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|
// 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.AioCb.html#method.read),
//! [`write`](struct.AioCb.html#method.write), and
//! [`fsync`](struct.AioCb.html#method.fsync) operations. 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`](struct.AioCb.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.
use crate::{Error, Result};
use crate::errno::Errno;
use std::os::unix::io::RawFd;
use libc::{c_void, off_t, size_t};
use std::borrow::{Borrow, BorrowMut};
use std::fmt;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::mem;
use std::ptr::{null, null_mut};
use crate::sys::signal::*;
use std::thread;
use crate::sys::time::TimeSpec;
libc_enum! {
/// Mode for `AioCb::fsync`. Controls whether only data or both data and
/// metadata are synced.
#[repr(i32)]
pub enum AioFsyncMode {
/// do it like `fsync`
O_SYNC,
/// on supported operating systems only, do it like `fdatasync`
#[cfg(any(target_os = "ios",
target_os = "linux",
target_os = "macos",
target_os = "netbsd",
target_os = "openbsd"))]
O_DSYNC
}
}
libc_enum! {
/// When used with [`lio_listio`](fn.lio_listio.html), determines whether a
/// given `aiocb` should be used for a read operation, a write operation, or
/// ignored. Has no effect for any other aio functions.
#[repr(i32)]
pub enum LioOpcode {
LIO_NOP,
LIO_WRITE,
LIO_READ,
}
}
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,
}
/// Owns (uniquely or shared) a memory buffer to keep it from `Drop`ing while
/// the kernel has a pointer to it.
pub enum Buffer<'a> {
/// No buffer to own.
///
/// Used for operations like `aio_fsync` that have no data, or for unsafe
/// operations that work with raw pointers.
None,
/// Keeps a reference to a slice
Phantom(PhantomData<&'a mut [u8]>),
/// Generic thing that keeps a buffer from dropping
BoxedSlice(Box<dyn Borrow<[u8]>>),
/// Generic thing that keeps a mutable buffer from dropping
BoxedMutSlice(Box<dyn BorrowMut<[u8]>>),
}
impl<'a> Debug for Buffer<'a> {
// Note: someday it may be possible to Derive Debug for a trait object, but
// not today.
// https://github.com/rust-lang/rust/issues/1563
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
Buffer::None => write!(fmt, "None"),
Buffer::Phantom(p) => p.fmt(fmt),
Buffer::BoxedSlice(ref bs) => {
let borrowed : &dyn Borrow<[u8]> = bs.borrow();
write!(fmt, "BoxedSlice({:?})",
borrowed as *const dyn Borrow<[u8]>)
},
Buffer::BoxedMutSlice(ref bms) => {
let borrowed : &dyn BorrowMut<[u8]> = bms.borrow();
write!(fmt, "BoxedMutSlice({:?})",
borrowed as *const dyn BorrowMut<[u8]>)
}
}
}
}
/// AIO Control Block.
///
/// The basic structure used by all aio functions. Each `AioCb` represents one
/// I/O request.
pub struct AioCb<'a> {
aiocb: libc::aiocb,
/// Tracks whether the buffer pointed to by `libc::aiocb.aio_buf` is mutable
mutable: bool,
/// Could this `AioCb` potentially have any in-kernel state?
in_progress: bool,
/// Optionally keeps a reference to the data.
///
/// Used to keep buffers from `Drop`'ing, and may be returned once the
/// `AioCb` is completed by [`buffer`](#method.buffer).
buffer: Buffer<'a>
}
impl<'a> AioCb<'a> {
/// Remove the inner `Buffer` and return it
///
/// It is an error to call this method while the `AioCb` is still in
/// progress.
pub fn buffer(&mut self) -> Buffer<'a> {
assert!(!self.in_progress);
let mut x = Buffer::None;
mem::swap(&mut self.buffer, &mut x);
x
}
/// Remove the inner boxed slice, if any, and return it.
