readv
CATCH_EINTR(n = readv(fd, msg->msg_iov, msg->msg_iovlen));
SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec,
syscall_len = readv(fd, iov, 1);
CASE_TEST(readv_badf); EXPECT_SYSER(1, readv(-1, &iov_one, 1), -1, EBADF); break;
CASE_TEST(readv_zero); EXPECT_SYSZR(1, readv(0, NULL, 0)); break;