[daemon] Refactor image_delete.go

This file was not well documented and had very high cyclomatic complexity.
This patch completely rearranges this file and the ImageDelete method to
be easier to follow and more maintainable in the future.

Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)

integration-cli/docker_cli_rmi_test.go

@@ -106,7 +106,7 @@ func (s *DockerSuite) TestRmiImgIDMultipleTag(c *check.C) {
 
 	// first checkout without force it fails
 	out, _, err = dockerCmdWithError("rmi", imgID)
-	expected := fmt.Sprintf("Conflict, cannot delete %s because the running container %s is using it, stop it and use -f to force", imgID[:12], containerID[:12])
+	expected := fmt.Sprintf("conflict: unable to delete %s (cannot be forced) - image is being used by running container %s", imgID[:12], containerID[:12])
 	if err == nil || !strings.Contains(out, expected) {
 		c.Fatalf("rmi tagged in multiple repos should have failed without force: %s, %v, expected: %s", out, err, expected)
 	}
@@ -148,7 +148,7 @@ func (s *DockerSuite) TestRmiImgIDForce(c *check.C) {
 
 	// first checkout without force it fails
 	out, _, err = dockerCmdWithError("rmi", imgID)
-	if err == nil || !strings.Contains(out, fmt.Sprintf("Conflict, cannot delete image %s because it is tagged in multiple repositories, use -f to force", imgID)) {
+	if err == nil || !strings.Contains(out, "(must be forced) - image is referenced in one or more repositories") {
 		c.Fatalf("rmi tagged in multiple repos should have failed without force:%s, %v", out, err)
 	}
 
@@ -172,7 +172,7 @@ func (s *DockerSuite) TestRmiImageIDForceWithRunningContainersAndMultipleTags(c
 	dockerCmd(c, "run", "-d", imgID, "top")
 
 	out, _, err := dockerCmdWithError("rmi", "-f", imgID)
-	if err == nil || !strings.Contains(out, "stop it and retry") {
+	if err == nil || !strings.Contains(out, "(cannot be forced) - image is being used by running container") {
 		c.Log(out)
 		c.Fatalf("rmi -f should not delete image with running containers")
 	}
@@ -251,10 +251,10 @@ func (s *DockerSuite) TestRmiBlank(c *check.C) {
 	if err == nil {
 		c.Fatal("Should have failed to delete '' image")
 	}
-	if strings.Contains(out, "No such image") {
+	if strings.Contains(out, "no such id") {
 		c.Fatalf("Wrong error message generated: %s", out)
 	}
-	if !strings.Contains(out, "Image name can not be blank") {
+	if !strings.Contains(out, "image name cannot be blank") {
 		c.Fatalf("Expected error message not generated: %s", out)
 	}
 
@@ -262,7 +262,7 @@ func (s *DockerSuite) TestRmiBlank(c *check.C) {
 	if err == nil {
 		c.Fatal("Should have failed to delete '' image")
 	}
-	if !strings.Contains(out, "No such image") {
+	if !strings.Contains(out, "no such id") {
 		c.Fatalf("Expected error message not generated: %s", out)
 	}
 }
@@ -287,8 +287,59 @@ func (s *DockerSuite) TestRmiContainerImageNotFound(c *check.C) {
 
 	// Try to remove the image of the running container and see if it fails as expected.
 	out, _, err := dockerCmdWithError("rmi", "-f", imageIds[0])
-	if err == nil || !strings.Contains(out, "is using it") {
+	if err == nil || !strings.Contains(out, "image is being used by running container") {
 		c.Log(out)
 		c.Fatal("The image of the running container should not be removed.")
 	}
 }
+
+// #13422
+func (s *DockerSuite) TestRmiUntagHistoryLayer(c *check.C) {
+	image := "tmp1"
+	// Build a image for testing.
+	dockerfile := `FROM busybox
+MAINTAINER foo
+RUN echo 0 #layer0
+RUN echo 1 #layer1
+RUN echo 2 #layer2
+`
+	_, err := buildImage(image, dockerfile, false)
+	c.Assert(err, check.IsNil)
+
+	out, _ := dockerCmd(c, "history", "-q", image)
+	ids := strings.Split(out, "\n")
+	idToTag := ids[2]
+
+	// Tag layer0 to "tmp2".
+	newTag := "tmp2"
+	dockerCmd(c, "tag", idToTag, newTag)
+	// Create a container based on "tmp1".
+	dockerCmd(c, "run", "-d", image, "true")
+
+	// See if the "tmp2" can be untagged.
+	out, _ = dockerCmd(c, "rmi", newTag)
+	if d := strings.Count(out, "Untagged: "); d != 1 {
+		c.Log(out)
+		c.Fatalf("Expected 1 untagged entry got %d: %q", d, out)
+	}
+
+	// Now let's add the tag again and create a container based on it.
+	dockerCmd(c, "tag", idToTag, newTag)
+	out, _ = dockerCmd(c, "run", "-d", newTag, "true")
+	cid := strings.TrimSpace(out)
+
+	// At this point we have 2 containers, one based on layer2 and another based on layer0.
+	// Try to untag "tmp2" without the -f flag.
+	out, _, err = dockerCmdWithError("rmi", newTag)
+	if err == nil || !strings.Contains(out, cid[:12]) || !strings.Contains(out, "(must force)") {
+		c.Log(out)
+		c.Fatalf("%q should not be untagged without the -f flag", newTag)
+	}
+
+	// Add the -f flag and test again.
+	out, _ = dockerCmd(c, "rmi", "-f", newTag)
+	if !strings.Contains(out, fmt.Sprintf("Untagged: %s:latest", newTag)) {
+		c.Log(out)
+		c.Fatalf("%q should be allowed to untag with the -f flag", newTag)
+	}
+}