///
/// The returned value will be the argument that was passed to
/// `from_boxed_slice` when this `AioCb` was created.
///
/// It is an error to call this method while the `AioCb` is still in
/// progress.
pub fn boxed_slice(&mut self) -> Option<Box<dyn Borrow<[u8]>>> {
assert!(!self.in_progress, "Can't remove the buffer from an AioCb that's still in-progress. Did you forget to call aio_return?");
if let Buffer::BoxedSlice(_) = self.buffer {
let mut oldbuffer = Buffer::None;
mem::swap(&mut self.buffer, &mut oldbuffer);
if let Buffer::BoxedSlice(inner) = oldbuffer {
Some(inner)
} else {
unreachable!();
}
} else {
None
}
}
/// Remove the inner boxed mutable slice, if any, and return it.
///
/// The returned value will be the argument that was passed to
/// `from_boxed_mut_slice` when this `AioCb` was created.
///
/// It is an error to call this method while the `AioCb` is still in
/// progress.
pub fn boxed_mut_slice(&mut self) -> Option<Box<dyn BorrowMut<[u8]>>> {
assert!(!self.in_progress, "Can't remove the buffer from an AioCb that's still in-progress. Did you forget to call aio_return?");
if let Buffer::BoxedMutSlice(_) = self.buffer {
let mut oldbuffer = Buffer::None;
mem::swap(&mut self.buffer, &mut oldbuffer);
if let Buffer::BoxedMutSlice(inner) = oldbuffer {
Some(inner)
} else {
unreachable!();
}
} else {
None
}
}
/// Returns the underlying file descriptor associated with the `AioCb`
pub fn fd(&self) -> RawFd {
self.aiocb.aio_fildes
}
/// Constructs a new `AioCb` with no associated buffer.
///
/// The resulting `AioCb` structure is suitable for use with `AioCb::fsync`.
///
/// # Parameters
///
/// * `fd`: File descriptor. Required for all aio functions.
/// * `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.
///
/// # Examples
///
/// Create an `AioCb` from a raw file descriptor and use it for an
/// [`fsync`](#method.fsync) operation.
///
/// ```
/// # 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// let f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_fd( f.as_raw_fd(), 0, SigevNone);
/// aiocb.fsync(AioFsyncMode::O_SYNC).expect("aio_fsync failed early");
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// aiocb.aio_return().expect("aio_fsync failed late");
/// # }
/// ```
pub fn from_fd(fd: RawFd, prio: libc::c_int,
sigev_notify: SigevNotify) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
a.aio_offset = 0;
a.aio_nbytes = 0;
a.aio_buf = null_mut();
AioCb {
aiocb: a,
mutable: false,
in_progress: false,
buffer: Buffer::None
}
}
/// Constructs a new `AioCb` from a mutable slice.
///
/// The resulting `AioCb` will be suitable for both read and write
/// operations, but only if the borrow checker can guarantee that the slice
/// will outlive the `AioCb`. That will usually be the case if the `AioCb`
/// is stack-allocated. If the borrow checker gives you trouble, try using
/// [`from_boxed_mut_slice`](#method.from_boxed_mut_slice) instead.
///
/// # Parameters
///
/// * `fd`: File descriptor. Required for all aio functions.
/// * `offs`: File offset
/// * `buf`: A memory buffer
/// * `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.
/// * `opcode`: This field is only used for `lio_listio`. It
/// determines which operation to use for this individual
/// aiocb
///
/// # Examples
///
/// Create an `AioCb` from a mutable slice and read into it.
///
/// ```
/// # 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// 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 aiocb = AioCb::from_mut_slice( f.as_raw_fd(),
/// 2, //offset
/// &mut rbuf,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.read().unwrap();
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.aio_return().unwrap() as usize, LEN);
/// }
/// assert_eq!(rbuf, b"cdef");
/// # }
/// ```
pub fn from_mut_slice(fd: RawFd, offs: off_t, buf: &'a mut [u8],
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
a.aio_offset = offs;
a.aio_nbytes = buf.len() as size_t;
a.aio_buf = buf.as_ptr() as *mut c_void;
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: true,
in_progress: false,
buffer: Buffer::Phantom(PhantomData),
}
}
/// The safest and most flexible way to create an `AioCb`.
