Source code
Revision control
Copy as Markdown
Other Tools
// vim: tw=80
//! POSIX Asynchronous I/O
//!
//! The POSIX AIO interface is used for asynchronous I/O on files and disk-like
//! devices. It supports [`read`](struct.AioRead.html#method.new),
//! [`write`](struct.AioWrite.html#method.new),
//! [`fsync`](struct.AioFsync.html#method.new),
//! [`readv`](struct.AioReadv.html#method.new), and
//! [`writev`](struct.AioWritev.html#method.new), operations, subject to
//! platform support. Completion
//! notifications can optionally be delivered via
//! [signals](../signal/enum.SigevNotify.html#variant.SigevSignal), via the
//! [`aio_suspend`](fn.aio_suspend.html) function, or via polling. Some
//! platforms support other completion
//! notifications, such as
//! [kevent](../signal/enum.SigevNotify.html#variant.SigevKevent).
//!
//! Multiple operations may be submitted in a batch with
//! [`lio_listio`](fn.lio_listio.html), though the standard does not guarantee
//! that they will be executed atomically.
//!
//! Outstanding operations may be cancelled with
//! [`cancel`](trait.Aio.html#method.cancel) or
//! [`aio_cancel_all`](fn.aio_cancel_all.html), though the operating system may
//! not support this for all filesystems and devices.
#[cfg(target_os = "freebsd")]
use std::io::{IoSlice, IoSliceMut};
use std::{
convert::TryFrom,
fmt::{self, Debug},
marker::{PhantomData, PhantomPinned},
mem,
os::unix::io::{AsFd, AsRawFd, BorrowedFd},
pin::Pin,
ptr, thread,
};
use libc::off_t;
use pin_utils::unsafe_pinned;
use crate::{
errno::Errno,
sys::{signal::*, time::TimeSpec},
Result,
};
libc_enum! {
/// Mode for `AioCb::fsync`. Controls whether only data or both data and
/// metadata are synced.
#[repr(i32)]
#[non_exhaustive]
pub enum AioFsyncMode {
/// do it like `fsync`
O_SYNC,
/// on supported operating systems only, do it like `fdatasync`
#[cfg(any(apple_targets,
target_os = "linux",
target_os = "freebsd",
netbsdlike))]
O_DSYNC
}
impl TryFrom<i32>
}
libc_enum! {
/// Mode for [`lio_listio`](fn.lio_listio.html)
#[repr(i32)]
pub enum LioMode {
/// Requests that [`lio_listio`](fn.lio_listio.html) block until all
/// requested operations have been completed
LIO_WAIT,
/// Requests that [`lio_listio`](fn.lio_listio.html) return immediately
LIO_NOWAIT,
}
}
/// Return values for [`AioCb::cancel`](struct.AioCb.html#method.cancel) and
/// [`aio_cancel_all`](fn.aio_cancel_all.html)
#[repr(i32)]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum AioCancelStat {
/// All outstanding requests were canceled
AioCanceled = libc::AIO_CANCELED,
/// Some requests were not canceled. Their status should be checked with
/// `AioCb::error`
AioNotCanceled = libc::AIO_NOTCANCELED,
/// All of the requests have already finished
AioAllDone = libc::AIO_ALLDONE,
}
/// Newtype that adds Send and Sync to libc::aiocb, which contains raw pointers
#[repr(transparent)]
struct LibcAiocb(libc::aiocb);
unsafe impl Send for LibcAiocb {}
unsafe impl Sync for LibcAiocb {}
/// Base class for all AIO operations. Should only be used directly when
/// checking for completion.
// We could create some kind of AsPinnedMut trait, and implement it for all aio
// ops, allowing the crate's users to get pinned references to `AioCb`. That
// could save some code for things like polling methods. But IMHO it would
// provide polymorphism at the wrong level. Instead, the best place for
// polymorphism is at the level of `Futures`.
#[repr(C)]
struct AioCb<'a> {
aiocb: LibcAiocb,
/// Could this `AioCb` potentially have any in-kernel state?
