fix: ignore git submodules

walk/git.go

@@ -9,6 +9,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strconv"
+	"strings"
 
 	"github.com/charmbracelet/log"
 	"github.com/numtide/treefmt/v2/git"
@@ -38,7 +39,7 @@ func (g *GitReader) Read(ctx context.Context, files []*File) (n int, err error)
 		r, w := io.Pipe()
 
 		// create a command which will execute from the specified sub path within root
-		cmd := exec.Command("git", "ls-files", "--cached", "--others", "--exclude-standard")
+		cmd := exec.Command("git", "ls-files", "--cached", "--others", "--exclude-standard", "--stage")
 		cmd.Dir = filepath.Join(g.root, g.path)
 		cmd.Stdout = w
 
@@ -51,19 +52,39 @@ func (g *GitReader) Read(ctx context.Context, files []*File) (n int, err error)
 		g.scanner = bufio.NewScanner(r)
 	}
 
-	nextLine := func() (string, error) {
-		line := g.scanner.Text()
+	nextFile := func() (string, error) {
+		for line := g.scanner.Text(); len(line) > 0; line = g.scanner.Text() {
+			lineSplit := strings.Split(line, "\t")
 
-		if len(line) == 0 || line[0] != '"' {
-			return line, nil
-		}
+			var stage, file string
+			// Untracked files just show as `<filename>`, while tracked files show as `<mode> <object> <stage><TAB><file>`
+			if len(lineSplit) == 1 {
+				stage, file = "", lineSplit[0]
+			} else {
+				stage, file = lineSplit[0], lineSplit[1]
+			}
+
+			// 160000 is the mode for submodules, skip them because they are separate projects that may have their own
+			// formatting rules
+			if strings.HasPrefix(stage, "160000") {
+				g.scanner.Scan()
+
+				continue
+			}
+
+			if file[0] != '"' {
+				return file, nil
+			}
+
+			unquoted, err := strconv.Unquote(file)
+			if err != nil {
+				return "", fmt.Errorf("failed to unquote file %s: %w", file, err)
+			}
 
-		unquoted, err := strconv.Unquote(line)
-		if err != nil {
-			return "", fmt.Errorf("failed to unquote line %s: %w", line, err)
+			return unquoted, nil
 		}
 
-		return unquoted, nil
+		return "", io.EOF
 	}
 
 LOOP:
@@ -82,7 +103,7 @@ LOOP:
 		default:
 			// read the next file
 			if g.scanner.Scan() {
-				entry, err := nextLine()
+				entry, err := nextFile()
 				if err != nil {
 					return n, err
 				}

walk/git_test.go

@@ -19,8 +19,21 @@ func TestGitReader(t *testing.T) {
 
 	tempDir := test.TempExamples(t)
 
+	// configure git username and email
+	cmd := exec.Command("git", "config", "--global", "user.name", "testing")
+	cmd.Dir = tempDir
+	as.NoError(cmd.Run(), "failed to set git username")
+	cmd = exec.Command("git", "config", "--global", "user.email", "testing@example.com")
+	cmd.Dir = tempDir
+	as.NoError(cmd.Run(), "failed to set git email")
+	// https://github.blog/open-source/git/git-security-vulnerabilities-announced/#cve-2022-39253
+	// We only use submodules we trust
+	cmd = exec.Command("git", "config", "--global", "protocol.file.allow", "always")
+	cmd.Dir = tempDir
+	as.NoError(cmd.Run(), "failed to allow file protocol")
+
 	// init a git repo
-	cmd := exec.Command("git", "init")
+	cmd = exec.Command("git", "init")
 	cmd.Dir = tempDir
 	as.NoError(cmd.Run(), "failed to init git repository")
 
@@ -37,6 +50,27 @@ func TestGitReader(t *testing.T) {
 	as.Equal(33, n)
 	as.ErrorIs(err, io.EOF)
 
+	// add a git submodule
+	tempSubmoduleDir := test.TempExamples(t)
+	cmd = exec.Command("git", "init")
+	cmd.Dir = tempSubmoduleDir
+	as.NoError(cmd.Run(), "failed to init git submodule repository")
+
+	// add everything to the submodule's git index
+	cmd = exec.Command("git", "add", ".")
+	cmd.Dir = tempSubmoduleDir
+	as.NoError(cmd.Run(), "failed to add everything to the submodule index")
+
+	// commit the submodule
+	cmd = exec.Command("git", "commit", "-m", "submodule")
+	cmd.Dir = tempSubmoduleDir
+	as.NoError(cmd.Run(), "failed to commit the submodule")
+
+	// add the submodule to the main git repository
+	cmd = exec.Command("git", "submodule", "add", tempSubmoduleDir)
+	cmd.Dir = tempDir
+	as.NoError(cmd.Run(), "failed to add the submodule to the main repository")
+
 	// add everything to the git index
 	cmd = exec.Command("git", "add", ".")
 	cmd.Dir = tempDir
@@ -63,8 +97,8 @@ func TestGitReader(t *testing.T) {
 		}
 	}
 
-	as.Equal(33, count)
-	as.Equal(33, statz.Value(stats.Traversed))
+	as.Equal(34, count)
+	as.Equal(34, statz.Value(stats.Traversed))
 	as.Equal(0, statz.Value(stats.Matched))
 	as.Equal(0, statz.Value(stats.Formatted))
 	as.Equal(0, statz.Value(stats.Changed))