///
/// Unlike [`from_slice`], this method returns a structure suitable for
/// placement on the heap. It may be used for write operations, but not
/// read operations. Unlike `from_ptr`, this method will ensure that the
/// buffer doesn't `drop` while the kernel is still processing it. Any
/// object that can be borrowed as a boxed slice will work.
///
/// # Parameters
///
/// * `fd`: File descriptor. Required for all aio functions.
/// * `offs`: File offset
/// * `buf`: A boxed slice-like object
/// * `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.
/// * `opcode`: This field is only used for `lio_listio`. It
/// determines which operation to use for this individual
/// aiocb
///
/// # Examples
///
/// Create an `AioCb` from a Vector and use it for writing
///
/// ```
/// # 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// let wbuf = Box::new(Vec::from("CDEF"));
/// let expected_len = wbuf.len();
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_boxed_slice( f.as_raw_fd(),
/// 2, //offset
/// wbuf,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.aio_return().unwrap() as usize, expected_len);
/// # }
/// ```
///
/// Create an `AioCb` from a `Bytes` object
///
/// ```
/// # use bytes::Bytes;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::os::unix::io::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// let wbuf = Box::new(Bytes::from(&b"CDEF"[..]));
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_boxed_slice( f.as_raw_fd(),
/// 2, //offset
/// wbuf,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// # }
/// ```
///
/// If a library needs to work with buffers that aren't `Box`ed, it can
/// create a `Box`ed container for use with this method. Here's an example
/// using an un`Box`ed `Bytes` object.
///
/// ```
/// # use bytes::Bytes;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::borrow::Borrow;
/// # use std::os::unix::io::AsRawFd;
/// # use tempfile::tempfile;
/// struct BytesContainer(Bytes);
/// impl Borrow<[u8]> for BytesContainer {
/// fn borrow(&self) -> &[u8] {
/// self.0.as_ref()
/// }
/// }
/// fn main() {
/// let wbuf = Bytes::from(&b"CDEF"[..]);
/// let boxed_wbuf = Box::new(BytesContainer(wbuf));
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_boxed_slice( f.as_raw_fd(),
/// 2, //offset
/// boxed_wbuf,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// }
/// ```
///
/// [`from_slice`]: #method.from_slice
pub fn from_boxed_slice(fd: RawFd, offs: off_t, buf: Box<dyn Borrow<[u8]>>,
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
{
let borrowed : &dyn Borrow<[u8]> = buf.borrow();
let slice : &[u8] = borrowed.borrow();
a.aio_nbytes = slice.len() as size_t;
a.aio_buf = slice.as_ptr() as *mut c_void;
}
a.aio_offset = offs;
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: false,
in_progress: false,
buffer: Buffer::BoxedSlice(buf),
}
}
/// The safest and most flexible way to create an `AioCb` for reading.
///
/// Like [`from_boxed_slice`], but the slice is a mutable one. More
/// flexible than [`from_mut_slice`], because a wide range of objects can be
/// used.
