fix: support exclude patterns on Windows (anchore#1228)

syft/source/source.go

@@ -392,6 +392,9 @@ func getDirectoryExclusionFunctions(root string, exclusions []string) ([]pathFil
 		return nil, err
 	}
 
+	// this handles Windows file paths by converting them to C:/something/else format
+	root = filepath.ToSlash(root)
+
 	if !strings.HasSuffix(root, "/") {
 		root += "/"
 	}
@@ -414,6 +417,8 @@ func getDirectoryExclusionFunctions(root string, exclusions []string) ([]pathFil
 	return []pathFilterFn{
 		func(path string, _ os.FileInfo) bool {
 			for _, exclusion := range exclusions {
+				// this is required to handle Windows filepaths
+				path = filepath.ToSlash(path)
 				matches, err := doublestar.Match(exclusion, path)
 				if err != nil {
 					return false

syft/source/source_test.go

@@ -579,6 +579,75 @@ func TestImageExclusions(t *testing.T) {
 	}
 }
 
+func Test_crossPlatformExclusions(t *testing.T) {
+	testCases := []struct {
+		desc    string
+		root    string
+		path    string
+		exclude string
+		match   bool
+	}{
+		{
+			desc:    "linux doublestar",
+			root:    "/usr",
+			path:    "/usr/var/lib/etc.txt",
+			exclude: "**/*.txt",
+			match:   true,
+		},
+		{
+			desc:    "linux relative",
+			root:    "/usr/var/lib",
+			path:    "/usr/var/lib/etc.txt",
+			exclude: "./*.txt",
+			match:   true,
+		},
+		{
+			desc:    "linux one level",
+			root:    "/usr",
+			path:    "/usr/var/lib/etc.txt",
+			exclude: "*/*.txt",
+			match:   false,
+		},
+		// NOTE: since these tests will run in linux and macOS, the windows paths will be
+		// considered relative if they do not start with a forward slash and paths with backslashes
+		// won't be modified by the filepath.ToSlash call, so these are emulating the result of
+		// filepath.ToSlash usage
+		{
+			desc:    "windows doublestar",
+			root:    "/C:/User/stuff",
+			path:    "/C:/User/stuff/thing.txt",
+			exclude: "**/*.txt",
+			match:   true,
+		},
+		{
+			desc:    "windows relative",
+			root:    "/C:/User/stuff",
+			path:    "/C:/User/stuff/thing.txt",
+			exclude: "./*.txt",
+			match:   true,
+		},
+		{
+			desc:    "windows one level",
+			root:    "/C:/User/stuff",
+			path:    "/C:/User/stuff/thing.txt",
+			exclude: "*/*.txt",
+			match:   false,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			fns, err := getDirectoryExclusionFunctions(test.root, []string{test.exclude})
+			require.NoError(t, err)
+
+			for _, f := range fns {
+				result := f(test.path, nil)
+				require.Equal(t, test.match, result)
+			}
+		})
+	}
+}
+
 // createArchive creates a new archive file at destinationArchivePath based on the directory found at sourceDirPath.
 func createArchive(t testing.TB, sourceDirPath, destinationArchivePath string) {
 	t.Helper()

syft/source/source_win_test.go

@@ -0,0 +1,54 @@
+//go:build windows
+// +build windows
+
+package source
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_crossPlatformExclusions(t *testing.T) {
+	testCases := []struct {
+		desc    string
+		root    string
+		path    string
+		exclude string
+		match   bool
+	}{
+		{
+			desc:    "windows doublestar",
+			root:    "C:\\User\\stuff",
+			path:    "C:\\User\\stuff\\thing.txt",
+			exclude: "**/*.txt",
+			match:   true,
+		},
+		{
+			desc:    "windows relative",
+			root:    "C:\\User\\stuff",
+			path:    "C:\\User\\stuff\\thing.txt",
+			exclude: "./*.txt",
+			match:   true,
+		},
+		{
+			desc:    "windows one level",
+			root:    "C:\\User\\stuff",
+			path:    "C:\\User\\stuff\\thing.txt",
+			exclude: "*/*.txt",
+			match:   false,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			fns, err := getDirectoryExclusionFunctions(test.root, []string{test.exclude})
+			require.NoError(t, err)
+
+			for _, f := range fns {
+				result := f(test.path, nil)
+				require.Equal(t, test.match, result)
+			}
+		})
+	}
+}