add safe libc::clock_nanosleep wrapper

Author: maxbla

src/time.rs

@@ -1,4 +1,5 @@
-use crate::sys::time::TimeSpec;
+use bitflags::bitflags;
+use crate::sys::time::{TimeSpec, TimeValLike};
 #[cfg(any(
     target_os = "freebsd",
     target_os = "dragonfly",
@@ -256,3 +257,38 @@ pub fn clock_getcpuclockid(pid: Pid) -> Result<ClockId> {
         Err(Error::Sys(Errno::from_i32(ret)))
     }
 }
+
+bitflags! {
+    /// Flags that are used for arming the timer.
+    pub struct ClockNanosleepFlags: libc::c_int {
+        const TFD_TIMER_ABSTIME = libc::TIMER_ABSTIME;
+    }
+}
+
+/// Suspend execution of this thread for the amount of time specified by rqtp
+/// and measured against the clock speficied by ClockId. If flags is
+/// TIMER_ABSTIME, this function will suspend execution until the time value of
+/// clock_id reaches the absolute time specified by rqtp. If a signal is caught
+/// by a signal-catching function, or a signal causes the process to terminate,
+/// this sleep is interrrupted.
+/// see also [man 3 clock_nanosleep](https://pubs.opengroup.org/onlinepubs/009695399/functions/clock_nanosleep.html)
+pub fn clock_nanosleep(
+    clock_id: ClockId,
+    flags: ClockNanosleepFlags,
+    rqtp: &TimeSpec,
+) -> Result<TimeSpec> {
+    let mut rmtp: TimeSpec = TimeSpec::nanoseconds(0);
+    let ret = unsafe {
+        libc::clock_nanosleep(
+            clock_id.as_raw(),
+            flags.bits(),
+            rqtp.as_ref() as *const _,
+            rmtp.as_mut() as *mut _,
+        )
+    };
+    if ret == 0 {
+        Ok(rmtp)
+    } else {
+        Err(Error::Sys(Errno::from_i32(ret)))
+    }
+}

test/test_time.rs

@@ -1,3 +1,4 @@
+use nix::sys::time::{TimeSpec, TimeValLike};
 #[cfg(any(
     target_os = "freebsd",
     target_os = "dragonfly",
@@ -6,7 +7,7 @@
     target_os = "emscripten",
 ))]
 use nix::time::clock_getcpuclockid;
-use nix::time::{clock_getres, clock_gettime, ClockId};
+use nix::time::{clock_getres, clock_gettime, clock_nanosleep, ClockId, ClockNanosleepFlags};
 
 #[test]
 pub fn test_clock_getres() {
@@ -54,3 +55,15 @@ pub fn test_clock_id_pid_cpu_clock_id() {
         .map(ClockId::now)
         .is_ok());
 }
+
+#[test]
+pub fn test_clock_nanosleep() {
+    let sleep_time = TimeSpec::microseconds(1);
+    let res = clock_nanosleep(
+        ClockId::CLOCK_MONOTONIC,
+        ClockNanosleepFlags::empty(),
+        &sleep_time,
+    );
+    let expected = TimeSpec::microseconds(0);
+    assert_eq!(res, Ok(expected));
+}