///
/// # Examples
///
/// Create an `AioCb` from a Vector and use it for reading
///
/// ```
/// # 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// const INITIAL: &[u8] = b"abcdef123456";
/// const LEN: usize = 4;
/// let rbuf = Box::new(vec![0; LEN]);
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// let mut aiocb = AioCb::from_boxed_mut_slice( f.as_raw_fd(),
/// 2, //offset
/// rbuf,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.read().unwrap();
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.aio_return().unwrap() as usize, LEN);
/// let mut buffer = aiocb.boxed_mut_slice().unwrap();
/// const EXPECT: &[u8] = b"cdef";
/// assert_eq!(buffer.borrow_mut(), EXPECT);
/// # }
/// ```
///
/// [`from_boxed_slice`]: #method.from_boxed_slice
/// [`from_mut_slice`]: #method.from_mut_slice
pub fn from_boxed_mut_slice(fd: RawFd, offs: off_t,
mut buf: Box<dyn BorrowMut<[u8]>>,
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
{
let borrowed : &mut dyn BorrowMut<[u8]> = buf.borrow_mut();
let slice : &mut [u8] = borrowed.borrow_mut();
a.aio_nbytes = slice.len() as size_t;
a.aio_buf = slice.as_mut_ptr() as *mut c_void;
}
a.aio_offset = offs;
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: true,
in_progress: false,
buffer: Buffer::BoxedMutSlice(buf),
}
}
/// Constructs a new `AioCb` from a mutable raw pointer
///
/// Unlike `from_mut_slice`, this method returns a structure suitable for
/// placement on the heap. It may be used for both reads and writes. Due
/// to its unsafety, this method is not recommended. It is most useful when
/// heap allocation is required but for some reason the data cannot be
/// wrapped in a `struct` that implements `BorrowMut<[u8]>`
///
/// # Parameters
///
/// * `fd`: File descriptor. Required for all aio functions.
/// * `offs`: File offset
/// * `buf`: Pointer to the memory buffer
/// * `len`: Length of the buffer pointed to by `buf`
/// * `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.
/// * `opcode`: This field is only used for `lio_listio`. It
/// determines which operation to use for this individual
/// aiocb
///
/// # Safety
///
/// The caller must ensure that the storage pointed to by `buf` outlives the
/// `AioCb`. The lifetime checker can't help here.
pub unsafe fn from_mut_ptr(fd: RawFd, offs: off_t,
buf: *mut c_void, len: usize,
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
a.aio_offset = offs;
a.aio_nbytes = len;
a.aio_buf = buf;
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: true,
in_progress: false,
buffer: Buffer::None
}
}
/// Constructs a new `AioCb` from a raw pointer.
///
/// Unlike `from_slice`, this method returns a structure suitable for
/// placement on the heap. Due to its unsafety, this method is not
/// recommended. It is most useful when heap allocation is required but for
/// some reason the data cannot be wrapped in a `struct` that implements
/// `Borrow<[u8]>`
///
/// # Parameters
///
/// * `fd`: File descriptor. Required for all aio functions.
/// * `offs`: File offset
/// * `buf`: Pointer to the memory buffer
/// * `len`: Length of the buffer pointed to by `buf`
/// * `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.
/// * `opcode`: This field is only used for `lio_listio`. It
/// determines which operation to use for this individual
/// aiocb
///
/// # Safety
///
/// The caller must ensure that the storage pointed to by `buf` outlives the
/// `AioCb`. The lifetime checker can't help here.
pub unsafe fn from_ptr(fd: RawFd, offs: off_t,
buf: *const c_void, len: usize,
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb<'a> {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
a.aio_offset = offs;
a.aio_nbytes = len;
// casting a const ptr to a mutable ptr here is ok, because we set the
// AioCb's mutable field to false
a.aio_buf = buf as *mut c_void;
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: false,
in_progress: false,
buffer: Buffer::None
}
}
/// Like `from_mut_slice`, but works on constant slices rather than
/// mutable slices.
///
/// An `AioCb` created this way cannot be used with `read`, and its
/// `LioOpcode` cannot be set to `LIO_READ`. This method is useful when
/// writing a const buffer with `AioCb::write`, since `from_mut_slice` can't
/// work with const buffers.
///
/// # Examples
///
/// Construct an `AioCb` from a slice and use it for writing.
