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/* posixmq 1.0.0 - Idiomatic rust library for using posix message queues * Copyright 2019, 2020 Torbjørn Birch Moltu * * Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or * http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or * http://opensource.org/licenses/MIT>, at your option. This file may not be * copied, modified, or distributed except according to those terms. */ //! Posix message queue wrapper with optional mio integration. //! //! Posix message queues are like pipes, but message-oriented which makes them //! safe to read by multiple processes. Messages are sorted based on an //! additional priority parameter. Queues are not placed in the normal file //! system, but uses a separate, flat namespace. Normal file permissions still //! apply though. //! For a longer introduction, see [`man mq_overview`](http://man7.org/linux/man-pages/man7/mq_overview.7.html) //! or [`man mq`](https://www.unix.com/man-page/netbsd/3/mq/). //! //! They are not all that useful, as only Linux and some BSDs implement them, //! and even there you might be limited to creating queues with a capacity of //! no more than 10 messages at a time. //! //! # Examples //! //! Send a couple messages: //! ```ignore //! use posixmq::PosixMq; //! //! // open the message queue if it exists, or create it if it doesn't. //! // names should start with a slash and have no more slashes. //! let mq = PosixMq::create("/hello_posixmq").unwrap(); //! mq.send(0, b"message").unwrap(); //! // messages with equal priority will be received in order //! mq.send(0, b"queue").unwrap(); //! // but this message has higher priority and will be received first //! mq.send(10, b"Hello,").unwrap(); //! ``` //! //! and receive them: //! ```ignore //! use posixmq::PosixMq; //! //! // open the queue read-only, or fail if it doesn't exist. //! let mq = PosixMq::open("/hello_posixmq").unwrap(); //! // delete the message queue when you don't need to open it again. //! // otherwise it will remain until the system is rebooted, consuming //! posixmq::remove_queue("/hello_posixmq").unwrap(); //! //! // the receive buffer must be at least as big as the biggest possible //! // message, or you will not be allowed to receive anything. //! let mut buf = vec![0; mq.attributes().unwrap().max_msg_len]; //! assert_eq!(mq.recv(&mut buf).unwrap(), (10, "Hello,".len())); //! assert_eq!(mq.recv(&mut buf).unwrap(), (0, "message".len())); //! assert_eq!(mq.recv(&mut buf).unwrap(), (0, "queue".len())); //! assert_eq!(&buf[..5], b"queue"); //! //! // check that there are no more messages //! assert_eq!(mq.attributes().unwrap().current_messages, 0); //! // note that acting on this value is race-prone. A better way to do this //! // would be to switch our descriptor to non-blocking mode, and check for //! // an error of type `ErrorKind::WouldBlock`. //! ``` //! //! With mio (and `features = ["mio_07"]` in Cargo.toml): #![cfg_attr(feature="mio_07", doc="```")] #![cfg_attr(not(feature="mio_07"), doc="```compile_fail")] //! # extern crate mio_07 as mio; //! # use mio::{Events, Poll, Interest, Token}; //! # use std::io::ErrorKind; //! # use std::thread; //! // set up queue //! let mut receiver = posixmq::OpenOptions::readonly() //! .nonblocking() //! .capacity(3) //! .max_msg_len(100) //! .create_new() //! .open("/mio") //! .unwrap(); //! //! // send something from another thread (or process) //! let sender = thread::spawn(move|| { //! let sender = posixmq::OpenOptions::writeonly().open("/mio").unwrap(); //! posixmq::remove_queue("/mio").unwrap(); //! sender.send(0, b"async").unwrap(); //! }); //! //! // set up mio and register //! let mut poll = Poll::new().unwrap(); //! poll.registry().register(&mut receiver, Token(0), Interest::READABLE).unwrap(); //! let mut events = Events::with_capacity(10); //! //! poll.poll(&mut events, None).unwrap(); //! for event in &events { //! if event.token() == Token(0) { //! loop { //! let mut buf = [0; 100]; //! match receiver.recv(&mut buf) { //! Err(ref e) if e.kind() == ErrorKind::WouldBlock => break, //! Err(e) => panic!("Error receiving message: {}", e), //! Ok((priority, len)) => { //! assert_eq!(priority, 0); //! assert_eq!(&buf[..len], b"async"); //! } //! } //! } //! } //! } //! //! sender.join().unwrap(); //! ``` //! //! See the examples/ directory for more. //! //! # Portability //! //! While the p in POSIX stands for Portable, that is not a fitting description //! of their message queues; Support is spotty even among *nix OSes. //! **Windows, macOS, OpenBSD, Android, ios, Rumprun, Fuchsia and Emscripten //! doesn't support posix message queues at all.** //! //! ## Compatible operating systems and features //! //! | Linux | FreeBSD 11+ | NetBSD | DragonFly BSD | Illumos | Solaris | VxWorks //! -|-|-|-|-|-|-|- //! core features | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes //! mio `Source` & `Evented` | Yes | Yes | unusable | Yes | No | No | No //! `FromRawFd`+`IntoRawFd`+[`try_clone()`](struct.PosixMq.html#method.try_clone) | Yes | No | Yes | Yes | No | No | No //! `AsRawFd`+[`set_cloexec()`](struct.PosixMq.html#method.set_cloexec) | Yes | Yes | Yes | Yes | No | No | No //! Tested? | Manually+CI | Manually+CI | Manually | Manually | Manually (on OmniOSce) | Cross-`check`ed on CI | No //! //! This library will fail to compile if the target OS doesn't have posix //! message queues. //! //! Feature explanations: //! //! * `FromRawFd`+`IntoRawFd`+[`try_clone()`](struct.PosixMq.html#method.try_clone): //! For theese to work, the inner `mqd_t` type must be an `int`/`RawFd` typedef, //! and known to represent a file descriptor. //! These impls are only available on OSes where this is known to be the case, //! to increase the likelyhood that the core features will compile on an //! unknown OS. //! * `AsRawFd`+[`set_cloexec()`](struct.PosixMq.html#method.set_cloexec): //! Similar to `FromRawFd` and `IntoRawFd`, but FreeBSD 11+ has [a function](https://svnweb.freebsd.org/base/head/include/mqueue.h?revision=306588&view=markup#l54) //! which lets one get a file descriptor from a `mqd_t`. //! Changing or querying close-on-exec requires `AsRawFd`, and is only //! only meaningful on operating systems that have the concept of `exec()`. //! [`is_cloexec()`](struct.PosixMq.html#method.is_cloexec) is always