Same functionality, but implemented with atomicwriter. There's a slight
difference in error-messages produced (but can be adjusted if we want).
Before:
docker image save -o ./no/such/foo busybox:latest
failed to save image: invalid output path: directory "no/such" does not exist
docker image save -o /no/permissions busybox:latest
failed to save image: stat /no/permissions: permission denied
After:
docker image save -o ./no/such/foo busybox:latest
failed to save image: invalid file path: stat no/such: no such file or directory
docker image save -o /no/permissions busybox:latest
failed to save image: failed to stat output path: lstat /no/permissions: permission denied
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
d47d2338b7