///
/// ```
/// # 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.aio_return().unwrap() as usize, WBUF.len());
/// # }
/// ```
// Note: another solution to the problem of writing const buffers would be
// to genericize AioCb for both &mut [u8] and &[u8] buffers. AioCb::read
// could take the former and AioCb::write could take the latter. However,
// then lio_listio wouldn't work, because that function needs a slice of
// AioCb, and they must all be of the same type.
pub fn from_slice(fd: RawFd, offs: off_t, buf: &'a [u8],
prio: libc::c_int, sigev_notify: SigevNotify,
opcode: LioOpcode) -> AioCb {
let mut a = AioCb::common_init(fd, prio, sigev_notify);
a.aio_offset = offs;
a.aio_nbytes = buf.len() as size_t;
// casting an immutable buffer to a mutable pointer looks unsafe,
// but technically its only unsafe to dereference it, not to create
// it.
a.aio_buf = buf.as_ptr() as *mut c_void;
assert!(opcode != LioOpcode::LIO_READ, "Can't read into an immutable buffer");
a.aio_lio_opcode = opcode as libc::c_int;
AioCb {
aiocb: a,
mutable: false,
in_progress: false,
buffer: Buffer::None,
}
}
fn common_init(fd: RawFd, prio: libc::c_int,
sigev_notify: SigevNotify) -> libc::aiocb {
// 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;
a.aio_reqprio = prio;
a.aio_sigevent = SigEvent::new(sigev_notify).sigevent();
a
}
/// Update the notification settings for an existing `aiocb`
pub fn set_sigev_notify(&mut self, sigev_notify: SigevNotify) {
self.aiocb.aio_sigevent = SigEvent::new(sigev_notify).sigevent();
}
/// 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// let wbuf = b"CDEF";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// &wbuf[..],
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// let cs = aiocb.cancel().unwrap();
/// if cs == AioCancelStat::AioNotCanceled {
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// }
/// // Must call `aio_return`, but ignore the result
/// let _ = aiocb.aio_return();
/// # }
/// ```
///
/// # References
///
/// [aio_cancel](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_cancel.html)
pub fn cancel(&mut self) -> Result<AioCancelStat> {
match unsafe { libc::aio_cancel(self.aiocb.aio_fildes, &mut self.aiocb) } {
libc::AIO_CANCELED => Ok(AioCancelStat::AioCanceled),
libc::AIO_NOTCANCELED => Ok(AioCancelStat::AioNotCanceled),
libc::AIO_ALLDONE => Ok(AioCancelStat::AioAllDone),
-1 => Err(Error::last()),
_ => panic!("unknown aio_cancel return value")
}
}
/// 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// assert_eq!(aiocb.aio_return().unwrap() as usize, WBUF.len());
/// # }
/// ```
///
/// # References
///
/// [aio_error](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_error.html)
pub fn error(&mut self) -> Result<()> {
match unsafe { libc::aio_error(&mut self.aiocb as *mut libc::aiocb) } {
0 => Ok(()),
num if num > 0 => Err(Error::from_errno(Errno::from_i32(num))),
-1 => Err(Error::last()),
num => panic!("unknown aio_error return value {:?}", num)
}
}
/// An asynchronous version of `fsync(2)`.
///
/// # References
///
/// [aio_fsync](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_fsync.html)
pub fn fsync(&mut self, mode: AioFsyncMode) -> Result<()> {
let p: *mut libc::aiocb = &mut self.aiocb;
Errno::result(unsafe {
libc::aio_fsync(mode as libc::c_int, p)
}).map(|_| {
self.in_progress = true;
})
}
/// Returns the `aiocb`'s `LioOpcode` field
///
/// If the value cannot be represented as an `LioOpcode`, returns `None`
/// instead.