present //! and returns `true` on OSes where close-on-exec cannot be disabled or one //! cannot `exec()`. (posix message queue descriptors should have //! close-on-exec set by default). //! * mio `Source` & `Evented`: The impls require both `AsRawFd` //! and that mio compiles on the OS. //! This does not guarantee that the event notification mechanism used by mio //! supports posix message queues though. (registering fails on NetBSD) //! //! On Linux, message queues and their permissions can be viewed in //! `/dev/mqueue/`. The kernel *can* be compiled to not support posix message //! queues, so it's not guaranteed to always work. (such as on Android) //! //! On FreeBSD, the kernel module responsible for posix message queues //! is not loaded by default; Run `kldload mqueuefs` as root to enable it. //! To list queues, the file system must additionally be mounted first: //! `mount -t mqueuefs null $somewhere`. //! Versions before 11 do not have the function used to get a file descriptor, //! so this library will not compile there. //! //! On NetBSD, re-opening message queues multiple times can eventually make all //! further opens fail. This does not affect programs that open a single //! queue once. //! The mio integration compiles, but registering message queues with mio fails. //! Because NetBSD ignores cloexec when opening or cloning descriptors, there //! is a race condition with other threads exec'ing before this library can //! enable close-on-exec for the descriptor. //! //! DragonFly BSD doesn't set cloexec when opening either, but does when //! cloning. //! //! ## OS-dependent restrictions and default values //! //! Not even limiting oneself to the core features is enough to guarantee //! portability! //! //! | Linux | FreeBSD | NetBSD | DragonFly BSD | Illumos //! -|-|-|-|-|- //! max priority | 32767 | 63 | **31** | 31 | 31 //! default capacity | 10 | 10 | 32 | 32 | 128 //! default max_msg_len | 8192 | 1024 | 992 | 992 | 1024 //! max capacity | **10**\* | 100 | 512 | 512 | No limit //! max max_msg_len | **8192**\* | 16384 | 16384 | 16384 | No limit //! allows empty messages | Yes | Yes | No | No | Yes //! enforces name rules | Yes | Yes | No | No | Yes //! allows "/.", "/.." and "/" | No | No | Yes | Yes | Yes //! //! On Linux the listed size limits only apply to unprivileged processes. //! As root there instead appears to be a combined limit on memory usage of the //! form `capacity*(max_msg_len+k)`, but is several times higher than 10*8192. //! //! # Differences from the C API //! //! * [`send()`](struct.PosixMq.html#method.send), //! [`recv()`](struct.PosixMq.html#method.recv) and the timed equivalents //! tries again when EINTR / `ErrorKind::Interrupted` is returned. //! (Consistent with how std does IO) //! * `open()` and all other methods which take `AsRef<[u8]>` prepends `'/'` to //! the name if missing. //! (They have to copy the name anyway, to append a terminating `'\0'`) //! Use [`open_c()`](struct.OpenOptions.html#method.open_c) and //! [`remove_queue_c()`](fn.remove_queue_c.html) if you need to interact with //! queues on NetBSD or DragonFly that doesn't have a leading `'/'`. //! //! # Minimum supported Rust version //! //! The minimum supported Rust version for posixmq 1.0.z releases is 1.31.1. //! Later 1.y.0 releases might increase this. Until rustup has builds for //! DragonFly BSD and Illumos, the minimum version will not be increased past //! what is available in the repositories for those operating systems. // # Why this crate requires `std` // // The libc crate doesn't expose `errno` in a portable way, // so `std::io::Error::last_os_error()` is required to give errors // more specific than "something went wrong". // Depending on std also means that functions can use `io::Error` and // `SystemTime` instead of custom types. #![allow(clippy::needless_return, clippy::redundant_closure, clippy::needless_lifetimes)] // style #![allow(clippy::range_plus_one)] // edge case: I think 1..x+1 is clearer than 1..=x #![allow(clippy::cast_lossless)] // improves portability when values are limited by the OS anyway // feel free to disable more lints use std::{io, mem, ptr}; use std::ffi::CStr; use std::io::ErrorKind; use std::fmt::{self, Debug, Formatter}; #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] use std::os::unix::io::{AsRawFd, RawFd}; #[cfg(any(target_os="linux", target_os="netbsd", target_os="dragonfly"))] use std::os::unix::io::{FromRawFd, IntoRawFd}; use std::time::{Duration, SystemTime}; extern crate libc; use libc::{c_int, c_uint, c_char}; #[cfg(not(all(target_arch="x86_64", target_os="linux", target_pointer_width="32")))] use libc::c_long; use libc::{mqd_t, mq_open, mq_close, mq_unlink, mq_send, mq_receive}; use libc::{mq_attr, mq_getattr, mq_setattr}; use libc::{timespec, time_t, mq_timedsend, mq_timedreceive}; #[cfg(target_os="freebsd")] use libc::mq_getfd_np; use libc::{mode_t, O_ACCMODE, O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, O_EXCL, O_NONBLOCK}; #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] use libc::{fcntl, F_GETFD, FD_CLOEXEC, ioctl, FIOCLEX, FIONCLEX}; #[cfg(any(target_os="linux", target_os="netbsd", target_os="dragonfly"))] use libc::F_DUPFD_CLOEXEC; #[cfg(feature="mio_06")] extern crate mio_06; #[cfg(feature="mio_06")] use mio_06::{event::Evented, unix::EventedFd, Ready, Poll, PollOpt}; #[cfg(feature="mio_07")] extern crate mio_07; #[cfg(feature="mio_07")] use mio_07::{event::Source, unix::SourceFd, Registry, Interest}; const CSTR_BUF_SIZE: usize = 48; fn with_name_as_cstr<F: FnOnce(&CStr)->Result<R,io::Error>, R>(mut name: &[u8], f: F) -> Result<R,io::Error> { if name.first() == Some(&b'/') { name = &name[1..]; } let mut longbuf: Box<[u8]>; let mut shortbuf: [u8; CSTR_BUF_SIZE]; let c_bytes = if name.len() + 2 <= CSTR_BUF_SIZE { shortbuf = [0; CSTR_BUF_SIZE]; &mut shortbuf[..name.len()+2] } else { longbuf = vec![0; name.len()+2].into_boxed_slice(); &mut longbuf }; c_bytes[0] = b'/'; c_bytes[1..name.len()+1].copy_from_slice(name); match CStr::from_bytes_with_nul(c_bytes) { Ok(name) => f(name), Err(_) => Err(io::Error::new(ErrorKind::InvalidInput, "contains nul byte")) } } // Cannot use std::fs's because it doesn't expose getters, // and rolling our own means we can also use it for mq-specific capacities. /// Flags and parameters which control how a [`PosixMq`](struct.PosixMq.html) /// message queue is opened or created. #[derive(Clone,Copy, PartialEq,Eq)] pub struct OpenOptions { flags: c_int, mode: mode_t, capacity: usize, max_msg_len: usize, } impl Debug for OpenOptions { fn fmt(&self, fmtr: &mut Formatter) -> fmt::Result { fmtr.debug_struct("OpenOptions") .field( "read", &((self.flags & O_ACCMODE) == O_RDWR || (self.flags & O_ACCMODE) == O_RDONLY) ) .field( "write", &((self.flags & O_ACCMODE) == O_RDWR || (self.flags & O_ACCMODE) == O_WRONLY) ) .field("create", &(self.flags & O_CREAT != 0)) .field("open", &(self.flags & O_EXCL == 0)) .field("mode", &format_args!