Fix create volume in a directory which is a symbolic link

Signed-off-by: Lei Jitang <leijitang@huawei.com>

daemon/volumes.go

@@ -189,10 +189,13 @@ func (container *Container) parseVolumeMountConfig() (map[string]*Mount, error)
 		if _, exists := container.Volumes[path]; exists {
 			continue
 		}
-
-		if stat, err := os.Stat(filepath.Join(container.basefs, path)); err == nil {
+		realpath, err := symlink.FollowSymlinkInScope(filepath.Join(container.basefs, path), container.basefs)
+		if err != nil {
+			return nil, fmt.Errorf("failed to evaluate the absolute path of symlink")
+		}
+		if stat, err := os.Stat(realpath); err == nil {
 			if !stat.IsDir() {
-				return nil, fmt.Errorf("file exists at %s, can't create volume there")
+				return nil, fmt.Errorf("file exists at %s, can't create volume there", realpath)
 			}
 		}
 

integration-cli/docker_cli_run_test.go

@@ -477,6 +477,42 @@ func TestRunWithVolumesFromExited(t *testing.T) {
 	logDone("run - regression test for #4979 - volumes-from on exited container")
 }
 
+// Test create volume in a dirctory which is a symbolic link
+func TestRunCreateVolumesInSymlinkDir(t *testing.T) {
+	defer deleteAllContainers()
+	// This test has to create a file on host
+	hostFile := "/tmp/abcd"
+	cmd := exec.Command("touch", hostFile)
+	if out, _, err := runCommandWithOutput(cmd); err != nil {
+		t.Fatalf("failed to create file %s on host: %v, output: %q", hostFile, err, out)
+	}
+	defer func() {
+		cmd := exec.Command("rm", "-f", hostFile)
+		if out, _, err := runCommandWithOutput(cmd); err != nil {
+			t.Fatalf("failed to remove file %s on host: %v, output: %q", hostFile, err, out)
+		}
+	}()
+	// create symlink directory /home/test link to /tmp
+	cmd = exec.Command(dockerBinary, "run", "--name=test", "busybox", "ln", "-s", "/tmp", "/home/test")
+	if out, _, err := runCommandWithOutput(cmd); err != nil {
+		t.Fatalf("failed to run container: %v, output: %q", err, out)
+	}
+	cmd = exec.Command(dockerBinary, "commit", "test", "busybox:test")
+	out, _, err := runCommandWithOutput(cmd)
+	if err != nil {
+		t.Fatalf("failed to commit container: %v, output: %q", err, out)
+	}
+	cleanedImageID := stripTrailingCharacters(out)
+	defer deleteImages(cleanedImageID)
+	// directory /home/test is link to /tmp, /home/test/abcd==/tmp/abcd
+	cmd = exec.Command(dockerBinary, "run", "-v", "/home/test/abcd", "busybox", "touch", "/home/test/abcd/Hello")
+	if out, _, err = runCommandWithOutput(cmd); err != nil {
+		t.Fatalf("failed to create volume in symlink directory: %v, output %q", err, out)
+	}
+
+	logDone("run - create volume in symlink directory")
+}
+
 // Regression test for #4830
 func TestRunWithRelativePath(t *testing.T) {
 	defer deleteAllContainers()