pub fn lio_opcode(&self) -> Option<LioOpcode> {
match self.aiocb.aio_lio_opcode {
libc::LIO_READ => Some(LioOpcode::LIO_READ),
libc::LIO_WRITE => Some(LioOpcode::LIO_WRITE),
libc::LIO_NOP => Some(LioOpcode::LIO_NOP),
_ => None
}
}
/// 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.aio_nbytes
}
/// Returns the file offset stored in the `AioCb`
pub fn offset(&self) -> off_t {
self.aiocb.aio_offset
}
/// Returns the priority of the `AioCb`
pub fn priority(&self) -> libc::c_int {
self.aiocb.aio_reqprio
}
/// Asynchronously reads from a file descriptor into a buffer
///
/// # References
///
/// [aio_read](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_read.html)
pub fn read(&mut self) -> Result<()> {
assert!(self.mutable, "Can't read into an immutable buffer");
let p: *mut libc::aiocb = &mut self.aiocb;
Errno::result(unsafe {
libc::aio_read(p)
}).map(|_| {
self.in_progress = true;
})
}
/// Returns the `SigEvent` stored in the `AioCb`
pub fn sigevent(&self) -> SigEvent {
SigEvent::from(&self.aiocb.aio_sigevent)
}
/// Retrieve return status of an asynchronous operation.
///
/// Should only be called once for each `AioCb`, after `AioCb::error`
/// indicates that it has completed. The result is the same as for the
/// synchronous `read(2)`, `write(2)`, of `fsync(2)` functions.
///
/// # References
///
/// [aio_return](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_return.html)
// Note: this should be just `return`, but that's a reserved word
pub fn aio_return(&mut self) -> Result<isize> {
let p: *mut libc::aiocb = &mut self.aiocb;
self.in_progress = false;
Errno::result(unsafe { libc::aio_return(p) })
}
/// Asynchronously writes from a buffer to a file descriptor
///
/// # References
///
/// [aio_write](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_write.html)
pub fn write(&mut self) -> Result<()> {
let p: *mut libc::aiocb = &mut self.aiocb;
Errno::result(unsafe {
libc::aio_write(p)
}).map(|_| {
self.in_progress = true;
})
}
}
/// 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// let wbuf = b"CDEF";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// &wbuf[..],
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// let cs = aio_cancel_all(f.as_raw_fd()).unwrap();
/// if cs == AioCancelStat::AioNotCanceled {
/// while (aiocb.error() == Err(Error::from(Errno::EINPROGRESS))) {
/// thread::sleep(time::Duration::from_millis(10));
/// }
/// }
/// // Must call `aio_return`, but ignore the result
/// let _ = aiocb.aio_return();
/// # }
/// ```
///
/// # References
///
/// [`aio_cancel`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_cancel.html)
pub fn aio_cancel_all(fd: RawFd) -> Result<AioCancelStat> {
match unsafe { libc::aio_cancel(fd, null_mut()) } {
libc::AIO_CANCELED => Ok(AioCancelStat::AioCanceled),
libc::AIO_NOTCANCELED => Ok(AioCancelStat::AioNotCanceled),
libc::AIO_ALLDONE => Ok(AioCancelStat::AioAllDone),
-1 => Err(Error::last()),
_ => panic!("unknown aio_cancel return value")
}
}
/// Suspends the calling process until at least one of the specified `AioCb`s
/// has 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::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut aiocb = AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_NOP);
/// aiocb.write().unwrap();
/// aio_suspend(&[&aiocb], None).expect("aio_suspend failed");
/// assert_eq!(aiocb.aio_return().unwrap() as usize, WBUF.len());
/// # }
/// ```
/// # References
///
/// [`aio_suspend`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/aio_suspend.html)
pub fn aio_suspend(list: &[&AioCb], timeout: Option<TimeSpec>) -> Result<()> {
let plist = list as *const [&AioCb] as *const [*const libc::aiocb];
let p = plist as *const *const libc::aiocb;
let timep = match timeout {
None => 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)
}
impl<'a> Debug for AioCb<'a> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("AioCb")
.field("aiocb", &self.aiocb)
.field("mutable", &self.mutable)
.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");
}
}
/// LIO Control Block.
///
/// The basic structure used to issue multiple AIO operations simultaneously.