// It would be really nice to perform the in-progress check entirely at
// compile time. But I can't figure out how, because:
// * Future::poll takes a `Pin<&mut self>` rather than `self`, and
// * Rust's lack of an equivalent of C++'s Guaranteed Copy Elision means
// that there's no way to write an AioCb constructor that neither boxes
// the object itself, nor moves it during return.
in_progress: bool,
_fd: PhantomData<BorrowedFd<'a>>,
}
impl<'a> AioCb<'a> {
pin_utils::unsafe_unpinned!(aiocb: LibcAiocb);
fn aio_return(mut self: Pin<&mut Self>) -> Result<usize> {
self.in_progress = false;
unsafe {
let p: *mut libc::aiocb = &mut self.aiocb.0;
Errno::result(libc::aio_return(p))
}
.map(|r| r as usize)
}
fn cancel(mut self: Pin<&mut Self>) -> Result<AioCancelStat> {
let r = unsafe {
libc::aio_cancel(self.aiocb.0.aio_fildes, &mut self.aiocb.0)
};
match r {
libc::AIO_CANCELED => Ok(AioCancelStat::AioCanceled),
libc::AIO_NOTCANCELED => Ok(AioCancelStat::AioNotCanceled),
libc::AIO_ALLDONE => Ok(AioCancelStat::AioAllDone),
-1 => Err(Errno::last()),
_ => panic!("unknown aio_cancel return value"),
}
}
fn common_init(
fd: BorrowedFd<'a>,
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
// Use mem::zeroed instead of explicitly zeroing each field, because the
// number and name of reserved fields is OS-dependent. On some OSes,
// some reserved fields are used the kernel for state, and must be
// explicitly zeroed when allocated.
let mut a = unsafe { mem::zeroed::<libc::aiocb>() };
a.aio_fildes = fd.as_raw_fd();
a.aio_reqprio = prio;
a.aio_sigevent = SigEvent::new(sigev_notify).sigevent();
AioCb {
aiocb: LibcAiocb(a),
in_progress: false,
_fd: PhantomData,
}
}
fn error(self: Pin<&mut Self>) -> Result<()> {
let r = unsafe { libc::aio_error(&self.aiocb().0) };
match r {
0 => Ok(()),
num if num > 0 => Err(Errno::from_raw(num)),
-1 => Err(Errno::last()),
num => panic!("unknown aio_error return value {num:?}"),
}
}
fn in_progress(&self) -> bool {
self.in_progress
}
fn set_in_progress(mut self: Pin<&mut Self>) {
self.as_mut().in_progress = true;
}
/// Update the notification settings for an existing AIO operation that has
/// not yet been submitted.
// Takes a normal reference rather than a pinned one because this method is
// normally called before the object needs to be pinned, that is, before
// it's been submitted to the kernel.
fn set_sigev_notify(&mut self, sigev_notify: SigevNotify) {
assert!(
!self.in_progress,
"Can't change notification settings for an in-progress operation"
);
self.aiocb.0.aio_sigevent = SigEvent::new(sigev_notify).sigevent();
}
}
impl<'a> Debug for AioCb<'a> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("AioCb")
.field("aiocb", &self.aiocb.0)
.field("in_progress", &self.in_progress)
.finish()
}
}
impl<'a> Drop for AioCb<'a> {
/// If the `AioCb` has no remaining state in the kernel, just drop it.
/// Otherwise, dropping constitutes a resource leak, which is an error
fn drop(&mut self) {
assert!(
thread::panicking() || !self.in_progress,
"Dropped an in-progress AioCb"
);
}
}
/// Methods common to all AIO operations
pub trait Aio {
/// The return type of [`Aio::aio_return`].
type Output;
/// Retrieve return status of an asynchronous operation.
///
/// Should only be called once for each operation, after [`Aio::error`]
/// indicates that it has completed. The result is the same as for the
/// synchronous `read(2)`, `write(2)`, of `fsync(2)` functions.
///
/// # References
///
fn aio_return(self: Pin<&mut Self>) -> Result<Self::Output>;
/// Cancels an outstanding AIO request.
///
/// The operating system is not required to implement cancellation for all
/// file and device types. Even if it does, there is no guarantee that the
/// operation has not already completed. So the caller must check the
/// result and handle operations that were not canceled or that have already
/// completed.
///
/// # Examples
///
/// Cancel an outstanding aio operation. Note that we must still call
/// `aio_return` to free resources, even though we don't care about the
/// result.