("{:03o}", self.mode)) .field("capacity", &self.capacity) .field("max_msg_len", &self.max_msg_len) .field("nonblocking", &((self.flags & O_NONBLOCK) != 0)) .finish() } } impl OpenOptions { fn new(flags: c_int) -> Self { OpenOptions { flags, // default permissions to only accessible for owner mode: 0o600, capacity: 0, max_msg_len: 0, } } /// Open message queue for receiving only. pub fn readonly() -> Self { OpenOptions::new(O_RDONLY) } /// Open message queue for sending only. pub fn writeonly() -> Self { OpenOptions::new(O_WRONLY) } /// Open message queue both for sending and receiving. pub fn readwrite() -> Self { OpenOptions::new(O_RDWR) } /// Set permissions to create the queue with. /// /// Some bits might be cleared by the process's umask when creating the /// queue, and unknown bits are ignored. /// /// This field is ignored if the queue already exists or should not be created. /// If this method is not called, queues are created with mode 600. pub fn mode(&mut self, mode: u32) -> &mut Self { // 32bit value for consistency with std::os::unix even though only 12 // bits are needed. Truncate if necessary because the OS ignores // unknown bits anyway. (and they're probably always zero as well). self.mode = mode as mode_t; return self; } /// Set the maximum size of each message. /// /// `recv()` will fail if given a buffer smaller than this value. /// /// If max_msg_len and capacity are both zero (or not set), the queue /// will be created with a maximum length and capacity decided by the /// operating system. /// If this value is specified, capacity should also be, or opening the /// message queue might fail. pub fn max_msg_len(&mut self, max_msg_len: usize) -> &mut Self { self.max_msg_len = max_msg_len; return self; } /// Set the maximum number of messages in the queue. /// /// When the queue is full, further `send()`s will either block /// or fail with an error of type `ErrorKind::WouldBlock`. /// /// If both capacity and max_msg_len are zero (or not set), the queue /// will be created with a maximum length and capacity decided by the /// operating system. /// If this value is specified, max_msg_len should also be, or opening the /// message queue might fail. pub fn capacity(&mut self, capacity: usize) -> &mut Self { self.capacity = capacity; return self; } /// Create message queue if it doesn't exist. pub fn create(&mut self) -> &mut Self { self.flags |= O_CREAT; self.flags &= !O_EXCL; return self; } /// Create a new queue, failing if the queue already exists. pub fn create_new(&mut self) -> &mut Self { self.flags |= O_CREAT | O_EXCL; return self; } /// Require the queue to already exist, failing if it doesn't. pub fn existing(&mut self) -> &mut Self { self.flags &= !(O_CREAT | O_EXCL); return self; } /// Open the message queue in non-blocking mode. /// /// This must be done if you want to use the message queue with mio. pub fn nonblocking(&mut self) -> &mut Self { self.flags |= O_NONBLOCK; return self; } /// Open a queue with the specified options. /// /// If the name doesn't start with a '/', one will be prepended. /// /// # Errors /// /// * Queue doesn't exist (ENOENT) => `ErrorKind::NotFound` /// * Name is just "/" (ENOENT) or is empty => `ErrorKind::NotFound` /// * Queue already exists (EEXISTS) => `ErrorKind::AlreadyExists` /// * Not permitted to open in this mode (EACCESS) => `ErrorKind::PermissionDenied` /// * More than one '/' in name (EACCESS) => `ErrorKind::PermissionDenied` /// * Invalid capacities (EINVAL) => `ErrorKind::InvalidInput` /// * Capacities too high (EMFILE) => `ErrorKind::Other` /// * Posix message queues are disabled (ENOSYS) => `ErrorKind::Other` /// * Name contains '\0' => `ErrorKind::InvalidInput` /// * Name is too long (ENAMETOOLONG) => `ErrorKind::Other` /// * Unlikely (ENFILE, EMFILE, ENOMEM, ENOSPC) => `ErrorKind::Other` /// * Possibly other pub fn open<N: AsRef<[u8]> + ?Sized>(&self, name: &N) -> Result<PosixMq, io::Error> { pub fn open_slice(opts: &OpenOptions, name: &[u8]) -> Result<PosixMq, io::Error> { with_name_as_cstr(name, |name| opts.open_c(&name) ) } open_slice(self, name.as_ref()) } /// Open a queue with the specified options and without inspecting `name` /// or allocating. /// /// This can on NetBSD be used to access message queues with names that /// doesn't start with a '/'. /// /// # Errors /// /// * Queue doesn't exist (ENOENT) => `ErrorKind::NotFound` /// * Name is just "/" (ENOENT) => `ErrorKind::NotFound` /// * Queue already exists (EEXISTS) => `ErrorKind::AlreadyExists` /// * Not permitted to open in this mode (EACCESS) => `ErrorKind::PermissionDenied` /// * More than one '/' in name (EACCESS) => `ErrorKind::PermissionDenied` /// * Invalid capacities (EINVAL) => `ErrorKind::InvalidInput` /// * Posix message queues are disabled (ENOSYS) => `ErrorKind::Other` /// * Name is empty (EINVAL) => `ErrorKind::InvalidInput` /// * Name is too long (ENAMETOOLONG) => `ErrorKind::Other` /// * Unlikely (ENFILE, EMFILE, ENOMEM, ENOSPC) => `ErrorKind::Other` /// * Possibly other pub fn open_c(&self, name: &CStr) -> Result<PosixMq, io::Error> { let opts = self; // because mq_open is a vararg function, mode_t cannot be passed // directly on FreeBSD where it's smaller than c_int. let permissions = opts.mode as c_int; let mut capacities = unsafe { mem::zeroed::<mq_attr>() }; let capacities_ptr = if opts.capacity != 0 || opts.max_msg_len != 0 { capacities.mq_maxmsg = opts.capacity as KernelLong; capacities.mq_msgsize = opts.max_msg_len as KernelLong; &mut capacities as *mut mq_attr } else { ptr::null_mut::<mq_attr>() }; let mqd = unsafe { mq_open(name.as_ptr(), opts.flags, permissions, capacities_ptr) }; // even when mqd_t is a pointer, -1 is the return value for