Merge pull request #15664 from skatsuta/fix-parse-null

builder: avoid parsing null- string to nil slice (issue #15634)

builder/parser/line_parsers.go

@@ -232,6 +232,11 @@ func parseString(rest string) (*Node, map[string]bool, error) {
 
 // parseJSON converts JSON arrays to an AST.
 func parseJSON(rest string) (*Node, map[string]bool, error) {
+	rest = strings.TrimLeftFunc(rest, unicode.IsSpace)
+	if !strings.HasPrefix(rest, "[") {
+		return nil, nil, fmt.Errorf(`Error parsing "%s" as a JSON array`, rest)
+	}
+
 	var myJSON []interface{}
 	if err := json.NewDecoder(strings.NewReader(rest)).Decode(&myJSON); err != nil {
 		return nil, nil, err

builder/parser/testfiles/ADD-COPY-with-JSON/Dockerfile

@@ -3,6 +3,8 @@ MAINTAINER	Seongyeol Lim <seongyeol37@gmail.com>
 
 COPY	.	/go/src/github.com/docker/docker
 ADD		.	/
+ADD		null /
+COPY	nullfile /tmp
 ADD		[ "vimrc", "/tmp" ]
 COPY	[ "bashrc", "/tmp" ]
 COPY	[ "test file", "/tmp" ]

builder/parser/testfiles/ADD-COPY-with-JSON/result

@@ -2,6 +2,8 @@
 (maintainer "Seongyeol Lim <seongyeol37@gmail.com>")
 (copy "." "/go/src/github.com/docker/docker")
 (add "." "/")
+(add "null" "/")
+(copy "nullfile" "/tmp")
 (add "vimrc" "/tmp")
 (copy "bashrc" "/tmp")
 (copy "test file" "/tmp")

integration-cli/docker_cli_build_test.go

@@ -5444,3 +5444,26 @@ func (s *DockerTrustSuite) TestBuildContextDirIsSymlink(c *check.C) {
 		c.Fatalf("build failed with exit status %d: %s", exitStatus, out)
 	}
 }
+
+// Issue #15634: COPY fails when path starts with "null"
+func (s *DockerSuite) TestBuildNullStringInAddCopyVolume(c *check.C) {
+	name := "testbuildnullstringinaddcopyvolume"
+
+	ctx, err := fakeContext(`
+		FROM busybox
+		
+		ADD null /
+		COPY nullfile /
+		VOLUME nullvolume
+		`,
+		map[string]string{
+			"null":     "test1",
+			"nullfile": "test2",
+		},
+	)
+	defer ctx.Close()
+	c.Assert(err, check.IsNil)
+
+	_, err = buildImageFromContext(name, ctx, true)
+	c.Assert(err, check.IsNil)
+}