Merge pull request #1770 from kolyshkin/fix-archive-detection

Fix archive detection

cli/command/image/build/context.go

@@ -89,7 +89,7 @@ func ValidateContextDirectory(srcPath string, excludes []string) error {
 func DetectArchiveReader(input io.ReadCloser) (rc io.ReadCloser, isArchive bool, err error) {
 	buf := bufio.NewReader(input)
 
-	magic, err := buf.Peek(archiveHeaderSize)
+	magic, err := buf.Peek(archiveHeaderSize * 2)
 	if err != nil && err != io.EOF {
 		return nil, false, errors.Errorf("failed to peek context header from STDIN: %v", err)
 	}

cli/command/image/build/context_test.go

@@ -297,3 +297,36 @@ func TestIsArchive(t *testing.T) {
 		assert.Check(t, is.Equal(testcase.expected, IsArchive(testcase.header)), testcase.doc)
 	}
 }
+
+func TestDetectArchiveReader(t *testing.T) {
+	var testcases = []struct {
+		file     string
+		desc     string
+		expected bool
+	}{
+		{
+			file:     "../testdata/tar.test",
+			desc:     "tar file without pax headers",
+			expected: true,
+		},
+		{
+			file:     "../testdata/gittar.test",
+			desc:     "tar file with pax headers",
+			expected: true,
+		},
+		{
+			file:     "../testdata/Dockerfile.test",
+			desc:     "not a tar file",
+			expected: false,
+		},
+	}
+	for _, testcase := range testcases {
+		content, err := os.Open(testcase.file)
+		assert.NilError(t, err)
+		defer content.Close()
+
+		_, isArchive, err := DetectArchiveReader(content)
+		assert.NilError(t, err)
+		assert.Check(t, is.Equal(testcase.expected, isArchive), testcase.file)
+	}
+}

cli/command/image/testdata/Dockerfile.test

@@ -0,0 +1,3 @@
+FROM busybox
+ADD ./README.md /
+CMD ["cat", "/README.md"]