On 5/18/2026 2:27 PM, Warner Losh wrote:
> Add I/O multiplexing system call shims: select, pselect, and ppoll
> with proper fd_set, timespec/timeval, and signal mask conversion.
>
> Signed-off-by: Stacey Son <[email protected]>
> Signed-off-by: Mikaël Urankar <[email protected]>
> Signed-off-by: Kyle Evans <[email protected]>
> Signed-off-by: Warner Losh <[email protected]>
> Assisted-by: Claude Opus 4.6 (1M context)
> ---
> bsd-user/freebsd/os-time.h | 202
> +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 202 insertions(+)
>
> diff --git a/bsd-user/freebsd/os-time.h b/bsd-user/freebsd/os-time.h
> index 05fa043442..12c5ba02e8 100644
> --- a/bsd-user/freebsd/os-time.h
> +++ b/bsd-user/freebsd/os-time.h
> @@ -427,5 +427,207 @@ static inline abi_long
> do_freebsd_ktimer_gettime(abi_long arg1, abi_long arg2)
> return ret;
> }
>
> +/* select(2) */
> +static inline abi_long do_freebsd_select(CPUArchState *env, int n,
> + abi_ulong rfd_addr, abi_ulong wfd_addr, abi_ulong efd_addr,
> + abi_ulong target_tv_addr)
> +{
> + fd_set rfds, wfds, efds;
> + fd_set *rfds_ptr, *wfds_ptr, *efds_ptr;
> + struct timeval tv, *tvp;
> + abi_long ret, error;
> +
> + ret = copy_from_user_fdset_ptr(&rfds, &rfds_ptr, rfd_addr, n);
> + if (ret != 0) {
> + return ret;
> + }
> + ret = copy_from_user_fdset_ptr(&wfds, &wfds_ptr, wfd_addr, n);
> + if (ret != 0) {
> + return ret;
> + }
> + ret = copy_from_user_fdset_ptr(&efds, &efds_ptr, efd_addr, n);
> + if (ret != 0) {
> + return ret;
> + }
> +
We can factor this with a macro
> + if (target_tv_addr != 0) {
> + if (t2h_freebsd_timeval(&tv, target_tv_addr)) {
> + return -TARGET_EFAULT;
> + }
> + tvp = &tv;
> + } else {
> + tvp = NULL;
> + }
> +
> + ret = get_errno(safe_select(n, rfds_ptr, wfds_ptr, efds_ptr, tvp));
> +
> + if (!is_error(ret)) {
We can simplify depth here by using an early return.
if (is_error(ret)) {
return ret;
}
> + if (rfd_addr != 0) {
> + error = copy_to_user_fdset(rfd_addr, &rfds, n);
> + if (error != 0) {
> + return error;
> + }
> + }
> + if (wfd_addr != 0) {
> + error = copy_to_user_fdset(wfd_addr, &wfds, n);
> + if (error != 0) {
> + return error;
> + }
> + }
> + if (efd_addr != 0) {
> + error = copy_to_user_fdset(efd_addr, &efds, n);
> + if (error != 0) {
> + return error;
> + }
> + }
Same, reuse the macro defined above.
> + if (target_tv_addr != 0) {
> + error = h2t_freebsd_timeval(&tv, target_tv_addr);
> + if (is_error(error)) {
> + return error;
> + }
> + }
> + }
> + return ret;
> +}
> +
> +/* pselect(2) */
> +static inline abi_long do_freebsd_pselect(CPUArchState *env, int n,
> + abi_ulong rfd_addr, abi_ulong wfd_addr, abi_ulong efd_addr,
> + abi_ulong ts_addr, abi_ulong set_addr)
> +{
> + CPUState *cpu = env_cpu(env);
> + TaskState *tstate = cpu->opaque;
> + fd_set rfds, wfds, efds;
> + fd_set *rfds_ptr, *wfds_ptr, *efds_ptr;
> + sigset_t *set_ptr;
> + struct timespec ts, *ts_ptr;
> + void *p;
> + abi_long ret, error;
> +
> + ret = copy_from_user_fdset_ptr(&rfds, &rfds_ptr, rfd_addr, n);
> + if (is_error(ret)) {
> + return ret;
> + }
> + ret = copy_from_user_fdset_ptr(&wfds, &wfds_ptr, wfd_addr, n);
> + if (is_error(ret)) {
> + return ret;
> + }
> + ret = copy_from_user_fdset_ptr(&efds, &efds_ptr, efd_addr, n);
> + if (is_error(ret)) {
> + return ret;
> + }
> +
Same than above.
