processExecutableOpen

fn processExecutableOpen(
    userdata: ?*anyopaque,
    flags: Dir.OpenFileOptions,
) process.OpenExecutableError!File {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    // _NSGetExecutablePath() returns a path that might be a symlink to
    // the executable. Here it does not matter since we open it.
    var symlink_path_buf: [c.PATH_MAX + 1]u8 = undefined;
    var n: u32 = symlink_path_buf.len;
    const rc = c._NSGetExecutablePath(&symlink_path_buf, &n);
    if (rc != 0) return error.NameTooLong;
    const symlink_path = std.mem.sliceTo(&symlink_path_buf, 0);
    return dirOpenFile(ev, .cwd(), symlink_path, flags);
}