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//! Posix Message Queue functions
//!
//! [Further reading and details on the C API](https://man7.org/linux/man-pages/man7/mq_overview.7.html)
use crate::Result;
use crate::errno::Errno;
use libc::{self, c_char, mqd_t, size_t};
use std::ffi::CString;
use crate::sys::stat::Mode;
use std::mem;
libc_bitflags!{
pub struct MQ_OFlag: libc::c_int {
O_RDONLY;
O_WRONLY;
O_RDWR;
O_CREAT;
O_EXCL;
O_NONBLOCK;
O_CLOEXEC;
}
}
libc_bitflags!{
pub struct FdFlag: libc::c_int {
FD_CLOEXEC;
}
}
#[repr(C)]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct MqAttr {
mq_attr: libc::mq_attr,
}
// x32 compatibility
// See https://sourceware.org/bugzilla/show_bug.cgi?id=21279
#[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))]
#[cfg_attr(docsrs, doc(cfg(all())))]
pub type mq_attr_member_t = i64;
#[cfg(not(all(target_arch = "x86_64", target_pointer_width = "32")))]
#[cfg_attr(docsrs, doc(cfg(all())))]
pub type mq_attr_member_t = libc::c_long;
impl MqAttr {
pub fn new(mq_flags: mq_attr_member_t,
mq_maxmsg: mq_attr_member_t,
mq_msgsize: mq_attr_member_t,
mq_curmsgs: mq_attr_member_t)
-> MqAttr
{
let mut attr = mem::MaybeUninit::<libc::mq_attr>::uninit();
unsafe {
let p = attr.as_mut_ptr();
(*p).mq_flags = mq_flags;
(*p).mq_maxmsg = mq_maxmsg;
(*p).mq_msgsize = mq_msgsize;
(*p).mq_curmsgs = mq_curmsgs;
MqAttr { mq_attr: attr.assume_init() }
}
}
pub const fn flags(&self) -> mq_attr_member_t {
self.mq_attr.mq_flags
}
/// The max number of messages that can be held by the queue
pub const fn maxmsg(&self) -> mq_attr_member_t {
self.mq_attr.mq_maxmsg
}
/// The maximum size of each message (in bytes)
pub const fn msgsize(&self) -> mq_attr_member_t {
self.mq_attr.mq_msgsize
}
/// The number of messages currently held in the queue
pub const fn curmsgs(&self) -> mq_attr_member_t {
self.mq_attr.mq_curmsgs
}
}
/// Open a message queue
///
/// See also [`mq_open(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_open.html)
// The mode.bits cast is only lossless on some OSes
#[allow(clippy::cast_lossless)]
pub fn mq_open(name: &CString,
oflag: MQ_OFlag,
mode: Mode,
attr: Option<&MqAttr>)
-> Result<mqd_t> {
let res = match attr {
Some(mq_attr) => unsafe {
libc::mq_open(name.as_ptr(),
oflag.bits(),
mode.bits() as libc::c_int,
&mq_attr.mq_attr as *const libc::mq_attr)
},
None => unsafe { libc::mq_open(name.as_ptr(), oflag.bits()) },
};
Errno::result(res)
}
/// Remove a message queue
///
/// See also [`mq_unlink(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_unlink.html)
pub fn mq_unlink(name: &CString) -> Result<()> {
let res = unsafe { libc::mq_unlink(name.as_ptr()) };
Errno::result(res).map(drop)
}
/// Close a message queue
///
/// See also [`mq_close(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_close.html)
pub fn mq_close(mqdes: mqd_t) -> Result<()> {
let res = unsafe { libc::mq_close(mqdes) };
Errno::result(res).map(drop)
}
/// Receive a message from a message queue
///
/// See also [`mq_receive(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html)
pub fn mq_receive(mqdes: mqd_t, message: &mut [u8], msg_prio: &mut u32) -> Result<usize> {
let len = message.len() as size_t;
let res = unsafe {
libc::mq_receive(mqdes,
message.as_mut_ptr() as *mut c_char,
len,
msg_prio as *mut u32)
};
Errno::result(res).map(|r| r as usize)
}
/// Send a message to a message queue
///
/// See also [`mq_send(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_send.html)
pub fn mq_send(mqdes: mqd_t, message: &[u8], msq_prio: u32) -> Result<()> {
let res = unsafe {
libc::mq_send(mqdes,
message.as_ptr() as *const c_char,
message.len(),
msq_prio)
};
Errno::result(res).map(drop)
}
/// Get message queue attributes
///
/// See also [`mq_getattr(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_getattr.html)
pub fn mq_getattr(mqd: mqd_t) -> Result<MqAttr> {
let mut attr = mem::MaybeUninit::<libc::mq_attr>::uninit();
let res = unsafe { libc::mq_getattr(mqd, attr.as_mut_ptr()) };
Errno::result(res).map(|_| unsafe{MqAttr { mq_attr: attr.assume_init() }})
}
/// Set the attributes of the message queue. Only `O_NONBLOCK` can be set, everything else will be ignored
/// Returns the old attributes
/// It is recommend to use the `mq_set_nonblock()` and `mq_remove_nonblock()` convenience functions as they are easier to use
///
/// [Further reading](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_setattr.html)
pub fn mq_setattr(mqd: mqd_t, newattr: &MqAttr) -> Result<MqAttr> {
let mut attr = mem::MaybeUninit::<libc::mq_attr>::uninit();
let res = unsafe {
libc::mq_setattr(mqd, &newattr.mq_attr as *const libc::mq_attr, attr.as_mut_ptr())
};
Errno::result(res).map(|_| unsafe{ MqAttr { mq_attr: attr.assume_init() }})
}
/// Convenience function.
/// Sets the `O_NONBLOCK` attribute for a given message queue descriptor
/// Returns the old attributes
#[allow(clippy::useless_conversion)] // Not useless on all OSes
pub fn mq_set_nonblock(mqd: mqd_t) -> Result<MqAttr> {
let oldattr = mq_getattr(mqd)?;
let newattr = MqAttr::new(mq_attr_member_t::from(MQ_OFlag::O_NONBLOCK.bits()),
oldattr.mq_attr.mq_maxmsg,
oldattr.mq_attr.mq_msgsize,
oldattr.mq_attr.mq_curmsgs);
mq_setattr(mqd, &newattr)
}
/// Convenience function.
/// Removes `O_NONBLOCK` attribute for a given message queue descriptor
/// Returns the old attributes
pub fn mq_remove_nonblock(mqd: mqd_t) -> Result<MqAttr> {
let oldattr = mq_getattr(mqd)?;
let newattr = MqAttr::new(0,
oldattr.mq_attr.mq_maxmsg,
oldattr.mq_attr.mq_msgsize,
oldattr.mq_attr.mq_curmsgs);
mq_setattr(mqd, &newattr)
}
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