Issue with docker cp on windows when copying directory content to an existing directory

[xialian]

Description
According to official docker documentation, docker cp src_path dest_path should support the following behavior: When src_path specifies and directory and ends with /. (for windows, \.), and the dest_path specifies an existing directory, the content of src_path (files and sub-directories) should be copied into dest_path. However, docker on windows gives an error instead in this case.

Steps to reproduce the issue:

1. On host machine: docker run -it --name test_container microsoft/nanoserver
2. Within the launched container: Create the the following directory and file C:\test_dir\test.txt, and then exit the container
3. On host machine: mkdir docker_test
4. On host machine: docker cp test_container:C:\test_dir\. .\docker_test

Describe the results you received:

Error response from daemon: GetFileAttributesEx \\?\Volume{71a5bce9-587d-4726-84a6-83f9c99ea9c7}\test_dir\.: The filename, directory name, or volume label syntax is incorrect

Describe the results you expected:
test.txt file should appear in .\docker_test on host machine

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker version:

Client:
 Version:      17.06.1-ce
 API version:  1.30
 Go version:   go1.8.3
 Git commit:   874a737
 Built:        Thu Aug 17 22:48:20 2017
 OS/Arch:      windows/amd64

Server:
 Version:      17.06.1-ce
 API version:  1.30 (minimum version 1.24)
 Go version:   go1.8.3
 Git commit:   874a737
 Built:        Thu Aug 17 23:03:03 2017
 OS/Arch:      windows/amd64
 Experimental: true

Output of docker info:

Containers: 2
 Running: 0
 Paused: 0
 Stopped: 2
Images: 4
Server Version: 17.06.1-ce
Storage Driver: windowsfilter
 Windows:
Logging Driver: json-file
Plugins:
 Volume: local
 Network: l2bridge l2tunnel nat null overlay transparent
 Log: awslogs etwlogs fluentd json-file logentries splunk syslog
Swarm: inactive
Default Isolation: hyperv
Kernel Version: 10.0 15063 (15063.0.amd64fre.rs2_release.170317-1834)
Operating System: Windows 10 Enterprise
OSType: windows
Architecture: x86_64
CPUs: 40
Total Memory: 31.92GiB
Name: xialian
ID: QZQC:GOOJ:GUWZ:HQLE:5F5J:X6IA:TRQX:Z7JA:3TYR:VWQJ:U66K:HMMH
Docker Root Dir: C:\ProgramData\Docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: -1
 Goroutines: 22
 System Time: 2017-08-25T11:43:05.89398-07:00
 EventsListeners: 0
Registry: https://index.docker.io/v1/
Experimental: true
Insecure Registries:
 10.120.64.57:5500
 10.120.66.6:5000
 127.0.0.0/8
Live Restore Enabled: false

Additional information:
I have also tried with various other kinds of src_path endings, including \, \*. None of them can correctly produce the behavior of copying content of a container directory (not the directory itself) to an existing host directory.
This issue is filed after discussion with @jhowardmsft.
@darrenstahlmsft @johnstep

[taha]

I'm experiencing the same issue. Any update on this?

[Jeff-Lewis]

We're just missing the last case (bold) as defined by Docker's documentation for Windows.

Assuming a path separator of /, a first argument of SRC_PATH and second argument of DEST_PATH, the behavior is as follows:

• SRC_PATH specifies a file
  • DEST_PATH does not exist
    • the file is saved to a file created at DEST_PATH
  • DEST_PATH does not exist and ends with /
    • Error condition: the destination directory must exist.
  • DEST_PATH exists and is a file
    • the destination is overwritten with the source file’s contents
  • DEST_PATH exists and is a directory
    • the file is copied into this directory using the basename from SRC_PATH
• SRC_PATH specifies a directory
  • DEST_PATH does not exist
    • DEST_PATH is created as a directory and the contents of the source directory are copied into this directory
  • DEST_PATH exists and is a file
    • Error condition: cannot copy a directory to a file
  • DEST_PATH exists and is a directory
    • SRC_PATH does not end with /. (that is: slash followed by dot)
      • the source directory is copied into this directory
    • SRC_PATH does end with /. (that is: slash followed by dot)
      • the content of the source directory is copied into this directory

[thaJeztah]

@jhowardmsft @johnstep ptal