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::io::Write;
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// let wbuf = b"CDEF";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = Box::pin(AioWrite::new(f.as_fd(),
/// 2, //offset
/// &wbuf[..],
/// 0, //priority
/// SigevNotify::SigevNone));
/// aiocb.as_mut().submit().unwrap();
/// let cs = aiocb.as_mut().cancel().unwrap();
/// if cs == AioCancelStat::AioNotCanceled {
/// while (aiocb.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// }
/// // Must call `aio_return`, but ignore the result
/// let _ = aiocb.as_mut().aio_return();
/// ```
///
/// # References
///
fn cancel(self: Pin<&mut Self>) -> Result<AioCancelStat>;
/// Retrieve error status of an asynchronous operation.
///
/// If the request has not yet completed, returns `EINPROGRESS`. Otherwise,
/// returns `Ok` or any other error.
///
/// # Examples
///
/// Issue an aio operation and use `error` to poll for completion. Polling
/// is an alternative to `aio_suspend`, used by most of the other examples.
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = Box::pin(AioWrite::new(f.as_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone));
/// aiocb.as_mut().submit().unwrap();
/// while (aiocb.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
///
/// # References
///
fn error(self: Pin<&mut Self>) -> Result<()>;
/// Returns the underlying file descriptor associated with the operation.
fn fd(&self) -> BorrowedFd;
/// Does this operation currently have any in-kernel state?
///
/// Dropping an operation that does have in-kernel state constitutes a
/// resource leak.
///
/// # Examples
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify::SigevNone;
/// # use std::{thread, time};
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// let f = tempfile().unwrap();
/// let mut aiof = Box::pin(AioFsync::new(f.as_fd(), AioFsyncMode::O_SYNC,
/// 0, SigevNone));
/// assert!(!aiof.as_mut().in_progress());
/// aiof.as_mut().submit().expect("aio_fsync failed early");
/// assert!(aiof.as_mut().in_progress());
/// while (aiof.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// aiof.as_mut().aio_return().expect("aio_fsync failed late");
/// assert!(!aiof.as_mut().in_progress());
/// ```
fn in_progress(&self) -> bool;
/// Returns the priority of the `AioCb`
fn priority(&self) -> i32;
/// Update the notification settings for an existing AIO operation that has
/// not yet been submitted.
fn set_sigev_notify(&mut self, sev: SigevNotify);
/// Returns the `SigEvent` that will be used for notification.
fn sigevent(&self) -> SigEvent;
/// Actually start the I/O operation.
///
/// After calling this method and until [`Aio::aio_return`] returns `Ok`,
/// the structure may not be moved in memory.
fn submit(self: Pin<&mut Self>) -> Result<()>;
}
macro_rules! aio_methods {
() => {
fn cancel(self: Pin<&mut Self>) -> Result<AioCancelStat> {
self.aiocb().cancel()
}
fn error(self: Pin<&mut Self>) -> Result<()> {
self.aiocb().error()
}
fn fd(&self) -> BorrowedFd<'a> {
// safe because self's lifetime is the same as the original file
// descriptor.
unsafe { BorrowedFd::borrow_raw(self.aiocb.aiocb.0.aio_fildes) }
}
fn in_progress(&self) -> bool {
self.aiocb.in_progress()
}
fn priority(&self) -> i32 {
self.aiocb.aiocb.0.aio_reqprio
}
fn set_sigev_notify(&mut self, sev: SigevNotify) {
self.aiocb.set_sigev_notify(sev)
}
fn sigevent(&self) -> SigEvent {
SigEvent::from(&self.aiocb.aiocb.0.aio_sigevent)
}
};
($func:ident) => {
aio_methods!();
fn aio_return(self: Pin<&mut Self>) -> Result<<Self as Aio>::Output> {
self.aiocb().aio_return()
}
fn submit(mut self: Pin<&mut Self>) -> Result<()> {
let p: *mut libc::aiocb = &mut self.as_mut().aiocb().aiocb.0;
Errno::result({ unsafe { libc::$func(p) } }).map(|_| {
self.aiocb().set_in_progress();
})
}
};
}
/// An asynchronous version of `fsync(2)`.
///
/// # References
///
/// # Examples
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify::SigevNone;
/// # use std::{thread, time};
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// let f = tempfile().unwrap();
/// let mut aiof = Box::pin(AioFsync::new(f.as_fd(), AioFsyncMode::O_SYNC,
/// 0, SigevNone));
/// aiof.as_mut().submit().expect("aio_fsync failed early");
/// while (aiof.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// aiof.as_mut().aio_return().expect("aio_fsync failed late");
/// ```
#[derive(Debug)]
#[repr(transparent)]
pub struct AioFsync<'a> {
aiocb: AioCb<'a>,
_pin: PhantomPinned,
}
impl<'a> AioFsync<'a> {
unsafe_pinned!(aiocb: AioCb<'a>);
/// Returns the operation's fsync mode: data and metadata or data only?
pub fn mode(&self) -> AioFsyncMode {
AioFsyncMode::try_from(self.aiocb.aiocb.0.aio_lio_opcode).unwrap()
}
/// Create a new `AioFsync`.
