Merge pull request aquasecurity#9 from DataDog/paulcacheux/new-dpkg-s…

…canner-opt

memory improvements in dpkg scanner

pkg/fanal/analyzer/pkg/dpkg/dpkg.go

@@ -61,34 +61,56 @@ func (a dpkgAnalyzer) PostAnalyze(_ context.Context, input analyzer.PostAnalysis
 		log.Logger.Debugf("Unable to parse %q file: %s", availableFile, err)
 	}
 
-	required := func(path string, d fs.DirEntry) bool {
-		return path != availableFile
-	}
-
 	packageFiles := make(map[string][]string)
 
-	// parse other files
-	err = fsutils.WalkDir(input.FS, "var/lib/dpkg", required, func(path string, d fs.DirEntry, r io.Reader) error {
-		// parse list files
-		if a.isListFile(filepath.Split(path)) {
-			scanner := bufio.NewScanner(r)
-			systemFiles, err := a.parseDpkgInfoList(scanner)
-			if err != nil {
-				return err
+	// parse list files
+	err = fsutils.WalkDir(input.FS, infoDir, fsutils.RequiredExt(".list"), func(path string, d fs.DirEntry, r io.Reader) error {
+		scanner := bufio.NewScanner(r)
+		systemFiles, err := a.parseDpkgInfoList(scanner)
+		if err != nil {
+			return err
+		}
+		packageFiles[strings.TrimSuffix(filepath.Base(path), ".list")] = systemFiles
+		systemInstalledFiles = append(systemInstalledFiles, systemFiles...)
+		return nil
+	})
+	if err != nil && !os.IsNotExist(err) {
+		return nil, xerrors.Errorf("dpkg walk error: %w", err)
+	}
+
+	// parse root status file
+	parseRootStatusFile := func() ([]types.PackageInfo, error) {
+		f, err := input.FS.Open(statusFile)
+		if err != nil {
+			if errors.Is(err, fs.ErrNotExist) {
+				return nil, nil
 			}
-			packageFiles[strings.TrimSuffix(filepath.Base(path), ".list")] = systemFiles
-			systemInstalledFiles = append(systemInstalledFiles, systemFiles...)
-			return nil
+			return nil, xerrors.Errorf("failed to open %s: %w", statusFile, err)
 		}
-		// parse status files
+		defer f.Close()
+
+		infos, err := a.parseDpkgStatus(statusFile, f, digests)
+		if err != nil {
+			return nil, xerrors.Errorf("dpkg status parse error: %w", err)
+		}
+		return infos, nil
+	}
+	rootStatusInfos, err := parseRootStatusFile()
+	if err != nil {
+		return nil, err
+	}
+	packageInfos = append(packageInfos, rootStatusInfos...)
+
+	// parse status files
+	err = fsutils.WalkDir(input.FS, statusDir, fsutils.RequiredAll(), func(path string, d fs.DirEntry, r io.Reader) error {
 		infos, err := a.parseDpkgStatus(path, r, digests)
 		if err != nil {
 			return err
 		}
 		packageInfos = append(packageInfos, infos...)
 		return nil
 	})
-	if err != nil {
+	if err != nil && !os.IsNotExist(err) {
 		return nil, xerrors.Errorf("dpkg walk error: %w", err)
 	}
 
@@ -171,7 +193,7 @@ func (a dpkgAnalyzer) parseDpkgAvailable(fsys fs.FS) (map[string]digest.Digest,
 	return pkgs, nil
 }
 
-// parseDpkgStatus parses /var/lib/dpkg/status or /var/lib/dpkg/status/*
+// parseDpkgStatus parses /var/lib/dpkg/status or /var/lib/dpkg/status.d/*
 func (a dpkgAnalyzer) parseDpkgStatus(filePath string, r io.Reader, digests map[string]digest.Digest) ([]types.PackageInfo, error) {
 	var pkg *types.Package
 	pkgs := make(map[string]*types.Package)

pkg/fanal/analyzer/pkg/dpkg/scanner.go

@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"io"
 	"net/textproto"
-	"strings"
 )
 
 type dpkgScanner struct {
@@ -42,7 +41,7 @@ func emptyLineSplit(data []byte, atEOF bool) (advance int, token []byte, err err
 		return 0, nil, nil
 	}
 
-	if i := strings.Index(string(data), "\n\n"); i >= 0 {
+	if i := bytes.Index(data, []byte("\n\n")); i >= 0 {
 		// We have a full empty line terminated block.
 		return i + 2, data[0:i], nil
 	}

pkg/utils/fsutils/fs.go

@@ -129,3 +129,9 @@ func RequiredFile(fileNames ...string) WalkDirRequiredFunc {
 		return slices.Contains(fileNames, filepath.Base(filePath))
 	}
 }
+
+func RequiredAll() WalkDirRequiredFunc {
+	return func(_ string, _ fs.DirEntry) bool {
+		return true
+	}
+}