Improve test accuracy for pkg/chrootarchive (part 2)

Check test correctness of untar by comparing destination with
source. For part 2, it checkes hashes of source and destination
files or the target files of symbolic links.

This is a supplement to the #11601 fix.

Signed-off-by: Yestin Sun <sunyi0804@gmail.com>

pkg/chrootarchive/archive_test.go

@@ -3,6 +3,7 @@ package chrootarchive
 import (
 	"bytes"
 	"fmt"
+	"hash/crc32"
 	"io"
 	"io/ioutil"
 	"os"
@@ -113,6 +114,16 @@ func prepareSourceDirectory(numberOfFiles int, targetPath string, makeSymLinks b
 	return totalSize, nil
 }
 
+func getHash(filename string) (uint32, error) {
+	stream, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return 0, err
+	}
+	hash := crc32.NewIEEE()
+	hash.Write(stream)
+	return hash.Sum32(), nil
+}
+
 func compareDirectories(src string, dest string) error {
 	changes, err := archive.ChangesDirs(dest, src)
 	if err != nil {
@@ -124,6 +135,21 @@ func compareDirectories(src string, dest string) error {
 	return nil
 }
 
+func compareFiles(src string, dest string) error {
+	srcHash, err := getHash(src)
+	if err != nil {
+		return err
+	}
+	destHash, err := getHash(dest)
+	if err != nil {
+		return err
+	}
+	if srcHash != destHash {
+		return fmt.Errorf("%s is different from %s", src, dest)
+	}
+	return nil
+}
+
 func TestChrootTarUntarWithSymlink(t *testing.T) {
 	tmpdir, err := ioutil.TempDir("", "docker-TestChrootTarUntarWithSymlink")
 	if err != nil {
@@ -176,6 +202,9 @@ func TestChrootCopyWithTar(t *testing.T) {
 	if err := CopyWithTar(srcfile, destfile); err != nil {
 		t.Fatal(err)
 	}
+	if err := compareFiles(srcfile, destfile); err != nil {
+		t.Fatal(err)
+	}
 
 	// Copy symbolic link
 	srcLinkfile := filepath.Join(src, "file-1-link")
@@ -184,6 +213,9 @@ func TestChrootCopyWithTar(t *testing.T) {
 	if err := CopyWithTar(srcLinkfile, destLinkfile); err != nil {
 		t.Fatal(err)
 	}
+	if err := compareFiles(srcLinkfile, destLinkfile); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestChrootCopyFileWithTar(t *testing.T) {
@@ -213,6 +245,9 @@ func TestChrootCopyFileWithTar(t *testing.T) {
 	if err := CopyFileWithTar(srcfile, destfile); err != nil {
 		t.Fatal(err)
 	}
+	if err := compareFiles(srcfile, destfile); err != nil {
+		t.Fatal(err)
+	}
 
 	// Copy symbolic link
 	srcLinkfile := filepath.Join(src, "file-1-link")
@@ -221,6 +256,9 @@ func TestChrootCopyFileWithTar(t *testing.T) {
 	if err := CopyFileWithTar(srcLinkfile, destLinkfile); err != nil {
 		t.Fatal(err)
 	}
+	if err := compareFiles(srcLinkfile, destLinkfile); err != nil {
+		t.Fatal(err)
+	}
 }
 
 func TestChrootUntarPath(t *testing.T) {