///
/// # Arguments
///
/// * `fd`: File descriptor to sync.
/// * `mode`: Whether to sync file metadata too, or just data.
/// * `prio`: If POSIX Prioritized IO is supported, then the
/// operation will be prioritized at the process's
/// priority level minus `prio`.
/// * `sigev_notify`: Determines how you will be notified of event
/// completion.
pub fn new(
fd: BorrowedFd<'a>,
mode: AioFsyncMode,
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
// To save some memory, store mode in an unused field of the AioCb.
// True it isn't very much memory, but downstream creates will likely
// create an enum containing this and other AioCb variants and pack
// those enums into data structures like Vec, so it adds up.
aiocb.aiocb.0.aio_lio_opcode = mode as libc::c_int;
AioFsync {
aiocb,
_pin: PhantomPinned,
}
}
}
impl<'a> Aio for AioFsync<'a> {
type Output = ();
aio_methods!();
fn aio_return(self: Pin<&mut Self>) -> Result<()> {
self.aiocb().aio_return().map(drop)
}
fn submit(mut self: Pin<&mut Self>) -> Result<()> {
let aiocb = &mut self.as_mut().aiocb().aiocb.0;
let mode = mem::replace(&mut aiocb.aio_lio_opcode, 0);
let p: *mut libc::aiocb = aiocb;
Errno::result(unsafe { libc::aio_fsync(mode, p) }).map(|_| {
self.aiocb().set_in_progress();
})
}
}
// AioFsync does not need AsMut, since it can't be used with lio_listio
impl<'a> AsRef<libc::aiocb> for AioFsync<'a> {
fn as_ref(&self) -> &libc::aiocb {
&self.aiocb.aiocb.0
}
}
/// Asynchronously reads from a file descriptor into a buffer
///
/// # References
///
///
/// # Examples
///
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::io::Write;
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"abcdef123456";
/// const LEN: usize = 4;
/// let mut rbuf = vec![0; LEN];
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// {
/// let mut aior = Box::pin(
/// AioRead::new(
/// f.as_fd(),
/// 2, //offset
/// &mut rbuf,
/// 0, //priority
/// SigevNotify::SigevNone
/// )
/// );
/// aior.as_mut().submit().unwrap();
/// while (aior.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aior.as_mut().aio_return().unwrap(), LEN);
/// }
/// assert_eq!(rbuf, b"cdef");
/// ```
#[derive(Debug)]
#[repr(transparent)]
pub struct AioRead<'a> {
aiocb: AioCb<'a>,
_data: PhantomData<&'a [u8]>,
_pin: PhantomPinned,
}
impl<'a> AioRead<'a> {
unsafe_pinned!(aiocb: AioCb<'a>);
/// Returns the requested length of the aio operation in bytes
///
/// This method returns the *requested* length of the operation. To get the
/// number of bytes actually read or written by a completed operation, use
/// `aio_return` instead.
pub fn nbytes(&self) -> usize {
self.aiocb.aiocb.0.aio_nbytes
}
/// Create a new `AioRead`, placing the data in a mutable slice.
///
/// # Arguments
///
/// * `fd`: File descriptor to read from
/// * `offs`: File offset
/// * `buf`: A memory buffer. It must outlive the `AioRead`.
/// * `prio`: If POSIX Prioritized IO is supported, then the
/// operation will be prioritized at the process's
/// priority level minus `prio`
/// * `sigev_notify`: Determines how you will be notified of event
/// completion.
pub fn new(
fd: BorrowedFd<'a>,
offs: off_t,
buf: &'a mut [u8],
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
aiocb.aiocb.0.aio_nbytes = buf.len();
aiocb.aiocb.0.aio_buf = buf.as_mut_ptr().cast();
aiocb.aiocb.0.aio_lio_opcode = libc::LIO_READ;
aiocb.aiocb.0.aio_offset = offs;
AioRead {
aiocb,
_data: PhantomData,
_pin: PhantomPinned,
}
}
/// Returns the file offset of the operation.
