Make container.Copy support volumes

Fixes #1992

Right now when you `docker cp` a path which is in a volume, the cp
itself works, however you end up getting files that are in the
container's fs rather than the files in the volume (which is not in the
container's fs).
This makes it so when you `docker cp` a path that is in a volume it
follows the volume to the real path on the host.

archive.go has been modified so that when you do `docker cp mydata:/foo
.`, and /foo is the volume, the outputed folder is called "foo" instead
of the volume ID (because we are telling it to tar up
`/var/lib/docker/vfs/dir/<some id>` and not "foo", but the user would be
expecting "foo", not the ID

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Upstream-commit: ef98fe0763024abd90bd5a573fec816895ee92e4
Component: engine

components/engine/integration-cli/docker_cli_cp_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -371,3 +372,109 @@ func TestCpUnprivilegedUser(t *testing.T) {
 
 	logDone("cp - unprivileged user")
 }
+
+func TestCpVolumePath(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", "cp-test-volumepath")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+	outDir, err := ioutil.TempDir("", "cp-test-volumepath-out")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(outDir)
+	_, err = os.Create(tmpDir + "/test")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	out, exitCode, err := cmd(t, "run", "-d", "-v", "/foo", "-v", tmpDir+"/test:/test", "-v", tmpDir+":/baz", "busybox", "/bin/sh", "-c", "touch /foo/bar")
+	if err != nil || exitCode != 0 {
+		t.Fatal("failed to create a container", out, err)
+	}
+
+	cleanedContainerID := stripTrailingCharacters(out)
+	defer deleteContainer(cleanedContainerID)
+
+	out, _, err = cmd(t, "wait", cleanedContainerID)
+	if err != nil || stripTrailingCharacters(out) != "0" {
+		t.Fatal("failed to set up container", out, err)
+	}
+
+	// Copy actual volume path
+	_, _, err = cmd(t, "cp", cleanedContainerID+":/foo", outDir)
+	if err != nil {
+		t.Fatalf("couldn't copy from volume path: %s:%s %v", cleanedContainerID, "/foo", err)
+	}
+	stat, err := os.Stat(outDir + "/foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !stat.IsDir() {
+		t.Fatal("expected copied content to be dir")
+	}
+	stat, err = os.Stat(outDir + "/foo/bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if stat.IsDir() {
+		t.Fatal("Expected file `bar` to be a file")
+	}
+
+	// Copy file nested in volume
+	_, _, err = cmd(t, "cp", cleanedContainerID+":/foo/bar", outDir)
+	if err != nil {
+		t.Fatalf("couldn't copy from volume path: %s:%s %v", cleanedContainerID, "/foo", err)
+	}
+	stat, err = os.Stat(outDir + "/bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if stat.IsDir() {
+		t.Fatal("Expected file `bar` to be a file")
+	}
+
+	// Copy Bind-mounted dir
+	_, _, err = cmd(t, "cp", cleanedContainerID+":/baz", outDir)
+	if err != nil {
+		t.Fatalf("couldn't copy from bind-mounted volume path: %s:%s %v", cleanedContainerID, "/baz", err)
+	}
+	stat, err = os.Stat(outDir + "/baz")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !stat.IsDir() {
+		t.Fatal("Expected `baz` to be a dir")
+	}
+
+	// Copy file nested in bind-mounted dir
+	_, _, err = cmd(t, "cp", cleanedContainerID+":/baz/test", outDir)
+	fb, err := ioutil.ReadFile(outDir + "/baz/test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	fb2, err := ioutil.ReadFile(tmpDir + "/test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(fb, fb2) {
+		t.Fatalf("Expected copied file to be duplicate of bind-mounted file")
+	}
+
+	// Copy bind-mounted file
+	_, _, err = cmd(t, "cp", cleanedContainerID+":/test", outDir)
+	fb, err = ioutil.ReadFile(outDir + "/test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	fb2, err = ioutil.ReadFile(tmpDir + "/test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(fb, fb2) {
+		t.Fatalf("Expected copied file to be duplicate of bind-mounted file")
+	}
+
+	logDone("cp - volume path")
+}