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
pub struct LioCb<'a> {
/// A collection of [`AioCb`]s. All of these will be issued simultaneously
/// by the [`listio`] method.
///
/// [`AioCb`]: struct.AioCb.html
/// [`listio`]: #method.listio
pub aiocbs: Vec<AioCb<'a>>,
/// The actual list passed to `libc::lio_listio`.
///
/// It must live for as long as any of the operations are still being
/// processesed, because the aio subsystem uses its address as a unique
/// identifier.
list: Vec<*mut libc::aiocb>,
/// A partial set of results. This field will get populated by
/// `listio_resubmit` when an `LioCb` is resubmitted after an error
results: Vec<Option<Result<isize>>>
}
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
impl<'a> LioCb<'a> {
/// Initialize an empty `LioCb`
pub fn with_capacity(capacity: usize) -> LioCb<'a> {
LioCb {
aiocbs: Vec::with_capacity(capacity),
list: Vec::with_capacity(capacity),
results: Vec::with_capacity(capacity)
}
}
/// 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, writes, and
/// fsyncs may be freely mixed.
///
/// This function is useful for reducing the context-switch overhead of
/// submitting many AIO operations. It can also be used with
/// `LioMode::LIO_WAIT` to block on the result of several independent
/// operations. Used that way, it is often useful in programs that
/// otherwise make little use of AIO.
///
/// # Examples
///
/// Use `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
/// [`AioCb::error`] to poll.
///
/// ```
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::os::unix::io::AsRawFd;
/// # use tempfile::tempfile;
/// # fn main() {
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut liocb = LioCb::with_capacity(1);
/// liocb.aiocbs.push(AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_WRITE));
/// liocb.listio(LioMode::LIO_WAIT,
/// SigevNotify::SigevNone).unwrap();
/// assert_eq!(liocb.aio_return(0).unwrap() as usize, WBUF.len());
/// # }
/// ```
///
/// # References
///
/// [`lio_listio`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html)
///
/// [`aio_suspend`]: fn.aio_suspend.html
/// [`AioCb::error`]: struct.AioCb.html#method.error
pub fn listio(&mut self, mode: LioMode,
sigev_notify: SigevNotify) -> Result<()> {
let sigev = SigEvent::new(sigev_notify);
let sigevp = &mut sigev.sigevent() as *mut libc::sigevent;
self.list.clear();
for a in &mut self.aiocbs {
a.in_progress = true;
self.list.push(a as *mut AioCb<'a>
as *mut libc::aiocb);
}
let p = self.list.as_ptr();
Errno::result(unsafe {
libc::lio_listio(mode as i32, p, self.list.len() as i32, sigevp)
}).map(drop)
}
/// Resubmits any incomplete operations with [`lio_listio`].
///
/// Sometimes, due to system resource limitations, an `lio_listio` call will
/// return `EIO`, or `EAGAIN`. Or, if a signal is received, it may return
/// `EINTR`. In any of these cases, only a subset of its constituent
/// operations will actually have been initiated. `listio_resubmit` will
/// resubmit any operations that are still uninitiated.
///
/// After calling `listio_resubmit`, results should be collected by
/// [`LioCb::aio_return`].