pub fn offset(&self) -> off_t {
self.aiocb.aiocb.0.aio_offset
}
}
impl<'a> Aio for AioRead<'a> {
type Output = usize;
aio_methods!(aio_read);
}
impl<'a> AsMut<libc::aiocb> for AioRead<'a> {
fn as_mut(&mut self) -> &mut libc::aiocb {
&mut self.aiocb.aiocb.0
}
}
impl<'a> AsRef<libc::aiocb> for AioRead<'a> {
fn as_ref(&self) -> &libc::aiocb {
&self.aiocb.aiocb.0
}
}
/// Asynchronously reads from a file descriptor into a scatter/gather list of buffers.
///
/// # References
///
///
/// # Examples
///
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::io::{IoSliceMut, Write};
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"abcdef123456";
/// let mut rbuf0 = vec![0; 4];
/// let mut rbuf1 = vec![0; 2];
/// let expected_len = rbuf0.len() + rbuf1.len();
/// let mut rbufs = [IoSliceMut::new(&mut rbuf0), IoSliceMut::new(&mut rbuf1)];
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// {
/// let mut aior = Box::pin(
/// AioReadv::new(
/// f.as_fd(),
/// 2, //offset
/// &mut rbufs,
/// 0, //priority
/// SigevNotify::SigevNone
/// )
/// );
/// aior.as_mut().submit().unwrap();
/// while (aior.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aior.as_mut().aio_return().unwrap(), expected_len);
/// }
/// assert_eq!(rbuf0, b"cdef");
/// assert_eq!(rbuf1, b"12");
/// ```
#[cfg(target_os = "freebsd")]
#[derive(Debug)]
#[repr(transparent)]
pub struct AioReadv<'a> {
aiocb: AioCb<'a>,
_data: PhantomData<&'a [&'a [u8]]>,
_pin: PhantomPinned,
}
#[cfg(target_os = "freebsd")]
impl<'a> AioReadv<'a> {
unsafe_pinned!(aiocb: AioCb<'a>);
/// Returns the number of buffers the operation will read into.
pub fn iovlen(&self) -> usize {
self.aiocb.aiocb.0.aio_nbytes
}
/// Create a new `AioReadv`, placing the data in a list of mutable slices.
///
/// # Arguments
///
/// * `fd`: File descriptor to read from
/// * `offs`: File offset
/// * `bufs`: A scatter/gather list of memory buffers. They must
/// outlive the `AioReadv`.
/// * `prio`: If POSIX Prioritized IO is supported, then the
/// operation will be prioritized at the process's
/// priority level minus `prio`
/// * `sigev_notify`: Determines how you will be notified of event
/// completion.
pub fn new(
fd: BorrowedFd<'a>,
offs: off_t,
bufs: &mut [IoSliceMut<'a>],
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
// In vectored mode, aio_nbytes stores the length of the iovec array,
// not the byte count.
aiocb.aiocb.0.aio_nbytes = bufs.len();
aiocb.aiocb.0.aio_buf = bufs.as_mut_ptr().cast();
aiocb.aiocb.0.aio_lio_opcode = libc::LIO_READV;
aiocb.aiocb.0.aio_offset = offs;
AioReadv {
aiocb,
_data: PhantomData,
_pin: PhantomPinned,
}
}
/// Returns the file offset of the operation.
pub fn offset(&self) -> off_t {
self.aiocb.aiocb.0.aio_offset
}
}
#[cfg(target_os = "freebsd")]
impl<'a> Aio for AioReadv<'a> {
type Output = usize;
aio_methods!(aio_readv);
}
#[cfg(target_os = "freebsd")]
impl<'a> AsMut<libc::aiocb> for AioReadv<'a> {
fn as_mut(&mut self) -> &mut libc::aiocb {
&mut self.aiocb.aiocb.0
}
}
#[cfg(target_os = "freebsd")]
impl<'a> AsRef<libc::aiocb> for AioReadv<'a> {
fn as_ref(&self) -> &libc::aiocb {
&self.aiocb.aiocb.0
}
}
/// Asynchronously writes from a buffer to a file descriptor
///
/// # References
///
///
/// # Examples
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiow = Box::pin(
/// AioWrite::new(
/// f.as_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone
/// )
/// );
/// aiow.as_mut().submit().unwrap();
/// while (aiow.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiow.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
#[derive(Debug)]
#[repr(transparent)]
pub struct AioWrite<'a> {
aiocb: AioCb<'a>,
_data: PhantomData<&'a [u8]>,
_pin: PhantomPinned,
}
impl<'a> AioWrite<'a> {
unsafe_pinned!(aiocb: AioCb<'a>);
/// Returns the requested length of the aio operation in bytes
///
/// This method returns the *requested* length of the operation. To get the
/// number of bytes actually read or written by a completed operation, use
/// `aio_return` instead.
pub fn nbytes(&self) -> usize {
self.aiocb.aiocb.0.aio_nbytes
}
/// Construct a new `AioWrite`.