> + /* Unlike select(), pselect() uses struct timespec instead of timeval */
> + if (ts_addr) {
> + if (t2h_freebsd_timespec(&ts, ts_addr)) {
> + return -TARGET_EFAULT;
> + }
> + ts_ptr = &ts;
> + } else {
> + ts_ptr = NULL;
> + }
> +
> + if (set_addr != 0) {
> + p = lock_user(VERIFY_READ, set_addr, sizeof(target_sigset_t), 1);
> + if (p == NULL) {
> + return -TARGET_EFAULT;
> + }
> + target_to_host_sigset(&tstate->sigsuspend_mask, p);
> + unlock_user(p, set_addr, 0);
> + set_ptr = &tstate->sigsuspend_mask;
> + } else {
> + set_ptr = NULL;
> + }
> +
> + ret = get_errno(safe_pselect(n, rfds_ptr, wfds_ptr, efds_ptr, ts_ptr,
> + set_ptr));
> + if (ret != -TARGET_ERESTART) {
> + tstate->in_sigsuspend = true;
> + }
> + if (!is_error(ret)) {
> + if (rfd_addr != 0) {
> + error = copy_to_user_fdset(rfd_addr, &rfds, n);
> + if (is_error(error)) {
> + return error;
> + }
> + }
> + if (wfd_addr != 0) {
> + error = copy_to_user_fdset(wfd_addr, &wfds, n);
> + if (is_error(error)) {
> + return error;
> + }
> + }
> + if (efd_addr != 0) {
> + error = copy_to_user_fdset(efd_addr, &efds, n);
> + if (is_error(error)) {
> + return error;
> + }
> + }
> + }
> + return ret;
> +}
> +
> +/* ppoll(2) */
> +static inline abi_long do_freebsd_ppoll(CPUArchState *env, abi_long arg1,
> + abi_long arg2, abi_ulong arg3, abi_ulong arg4)
> +{
> + CPUState *cpu = env_cpu(env);
> + TaskState *tstate = cpu->opaque;
> + abi_long ret;
> + nfds_t i, nfds = arg2;
> + struct pollfd *pfd;
> + struct target_pollfd *target_pfd;
> + struct timespec ts, *ts_ptr;
> + sigset_t *set_ptr;
> + void *p;
> +
> + target_pfd = lock_user(VERIFY_WRITE, arg1,
> + sizeof(struct target_pollfd) * nfds, 1);
> + if (!target_pfd) {
> + return -TARGET_EFAULT;
> + }
> + pfd = alloca(sizeof(struct pollfd) * nfds);
> + for (i = 0; i < nfds; i++) {
> + pfd[i].fd = tswap32(target_pfd[i].fd);
> + pfd[i].events = tswap16(target_pfd[i].events);
> + }
> +
> + /* Unlike poll(), ppoll() uses struct timespec. */
> + if (arg3) {
> + if (t2h_freebsd_timespec(&ts, arg3)) {
> + return -TARGET_EFAULT;
> + }
> + ts_ptr = &ts;
> + } else {
> + ts_ptr = NULL;
> + }
> +
> + if (arg4 != 0) {
> + p = lock_user(VERIFY_READ, arg4, sizeof(target_sigset_t), 1);
> + if (p == NULL) {
> + return -TARGET_EFAULT;
> + }
> + target_to_host_sigset(&tstate->sigsuspend_mask, p);
> + unlock_user(p, arg4, 0);
> + set_ptr = &tstate->sigsuspend_mask;
> + } else {
> + set_ptr = NULL;
> + }
> +
> + ret = get_errno(ppoll(pfd, nfds, ts_ptr, set_ptr));
> + if (ret != -TARGET_ERESTART) {
> + tstate->in_sigsuspend = true;
> + }
> + if (!is_error(ret)) {
> + for (i = 0; i < nfds; i++) {
> + target_pfd[i].revents = tswap16(pfd[i].revents);
> + }
> + }
> + unlock_user(target_pfd, arg1, sizeof(struct target_pollfd) * nfds);
> +
> + return ret;
> +}
> +
> +/* kqueue(2) */
>
> #endif /* FREEBSD_OS_TIME_H */
>
