Add support for mq_notify() on Linux #2467
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| #[cfg(target_os = "linux")] | ||
| pub fn mq_notify(mqdes: &MqdT, notify: SigEvent) -> Result<()> { | ||
| let sig_event = notify.sigevent(); | ||
| let res = unsafe { libc::syscall(libc::SYS_mq_notify, mqdes.0, &sig_event as *const libc_sigevent) }; |
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From the Linux manual, glibc has provided a library wrapper for this syscall, we should prefer to use that. If the symbol is not exposed by the libc crate, we should add it there first (to the libc-0.2 branch), and then we adjust the dependency and add it on the Nix side.
| /// See also [`mq_notify(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_notify.html) | ||
| #[cfg(target_os = "linux")] | ||
| pub fn mq_notify(mqdes: &MqdT, notify: SigEvent) -> Result<()> { | ||
| let sig_event = notify.sigevent(); |
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.sigevent() would copy the underlying structure, we can use as_mut_ptr() to get the pointer directly.
Update: Just found this function returns a mutable pointer, which is not needed by this PR, looks like we need to add an as_ptr() function, which should be implemented in a way similar to how as_mut_ptr() was implemented.
| /// | ||
| /// See also [`mq_notify(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_notify.html) | ||
| #[cfg(target_os = "linux")] | ||
| pub fn mq_notify(mqdes: &MqdT, notify: SigEvent) -> Result<()> { |
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Why are we taking notify by value?
| let _ = nix::mqueue::mq_unlink(mq_name); | ||
| 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?"); |
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You can use the skip!() macro provided in test/common/mod.rs, which uses io::stderr() directly to ensure it won't be captured by cargo test so that the message will always be printed:
skip!("test_mq_send_receive_notify: message queues not supported or module not loaded, skipping test")
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What does this PR do
This PR adds support for the
mq_notify()API that allows a process to register for POSIX message queue notifications.Checklist:
CONTRIBUTING.md