Diff within files

cmd/diff.go

@@ -19,16 +19,18 @@ package cmd
 import (
 	"errors"
 	"fmt"
-	"os"
-	"strings"
-	"sync"
-
 	"github.com/GoogleCloudPlatform/container-diff/differs"
 	pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
+	"github.com/GoogleCloudPlatform/container-diff/util"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"os"
+	"strings"
+	"sync"
 )
 
+var filename string
+
 var diffCmd = &cobra.Command{
 	Use:   "diff",
 	Short: "Compare two images: [image1] [image2]",
@@ -40,6 +42,9 @@ var diffCmd = &cobra.Command{
 		if err := checkIfValidAnalyzer(types); err != nil {
 			return err
 		}
+		if err := checkFilenameFlag(types); err != nil {
+			return err
+		}
 		return nil
 	},
 	Run: func(cmd *cobra.Command, args []string) {
@@ -57,6 +62,15 @@ func checkDiffArgNum(args []string) error {
 	return nil
 }
 
+func checkFilenameFlag(types string) error {
+	if filename != "" {
+		if !strings.Contains(types, "file") {
+			return errors.New("Please include --types=file with the --filename flag")
+		}
+	}
+	return nil
+}
+
 func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	diffTypes, err := differs.GetAnalyzers(diffArgs)
 	if err != nil {
@@ -109,14 +123,32 @@ func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	}
 	outputResults(diffs)
 
+	if filename != "" {
+		fmt.Fprintln(os.Stderr, "Computing filename diffs")
+		err := diffFile(imageMap[image1Arg], imageMap[image2Arg])
+		if err != nil {
+			return err
+		}
+	}
+
 	if save {
 		logrus.Infof("Images were saved at %s and %s", imageMap[image1Arg].FSPath,
 			imageMap[image2Arg].FSPath)
 	}
 	return nil
 }
 
+func diffFile(image1, image2 *pkgutil.Image) error {
+	diff, err := util.DiffFile(image1, image2, filename)
+	if err != nil {
+		return err
+	}
+	util.TemplateOutput(diff, "FilenameDiff")
+	return nil
+}
+
 func init() {
+	diffCmd.Flags().StringVarP(&filename, "filename", "f", "", "Set this flag to the path of a file in both containers to view the diff of the file. Must be used with --types=file flag.")
 	RootCmd.AddCommand(diffCmd)
 	addSharedFlags(diffCmd)
 }

pkg/util/fs_utils.go

@@ -53,6 +53,25 @@ func GetSize(path string) int64 {
 	return stat.Size()
 }
 
+//GetFileContents returns the contents of a file at the specified path
+func GetFileContents(path string) (*string, error) {
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return nil, err
+	}
+
+	contents, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	strContents := string(contents)
+	//If file is empty, return nil
+	if strContents == "" {
+		return nil, nil
+	}
+	return &strContents, nil
+}
+
 func getDirectorySize(path string) (int64, error) {
 	var size int64
 	err := filepath.Walk(path, func(_ string, info os.FileInfo, err error) error {

util/diff_utils.go

@@ -34,6 +34,12 @@ type DirDiff struct {
 	Mods []EntryDiff
 }
 
+type FileNameDiff struct {
+	Filename    string
+	Description string
+	Diff        string
+}
+
 type EntryDiff struct {
 	Name  string
 	Size1 int64
@@ -118,6 +124,64 @@ func DiffDirectory(d1, d2 pkgutil.Directory) (DirDiff, bool) {
 	return DirDiff{addedEntries, deletedEntries, modifiedEntries}, same
 }
 
+func DiffFile(image1, image2 *pkgutil.Image, filename string) (*FileNameDiff, error) {
+	//Join paths
+	image1FilePath := filepath.Join(image1.FSPath, filename)
+	image2FilePath := filepath.Join(image2.FSPath, filename)
+
+	//Get contents of files
+	image1FileContents, err := pkgutil.GetFileContents(image1FilePath)
+	if err != nil {
+		return nil, err
+	}
+
+	image2FileContents, err := pkgutil.GetFileContents(image2FilePath)
+	if err != nil {
+		return nil, err
+	}
+
+	description := ""
+	//Check if file contents are empty or if they are the same
+	if image1FileContents == nil && image2FileContents == nil {
+		description := "Both files are empty"
+		return &FileNameDiff{filename, description, ""}, nil
+	}
+
+	if image1FileContents == nil {
+		description := fmt.Sprintf("%s contains an empty file, the contents of %s are:", image1.Source, image2.Source)
+		return &FileNameDiff{filename, description, *image2FileContents}, nil
+	}
+
+	if image2FileContents == nil {
+		description := fmt.Sprintf("%s contains an empty file, the contents of %s are:", image2.Source, image1.Source)
+		return &FileNameDiff{filename, description, *image1FileContents}, nil
+	}
+
+	if *image1FileContents == *image2FileContents {
+		description := "Both files are the same, the contents are:"
+		return &FileNameDiff{filename, description, *image1FileContents}, nil
+	}
+
+	//Carry on with diffing, make string array for difflib requirements
+	image1Contents := []string{string(*image1FileContents)}
+	image2Contents := []string{string(*image2FileContents)}
+
+	//Run diff
+	diff := difflib.UnifiedDiff{
+		A:        image1Contents,
+		B:        image2Contents,
+		FromFile: image1.Source,
+		ToFile:   image2.Source,
+	}
+
+	text, err := difflib.GetUnifiedDiffString(diff)
+
+	if err != nil {
+		return nil, err
+	}
+	return &FileNameDiff{filename, description, text}, nil
+}
+
 // Checks for content differences between files of the same name from different directories
 func GetModifiedEntries(d1, d2 pkgutil.Directory) []string {
 	d1files := d1.Content

util/format_utils.go

@@ -20,10 +20,10 @@ import (
 	"bufio"
 	"encoding/json"
 	"errors"
-	"html/template"
 	"os"
 	"strings"
 	"text/tabwriter"
+	"text/template"
 
 	"github.com/sirupsen/logrus"
 )
@@ -33,6 +33,7 @@ var templates = map[string]string{
 	"MultiVersionPackageDiff":     MultiVersionDiffOutput,
 	"HistDiff":                    HistoryDiffOutput,
 	"DirDiff":                     FSDiffOutput,
+	"FilenameDiff":                FilenameDiffOutput,
 	"ListAnalyze":                 ListAnalysisOutput,
 	"FileAnalyze":                 FileAnalysisOutput,
 	"MultiVersionPackageAnalyze":  MultiVersionPackageOutput,

util/template_utils.go

@@ -65,6 +65,12 @@ Docker history lines found only in {{.Image1}}:{{if not .Diff.Adds}} None{{else}
 
 Docker history lines found only in {{.Image2}}:{{if not .Diff.Dels}} None{{else}}{{block "list2" .Diff.Dels}}{{"\n"}}{{range .}}{{print "-" .}}{{"\n"}}{{end}}{{end}}{{end}}
 `
+const FilenameDiffOutput = `
+-----Diff of {{.Filename}}-----
+{{.Description}}
+
+{{.Diff}}
+`
 
 const ListAnalysisOutput = `
 -----{{.AnalyzeType}}-----