gitattributes: Disallow empty list of attribute names

When the user passes an empty list of attributes, we cannot properly
parse the output from git-check-attr(1). To protect against that, return
an error when the list of names passed to `gitattributes.CheckAttr()` is
empty.

2 files changed, 15 insertions, 0 deletions

diff --git a/internal/git/gitattributes/check_attr.go b/internal/git/gitattributes/check_attr.go
index acacf8cc8..8596efaa3 100644
--- a/internal/git/gitattributes/check_attr.go
+++ b/internal/git/gitattributes/check_attr.go
@@ -10,6 +10,7 @@ import (
 
 	"gitlab.com/gitlab-org/gitaly/v16/internal/command"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/structerr"
 )
 
 // CheckAttrCmd can be used to get the gitattributes(5) for a set of files in a
@@ -26,6 +27,10 @@ type CheckAttrCmd struct {
 
 // CheckAttr creates a CheckAttrCmd that checks the given list of attribute names.
 func CheckAttr(ctx context.Context, repo git.RepositoryExecutor, revision git.Revision, names []string) (*CheckAttrCmd, func(), error) {
+	if len(names) == 0 {
+		return nil, nil, structerr.NewInvalidArgument("empty list of attribute names")
+	}
+
 	cmd, err := repo.Exec(ctx, git.Command{
 		Name: "check-attr",
 		Flags: []git.Option{
diff --git a/internal/git/gitattributes/check_attr_test.go b/internal/git/gitattributes/check_attr_test.go
index dcd7e4e0a..1e65b17f9 100644
--- a/internal/git/gitattributes/check_attr_test.go
+++ b/internal/git/gitattributes/check_attr_test.go
@@ -7,10 +7,20 @@ import (
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git/gittest"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git/localrepo"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/structerr"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/testhelper"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/testhelper/testcfg"
 )
 
+func TestCheckAttr(t *testing.T) {
+	t.Parallel()
+
+	ctx := testhelper.Context(t)
+	_, finish, err := CheckAttr(ctx, nil, "HEAD", nil)
+	require.Equal(t, structerr.NewInvalidArgument("empty list of attribute names"), err)
+	require.Nil(t, finish)
+}
+
 func TestCheckAttrCmd_Check(t *testing.T) {
 	ctx := testhelper.Context(t)
 	cfg := testcfg.Build(t)