diff options
Diffstat (limited to 'src/mqueue.rs')
-rw-r--r-- | src/mqueue.rs | 70 |
1 files changed, 53 insertions, 17 deletions
diff --git a/src/mqueue.rs b/src/mqueue.rs index 20740b54..792a5d22 100644 --- a/src/mqueue.rs +++ b/src/mqueue.rs @@ -1,12 +1,40 @@ //! Posix Message Queue functions //! +//! # Example +//! +// no_run because a kernel module may be required. +//! ```no_run +//! # use std::ffi::CString; +//! # use nix::mqueue::*; +//! use nix::sys::stat::Mode; +//! +//! const MSG_SIZE: mq_attr_member_t = 32; +//! let mq_name= CString::new("/a_nix_test_queue").unwrap(); +//! +//! let oflag0 = MQ_OFlag::O_CREAT | MQ_OFlag::O_WRONLY; +//! let mode = Mode::S_IWUSR | Mode::S_IRUSR | Mode::S_IRGRP | Mode::S_IROTH; +//! let mqd0 = mq_open(&mq_name, oflag0, mode, None).unwrap(); +//! let msg_to_send = b"msg_1"; +//! mq_send(&mqd0, msg_to_send, 1).unwrap(); +//! +//! let oflag1 = MQ_OFlag::O_CREAT | MQ_OFlag::O_RDONLY; +//! let mqd1 = mq_open(&mq_name, oflag1, mode, None).unwrap(); +//! let mut buf = [0u8; 32]; +//! let mut prio = 0u32; +//! let len = mq_receive(&mqd1, &mut buf, &mut prio).unwrap(); +//! assert_eq!(prio, 1); +//! assert_eq!(msg_to_send, &buf[0..len]); +//! +//! mq_close(mqd1).unwrap(); +//! mq_close(mqd0).unwrap(); +//! ``` //! [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 std::ffi::CStr; use crate::sys::stat::Mode; use std::mem; @@ -34,6 +62,14 @@ pub struct MqAttr { mq_attr: libc::mq_attr, } +/// Identifies an open POSIX Message Queue +// A safer wrapper around libc::mqd_t, which is a pointer on some platforms +// Deliberately is not Clone to prevent use-after-close scenarios +#[repr(transparent)] +#[derive(Debug)] +#[allow(missing_copy_implementations)] +pub struct MqdT(mqd_t); + // x32 compatibility // See https://sourceware.org/bugzilla/show_bug.cgi?id=21279 #[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))] @@ -87,11 +123,11 @@ impl MqAttr { /// 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, +pub fn mq_open(name: &CStr, oflag: MQ_OFlag, mode: Mode, attr: Option<&MqAttr>) - -> Result<mqd_t> { + -> Result<MqdT> { let res = match attr { Some(mq_attr) => unsafe { libc::mq_open(name.as_ptr(), @@ -101,13 +137,13 @@ pub fn mq_open(name: &CString, }, None => unsafe { libc::mq_open(name.as_ptr(), oflag.bits()) }, }; - Errno::result(res) + Errno::result(res).map(MqdT) } /// 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<()> { +pub fn mq_unlink(name: &CStr) -> Result<()> { let res = unsafe { libc::mq_unlink(name.as_ptr()) }; Errno::result(res).map(drop) } @@ -115,18 +151,18 @@ pub fn mq_unlink(name: &CString) -> Result<()> { /// 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) }; +pub fn mq_close(mqdes: MqdT) -> Result<()> { + let res = unsafe { libc::mq_close(mqdes.0) }; 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> { +pub fn mq_receive(mqdes: &MqdT, message: &mut [u8], msg_prio: &mut u32) -> Result<usize> { let len = message.len() as size_t; let res = unsafe { - libc::mq_receive(mqdes, + libc::mq_receive(mqdes.0, message.as_mut_ptr() as *mut c_char, len, msg_prio as *mut u32) @@ -137,9 +173,9 @@ pub fn mq_receive(mqdes: mqd_t, message: &mut [u8], msg_prio: &mut u32) -> Resul /// 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<()> { +pub fn mq_send(mqdes: &MqdT, message: &[u8], msq_prio: u32) -> Result<()> { let res = unsafe { - libc::mq_send(mqdes, + libc::mq_send(mqdes.0, message.as_ptr() as *const c_char, message.len(), msq_prio) @@ -150,9 +186,9 @@ pub fn mq_send(mqdes: mqd_t, message: &[u8], msq_prio: u32) -> Result<()> { /// 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> { +pub fn mq_getattr(mqd: &MqdT) -> Result<MqAttr> { let mut attr = mem::MaybeUninit::<libc::mq_attr>::uninit(); - let res = unsafe { libc::mq_getattr(mqd, attr.as_mut_ptr()) }; + let res = unsafe { libc::mq_getattr(mqd.0, attr.as_mut_ptr()) }; Errno::result(res).map(|_| unsafe{MqAttr { mq_attr: attr.assume_init() }}) } @@ -161,10 +197,10 @@ pub fn mq_getattr(mqd: mqd_t) -> Result<MqAttr> { /// 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> { +pub fn mq_setattr(mqd: &MqdT, 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()) + libc::mq_setattr(mqd.0, &newattr.mq_attr as *const libc::mq_attr, attr.as_mut_ptr()) }; Errno::result(res).map(|_| unsafe{ MqAttr { mq_attr: attr.assume_init() }}) } @@ -173,7 +209,7 @@ pub fn mq_setattr(mqd: mqd_t, newattr: &MqAttr) -> Result<MqAttr> { /// 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> { +pub fn mq_set_nonblock(mqd: &MqdT) -> 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, @@ -185,7 +221,7 @@ pub fn mq_set_nonblock(mqd: mqd_t) -> Result<MqAttr> { /// 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> { +pub fn mq_remove_nonblock(mqd: &MqdT) -> Result<MqAttr> { let oldattr = mq_getattr(mqd)?; let newattr = MqAttr::new(0, oldattr.mq_attr.mq_maxmsg, |