Import files from compare_target_files for use in diff_target_files

Copied from cl/240594925.

Bug: 121158314
Test: copied unit tests
Change-Id: I2e91126285dcd33171ff8b8dbfcfa5d48501f535
diff --git a/cmd/diff_target_files/glob.go b/cmd/diff_target_files/glob.go
new file mode 100644
index 0000000..ed91af7
--- /dev/null
+++ b/cmd/diff_target_files/glob.go
@@ -0,0 +1,81 @@
+// Copyright 2019 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"errors"
+	"path/filepath"
+	"strings"
+)
+
+// Match returns true if name matches pattern using the same rules as filepath.Match, but supporting
+// recursive globs (**).
+func Match(pattern, name string) (bool, error) {
+	if filepath.Base(pattern) == "**" {
+		return false, errors.New("pattern has '**' as last path element")
+	}
+
+	patternDir := pattern[len(pattern)-1] == '/'
+	nameDir := name[len(name)-1] == '/'
+
+	if patternDir != nameDir {
+		return false, nil
+	}
+
+	if nameDir {
+		name = name[:len(name)-1]
+		pattern = pattern[:len(pattern)-1]
+	}
+
+	for {
+		var patternFile, nameFile string
+		pattern, patternFile = filepath.Dir(pattern), filepath.Base(pattern)
+
+		if patternFile == "**" {
+			if strings.Contains(pattern, "**") {
+				return false, errors.New("pattern contains multiple '**'")
+			}
+			// Test if the any prefix of name matches the part of the pattern before **
+			for {
+				if name == "." || name == "/" {
+					return name == pattern, nil
+				}
+				if match, err := filepath.Match(pattern, name); err != nil {
+					return false, err
+				} else if match {
+					return true, nil
+				}
+				name = filepath.Dir(name)
+			}
+		} else if strings.Contains(patternFile, "**") {
+			return false, errors.New("pattern contains other characters between '**' and path separator")
+		}
+
+		name, nameFile = filepath.Dir(name), filepath.Base(name)
+
+		if nameFile == "." && patternFile == "." {
+			return true, nil
+		} else if nameFile == "/" && patternFile == "/" {
+			return true, nil
+		} else if nameFile == "." || patternFile == "." || nameFile == "/" || patternFile == "/" {
+			return false, nil
+		}
+
+		match, err := filepath.Match(patternFile, nameFile)
+		if err != nil || !match {
+			return match, err
+		}
+	}
+}