From dcd4198c1d3865b5968954bc3e3329a6862615e3 Mon Sep 17 00:00:00 2001
From: William Salmon <will.salmon@codethink.co.uk>
Date: Mon, 14 Jul 2025 17:46:01 +0100
Subject: [PATCH] Add a timed send to match the timed receive

---
 CHANGELOG.md    |  7 ++++++
 src/mqueue.rs   | 20 ++++++++++++++++
 test/test_mq.rs | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e320bc824..a1d8c2ff14 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,13 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 # Change Log
 
+## [Unreleased] - ReleaseDate
+
+### Added
+
+- Added `mq_timedsend` to `::nix::mqueue`.
+  ([#2650](https://github.com/nix-rust/nix/pull/2650))
+
 ## [0.30.1] - 2025-05-04
 
 ### Fixed
diff --git a/src/mqueue.rs b/src/mqueue.rs
index 7684d56858..9b8e754a3e 100644
--- a/src/mqueue.rs
+++ b/src/mqueue.rs
@@ -235,6 +235,26 @@ feature! {
         };
         Errno::result(res).map(|r| r as usize)
     }
+    /// Send a message to a message queue with a timeout
+    ///
+    /// See also ['mq_timedsend(2)'](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_send.html)
+    pub fn mq_timedsend(
+        mqdes: &MqdT,
+        message: &[u8],
+        msg_prio: u32,
+        abstime: &TimeSpec,
+    ) -> Result<()> {
+        let res = unsafe {
+            libc::mq_timedsend(
+                mqdes.0,
+                message.as_ptr().cast(),
+                message.len(),
+                msg_prio,
+                abstime.as_ref(),
+            )
+        };
+        Errno::result(res).map(drop)
+    }
 }
 
 /// Send a message to a message queue
diff --git a/test/test_mq.rs b/test/test_mq.rs
index 874a72b44d..d34881dc70 100644
--- a/test/test_mq.rs
+++ b/test/test_mq.rs
@@ -4,6 +4,7 @@ use std::str;
 use nix::errno::Errno;
 use nix::mqueue::{
     mq_attr_member_t, mq_close, mq_open, mq_receive, mq_send, mq_timedreceive,
+    mq_timedsend, mq_unlink,
 };
 use nix::mqueue::{MQ_OFlag, MqAttr};
 use nix::sys::stat::Mode;
@@ -89,6 +90,68 @@ fn test_mq_timedreceive() {
     assert_eq!(msg_to_send, str::from_utf8(&buf[0..len]).unwrap());
 }
 
+#[test]
+fn test_mq_timedsend() {
+    const MSG_SIZE: mq_attr_member_t = 32;
+    let attr = MqAttr::new(0, 10, MSG_SIZE, 0);
+    let mq_name = "/a_nix_test_queue_timedsend";
+
+    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";
+    let abstime =
+        clock_gettime(ClockId::CLOCK_REALTIME).unwrap() + TimeSpec::seconds(1);
+    mq_timedsend(&mqd0, msg_to_send.as_bytes(), 1, &abstime).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 len = mq_receive(&mqd1, &mut buf, &mut prio).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());
+    mq_unlink(mq_name).unwrap();
+}
+
+#[test]
+fn test_mq_timedsend_full() {
+    const MSG_SIZE: mq_attr_member_t = 32;
+    let attr = MqAttr::new(0, 10, MSG_SIZE, 0);
+    let mq_name = "/a_nix_test_queue_fill";
+
+    let oflag0 = MQ_OFlag::O_CREAT | MQ_OFlag::O_WRONLY | MQ_OFlag::O_CLOEXEC;
+    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";
+    for _i in 0..10 {
+        mq_send(&mqd0, msg_to_send.as_bytes(), 1).unwrap();
+    }
+
+    let abstime =
+        clock_gettime(ClockId::CLOCK_REALTIME).unwrap() + TimeSpec::seconds(1);
+    assert_eq!(
+        mq_timedsend(&mqd0, msg_to_send.as_bytes(), 1, &abstime),
+        Err(Errno::ETIMEDOUT)
+    );
+
+    mq_close(mqd0).unwrap();
+    mq_unlink(mq_name).unwrap();
+}
+
 #[test]
 fn test_mq_getattr() {
     use nix::mqueue::mq_getattr;