error if mqd == -1isize as mqd_t { return Err(io::Error::last_os_error()); } let mq = PosixMq{mqd}; // NetBSD and DragonFly BSD doesn't set cloexec by default and // ignores O_CLOEXEC. Setting it with FIOCLEX works though. // Propagate error if setting cloexec somehow fails, even though // close-on-exec won't matter in most cases. #[cfg(any(target_os="netbsd", target_os="dragonfly"))] mq.set_cloexec(true)?; Ok(mq) } } /// Delete a posix message queue. /// /// A `'/'` is prepended to the name if it doesn't start with one already. /// (it would have to append a `'\0'` and therefore allocate or copy anyway.) /// /// Processes that have it open will still be able to use it. /// /// # Errors /// /// * Queue doesn't exist (ENOENT) => `ErrorKind::NotFound` /// * Name is invalid (ENOENT or EACCESS) => `ErrorKind::NotFound` or `ErrorKind::PermissionDenied` /// * Not permitted to delete the queue (EACCES) => `ErrorKind::PermissionDenied` /// * Posix message queues are disabled (ENOSYS) => `ErrorKind::Other` /// * Name contains '\0' bytes => `ErrorKind::InvalidInput` /// * Name is too long (ENAMETOOLONG) => `ErrorKind::Other` /// * Possibly other pub fn remove_queue<N: AsRef<[u8]> + ?Sized>(name: &N) -> Result<(), io::Error> { fn remove_queue_slice(name: &[u8]) -> Result<(), io::Error> { with_name_as_cstr(name, |name| remove_queue_c(&name) ) } remove_queue_slice(name.as_ref()) } /// Delete a posix message queue, without inspecting `name` or allocating. /// /// This function is on NetBSD necessary to remove queues with names that /// doesn't start with a '/'. /// /// # Errors /// /// * Queue doesn't exist (ENOENT) => `ErrorKind::NotFound` /// * Not permitted to delete the queue (EACCES) => `ErrorKind::PermissionDenied` /// * Posix message queues are disabled (ENOSYS) => `ErrorKind::Other` /// * More than one '/' in name (EACCESS) => `ErrorKind::PermissionDenied` /// * Name is empty (EINVAL) => `ErrorKind::InvalidInput` /// * Name is invalid (ENOENT, EACCESS or EINVAL) => `ErrorKind::NotFound` /// `ErrorKind::PermissionDenied` or `ErrorKind::InvalidInput` /// * Name is too long (ENAMETOOLONG) => `ErrorKind::Other` /// * Possibly other pub fn remove_queue_c(name: &CStr) -> Result<(), io::Error> { let name = name.as_ptr(); let ret = unsafe { mq_unlink(name) }; if ret != 0 { return Err(io::Error::last_os_error()); } Ok(()) } // The fields of `mq_attr` and `timespec` are of type `long` on all targets // except x86_64-unknown-linux-gnux32, where they are `long long` (to match up // with normal x86_64 `long`). // Rusts lack of implicit widening makes this peculiarity annoying. #[cfg(all(target_arch="x86_64", target_os="linux", target_pointer_width="32"))] type KernelLong = i64; #[cfg(not(all(target_arch="x86_64", target_os="linux", target_pointer_width="32")))] type KernelLong = c_long; /// Contains information about the capacities and state of a posix message queue. /// /// Created by [`PosixMq::attributes()`](struct.PosixMq.html#method.attributes). #[derive(Clone,Copy, PartialEq,Eq, Default)] pub struct Attributes { /// The maximum size of messages that can be stored in the queue. pub max_msg_len: usize, /// The maximum number of messages in the queue. pub capacity: usize, /// The number of messages currently in the queue at the time the /// attributes were retrieved. pub current_messages: usize, /// Whether the descriptor was set to nonblocking mode when /// the attributes were retrieved. pub nonblocking: bool, _private: () } impl Debug for Attributes { fn fmt(&self, fmtr: &mut fmt::Formatter) -> fmt::Result { fmtr.debug_struct("Attributes") .field("max_msg_len", &self.max_msg_len) .field("capacity", &self.capacity) .field("current_messages", &self.current_messages) .field("nonblocking", &self.nonblocking) .finish() } } macro_rules! retry_if_interrupted {($call:expr) => {{ loop {// catch EINTR and retry let ret = $call; if ret != -1 { break ret; } let err = io::Error::last_os_error(); if err.kind() != ErrorKind::Interrupted { return Err(err) } } }}} /// Returns saturated timespec as err if systemtime cannot be represented fn deadline_to_realtime(deadline: SystemTime) -> Result<timespec, timespec> { /// Don't use struct literal in case timespec has extra fields on some platform. fn new_timespec(secs: time_t, nsecs: KernelLong) -> timespec { let mut ts: timespec = unsafe { mem::zeroed() }; ts.tv_sec = secs; ts.tv_nsec = nsecs; return ts; } // mq_timedsend() and mq_timedreceive() takes an absolute point in time, // based on CLOCK_REALTIME aka SystemTime. match deadline.duration_since(SystemTime::UNIX_EPOCH) { // Currently SystemTime has the same range as the C types, but // avoid truncation in case this changes. Ok(expires) if expires.as_secs() > time_t::max_value() as u64 => Err(new_timespec(time_t::max_value(), 0)), Ok(expires) => Ok(new_timespec(expires.as_secs() as time_t, expires.subsec_nanos() as KernelLong)), // A pre-1970 deadline is probably a bug, but handle it anyway. // Based on https://github.com/solemnwarning/timespec/blob/master/README.md // the subsecond part of timespec should be positive and counts toward // positive infinity; (-1, 0) < (-1, 999999999) < (0, 0). This has the // advantage of simplifying addition and subtraction, but is the // opposite of Duration which counts away from zero. // The minimum representable value is therefore (-min_value(), 0) Err(ref earlier) if earlier.duration() > Duration::new(time_t::max_value() as u64 + 1, 0) => Err(new_timespec(time_t::min_value()+1, 0)), // add one to avoid negation bugs Err(ref earlier) if earlier.duration().subsec_nanos() == 0 => Ok(new_timespec(-(earlier.duration().as_secs() as time_t), 0)), Err(earlier) => { // convert fractional part from counting away from zero to counting // toward positive infinity let before = earlier.duration(); let secs = -(before.as_secs() as time_t) - 1; let nsecs = 1_000_000_000 - before.subsec_nanos() as KernelLong; Ok(new_timespec(secs, nsecs)) } } } /// Returns an error if timeout is not representable or the produced deadline /// overflows. fn timeout_to_realtime(timeout: Duration) -> Result<timespec, io::Error> { if let Ok(now) = deadline_to_realtime(SystemTime::now()) { let mut expires = now; expires.tv_sec = expires.tv_sec.wrapping_add(timeout.as_secs() as time_t); // nanosecond values only use 30 bits, so adding two together is