feat: backup JARs

karchx · Jun 25, 2022 · Jun 27, 2022 · Jun 28, 2022 · Jun 28, 2022 · Jun 29, 2022
commit 8de522d67748c75dd1e63ab26c6f896336e8fe79
diff --git a/jar/backup.go b/jar/backup.go
@@ -0,0 +1,59 @@
+package jar
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func BackupFiles(jar string) {
+	pathdst := filepath.Join(".", "backup")
+	if _, err := os.Stat(pathdst); os.IsNotExist(err) {
+		err := os.Mkdir(pathdst, os.ModePerm)
+		if err != nil {
+			fmt.Errorf("create backup %v", err)
+		}
+	}
+
+	jarSplit := strings.Split(jar, "/")
+
+	if len(jarSplit) == 3 {
+		pathdst = pathdst + "/" + jarSplit[2] + ".bak"
+	}
+
+	if len(jarSplit) == 4 {
+		pathdst = pathdst + "/" + jarSplit[3] + ".bak"
+	}
+
+	_, err := copyJars(jar, pathdst)
+	if err != nil {
+		fmt.Errorf("copy file %v ", err)
+	}
+}
+
+func copyJars(src, dst string) (int64, error) {
+	sourceFileStat, err := os.Stat(src)
+	if err != nil {
+		return 0, err
+	}
+
+	if !sourceFileStat.Mode().IsRegular() {
+		return 0, fmt.Errorf("%s is not a regular file", src)
+	}
+
+	source, err := os.Open(src)
+	if err != nil {
+		return 0, err
+	}
+	defer source.Close()
+
+	destination, err := os.Create(dst)
+	if err != nil {
+		return 0, err
+	}
+	defer destination.Close()
+	nBytes, err := io.Copy(destination, source)
+	return nBytes, err
+}
diff --git a/jar/walker.go b/jar/walker.go
@@ -51,6 +51,8 @@ type Walker struct {
 	// Rewrite indicates if the Walker should rewrite JARs in place as it
 	// iterates through the filesystem.
 	Rewrite bool
+
+	Backup bool
 	// SkipDir, if provided, allows the walker to skip certain directories
 	// as it scans.
 	SkipDir func(path string, de fs.DirEntry) bool
@@ -133,6 +135,10 @@ func (w *walker) skipDir(path string, d fs.DirEntry) bool {
 }
 
 func (w *walker) visit(p string, d fs.DirEntry) error {
+	if w.Backup {
+		BackupFiles(w.filepath(p))
+	}
+
 	if d.IsDir() || !d.Type().IsRegular() {
 		return nil
 	}
@@ -215,5 +221,6 @@ func (w *walker) visit(p string, d fs.DirEntry) error {
 		return fmt.Errorf("overwriting %s: %v", p, err)
 	}
 	w.handleRewrite(p, r)
+
 	return nil
 }
diff --git a/log4jscanner.go b/log4jscanner.go
@@ -40,6 +40,7 @@ Flags:
     -f, --force    Don't skip network and userland filesystems. (smb,nfs,afs,fuse)
     -w, --rewrite  Rewrite vulnerable JARs as they are detected.
     -v, --verbose  Print verbose logs to stderr.
+    -b, --backup   Make a backup of the scanned files
 
 `)
 }
@@ -49,8 +50,8 @@ var skipDirs = map[string]bool{
 	".git":         true,
 	"node_modules": true,
 	".idea":        true,
-	".svn":			true,
-	".p4root":		true,
+	".svn":         true,
+	".p4root":      true,
 
 	// TODO(ericchiang): expand
 }
@@ -63,6 +64,8 @@ func main() {
 		v       bool
 		force   bool
 		f       bool
+		backup  bool
+		b       bool
 		toSkip  []string
 	)
 	appendSkip := func(dir string) error {
@@ -76,6 +79,8 @@ func main() {
 	flag.BoolVar(&v, "v", false, "")
 	flag.BoolVar(&force, "force", false, "")
 	flag.BoolVar(&f, "f", false, "")
+	flag.BoolVar(&b, "b", false, "")
+	flag.BoolVar(&backup, "backup", false, "")
 	flag.Func("s", "", appendSkip)
 	flag.Func("skip", "", appendSkip)
 	flag.Usage = usage
@@ -94,6 +99,9 @@ func main() {
 	if w {
 		rewrite = w
 	}
+	if b {
+		backup = b
+	}
 	log.SetFlags(log.LstdFlags | log.Lshortfile)
 	logf := func(format string, v ...interface{}) {
 		if verbose {
@@ -103,6 +111,7 @@ func main() {
 	seen := 0
 	walker := jar.Walker{
 		Rewrite: rewrite,
+		Backup:  backup,
 		SkipDir: func(path string, d fs.DirEntry) bool {
 			seen++
 			if seen%5000 == 0 {