Remove return value from pause

`pause` will always return `-1` as a result and sets `errno` to
`EINTR`, which indicates that a signal was caught by the process. Since
this is the point of `pause` return an error here makes little sense.

Closes #827.

CHANGELOG.md

@@ -94,7 +94,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Both `ip_mreq` and `ipv6_mreq` have been replaced with `IpMembershipRequest` and
   `Ipv6MembershipRequest`.
   ([#814](https://github.com/nix-rust/nix/pull/814))
-
+- Removed return type from `pause`.
+  ([#829](https://github.com/nix-rust/nix/pull/829))
 
 ### Fixed
 - Fix compilation and tests for OpenBSD targets

src/unistd.rs

@@ -1316,14 +1316,12 @@ pub fn initgroups(user: &CStr, group: Gid) -> Result<()> {
     Errno::result(res).map(|_| ())
 }
 
-/// Suspend the thread until a signal is received
+/// Suspend the thread until a signal is received.
 ///
-/// See also [pause(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/pause.html)
+/// See also [pause(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/pause.html).
 #[inline]
-pub fn pause() -> Result<()> {
-    let res = unsafe { libc::pause() };
-
-    Errno::result(res).map(drop)
+pub fn pause() {
+    unsafe { libc::pause() };
 }
 
 /// Suspend execution for an interval of time

test/sys/test_wait.rs

@@ -12,7 +12,10 @@ fn test_wait_signal() {
 
     // Safe: The child only calls `pause` and/or `_exit`, which are async-signal-safe.
     match fork().expect("Error: Fork Failed") {
-      Child => pause().unwrap_or_else(|_| unsafe { _exit(123) }),
+      Child => {
+          pause();
+          unsafe { _exit(123) }
+      },
       Parent { child } => {
           kill(child, Some(SIGKILL)).expect("Error: Kill Failed");
           assert_eq!(waitpid(child, None), Ok(WaitStatus::Signaled(child, SIGKILL, false)));