safe // even if tv_nsec is an i32 expires.tv_nsec += timeout.subsec_nanos() as KernelLong; const NANO: KernelLong = 1_000_000_000; expires.tv_sec = expires.tv_sec.wrapping_add(expires.tv_nsec / NANO); expires.tv_nsec %= NANO; // check that the unsigned timeout is representable as a signed and // possibly smaller time_t, and the additions didn't overflow. // The second check will fail to catch Duration::new(!0, 999_999_999) // (which makes tv_sec wrap completely to the original value), but // the unsigned max value is not representable as a signed value and // will be caught by the first check. // Using wrapping_add and catching overflow afterwards avoids repeating // the error creation and also handles negative system time. if timeout.as_secs() > time_t::max_value() as u64 || expires.tv_sec < now.tv_sec { Err(io::Error::new(ErrorKind::InvalidInput, "timeout is too long")) } else { Ok(expires) } } else { Err(io::Error::new(ErrorKind::Other, "system time is not representable")) } } /// A descriptor for an open posix message queue. /// /// Message queues can be sent to and / or received from depending on the /// options it was opened with. /// /// The descriptor is closed when this struct is dropped. /// /// See [the documentation in the crate root](index.html) for examples, /// portability notes and OS details. pub struct PosixMq { mqd: mqd_t } impl PosixMq { /// Open an existing message queue in read-write mode. /// /// See [`OpenOptions::open()`](struct.OpenOptions.html#method.open) for /// details and possible errors. pub fn open<N: AsRef<[u8]> + ?Sized>(name: &N) -> Result<Self, io::Error> { OpenOptions::readwrite().open(name) } /// Open a message queue in read-write mode, creating it if it doesn't exists. /// /// See [`OpenOptions::open()`](struct.OpenOptions.html#method.open) for /// details and possible errors. pub fn create<N: AsRef<[u8]> + ?Sized>(name: &N) -> Result<Self, io::Error> { OpenOptions::readwrite().create().open(name) } /// Add a message to the queue. /// /// For maximum portability, avoid using priorities >= 32 or sending /// zero-length messages. /// /// # Errors /// /// * Queue is full and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * Message is too big for the queue (EMSGSIZE) => `ErrorKind::Other` /// * Message is zero-length and the OS doesn't allow this (EMSGSIZE) => `ErrorKind::Other` /// * Priority is too high (EINVAL) => `ErrorKind::InvalidInput` /// * Queue is opened in read-only mode (EBADF) => `ErrorKind::Other` /// * Possibly other => `ErrorKind::Other` pub fn send(&self, priority: u32, msg: &[u8]) -> Result<(), io::Error> { let mptr = msg.as_ptr() as *const c_char; retry_if_interrupted!(unsafe { mq_send(self.mqd, mptr, msg.len(), priority as c_uint) }); Ok(()) } /// Take the message with the highest priority from the queue. /// /// The buffer must be at least as big as the maximum message length. /// /// # Errors /// /// * Queue is empty and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * The receive buffer is smaller than the queue's maximum message size (EMSGSIZE) => `ErrorKind::Other` /// * Queue is opened in write-only mode (EBADF) => `ErrorKind::Other` /// * Possibly other => `ErrorKind::Other` pub fn recv(&self, msgbuf: &mut [u8]) -> Result<(u32, usize), io::Error> { let bptr = msgbuf.as_mut_ptr() as *mut c_char; let mut priority = 0 as c_uint; let len = retry_if_interrupted!( unsafe { mq_receive(self.mqd, bptr, msgbuf.len(), &mut priority) } ); // c_uint is unlikely to differ from u32, but even if it's bigger, the // range of supported values will likely be far smaller. Ok((priority as u32, len as usize)) } /// Returns an `Iterator` which calls [`recv()`](#method.recv) repeatedly /// with an appropriately sized buffer. /// /// If the message queue is opened in non-blocking mode the iterator can be /// used to drain the queue. Otherwise it will block and never end. pub fn iter<'a>(&'a self) -> Iter<'a> { self.into_iter() } fn timedsend(&self, priority: u32, msg: &[u8], deadline: ×pec) -> Result<(), io::Error> { let mptr = msg.as_ptr() as *const c_char; retry_if_interrupted!(unsafe { mq_timedsend(self.mqd, mptr, msg.len(), priority as c_uint, deadline) }); Ok(()) } /// Add a message to the queue or cancel if it's still full after a given /// duration. /// /// Returns immediately if opened in nonblocking mode, and the timeout has /// no effect. /// /// For maximum portability, avoid using priorities >= 32 or sending /// zero-length messages. /// /// # Errors /// /// * Timeout expired (ETIMEDOUT) => `ErrorKind::TimedOut` /// * Message is too big for the queue (EMSGSIZE) => `ErrorKind::Other` /// * OS doesn't allow empty messages (EMSGSIZE) => `ErrorKind::Other` /// * Priority is too high (EINVAL) => `ErrorKind::InvalidInput` /// * Queue is full and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * Queue is opened in write-only mode (EBADF) => `ErrorKind::Other` /// * Timeout is too long / not representable => `ErrorKind::InvalidInput` /// * Possibly other => `ErrorKind::Other` pub fn send_timeout(&self, priority: u32, msg: &[u8], timeout: Duration) -> Result<(), io::Error> { timeout_to_realtime(timeout).and_then(|expires| self.timedsend(priority, msg, &expires) ) } /// Add a message to the queue or cancel if the queue is still full at a /// certain point in time. /// /// Returns immediately if opened in nonblocking mode, and the timeout has /// no effect. /// The deadline is a `SystemTime` because the queues are intended for /// inter-process commonication, and `Instant` might be process-specific. /// /// For maximum portability, avoid using priorities >= 32 or sending /// zero-length messages. /// /// # Errors /// /// * Deadline reached (ETIMEDOUT) => `ErrorKind::TimedOut` /// * Message is too big for the queue (EMSGSIZE) => `ErrorKind::Other` /// * OS doesn't allow empty messages (EMSGSIZE) => `ErrorKind::Other` /// * Priority is too high (EINVAL) => `ErrorKind::InvalidInput` /// * Queue is full and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * Queue is opened in write-only mode (EBADF) => `ErrorKind::Other` /// * Possibly other => `ErrorKind::Other` pub fn send_deadline(&self, priority: u32, msg: &[u8], deadline: SystemTime) -> Result<(), io::Error> { match deadline_to_realtime(deadline) { Ok(expires) => self.timedsend(priority, msg, &expires), Err(_) => Err(io::Error::new(ErrorKind::InvalidInput, "deadline is not representable")) } } fn timedreceive(&self, msgbuf: &mut[u8], deadline: ×pec) -> Result<(u32, usize), io::Error> { let bptr = msgbuf.as_mut_ptr() as *mut c_char; let mut priority: c_uint = 0; let len = retry_if_interrupted!