Add scanner for RAR 4/5 archives (#25)

* Add scanner for RAR 4/5 archives

* Add merge command. Improve rar scanner.

Author: ostafen

cmd/cmd/merge.go

@@ -0,0 +1,129 @@
+// Copyright (c) 2025 Stefano Scafiti
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+package cmd
+
+import (
+	"bufio"
+	"crypto/rand"
+	"fmt"
+	"io"
+	mrand "math/rand/v2"
+	"os"
+
+	"github.com/ostafen/digler/internal/logger"
+	osutils "github.com/ostafen/digler/pkg/util/os"
+	"github.com/spf13/cobra"
+)
+
+func DefineMergeCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "merge <file1> <file2> ...",
+		Short: "Merge multiple files into a single disk image",
+		Long: `The 'merge' command combines multiple files into a single flat disk image.
+This is useful for testing scanners and plugins with known, reproducible data.
+By default, files are concatenated in the order given. You can optionally add zero-byte padding between files to simulate gaps.`,
+		Args:         cobra.MinimumNArgs(1),
+		SilenceUsage: true,
+		RunE:         RunMerge,
+	}
+
+	cmd.Flags().StringP("output", "o", "", "Path to the output disk image file (required)")
+	cmd.Flags().Int64("padding", 0, "Number of zero bytes to insert between files (optional)")
+	cmd.Flags().Int("min-gap", 4*1024, "minimum gap size in bytes between files")
+	cmd.Flags().Int("max-gap", 512*1024, "maximum gap size in bytes between files")
+	cmd.Flags().Int("block-size", 512, "block size in bytes")
+
+	_ = cmd.MarkFlagRequired("output")
+
+	return cmd
+}
+
+func RunMerge(cmd *cobra.Command, args []string) error {
+	filePaths := make([]string, 0, len(args))
+	for _, arg := range args {
+		paths, err := osutils.ListFiles(arg)
+		if err != nil {
+			return err
+		}
+		filePaths = append(filePaths, paths...)
+	}
+
+	out, _ := cmd.Flags().GetString("output")
+
+	minGap, _ := cmd.Flags().GetInt("min-gap")
+	maxGap, _ := cmd.Flags().GetInt("max-gap")
+
+	if minGap > maxGap {
+		return fmt.Errorf("min-gap (%d) cannot be greater than max-gap (%d)", minGap, maxGap)
+	}
+	if minGap <= 0 {
+		return fmt.Errorf("min-gap must be greater than 0")
+	}
+
+	blockSize, _ := cmd.Flags().GetInt("block-size")
+	if blockSize <= 0 {
+		return fmt.Errorf("block size must be greater than 0")
+	}
+
+	f, err := os.Create(out)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	logger := logger.New(os.Stdout, logger.InfoLevel)
+
+	logger.Infof("Merging %d files into %s", len(filePaths), out)
+
+	w := bufio.NewWriter(f)
+
+	gapSize := minGap + mrand.IntN(maxGap-minGap+1)
+	// Ensure gap size is a multiple of block size
+	gapSize = min(1, gapSize/blockSize) * blockSize
+
+	bytesWritten := int64(0)
+	for _, path := range filePaths {
+		_, err := io.CopyN(w, rand.Reader, int64(gapSize))
+		if err != nil {
+			return err
+		}
+		bytesWritten += int64(gapSize)
+
+		nCopied, err := osutils.CopyFile(w, path)
+		if err != nil {
+			return err
+		}
+		bytesWritten += nCopied
+
+		padding := int64(blockSize) - nCopied%int64(blockSize)
+
+		gapSize = minGap + mrand.IntN(maxGap-minGap+1)
+		// Ensure next file starts at a block boundary
+		gapSize = min(1, gapSize/blockSize) * blockSize
+		gapSize += int(padding)
+	}
+
+	if err := w.Flush(); err != nil {
+		return fmt.Errorf("error flushing writer: %w", err)
+	}
+
+	logger.Infof("Merging successfully completed. %d bytes written.", bytesWritten)
+	return nil
+}

cmd/cmd/root.go

@@ -34,6 +34,7 @@ func Execute() error {
 	rootCmd.AddCommand(DefineRecoverCommand())
 	rootCmd.AddCommand(DefineMountCommand())
 	rootCmd.AddCommand(DefineFormatsCommand())
+	rootCmd.AddCommand(DefineMergeCommand())
 
 	return rootCmd.Execute()
 }

internal/format/header.go

@@ -52,6 +52,7 @@ var fileHeaders = []FileHeader{
 	tiffFileHeader,
 	// generic/documents formats
 	zipFileHeader,
+	rarFileHeader,
 	pdfFileHeader,
 }