///
/// # Arguments
///
/// * `fd`: File descriptor to write to
/// * `offs`: File offset
/// * `buf`: A memory buffer. It must outlive the `AioWrite`.
/// * `prio`: If POSIX Prioritized IO is supported, then the
/// operation will be prioritized at the process's
/// priority level minus `prio`
/// * `sigev_notify`: Determines how you will be notified of event
/// completion.
pub fn new(
fd: BorrowedFd<'a>,
offs: off_t,
buf: &'a [u8],
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
aiocb.aiocb.0.aio_nbytes = buf.len();
// casting an immutable buffer to a mutable pointer looks unsafe,
// but technically its only unsafe to dereference it, not to create
// it. Type Safety guarantees that we'll never pass aiocb to
// aio_read or aio_readv.
aiocb.aiocb.0.aio_buf = buf.as_ptr().cast_mut().cast();
aiocb.aiocb.0.aio_lio_opcode = libc::LIO_WRITE;
aiocb.aiocb.0.aio_offset = offs;
AioWrite {
aiocb,
_data: PhantomData,
_pin: PhantomPinned,
}
}
/// Returns the file offset of the operation.
pub fn offset(&self) -> off_t {
self.aiocb.aiocb.0.aio_offset
}
}
impl<'a> Aio for AioWrite<'a> {
type Output = usize;
aio_methods!(aio_write);
}
impl<'a> AsMut<libc::aiocb> for AioWrite<'a> {
fn as_mut(&mut self) -> &mut libc::aiocb {
&mut self.aiocb.aiocb.0
}
}
impl<'a> AsRef<libc::aiocb> for AioWrite<'a> {
fn as_ref(&self) -> &libc::aiocb {
&self.aiocb.aiocb.0
}
}
/// Asynchronously writes from a scatter/gather list of buffers to a file descriptor.
///
/// # References
///
///
/// # Examples
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::io::IoSlice;
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const wbuf0: &[u8] = b"abcdef";
/// const wbuf1: &[u8] = b"123456";
/// let len = wbuf0.len() + wbuf1.len();
/// let wbufs = [IoSlice::new(wbuf0), IoSlice::new(wbuf1)];
/// let mut f = tempfile().unwrap();
/// let mut aiow = Box::pin(
/// AioWritev::new(
/// f.as_fd(),
/// 2, //offset
/// &wbufs,
/// 0, //priority
/// SigevNotify::SigevNone
/// )
/// );
/// aiow.as_mut().submit().unwrap();
/// while (aiow.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiow.as_mut().aio_return().unwrap(), len);
/// ```
#[cfg(target_os = "freebsd")]
#[derive(Debug)]
#[repr(transparent)]
pub struct AioWritev<'a> {
aiocb: AioCb<'a>,
_data: PhantomData<&'a [&'a [u8]]>,
_pin: PhantomPinned,
}
#[cfg(target_os = "freebsd")]
impl<'a> AioWritev<'a> {
unsafe_pinned!(aiocb: AioCb<'a>);
/// Returns the number of buffers the operation will read into.
pub fn iovlen(&self) -> usize {
self.aiocb.aiocb.0.aio_nbytes
}
/// Construct a new `AioWritev`.
///
/// # Arguments
///
/// * `fd`: File descriptor to write to
/// * `offs`: File offset
/// * `bufs`: A scatter/gather list of memory buffers. They must
/// outlive the `AioWritev`.
