add option to generate a new fingerprint file or not.

internal/cmd/fingerprint/fingerprint.go

@@ -1,6 +1,7 @@
 package fingerprint
 
 import (
+	"errors"
 	"fmt"
 	"path/filepath"
 
@@ -14,13 +15,15 @@ var inclusions []string
 var shouldFingerprintCompressedContent bool
 var outputDir string
 var minFingerprintContentLength int
+var shouldRegenerateFingerprintFile bool
 
 const (
 	ExclusionFlag                   = "exclusion"
 	InclusionFlag                   = "inclusion"
 	FingerprintCompressedContent    = "fingerprint-compressed-content"
 	OutputDirFlag                   = "output-dir"
 	MinFingerprintContentLengthFlag = "min-fingerprint-content-length"
+	RegenerateFingerprintFile       = "regenerate"
 )
 
 func NewFingerprintCmd(fingerprinter fingerprint.IFingerprint) *cobra.Command {
@@ -60,6 +63,7 @@ $ debricked scan . --include '**/node_modules/**'`)
 	cmd.Flags().BoolVar(&shouldFingerprintCompressedContent, FingerprintCompressedContent, false, `Fingerprint the contents of compressed files by unpacking them in memory, Supported files: `+fmt.Sprintf("%v", fingerprint.ZIP_FILE_ENDINGS))
 	cmd.Flags().StringVar(&outputDir, OutputDirFlag, ".", "The directory to write the output file to")
 	cmd.Flags().IntVar(&minFingerprintContentLength, MinFingerprintContentLengthFlag, 45, "Set minimum content length (in bytes) for files to fingerprint. Defaults to 45 bytes.")
+	cmd.Flags().BoolVar(&shouldRegenerateFingerprintFile, RegenerateFingerprintFile, true, `Toggle if generated fingerprint file should be overwritten on subequent scans. Defaults to true`)
 
 	viper.MustBindEnv(ExclusionFlag)
 
@@ -72,19 +76,31 @@ func RunE(f fingerprint.IFingerprint) func(_ *cobra.Command, args []string) erro
 		if len(args) > 0 {
 			path = args[0]
 		}
+		var outputFilePath = filepath.Join(outputDir, fingerprint.OutputFileNameFingerprints)
 		options := fingerprint.DebrickedOptions{
+			OutputPath:                   outputFilePath,
+			Regenerate:                   shouldRegenerateFingerprintFile,
 			Path:                         path,
 			Exclusions:                   exclusions,
 			Inclusions:                   inclusions,
 			FingerprintCompressedContent: shouldFingerprintCompressedContent,
 			MinFingerprintContentLength:  minFingerprintContentLength,
 		}
 		output, err := f.FingerprintFiles(options)
-
 		if err != nil {
+			if errors.Is(err, &fingerprint.FingerprintFileExistsError{}) {
+				fmt.Println(
+					"Fingerprint file exists and command is configured to not overwrite. ",
+					"To generate a new fingerprint file either remove/rename old file or ",
+					"change flag '--regenerate' to 'true'",
+				)
+
+				return nil
+			}
+
 			return err
 		}
-		outputFilePath := filepath.Join(outputDir, fingerprint.OutputFileNameFingerprints)
+
 		err = output.ToFile(outputFilePath)
 		if err != nil {
 			return err

internal/cmd/fingerprint/fingerprint_test.go

@@ -1,6 +1,7 @@
 package fingerprint
 
 import (
+	"io"
 	"os"
 	"testing"
 
@@ -52,5 +53,25 @@ func TestRunE(t *testing.T) {
 	err := runE(nil, []string{"."})
 
 	assert.NoError(t, err)
+}
+
+func TestRunEFileExistsError(t *testing.T) {
+	defer func() {
+		os.Remove(fingerprint.OutputFileNameFingerprints)
+	}()
+	fingerprintMock := testdata.NewFingerprintMockFileExistsError()
+	runE := RunE(fingerprintMock)
 
