Merge #1966

1966: Added `mq_timedreceive` to `::nix::mqueue`. r=asomers a=DavidCollard

Noticed when working on a project that `mq_timedreceive` is missing from the `mqueue` module.

Not entirely familiar with best practices around feature gating in tests - I feel like I might have messed up by not including a `#[cfg(feature = "time")]`. Would like a little guidance there.

Co-authored-by: David Collard <davidcollardprofessional@gmail.com>

Author: bors[bot]

CHANGELOG.md

@@ -11,6 +11,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
   (#[1662](https://github.com/nix-rust/nix/pull/1662))
 - Added `CanRaw` to `SockProtocol` and `CanBcm` as a separate `SocProtocol` constant.
   ([#1912](https://github.com/nix-rust/nix/pull/1912))
+- Added `mq_timedreceive` to `::nix::mqueue`.
+  ([#1966])(https://github.com/nix-rust/nix/pull/1966)
 
 ### Changed
 

src/mqueue.rs

@@ -197,6 +197,32 @@ pub fn mq_receive(
     Errno::result(res).map(|r| r as usize)
 }
 
+feature! {
+    #![feature = "time"]
+    use crate::sys::time::TimeSpec;
+    /// Receive a message from a message queue with a timeout
+    ///
+    /// See also ['mq_timedreceive(2)'](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_receive.html)
+    pub fn mq_timedreceive(
+        mqdes: &MqdT,
+        message: &mut [u8],
+        msg_prio: &mut u32,
+        abstime: &TimeSpec,
+    ) -> Result<usize> {
+        let len = message.len() as size_t;
+        let res = unsafe {
+            libc::mq_timedreceive(
+                mqdes.0,
+                message.as_mut_ptr() as *mut c_char,
+                len,
+                msg_prio as *mut u32,
+                abstime.as_ref(),
+            )
+        };
+        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)

test/test_mq.rs

@@ -3,9 +3,13 @@ use std::ffi::CString;
 use std::str;
 
 use nix::errno::Errno;
-use nix::mqueue::{mq_attr_member_t, mq_close, mq_open, mq_receive, mq_send};
+use nix::mqueue::{
+    mq_attr_member_t, mq_close, mq_open, mq_receive, mq_send, mq_timedreceive,
+};
 use nix::mqueue::{MQ_OFlag, MqAttr};
 use nix::sys::stat::Mode;
+use nix::sys::time::{TimeSpec, TimeValLike};
+use nix::time::{clock_gettime, ClockId};
 
 // Defined as a macro such that the error source is reported as the caller's location.
 macro_rules! assert_attr_eq {
@@ -55,6 +59,37 @@ fn test_mq_send_and_receive() {
     assert_eq!(msg_to_send, str::from_utf8(&buf[0..len]).unwrap());
 }
 
+#[test]
+fn test_mq_timedreceive() {
+    const MSG_SIZE: mq_attr_member_t = 32;
+    let attr = MqAttr::new(0, 10, MSG_SIZE, 0);
+    let mq_name = &CString::new(b"/a_nix_test_queue".as_ref()).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 r0 = mq_open(mq_name, oflag0, mode, Some(&attr));
+    if let Err(Errno::ENOSYS) = r0 {
+        println!("message queues not supported or module not loaded?");
+        return;
+    };
+    let mqd0 = r0.unwrap();
+    let msg_to_send = "msg_1";
+    mq_send(&mqd0, msg_to_send.as_bytes(), 1).unwrap();
+
+    let oflag1 = MQ_OFlag::O_CREAT | MQ_OFlag::O_RDONLY;
+    let mqd1 = mq_open(mq_name, oflag1, mode, Some(&attr)).unwrap();
+    let mut buf = [0u8; 32];
+    let mut prio = 0u32;
+    let abstime =
+        clock_gettime(ClockId::CLOCK_REALTIME).unwrap() + TimeSpec::seconds(1);
+    let len = mq_timedreceive(&mqd1, &mut buf, &mut prio, &abstime).unwrap();
+    assert_eq!(prio, 1);
+
+    mq_close(mqd1).unwrap();
+    mq_close(mqd0).unwrap();
+    assert_eq!(msg_to_send, str::from_utf8(&buf[0..len]).unwrap());
+}
+
 #[test]
 fn test_mq_getattr() {
     use nix::mqueue::mq_getattr;