fn isBadFilename(filename: []const u8) bool
fn isBadFilename(filename: []const u8) bool { if (filename.len == 0 or filename[0] == '/') return true; var it = std.mem.splitScalar(u8, filename, '/'); while (it.next()) |part| { if (std.mem.eql(u8, part, "..")) return true; } return false; }