( unsafe { mq_timedreceive(self.mqd, bptr, msgbuf.len(), &mut priority, deadline) } ); Ok((priority as u32, len as usize)) } /// Take the message with the highest priority from the queue or cancel if /// the queue still empty after a given duration. /// /// Returns immediately if opened in nonblocking mode, and the timeout has /// no effect. /// /// # Errors /// /// * Timeout expired (ETIMEDOUT) => `ErrorKind::TimedOut` /// * The receive buffer is smaller than the queue's maximum message size (EMSGSIZE) => `ErrorKind::Other` /// * Queue is empty and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * Queue is opened in read-only mode (EBADF) => `ErrorKind::Other` /// * Timeout is too long / not representable => `ErrorKind::InvalidInput` /// * Possibly other => `ErrorKind::Other` pub fn recv_timeout(&self, msgbuf: &mut[u8], timeout: Duration) -> Result<(u32, usize), io::Error> { timeout_to_realtime(timeout).and_then(|expires| self.timedreceive(msgbuf, &expires) ) } /// Take the message with the highest priority from the queue or cancel if /// the queue is still empty at a point in time. /// /// Returns immediately if opened in nonblocking mode, and the timeout has /// no effect. /// The deadline is a `SystemTime` because the queues are intended for /// inter-process commonication, and `Instant` might be process-specific. /// /// # Errors /// /// * Deadline reached (ETIMEDOUT) => `ErrorKind::TimedOut` /// * The receive buffer is smaller than the queue's maximum message size (EMSGSIZE) => `ErrorKind::Other` /// * Queue is empty and opened in nonblocking mode (EAGAIN) => `ErrorKind::WouldBlock` /// * Queue is opened in read-only mode (EBADF) => `ErrorKind::Other` /// * Possibly other => `ErrorKind::Other` pub fn recv_deadline(&self, msgbuf: &mut[u8], deadline: SystemTime) -> Result<(u32, usize), io::Error> { match deadline_to_realtime(deadline) { Ok(expires) => self.timedreceive(msgbuf, &expires), Err(_) => Err(io::Error::new(ErrorKind::InvalidInput, "deadline is not representable")) } } /// Get information about the state of the message queue. /// /// # Errors /// /// Retrieving these attributes should only fail if the underlying /// descriptor has been closed or is not a message queue. /// /// On operating systems where the descriptor is a pointer, such as on /// FreeBSD and Illumos, such bugs will enable undefined behavior /// and this call will dereference freed or uninitialized memory. /// (That doesn't make this function unsafe though - /// [`PosixMq::from_raw_mqd()`](#method.from_raw_mqd) and `mq_close()` are.) /// /// While a `send()` or `recv()` ran in place of this call would also have /// failed immediately and therefore not blocked, The descriptor might have /// become used for another queue when a *later* `send()` or `recv()` is /// performed. The descriptor might then be in blocking mode. /// /// # Examples /// /// ``` /// # let _ = posixmq::remove_queue("/with_custom_capacity"); /// let mq = posixmq::OpenOptions::readwrite() /// .create_new() /// .max_msg_len(100) /// .capacity(3) /// .open("/with_custom_capacity") /// .expect("create queue"); /// let attrs = mq.attributes().expect("get attributes for queue"); /// assert_eq!(attrs.max_msg_len, 100); /// assert_eq!(attrs.capacity, 3); /// assert_eq!(attrs.current_messages, 0); /// assert!(!attrs.nonblocking); /// ``` /// /// Ignore the error: /// /// (Will only happen with buggy code (incorrect usage of /// [`from_raw_fd()`](#method.from_raw_fd) or similar)). /// #[cfg_attr( any(target_os="linux", target_os="android", target_os="netbsd", target_os="dragonfly"), doc="```" )] #[cfg_attr( not(any(target_os="linux", target_os="android", target_os="netbsd", target_os="dragonfly")), doc="```no_compile" )] /// # use std::os::unix::io::FromRawFd; /// # let bad = unsafe { posixmq::PosixMq::from_raw_fd(-1) }; /// let attrs = bad.attributes().unwrap_or_default(); /// assert_eq!(attrs.max_msg_len, 0); /// assert_eq!(attrs.capacity, 0); /// assert_eq!(attrs.current_messages, 0); /// assert!(!attrs.nonblocking); /// ``` pub fn attributes(&self) -> Result<Attributes, io::Error> { let mut attrs: mq_attr = unsafe { mem::zeroed() }; if unsafe { mq_getattr(self.mqd, &mut attrs) } == -1 { Err(io::Error::last_os_error()) } else { Ok(Attributes { max_msg_len: attrs.mq_msgsize as usize, capacity: attrs.mq_maxmsg as usize, current_messages: attrs.mq_curmsgs as usize, nonblocking: (attrs.mq_flags & (O_NONBLOCK as KernelLong)) != 0, _private: () }) } } /// Check whether this descriptor is in nonblocking mode. /// /// # Errors /// /// Should only fail as result of buggy code that either created this /// descriptor from something that is not a queue, or has already closed /// the underlying descriptor. /// (This function will not silently succeed if the fd points to anything /// other than a queue (for example a socket), as this function /// is a wrapper around [`attributes()`][#method.attributes].) /// To ignore failure, one can write `.is_nonblocking().unwrap_or(false)`. /// /// ## An error doesn't guarantee that any further [`send()`](#method.send) or [`recv()`](#method.recv) wont block. /// /// While a `send()` or `recv()` ran in place of this call would also have /// failed immediately and therefore not blocked, the descriptor might have /// become used for another queue when a *later* `send()` or `recv()` is /// performed. The descriptor might then be in blocking mode. pub fn is_nonblocking(&self) -> Result<bool, io::Error> { match self.attributes() { Ok(attrs) => Ok(attrs.nonblocking), Err(e) => Err(e), } } /// Enable or disable nonblocking mode for this descriptor. /// /// This can also be set when opening the message queue, /// with [`OpenOptions::nonblocking()`](struct.OpenOptions.html#method.nonblocking). /// /// # Errors /// /// Setting nonblocking mode should only fail due to incorrect usage of /// `from_raw_fd()` or `as_raw_fd()`, see the documentation on /// [`attributes()`](struct.PosixMq.html#method.attributes) for details. pub fn set_nonblocking(&self, nonblocking: bool) -> Result<(), io::Error> { let