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

1 files changed, 133 insertions, 0 deletions

diff --git a/cmd/diff_target_files/compare.go b/cmd/diff_target_files/compare.go
new file mode 100644
index 00000000..00cd9ca1
--- /dev/null
+++ b/cmd/diff_target_files/compare.go
@@ -0,0 +1,133 @@
+// 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 (
+	"bytes"
+	"fmt"
+)
+
+// compareTargetFiles takes two ZipArtifacts and compares the files they contain by examining
+// the path, size, and CRC of each file.
+func compareTargetFiles(priZip, refZip ZipArtifact, artifact string, whitelists []whitelist, filters []string) (zipDiff, error) {
+	priZipFiles, err := priZip.Files()
+	if err != nil {
+		return zipDiff{}, fmt.Errorf("error fetching target file lists from primary zip %v", err)
+	}
+
+	refZipFiles, err := refZip.Files()
+	if err != nil {
+		return zipDiff{}, fmt.Errorf("error fetching target file lists from reference zip %v", err)
+	}
+
+	priZipFiles, err = filterTargetZipFiles(priZipFiles, artifact, filters)
+	if err != nil {
+		return zipDiff{}, err
+	}
+
+	refZipFiles, err = filterTargetZipFiles(refZipFiles, artifact, filters)
+	if err != nil {
+		return zipDiff{}, err
+	}
+
+	// Compare the file lists from both builds
+	diff := diffTargetFilesLists(refZipFiles, priZipFiles)
+
+	return applyWhitelists(diff, whitelists)
+}
+
+// zipDiff contains the list of files that differ between two zip files.
+type zipDiff struct {
+	modified         [][2]*ZipArtifactFile
+	onlyInA, onlyInB []*ZipArtifactFile
+}
+
+// String pretty-prints the list of files that differ between two zip files.
+func (d *zipDiff) String() string {
+	buf := &bytes.Buffer{}
+
+	must := func(n int, err error) {
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	var sizeChange int64
+
+	if len(d.modified) > 0 {
+		must(fmt.Fprintln(buf, "files modified:"))
+		for _, f := range d.modified {
+			must(fmt.Fprintf(buf, "   %v (%v bytes -> %v bytes)\n", f[0].Name, f[0].UncompressedSize64, f[1].UncompressedSize64))
+			sizeChange += int64(f[1].UncompressedSize64) - int64(f[0].UncompressedSize64)
+		}
+	}
+
+	if len(d.onlyInA) > 0 {
+		must(fmt.Fprintln(buf, "files removed:"))
+		for _, f := range d.onlyInA {
+			must(fmt.Fprintf(buf, " - %v (%v bytes)\n", f.Name, f.UncompressedSize64))
+			sizeChange -= int64(f.UncompressedSize64)
+		}
+	}
+
+	if len(d.onlyInB) > 0 {
+		must(fmt.Fprintln(buf, "files added:"))
+		for _, f := range d.onlyInB {
+			must(fmt.Fprintf(buf, " + %v (%v bytes)\n", f.Name, f.UncompressedSize64))
+			sizeChange += int64(f.UncompressedSize64)
+		}
+	}
+
+	if len(d.modified) > 0 || len(d.onlyInA) > 0 || len(d.onlyInB) > 0 {
+		must(fmt.Fprintf(buf, "total size change: %v bytes\n", sizeChange))
+	}
+
+	return buf.String()
+}
+
+func diffTargetFilesLists(a, b []*ZipArtifactFile) zipDiff {
+	i := 0
+	j := 0
+
+	diff := zipDiff{}
+
+	for i < len(a) && j < len(b) {
+		if a[i].Name == b[j].Name {
+			if a[i].UncompressedSize64 != b[j].UncompressedSize64 || a[i].CRC32 != b[j].CRC32 {
+				diff.modified = append(diff.modified, [2]*ZipArtifactFile{a[i], b[j]})
+			}
+			i++
+			j++
+		} else if a[i].Name < b[j].Name {
+			// a[i] is not present in b
+			diff.onlyInA = append(diff.onlyInA, a[i])
+			i++
+		} else {
+			// b[j] is not present in a
+			diff.onlyInB = append(diff.onlyInB, b[j])
+			j++
+		}
+	}
+	for i < len(a) {
+		diff.onlyInA = append(diff.onlyInA, a[i])
+		i++
+	}
+	for j < len(b) {
+		diff.onlyInB = append(diff.onlyInB, b[j])
+		j++
+	}
+
+	return diff
+}