
// We just ignore it
return filepath.SkipDir
}
return err
}
// Rebase path
path, err := filepath.Rel(dest, fullPath)
if err != nil {
return err
}
path = filepath.Join("/", path)
// Skip AUFS metadata
if matched, err := filepath.Match("/.wh..wh.*", path); err != nil {
return err
} else if matched {
addDir(fullPath)
if err := os.RemoveAll(fullPath); err != nil {
return err
}
}
filename := filepath.Base(path)
if strings.HasPrefix(filename, ".wh.") {
rmTargetName := filename[len(".wh."):]
rmTargetPath := filepath.Join(filepath.Dir(fullPath), rmTargetName)
// Remove the file targeted by the whiteout
addDir(rmTargetPath)
if err := os.RemoveAll(rmTargetPath); err != nil {
return err
}
// Remove the whiteout itself
addDir(fullPath)
if err := os.RemoveAll(fullPath); err != nil {
return err
}
}
return nil
})
if err != nil {
return err
}
for k, v := range modifiedDirs {
aTime := time.Unix(v.Atim.Unix())
mTime := time.Unix(v.Mtim.Unix())
if err := os.Chtimes(k, aTime, mTime); err != nil {
return err
}
}
return nil
}