| 17 | |
| 18 | #[inline] |
| 19 | pub(crate) fn poll(fds: &mut [PollFd<'_>], timeout: Option<&Timespec>) -> io::Result<usize> { |
| 20 | let (fds_addr_mut, fds_len) = slice_mut(fds); |
| 21 | |
| 22 | #[cfg(target_pointer_width = "32")] |
| 23 | unsafe { |
| 24 | // If we don't have Linux 5.1, and the timeout fits in a |
| 25 | // `__kernel_old_timespec`, use plain `ppoll`. |
| 26 | // |
| 27 | // We do this unconditionally, rather than trying `ppoll_time64` and |
| 28 | // falling back on `Errno::NOSYS`, because seccomp configurations will |
| 29 | // sometimes abort the process on syscalls they don't recognize. |
| 30 | #[cfg(not(feature = "linux_5_1"))] |
| 31 | { |
| 32 | use linux_raw_sys::general::__kernel_old_timespec; |
| 33 | |
| 34 | // If we don't have a timeout, or if we can convert the timeout to |
| 35 | // a `__kernel_old_timespec`, the use `__NR_ppoll`. |
| 36 | fn convert(timeout: &Timespec) -> Option<__kernel_old_timespec> { |
| 37 | Some(__kernel_old_timespec { |
| 38 | tv_sec: timeout.tv_sec.try_into().ok()?, |
| 39 | tv_nsec: timeout.tv_nsec.try_into().ok()?, |
| 40 | }) |
| 41 | } |
| 42 | let old_timeout = if let Some(timeout) = timeout { |
| 43 | match convert(timeout) { |
| 44 | // Could not convert timeout. |
| 45 | None => None, |
| 46 | // Could convert timeout. Ok! |
| 47 | Some(old_timeout) => Some(Some(old_timeout)), |
| 48 | } |
| 49 | } else { |
| 50 | // No timeout. Ok! |
| 51 | Some(None) |
| 52 | }; |
| 53 | if let Some(mut old_timeout) = old_timeout { |
| 54 | // Call `ppoll`. |
| 55 | // |
| 56 | // Linux's `ppoll` mutates the timeout argument. Our public |
| 57 | // interface does not do this, because it's not portable to other |
| 58 | // platforms, so we create a temporary value to hide this behavior. |
| 59 | return ret_usize(syscall!( |
| 60 | __NR_ppoll, |
| 61 | fds_addr_mut, |
| 62 | fds_len, |
| 63 | opt_mut(old_timeout.as_mut()), |
| 64 | zero(), |
| 65 | size_of::<kernel_sigset_t, _>() |
| 66 | )); |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | // We either have Linux 5.1 or the timeout didn't fit in |
| 71 | // `__kernel_old_timespec` so `__NR_ppoll_time64` will either |
| 72 | // succeed or fail due to our having no other options. |
| 73 | |
| 74 | // Call `ppoll_time64`. |
| 75 | // |
| 76 | // Linux's `ppoll_time64` mutates the timeout argument. Our public |