mut attrs: mq_attr = unsafe { mem::zeroed() }; attrs.mq_flags = if nonblocking {O_NONBLOCK as KernelLong} else {0}; let res = unsafe { mq_setattr(self.mqd, &attrs, ptr::null_mut()) }; if res == -1 { return Err(io::Error::last_os_error()); } Ok(()) } /// Create a new descriptor for the same message queue. /// /// The new descriptor will have close-on-exec set. /// /// This function is not available on FreeBSD, Illumos or Solaris. #[cfg(any(target_os="linux", target_os="dragonfly", target_os="netbsd"))] pub fn try_clone(&self) -> Result<Self, io::Error> { let mq = match unsafe { fcntl(self.mqd, F_DUPFD_CLOEXEC, 0) } { -1 => return Err(io::Error::last_os_error()), fd => PosixMq{mqd: fd}, }; // NetBSD ignores the cloexec part of F_DUPFD_CLOEXEC // (but DragonFly BSD respects it here) #[cfg(target_os="netbsd")] mq.set_cloexec(true)?; Ok(mq) } /// Check whether this descriptor will be closed if the process `exec`s /// into another program. /// /// Posix message queues are closed on exec by default, /// but this can be changed with [`set_cloexec()`](#method.set_cloexec). /// /// This function is not available on Illumos, Solaris or VxWorks. /// /// # Errors /// /// Retrieving this flag should only fail if the descriptor /// is already closed. /// In that case it will obviously not be open after execing, /// so treating errors as `true` should be safe. /// /// # Examples /// /// ``` /// let queue = posixmq::PosixMq::create("is_cloexec").expect("open queue"); /// # posixmq::remove_queue("is_cloexec").expect("delete queue"); /// assert!(queue.is_cloexec().unwrap_or(true)); /// ``` pub fn is_cloexec(&self) -> Result<bool, io::Error> { #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] match unsafe { fcntl(self.as_raw_fd(), F_GETFD) } { -1 => Err(io::Error::last_os_error()), flags => Ok((flags & FD_CLOEXEC) != 0), } #[cfg(not(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", )))] Err(io::Error::new( ErrorKind::Other, "close-on-exec information is not available" )) } /// Change close-on-exec for this descriptor. /// /// It is on by default, so this method should only be called when one /// wants the descriptor to remain open afte `exec`ing. /// /// This function is not available on Illumos, Solaris or VxWorks. /// /// # Errors /// /// This function should only fail if the underlying file descriptor has /// been closed (due to incorrect usage of `from_raw_fd()` or similar), /// and not reused for something else yet. #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] pub fn set_cloexec(&self, cloexec: bool) -> Result<(), io::Error> { let op = if cloexec {FIOCLEX} else {FIONCLEX}; match unsafe { ioctl(self.as_raw_fd(), op) } { // Don't hide the error here, because callers can ignore the // returned value if they want. -1 => Err(io::Error::last_os_error()), _ => Ok(()) } } /// Create a `PosixMq` from an already opened message queue descriptor. /// /// This function should only be used for ffi or if calling `mq_open()` /// directly for some reason. /// Use [`from_raw_fd()`](#method.from_raw_fd) instead if the surrounding /// code requires `mqd_t` to be a file descriptor. /// /// # Safety /// /// On some operating systems `mqd_t` is a pointer, which means that the /// safety of most other methods depend on it being correct. pub unsafe fn from_raw_mqd(mqd: mqd_t) -> Self { PosixMq{mqd} } /// Get the raw message queue descriptor. /// /// This function should only be used for passing to ffi code or to access /// portable features not exposed by this wrapper (such as calling /// `mq_notify()` or not automatically retrying on EINTR / /// `ErrorKind::Interrupted` when sending or receiving). /// /// If you need a file descriptor, use `as_raw_fd()` instead for increased /// portability. /// ([`as_raw_fd()`](#method.as_raw_fd) can sometimes retrieve an /// underlying file descriptor even if `mqd_t` is not an `int`.) pub fn as_raw_mqd(&self) -> mqd_t { self.mqd } /// Convert this wrapper into the raw message queue descriptor without /// closing it. /// /// This function should only be used for ffi; If you need a file /// descriptor use [`into_raw_fd()`](#method.into_raw_fd) instead. pub fn into_raw_mqd(self) -> mqd_t { let mqd = self.mqd; mem::forget(self); return mqd; } } /// Get an underlying file descriptor for the message queue. /// /// If you just need the raw `mqd_t`, use /// [`as_raw_mqd()`](struct.PosixMq.html#method.as_raw_mqd) /// instead for increased portability. /// /// This impl is not available on Illumos, Solaris or VxWorks. #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] impl AsRawFd for PosixMq { // On Linux, NetBSD and DragonFly BSD, `mqd_t` is a plain file descriptor // and can trivially be convverted, but this is not guaranteed, nor the // case on FreeBSD, Illumos and Solaris. #[cfg(not(target_os="freebsd"))] fn as_raw_fd(&self) -> RawFd { self.mqd } // FreeBSD has mq_getfd_np() (where _np stands for non-portable) #[cfg(target_os="freebsd")] fn as_raw_fd(&self) -> RawFd { unsafe { mq_getfd_np(self.mqd) } } } /// Create a `PosixMq` wrapper from a raw file descriptor. /// /// Note that the message queue will be closed when the returned `PosixMq` goes /// out of scope / is dropped. /// /// This impl is not available on FreeBSD, Illumos or Solaris; If you got a /// `mqd_t` in a portable fashion (from FFI code or by calling `mq_open()` /// yourself for some reason), use /// [`from_raw_mqd()`](struct.PosixMq.html#method.from_raw_mqd) instead. #[cfg(any(target_os="linux", target_os="netbsd", target_os="dragonfly"))] impl FromRawFd for PosixMq { unsafe fn from_raw_fd(fd: RawFd) -> Self { PosixMq{mqd: fd} } } /// Convert the `PosixMq` into a raw file descriptor without closing the /// message queue. /// /// This impl is not available on FreeBSD, Illumos or Solaris. If you need to /// transfer ownership to FFI code accepting a `mqd_t`, use /// [`into_raw_mqd()`](struct.PosixMq.html#method.into_raw_mqd) instead. #[cfg(any(target_os="linux", target_os="netbsd", target_os="dragonfly"))] impl IntoRawFd for PosixMq { fn into_raw_fd(self) -> RawFd { let fd = self.mqd; mem::forget(self); return fd; } } impl IntoIterator for PosixMq { type Item = (u32, Vec<u8>); type IntoIter = IntoIter; fn into_iter(self) -> IntoIter { IntoIter { max_msg_len: match self.attributes() { Ok(attrs) => attrs.max_msg_len, Err(_) => 