ignore irregular files while indexing directory (#616)

* stop hidding  command from help doc

Signed-off-by: Jonas Galvão Xavier <jonas.agx@gmail.com>

* do not index irregular files

Signed-off-by: Jonas Galvão Xavier <jonas.agx@gmail.com>

* fix fixture dir and err name

Signed-off-by: Jonas Galvão Xavier <jonas.agx@gmail.com>

* improve the description of irregular files

Signed-off-by: Jonas Galvão Xavier <jonas.agx@gmail.com>

* explicitly check indexed file name

Signed-off-by: Jonas Galvão Xavier <jonas.agx@gmail.com>

syft/source/directory_resolver.go

@@ -25,6 +25,8 @@ var unixSystemRuntimePrefixes = []string{
 	"/dev",
 }
 
+var ErrIgnoreIrregularFile = errors.New("ignoring irregular file type")
+
 var _ FileResolver = (*directoryResolver)(nil)
 
 type pathFilterFn func(string) bool
@@ -137,7 +139,7 @@ func (r *directoryResolver) indexPath(path string, info os.FileInfo, err error)
 }
 
 func (r *directoryResolver) handleFileAccessErr(path string, err error) error {
-	if errors.Is(err, os.ErrPermission) || errors.Is(err, os.ErrNotExist) {
+	if errors.Is(err, os.ErrPermission) || errors.Is(err, os.ErrNotExist) || errors.Is(err, ErrIgnoreIrregularFile) {
 		// don't allow for permission errors to stop indexing, keep track of the paths and continue.
 		log.Warnf("unable to access path=%q: %+v", path, err)
 		r.errPaths[path] = err
@@ -176,6 +178,8 @@ func (r directoryResolver) addPathToIndex(p string, info os.FileInfo) (string, e
 		if err != nil {
 			return "", err
 		}
+	case IrregularFile:
+		return "", ErrIgnoreIrregularFile
 	default:
 		ref, err = r.fileTree.AddFile(file.Path(p))
 		if err != nil {

syft/source/directory_resolver_test.go

@@ -1,10 +1,13 @@
 package source
 
 import (
+	"io/ioutil"
 	"os"
 	"path"
+	"path/filepath"
 	"reflect"
 	"strings"
+	"syscall"
 	"testing"
 
 	"github.com/scylladb/go-set/strset"
@@ -459,3 +462,29 @@ func Test_directoryResolver_FilesByMIMEType(t *testing.T) {
 		})
 	}
 }
+
+func Test_ignoreIrregularFiles(t *testing.T) {
+	// NOTE: craeting a pipe/fifo file on demand since git doesn't let me
+	// commit one. The directory resolver should ignore it (and any other
+	// file that is neither regular, a symlink or directory) when indexing a directory
+	dir := "./test-fixtures/irregular-files"
+	f := "f.fifo"
+
+	err := syscall.Mknod(filepath.Join(dir, f), syscall.S_IFIFO|0666, 0)
+	assert.NoError(t, err)
+	defer func() {
+		err := os.Remove(filepath.Join(dir, f))
+		assert.NoError(t, err)
+	}()
+
+	fileRefs, err := ioutil.ReadDir(dir)
+	assert.NoError(t, err)
+	assert.Len(t, fileRefs, 2) // two files (f.fifo and readme)
+
+	resolver, err := newDirectoryResolver(dir)
+	assert.NoError(t, err)
+
+	assert.Len(t, resolver.fileTree.AllFiles(), 1)
+	rp := resolver.fileTree.AllFiles()[0].RealPath
+	assert.True(t, strings.Contains(string(rp), filepath.Join(dir, "readme")))
+}

syft/source/file_type.go

@@ -8,6 +8,10 @@ import (
 const (
 	UnknownFileType FileType = "UnknownFileType"
 	RegularFile     FileType = "RegularFile"
+	// IrregularFile is how syft defines files that are neither regular, symbolic or directory.
+	// For ref: the seven standard Unix file types are regular, directory, symbolic link,
+	// FIFO special, block special, character special, and socket as defined by POSIX.
+	IrregularFile   FileType = "IrregularFile"
 	HardLink        FileType = "HardLink"
 	SymbolicLink    FileType = "SymbolicLink"
 	CharacterDevice FileType = "CharacterDevice"
@@ -45,6 +49,8 @@ func newFileTypeFromMode(mode os.FileMode) FileType {
 		return SymbolicLink
 	case mode.IsDir():
 		return Directory
+	case !mode.IsRegular():
+		return IrregularFile
 	default:
 		return RegularFile
 	}

syft/source/test-fixtures/irregular-files/readme

@@ -0,0 +1,2 @@
+this directory exists for unit tests on irregular files. You can't see other files here because they are removed after each test. 
+This readme is a better version of Russell's teapot.