fix podman cp can create an extra directory when the source is the container's root directory

[zhangguanzhang]

(Edited, moving comment from @zhangguanzhang to here)

Fixes: #6596
Example of the issue:

$ mkdir test
$ ls
drwxr-xr-x  2 root root         6 Jun 15 16:54 test
$ cat >Dockerfile<<EOF
FROM scratch
COPY Dockerfile /
EOF
$ podman build -t podman-test:1.0.0 .
STEP 1: FROM scratch
STEP 2: COPY Dockerfile /
STEP 3: COMMIT podman-test:1.0.0
--> 839962c7269
839962c7269777d5f50d68428d5def260b6842f7c0607978b8567668f2a8c067

$ podman create podman-test:1.0.0 dummy
53914c7a1191e96b7fee0fcb9b152480640c392321edadfe657c10afda1431a2
$ podman cp 539:/   non_dir
$ ls non_dir
Dockerfile

If you copy the container's root directory to an existing directory, It creates an extra layer of the directory called merged

$ podman cp 539:/ test
$ ls -l  test
total 0
drwxr-xr-x 2 root root 24 Jun 15 23:30 merged
$ ls -l  test/merged/
total 4
-rw-r--r-- 1 root root 31 Jun 13 22:50 Dockerfile

Signed-off-by: zhangguanzhang [email protected]

[openshift-ci-robot]

Hi @zhangguanzhang. Thanks for your PR.

I'm waiting for a containers member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[zhangguanzhang]

fix #6596

[rhatdan]

You need to rebase your PR and remove the merge PR.

[rhatdan]

Also could you add a test for this?

[zhangguanzhang]

I'll try it first and update it later

[rhatdan]

/approve
LGTM

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rhatdan, zhangguanzhang

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [rhatdan]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[TomSweeneyRedHat]

@zhangguanzhang It would be helpful if you could add a little more information to the description for historical purposes. Can you add a quick example in the description showing the issue that this PR is fixing please?

[zhangguanzhang]

I've added some explanatory information

[zhangguanzhang]

$ mkdir test
$ ls
drwxr-xr-x  2 root root         6 Jun 15 16:54 test
$ cat >Dockerfile<<EOF
FROM scratch
COPY Dockerfile /
EOF
$ podman build -t podman-test:1.0.0 .
STEP 1: FROM scratch
STEP 2: COPY Dockerfile /
STEP 3: COMMIT podman-test:1.0.0
--> 839962c7269
839962c7269777d5f50d68428d5def260b6842f7c0607978b8567668f2a8c067

$ podman create podman-test:1.0.0 dummy
53914c7a1191e96b7fee0fcb9b152480640c392321edadfe657c10afda1431a2
$ podman cp 539:/   non_dir
$ ls non_dir
Dockerfile

If you copy the container's root directory to an existing directory, It creates an extra layer of the directory called merged

$ podman cp 539:/ test
$ ls -l  test
total 0
drwxr-xr-x 2 root root 24 Jun 15 23:30 merged
$ ls -l  test/merged/
total 4
-rw-r--r-- 1 root root 31 Jun 13 22:50 Dockerfile

[rhatdan]

/ok-to-test

[TomSweeneyRedHat]

LGTM
@zhangguanzhang Thanks a bunch for the follow-up explanation. I copied it up to the main description so it wouldn't get lost in the replies.

[jwhonce]

LGTM, asked @mheon to also take a look

[mheon]

/lgtm