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feat: Safer epoll timeout
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@JonathanWoollett-Light
JonathanWoollett-Light committed Nov 24, 2023
1 parent c1147c6 commit b79c2b8
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Showing 4 changed files with 237 additions and 230 deletions.
3 changes: 3 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,9 @@ feature! {
#[allow(missing_docs)]
pub mod unistd;

#[cfg(any(feature = "poll", feature = "event"))]
mod poll_timeout;

use std::ffi::{CStr, CString, OsStr};
use std::mem::MaybeUninit;
use std::os::unix::ffi::OsStrExt;
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226 changes: 2 additions & 224 deletions src/poll.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
//! Wait for events to trigger on specific file descriptors
use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd};
use std::time::Duration;

use crate::errno::Errno;
pub use crate::poll_timeout::PollTimeout;
use crate::Result;

/// This is a wrapper around `libc::pollfd`.
///
/// It's meant to be used as an argument to the [`poll`](fn.poll.html) and
Expand Down Expand Up @@ -175,229 +176,6 @@ libc_bitflags! {
}
}

/// Timeout argument for [`poll`].
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd)]
pub struct PollTimeout(i32);

impl PollTimeout {
/// Blocks indefinitely.
///
/// > Specifying a negative value in timeout means an infinite timeout.
pub const NONE: Self = Self(-1);
/// Returns immediately.
///
/// > Specifying a timeout of zero causes poll() to return immediately, even if no file
/// > descriptors are ready.
pub const ZERO: Self = Self(0);
/// Blocks for at most [`std::i32::MAX`] milliseconds.
pub const MAX: Self = Self(i32::MAX);
/// Returns if `self` equals [`PollTimeout::NONE`].
pub fn is_none(&self) -> bool {
// > Specifying a negative value in timeout means an infinite timeout.
*self <= Self::NONE
}
/// Returns if `self` does not equal [`PollTimeout::NONE`].
pub fn is_some(&self) -> bool {
!self.is_none()
}
/// Returns the timeout in milliseconds if there is some, otherwise returns `None`.
pub fn as_millis(&self) -> Option<u32> {
self.is_some().then_some(u32::try_from(self.0).unwrap())
}
/// Returns the timeout as a `Duration` if there is some, otherwise returns `None`.
pub fn timeout(&self) -> Option<Duration> {
self.as_millis()
.map(|x| Duration::from_millis(u64::from(x)))
}
}

/// Error type for integer conversions into `PollTimeout`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PollTimeoutTryFromError {
/// Passing a value less than -1 is invalid on some systems, see
/// <https://man.freebsd.org/cgi/man.cgi?poll#end>.
TooNegative,
/// Passing a value greater than `i32::MAX` is invalid.
TooPositive,
}

impl std::fmt::Display for PollTimeoutTryFromError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::TooNegative => write!(f, "Passed a negative timeout less than -1."),
Self::TooPositive => write!(f, "Passed a positive timeout greater than `i32::MAX` milliseconds.")
}
}
}

impl std::error::Error for PollTimeoutTryFromError {}

impl<T: Into<PollTimeout>> From<Option<T>> for PollTimeout {
fn from(x: Option<T>) -> Self {
x.map_or(Self::NONE, |x| x.into())
}
}
impl TryFrom<Duration> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: Duration) -> std::result::Result<Self, Self::Error> {
Ok(Self(
i32::try_from(x.as_millis())
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
))
}
}
impl TryFrom<u128> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: u128) -> std::result::Result<Self, Self::Error> {
Ok(Self(
i32::try_from(x)
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
))
}
}
impl TryFrom<u64> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: u64) -> std::result::Result<Self, Self::Error> {
Ok(Self(
i32::try_from(x)
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
))
}
}
impl TryFrom<u32> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: u32) -> std::result::Result<Self, Self::Error> {
Ok(Self(
i32::try_from(x)
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
))
}
}
impl From<u16> for PollTimeout {
fn from(x: u16) -> Self {
Self(i32::from(x))
}
}
impl From<u8> for PollTimeout {
fn from(x: u8) -> Self {
Self(i32::from(x))
}
}
impl TryFrom<i128> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: i128) -> std::result::Result<Self, Self::Error> {
match x {
..=-2 => Err(PollTimeoutTryFromError::TooNegative),
-1.. => Ok(Self(
i32::try_from(x)
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
)),
}
}
}
impl TryFrom<i64> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: i64) -> std::result::Result<Self, Self::Error> {
match x {
..=-2 => Err(PollTimeoutTryFromError::TooNegative),
-1.. => Ok(Self(
i32::try_from(x)
.map_err(|_| PollTimeoutTryFromError::TooPositive)?,
)),
}
}
}
impl TryFrom<i32> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: i32) -> std::result::Result<Self, Self::Error> {
match x {
..=-2 => Err(PollTimeoutTryFromError::TooNegative),
-1.. => Ok(Self(x)),
}
}
}
impl TryFrom<i16> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: i16) -> std::result::Result<Self, Self::Error> {
match x {
..=-2 => Err(PollTimeoutTryFromError::TooNegative),
-1.. => Ok(Self(i32::from(x))),
}
}
}
impl TryFrom<i8> for PollTimeout {
type Error = PollTimeoutTryFromError;
fn try_from(x: i8) -> std::result::Result<Self, Self::Error> {
match x {
..=-2 => Err(PollTimeoutTryFromError::TooNegative),
-1.. => Ok(Self(i32::from(x))),
}
}
}
impl TryFrom<PollTimeout> for Duration {
type Error = ();
fn try_from(x: PollTimeout) -> std::result::Result<Self, ()> {
x.timeout().ok_or(())
}
}
impl TryFrom<PollTimeout> for u128 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl TryFrom<PollTimeout> for u64 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl TryFrom<PollTimeout> for u32 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl TryFrom<PollTimeout> for u16 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl TryFrom<PollTimeout> for u8 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl From<PollTimeout> for i128 {
fn from(x: PollTimeout) -> Self {
Self::from(x.0)
}
}
impl From<PollTimeout> for i64 {
fn from(x: PollTimeout) -> Self {
Self::from(x.0)
}
}
impl From<PollTimeout> for i32 {
fn from(x: PollTimeout) -> Self {
x.0
}
}
impl TryFrom<PollTimeout> for i16 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}
impl TryFrom<PollTimeout> for i8 {
type Error = <Self as TryFrom<i32>>::Error;
fn try_from(x: PollTimeout) -> std::result::Result<Self, Self::Error> {
Self::try_from(x.0)
}
}

/// `poll` waits for one of a set of file descriptors to become ready to perform I/O.
/// ([`poll(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html))
///
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