/// * `prio`: If POSIX Prioritized IO is supported, then the
/// operation will be prioritized at the process's
/// priority level minus `prio`
/// * `sigev_notify`: Determines how you will be notified of event
/// completion.
pub fn new(
fd: BorrowedFd<'a>,
offs: off_t,
bufs: &[IoSlice<'a>],
prio: i32,
sigev_notify: SigevNotify,
) -> Self {
let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
// In vectored mode, aio_nbytes stores the length of the iovec array,
// not the byte count.
aiocb.aiocb.0.aio_nbytes = bufs.len();
// casting an immutable buffer to a mutable pointer looks unsafe,
// but technically its only unsafe to dereference it, not to create
// it. Type Safety guarantees that we'll never pass aiocb to
// aio_read or aio_readv.
aiocb.aiocb.0.aio_buf = bufs.as_ptr().cast_mut().cast();
aiocb.aiocb.0.aio_lio_opcode = libc::LIO_WRITEV;
aiocb.aiocb.0.aio_offset = offs;
AioWritev {
aiocb,
_data: PhantomData,
_pin: PhantomPinned,
}
}
/// Returns the file offset of the operation.
pub fn offset(&self) -> off_t {
self.aiocb.aiocb.0.aio_offset
}
}
#[cfg(target_os = "freebsd")]
impl<'a> Aio for AioWritev<'a> {
type Output = usize;
aio_methods!(aio_writev);
}
#[cfg(target_os = "freebsd")]
impl<'a> AsMut<libc::aiocb> for AioWritev<'a> {
fn as_mut(&mut self) -> &mut libc::aiocb {
&mut self.aiocb.aiocb.0
}
}
#[cfg(target_os = "freebsd")]
impl<'a> AsRef<libc::aiocb> for AioWritev<'a> {
fn as_ref(&self) -> &libc::aiocb {
&self.aiocb.aiocb.0
}
}
/// Cancels outstanding AIO requests for a given file descriptor.
///
/// # Examples
///
/// Issue an aio operation, then cancel all outstanding operations on that file
/// descriptor.
///
/// ```
/// # use nix::errno::Errno;
/// # use nix::Error;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::{thread, time};
/// # use std::io::Write;
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// let wbuf = b"CDEF";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = Box::pin(AioWrite::new(f.as_fd(),
/// 2, //offset
/// &wbuf[..],
/// 0, //priority
/// SigevNotify::SigevNone));
/// aiocb.as_mut().submit().unwrap();
/// let cs = aio_cancel_all(f.as_fd()).unwrap();
/// if cs == AioCancelStat::AioNotCanceled {
/// while (aiocb.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// }
/// // Must call `aio_return`, but ignore the result
/// let _ = aiocb.as_mut().aio_return();
/// ```
///
/// # References
///
pub fn aio_cancel_all<F: AsFd>(fd: F) -> Result<AioCancelStat> {
match unsafe { libc::aio_cancel(fd.as_fd().as_raw_fd(), ptr::null_mut()) } {
libc::AIO_CANCELED => Ok(AioCancelStat::AioCanceled),
libc::AIO_NOTCANCELED => Ok(AioCancelStat::AioNotCanceled),
libc::AIO_ALLDONE => Ok(AioCancelStat::AioAllDone),
-1 => Err(Errno::last()),
_ => panic!("unknown aio_cancel return value"),
}
}
/// Suspends the calling process until at least one of the specified operations
/// have completed, a signal is delivered, or the timeout has passed.
///
/// If `timeout` is `None`, `aio_suspend` will block indefinitely.
///
/// # Examples
///
/// Use `aio_suspend` to block until an aio operation completes.
///
/// ```
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::os::unix::io::AsFd;
/// # use tempfile::tempfile;
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = Box::pin(AioWrite::new(f.as_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone));
/// aiocb.as_mut().submit().unwrap();
/// aio_suspend(&[&*aiocb], None).expect("aio_suspend failed");
/// assert_eq!(aiocb.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
/// # References
///
pub fn aio_suspend(
list: &[&dyn AsRef<libc::aiocb>],
timeout: Option<TimeSpec>,
) -> Result<()> {
// Note that this allocation could be eliminated by making the argument
// generic, and accepting arguments like &[AioWrite]. But that would
// prevent using aio_suspend to wait on a heterogeneous list of mixed
// operations.
let v = list
.iter()
.map(|x| x.as_ref() as *const libc::aiocb)
.collect::<Vec<*const libc::aiocb>>();
let p = v.as_ptr();
let timep = match timeout {
None => ptr::null::<libc::timespec>(),
Some(x) => x.as_ref() as *const libc::timespec,
};
Errno::result(unsafe { libc::aio_suspend(p, list.len() as i32, timep) })
.map(drop)
}
/// Submits multiple asynchronous I/O requests with a single system call.
