blob: f70360300d5b02e3c0d404c72f1067988e2bbe0f [file] [log] [blame]
package dockerfile
import (
// normaliseDest normalises the destination of a COPY/ADD command in a
// platform semantically consistent way.
func normaliseDest(cmdName, workingDir, requested string) (string, error) {
dest := filepath.FromSlash(requested)
endsInSlash := strings.HasSuffix(dest, string(os.PathSeparator))
// We are guaranteed that the working directory is already consistent,
// However, Windows also has, for now, the limitation that ADD/COPY can
// only be done to the system drive, not any drives that might be present
// as a result of a bind mount.
// So... if the path requested is Linux-style absolute (/foo or \\foo),
// we assume it is the system drive. If it is a Windows-style absolute
// (DRIVE:\\foo), error if DRIVE is not C. And finally, ensure we
// strip any configured working directories drive letter so that it
// can be subsequently legitimately converted to a Windows volume-style
// pathname.
// Not a typo - filepath.IsAbs, not system.IsAbs on this next check as
// we only want to validate where the DriveColon part has been supplied.
if filepath.IsAbs(dest) {
if strings.ToUpper(string(dest[0])) != "C" {
return "", fmt.Errorf("Windows does not support %s with a destinations not on the system drive (C:)", cmdName)
dest = dest[2:] // Strip the drive letter
// Cannot handle relative where WorkingDir is not the system drive.
if len(workingDir) > 0 {
if ((len(workingDir) > 1) && !system.IsAbs(workingDir[2:])) || (len(workingDir) == 1) {
return "", fmt.Errorf("Current WorkingDir %s is not platform consistent", workingDir)
if !system.IsAbs(dest) {
if string(workingDir[0]) != "C" {
return "", fmt.Errorf("Windows does not support %s with relative paths when WORKDIR is not the system drive", cmdName)
dest = filepath.Join(string(os.PathSeparator), workingDir[2:], dest)
// Make sure we preserve any trailing slash
if endsInSlash {
dest += string(os.PathSeparator)
return dest, nil