0, }, mq: self, } } } impl<'a> IntoIterator for &'a PosixMq { type Item = (u32, Vec<u8>); type IntoIter = Iter<'a>; fn into_iter(self) -> Iter<'a> { Iter { max_msg_len: match self.attributes() { Ok(attrs) => attrs.max_msg_len, Err(_) => 0, }, mq: self, } } } impl Debug for PosixMq { fn fmt(&self, fmtr: &mut Formatter) -> fmt::Result { let mut representation = fmtr.debug_struct("PosixMq"); // display raw value and name unless we know it's a plain fd #[cfg(not(any( target_os="linux", target_os="netbsd", target_os="dragonfly", )))] representation.field("mqd", &self.mqd); // show file descriptor where we have one #[cfg(any( target_os="linux", target_os="freebsd", target_os="netbsd", target_os="dragonfly", ))] representation.field("fd", &self.as_raw_fd()); return representation.finish(); } } impl Drop for PosixMq { fn drop(&mut self) { unsafe { mq_close(self.mqd) }; } } // On some platforms mqd_t is a pointer, so Send and Sync aren't // auto-implemented there. While I don't feel certain enough to // blanket-implement Sync, I can't see why an implementation would make it UB // to move operations to another thread. unsafe impl Send for PosixMq {} // On FreeBSD, mqd_t is a `struct{int fd, struct sigev_node* node}*`, // but the sigevent is only accessed by `mq_notify()`, so it's thread-safe // as long as that function requires `&mut self` or isn't exposed. // src: https://svnweb.freebsd.org/base/head/lib/librt/mq.c?view=markup // On Illumos, mqd_t points to a rather complex struct, but the functions use // mutexes and semaphores, so I assume they're totally thread-safe. // src: https://github.com/illumos/illumos-gate/blob/master/usr/src/lib/libc/port/rt/mqueue.c // Solaris I assume is equivalent to Illumos, because the Illumos code has // barely been modified after the initial source code release. // Linux, NetBSD and DragonFly BSD gets Sync auto-implemented because // mqd_t is an int. #[cfg(any(target_os="freebsd", target_os="illumos", target_os="solaris"))] unsafe impl Sync for PosixMq {} /// Allow receiving event notifications through mio (version 0.6). /// /// This impl requires the `mio_06` feature to be enabled: /// /// ```toml /// [dependencies] /// posixmq = {version="1.0", features=["mio_06"]} /// ``` /// /// Remember to open the queue in non-blocking mode. (with `OpenOptions.noblocking()`) #[cfg(feature="mio_06")] impl Evented for PosixMq { fn register(&self, poll: &Poll, token: mio_06::Token, interest: Ready, opts: PollOpt) -> Result<(), io::Error> { EventedFd(&self.as_raw_fd()).register(poll, token, interest, opts) } fn reregister(&self, poll: &Poll, token: mio_06::Token, interest: Ready, opts: PollOpt) -> Result<(), io::Error> { EventedFd(&self.as_raw_fd()).reregister(poll, token, interest, opts) } fn deregister(&self, poll: &Poll) -> Result<(), io::Error> { EventedFd(&self.as_raw_fd()).deregister(poll) } } /// Allow receiving event notifications through mio (version 0.7). /// /// This impl requires the `mio_07` feature to be enabled: /// /// ```toml /// [dependencies] /// posixmq = {version="1.0", features=["mio_07"]} /// ``` /// /// Due to a [long-lived bug in cargo]() this will currently enable /// the os_reactor feature of mio. This is not intended, and can change in the /// future. /// /// You probably want to make the queue non-blocking: Either use /// [`OpenOptions.noblocking()`](struct.OpenOptions.html#method.nonblocking) /// when preparing to open the queue, or call [`set_nonblocking(true)`](struct.PosixMq.html#method.set_nonblocking). #[cfg(feature="mio_07")] impl Source for &PosixMq { fn register(&mut self, registry: &Registry, token: mio_07::Token, interest: Interest) -> Result<(), io::Error> { SourceFd(&self.as_raw_fd()).register(registry, token, interest) } fn reregister(&mut self, registry: &Registry, token: mio_07::Token, interest: Interest) -> Result<(), io::Error> { SourceFd(&self.as_raw_fd()).reregister(registry, token, interest) } fn deregister(&mut self, registry: &Registry) -> Result<(), io::Error> { SourceFd(&self.as_raw_fd()).deregister(registry) } } #[cfg(feature="mio_07")] impl Source for PosixMq { fn register(&mut self, registry: &Registry, token: mio_07::Token, interest: Interest) -> Result<(), io::Error> { {&mut &*self}.register(registry, token, interest) } fn reregister(&mut self, registry: &Registry, token: mio_07::Token, interest: Interest) -> Result<(), io::Error> { {&mut &*self}.reregister(registry, token, interest) } fn deregister(&mut self, registry: &Registry) -> Result<(), io::Error> { {&mut &*self}.deregister(registry) } } /// An `Iterator` that calls [`recv()`](struct.PosixMq.html#method.recv) on a borrowed [`PosixMq`](struct.PosixMq.html). /// /// Iteration ends when a `recv()` fails with an `ErrorKind::WouldBlock` error, /// but is infinite if the descriptor is in blocking mode. /// /// # Panics /// /// `next()` will panic if an error of type other than `ErrorKind::WouldBlock` /// or `ErrorKind::Interrupted` occurs. #[derive(Clone)] pub struct Iter<'a> { mq: &'a PosixMq, /// Cached max_msg_len: usize, } impl<'a> Iterator for Iter<'a> { type Item = (u32, Vec<u8>); fn next(&mut self) -> Option<(u32, Vec<u8>)> { let mut buf = vec![0; self.max_msg_len]; match self.mq.recv(&mut buf) { Err(ref e) if e.kind() == ErrorKind::WouldBlock => None, Err(e) => panic!("Cannot receive from posix message queue: {}", e), Ok((priority, len)) => { buf.truncate(len); Some((priority, buf)) } } } } /// An `Iterator` that [`recv()`](struct.PosixMq.html#method.recv)s /// messages from an owned [`PosixMq`](struct.PosixMq.html). /// /// Iteration ends when a `recv()` fails with an `ErrorKind::WouldBlock` error, /// but is infinite if the descriptor is in blocking mode. /// /// # Panics /// /// `next()` will panic if an error of type other than `ErrorKind::WouldBlock` /// or `ErrorKind::Interrupted` occurs. pub struct IntoIter { mq: PosixMq, max_msg_len: usize, } impl Iterator for IntoIter { type Item = (u32, Vec<u8>); fn next(&mut self) -> Option<(u32, Vec<u8>)> { Iter{mq: &self.mq, max_msg_len: self.max_msg_len}.next() } } #[cfg(debug_assertions)] mod doctest_md_files { macro_rules! mdfile {($content:expr, $(#[$meta:meta])* $attach_to:ident) => { #[doc=$content] #[allow(unused)] $(#[$meta])* // can't #[cfg_attr(, doc=)] in .md file enum $attach_to {} }} mdfile!{include_str!("README.md"), Readme} }