+	rescueStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	err := runE(nil, []string{"."})
+
+	_ = w.Close()
+	output, _ := io.ReadAll(r)
+	os.Stdout = rescueStdout
+
+	assert.NoError(t, err)
+	assert.Contains(t, string(output), "change flag '--regenerate' to 'true'")
 }

internal/fingerprint/fingerprint.go

@@ -24,6 +24,8 @@ type DebrickedOptions struct {
 	Inclusions                   []string
 	FingerprintCompressedContent bool
 	MinFingerprintContentLength  int
+	OutputPath                   string
+	Regenerate                   bool
 }
 
 var ZIP_FILE_ENDINGS = []string{".jar", ".nupkg", ".war", ".zip", ".ear", ".whl"}
@@ -59,6 +61,12 @@ func NewFingerprinter() *Fingerprinter {
 	}
 }
 
+type FingerprintFileExistsError struct{}
+
+func (_ *FingerprintFileExistsError) Error() string {
+	return "Fingerprint file already exists and command is configured to not overwrite."
+}
+
 type FileFingerprint struct {
 	path          string
 	contentLength int64
@@ -78,14 +86,23 @@ func (f *Fingerprinter) FingerprintFiles(options DebrickedOptions) (Fingerprints
 
 	fingerprints := Fingerprints{}
 
+	_, err := os.Open(options.OutputPath)
+	var fingerprintFileExists = false
+	if !errors.Is(err, os.ErrNotExist) {
+		fingerprintFileExists = true
+	}
+	if !options.Regenerate && fingerprintFileExists {
+		return fingerprints, &FingerprintFileExistsError{}
+	}
+
 	f.spinnerManager.Start()
 	spinnerMessage := "files processed"
 	spinner := f.spinnerManager.AddSpinner(spinnerMessage)
 
 	nbFiles := 0
 	lastLogNb := 0
 
-	err := filepath.Walk(options.Path, func(path string, fileInfo os.FileInfo, err error) error {
+	err = filepath.Walk(options.Path, func(path string, fileInfo os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}

internal/fingerprint/fingerprint_test.go

@@ -183,6 +183,25 @@ func TestFingerprintFiles(t *testing.T) {
 
 }
 
+func TestFingerprintFilesAlreadyExists(t *testing.T) {
+	temp, _ := os.CreateTemp("testdata/fingerprinter", "temp-fingerprint-*.txt")
+	fingerprinter := NewFingerprinter()
+	_, err := fingerprinter.FingerprintFiles(
+		DebrickedOptions{
+			OutputPath:                   temp.Name(),
+			Path:                         "testdata/fingerprinter",
+			Exclusions:                   []string{},
+			Inclusions:                   []string{},
+			FingerprintCompressedContent: false,
+			MinFingerprintContentLength:  0,
+			Regenerate:                   false,
+		},
+	)
+	os.Remove(temp.Name())
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "Fingerprint file already exists")
+}
+
 func TestFingerprintFilesBackslash(t *testing.T) {
 
 	tempDir, err := os.MkdirTemp("", "slash-test")

internal/fingerprint/testdata/fingerprinter_mock.go

@@ -14,6 +14,12 @@ func NewFingerprintMock() *FingerprintMock {
 	}
 }
 
+func NewFingerprintMockFileExistsError() *FingerprintMock {
+	return &FingerprintMock{
+		error: &fingerprint.FingerprintFileExistsError{},
+	}
+}
+
 func (f *FingerprintMock) FingerprintFiles(
 	options fingerprint.DebrickedOptions,
 ) (fingerprint.Fingerprints, error) {

internal/scan/scanner.go

@@ -172,6 +172,7 @@ func (dScanner *DebrickedScanner) scanFingerprint(options DebrickedOptions) erro
 				Inclusions:                   append(options.Inclusions, fingerprint.DefaultInclusionsFingerprint()...),
 				MinFingerprintContentLength:  options.MinFingerprintContentLength,
 				FingerprintCompressedContent: false,
+				Regenerate:                   options.Regenerate > 0,
 			},
 		)
 		if err != nil {