///
/// They are not guaranteed to complete atomically, and the order in which the
/// requests are carried out is not specified. Reads, and writes may be freely
/// mixed.
///
/// # Examples
///
/// Use `lio_listio` to submit an aio operation and wait for its completion. In
/// this case, there is no need to use aio_suspend to wait or `error` to poll.
/// This mode is useful for otherwise-synchronous programs that want to execute
/// a handful of I/O operations in parallel.
/// ```
/// # use std::os::unix::io::AsFd;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use tempfile::tempfile;
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiow = Box::pin(AioWrite::new(
/// f.as_fd(),
/// 2, // offset
/// WBUF,
/// 0, // priority
/// SigevNotify::SigevNone
/// ));
/// lio_listio(LioMode::LIO_WAIT, &mut[aiow.as_mut()], SigevNotify::SigevNone)
/// .unwrap();
/// // At this point, we are guaranteed that aiow is complete.
/// assert_eq!(aiow.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
///
/// Use `lio_listio` to submit multiple asynchronous operations with a single
/// syscall, but receive notification individually. This is an efficient
/// technique for reducing overall context-switch overhead, especially when
/// combined with kqueue.
/// ```
/// # use std::os::unix::io::AsFd;
/// # use std::thread;
/// # use std::time;
/// # use nix::errno::Errno;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use tempfile::tempfile;
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiow = Box::pin(AioWrite::new(
/// f.as_fd(),
/// 2, // offset
/// WBUF,
/// 0, // priority
/// SigevNotify::SigevNone
/// ));
/// lio_listio(LioMode::LIO_NOWAIT, &mut[aiow.as_mut()], SigevNotify::SigevNone)
/// .unwrap();
/// // We must wait for the completion of each individual operation
/// while (aiow.as_mut().error() == Err(Errno::EINPROGRESS)) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiow.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
///
/// Use `lio_listio` to submit multiple operations, and receive notification
/// only when all of them are complete. This can be useful when there is some
/// logical relationship between the operations. But beware! Errors or system
/// resource limitations may cause `lio_listio` to return `EIO`, `EAGAIN`, or
/// `EINTR`, in which case some but not all operations may have been submitted.
/// In that case, you must check the status of each individual operation, and
/// possibly resubmit some.
/// ```
/// # use libc::c_int;
/// # use std::os::unix::io::AsFd;
/// # use std::sync::atomic::{AtomicBool, Ordering};
/// # use std::thread;
/// # use std::time;
/// # use nix::errno::Errno;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::*;
/// # use tempfile::tempfile;
/// pub static SIGNALED: AtomicBool = AtomicBool::new(false);
///
/// extern fn sigfunc(_: c_int) {
/// SIGNALED.store(true, Ordering::Relaxed);
/// }
/// let sa = SigAction::new(SigHandler::Handler(sigfunc),
/// SaFlags::SA_RESETHAND,
/// SigSet::empty());
/// SIGNALED.store(false, Ordering::Relaxed);
/// unsafe { sigaction(Signal::SIGUSR2, &sa) }.unwrap();
///
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiow = Box::pin(AioWrite::new(
/// f.as_fd(),
/// 2, // offset
/// WBUF,
/// 0, // priority
/// SigevNotify::SigevNone
/// ));
/// let sev = SigevNotify::SigevSignal { signal: Signal::SIGUSR2, si_value: 0 };
/// lio_listio(LioMode::LIO_NOWAIT, &mut[aiow.as_mut()], sev).unwrap();
/// while !SIGNALED.load(Ordering::Relaxed) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// // At this point, since `lio_listio` returned success and delivered its
/// // notification, we know that all operations are complete.
/// assert_eq!(aiow.as_mut().aio_return().unwrap(), WBUF.len());
/// ```
#[deprecated(
since = "0.27.0",
)]
pub fn lio_listio(
mode: LioMode,
list: &mut [Pin<&mut dyn AsMut<libc::aiocb>>],
sigev_notify: SigevNotify,
) -> Result<()> {
let p = list as *mut [Pin<&mut dyn AsMut<libc::aiocb>>]
as *mut [*mut libc::aiocb] as *mut *mut libc::aiocb;
let sigev = SigEvent::new(sigev_notify);
let sigevp = &mut sigev.sigevent() as *mut libc::sigevent;
Errno::result(unsafe {
libc::lio_listio(mode as i32, p, list.len() as i32, sigevp)
})
.map(drop)
}