///
/// # Examples
/// ```no_run
/// # use nix::Error;
/// # use nix::errno::Errno;
/// # use nix::sys::aio::*;
/// # use nix::sys::signal::SigevNotify;
/// # use std::os::unix::io::AsRawFd;
/// # use std::{thread, time};
/// # use tempfile::tempfile;
/// # fn main() {
/// const WBUF: &[u8] = b"abcdef123456";
/// let mut f = tempfile().unwrap();
/// let mut liocb = LioCb::with_capacity(1);
/// liocb.aiocbs.push(AioCb::from_slice( f.as_raw_fd(),
/// 2, //offset
/// WBUF,
/// 0, //priority
/// SigevNotify::SigevNone,
/// LioOpcode::LIO_WRITE));
/// let mut err = liocb.listio(LioMode::LIO_WAIT, SigevNotify::SigevNone);
/// while err == Err(Error::Sys(Errno::EIO)) ||
/// err == Err(Error::Sys(Errno::EAGAIN)) {
/// thread::sleep(time::Duration::from_millis(10));
/// err = liocb.listio_resubmit(LioMode::LIO_WAIT, SigevNotify::SigevNone);
/// }
/// assert_eq!(liocb.aio_return(0).unwrap() as usize, WBUF.len());
/// # }
/// ```
///
/// # References
///
/// [`lio_listio`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html)
///
/// [`lio_listio`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html
/// [`LioCb::aio_return`]: struct.LioCb.html#method.aio_return
// Note: the addresses of any EINPROGRESS or EOK aiocbs _must_ not be
// changed by this method, because the kernel relies on their addresses
// being stable.
// Note: aiocbs that are Ok(()) must be finalized by aio_return, or else the
// sigev_notify will immediately refire.
pub fn listio_resubmit(&mut self, mode:LioMode,
sigev_notify: SigevNotify) -> Result<()> {
let sigev = SigEvent::new(sigev_notify);
let sigevp = &mut sigev.sigevent() as *mut libc::sigevent;
self.list.clear();
while self.results.len() < self.aiocbs.len() {
self.results.push(None);
}
for (i, a) in self.aiocbs.iter_mut().enumerate() {
if self.results[i].is_some() {
// Already collected final status for this operation
continue;
}
match a.error() {
Ok(()) => {
// aiocb is complete; collect its status and don't resubmit
self.results[i] = Some(a.aio_return());
},
Err(Error::Sys(Errno::EAGAIN)) => {
self.list.push(a as *mut AioCb<'a> as *mut libc::aiocb);
},
Err(Error::Sys(Errno::EINPROGRESS)) => {
// aiocb is was successfully queued; no need to do anything
},
Err(Error::Sys(Errno::EINVAL)) => panic!(
"AioCb was never submitted, or already finalized"),
_ => unreachable!()
}
}
let p = self.list.as_ptr();
Errno::result(unsafe {
libc::lio_listio(mode as i32, p, self.list.len() as i32, sigevp)
}).map(drop)
}
/// Collect final status for an individual `AioCb` submitted as part of an
/// `LioCb`.
///
/// This is just like [`AioCb::aio_return`], except it takes into account
/// operations that were restarted by [`LioCb::listio_resubmit`]
///
/// [`AioCb::aio_return`]: struct.AioCb.html#method.aio_return
/// [`LioCb::listio_resubmit`]: #method.listio_resubmit
pub fn aio_return(&mut self, i: usize) -> Result<isize> {
if i >= self.results.len() || self.results[i].is_none() {
self.aiocbs[i].aio_return()
} else {
self.results[i].unwrap()
}
}
/// Retrieve error status of an individual `AioCb` submitted as part of an
/// `LioCb`.
///
/// This is just like [`AioCb::error`], except it takes into account
/// operations that were restarted by [`LioCb::listio_resubmit`]
///
/// [`AioCb::error`]: struct.AioCb.html#method.error
/// [`LioCb::listio_resubmit`]: #method.listio_resubmit
pub fn error(&mut self, i: usize) -> Result<()> {
if i >= self.results.len() || self.results[i].is_none() {
self.aiocbs[i].error()
} else {
Ok(())
}
}
}
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
impl<'a> Debug for LioCb<'a> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("LioCb")
.field("aiocbs", &self.aiocbs)
.finish()
}
}
#[cfg(not(any(target_os = "ios", target_os = "macos")))]
impl<'a> From<Vec<AioCb<'a>>> for LioCb<'a> {
fn from(src: Vec<AioCb<'a>>) -> LioCb<'a> {
LioCb {
list: Vec::with_capacity(src.capacity()),
results: Vec::with_capacity(src.capacity()),
aiocbs: src,
}
}
}
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