Add diff_target_files tool

Add a tool that lists files that have changed between two builds by
comparing the target-files.zip artifacts.

Bug: 121158314
Test: unit tests
Change-Id: I3ca5dd1fdf652dffef923ad7307fd71e49e2e95a

cmd/diff_target_files/Android.bp

@@ -0,0 +1,16 @@
+blueprint_go_binary {
+    name: "diff_target_files",
+    srcs: [
+        "compare.go",
+        "diff_target_files.go",
+        "glob.go",
+        "target_files.go",
+        "whitelist.go",
+        "zip_artifact.go",
+    ],
+    testSrcs: [
+        "compare_test.go",
+        "glob_test.go",
+        "whitelist_test.go",
+    ],
+}

cmd/diff_target_files/diff_target_files.go

@@ -0,0 +1,82 @@
+// 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 (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+)
+
+var (
+	whitelists     = newMultiString("whitelist", "whitelist patterns in the form <pattern>[:<regex of line to ignore>]")
+	whitelistFiles = newMultiString("whitelist_file", "files containing whitelist definitions")
+
+	filters = newMultiString("filter", "filter patterns to apply to files in target-files.zip before comparing")
+)
+
+func newMultiString(name, usage string) *multiString {
+	var f multiString
+	flag.Var(&f, name, usage)
+	return &f
+}
+
+type multiString []string
+
+func (ms *multiString) String() string     { return strings.Join(*ms, ", ") }
+func (ms *multiString) Set(s string) error { *ms = append(*ms, s); return nil }
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() != 2 {
+		fmt.Fprintf(os.Stderr, "Error, exactly two arguments are required\n")
+		os.Exit(1)
+	}
+
+	whitelists, err := parseWhitelists(*whitelists, *whitelistFiles)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error parsing whitelists: %v\n", err)
+		os.Exit(1)
+	}
+
+	priZip, err := NewLocalZipArtifact(flag.Arg(0))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error opening zip file %v: %v\n", flag.Arg(0), err)
+		os.Exit(1)
+	}
+	defer priZip.Close()
+
+	refZip, err := NewLocalZipArtifact(flag.Arg(1))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error opening zip file %v: %v\n", flag.Arg(1), err)
+		os.Exit(1)
+	}
+	defer refZip.Close()
+
+	diff, err := compareTargetFiles(priZip, refZip, targetFilesPattern, whitelists, *filters)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error comparing zip files: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Print(diff.String())
+
+	if len(diff.modified) > 0 || len(diff.onlyInA) > 0 || len(diff.onlyInB) > 0 {
+		fmt.Fprintln(os.Stderr, "differences found")
+		os.Exit(1)
+	}
+}