[starnix] Implement epoll_pwait2().

Implements epoll_pwait2() which is the same as epoll_pwait() except it
takes a timespec* for the timeout.

Change-Id: Iaa6b16afe6c5b2081476f3a63a23e98ce6e905b9
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/774663
Reviewed-by: Theodore Dubois <tbodt@google.com>
Commit-Queue: Brett Wilson <brettw@google.com>

Author: brettw

src/proc/bin/starnix/fs/syscalls.rs

@@ -1556,19 +1556,19 @@ pub fn sys_epoll_wait(
     sys_epoll_pwait(current_task, epfd, events, max_events, timeout, UserRef::<sigset_t>::default())
 }
 
-pub fn sys_epoll_pwait(
+// Backend for sys_epoll_pwait and sys_epoll_pwait2 that takes an already-decoded duration.
+fn do_epoll_pwait(
     current_task: &mut CurrentTask,
     epfd: FdNumber,
     events: UserRef<EpollEvent>,
     max_events: i32,
-    timeout: i32,
+    timeout: zx::Duration,
     user_sigmask: UserRef<sigset_t>,
 ) -> Result<usize, Errno> {
     if max_events < 1 {
         return error!(EINVAL);
     }
 
-    let timeout = duration_from_poll_timeout(timeout)?;
     let file = current_task.files.get(epfd)?;
     let epoll_file = file.downcast_file::<EpollFileObject>().ok_or_else(|| errno!(EINVAL))?;
 
@@ -1590,6 +1590,35 @@ pub fn sys_epoll_pwait(
     Ok(active_events.len())
 }
 
+pub fn sys_epoll_pwait(
+    current_task: &mut CurrentTask,
+    epfd: FdNumber,
+    events: UserRef<EpollEvent>,
+    max_events: i32,
+    timeout: i32,
+    user_sigmask: UserRef<sigset_t>,
+) -> Result<usize, Errno> {
+    let timeout = duration_from_poll_timeout(timeout)?;
+    do_epoll_pwait(current_task, epfd, events, max_events, timeout, user_sigmask)
+}
+
+pub fn sys_epoll_pwait2(
+    current_task: &mut CurrentTask,
+    epfd: FdNumber,
+    events: UserRef<EpollEvent>,
+    max_events: i32,
+    user_timespec: UserRef<timespec>,
+    user_sigmask: UserRef<sigset_t>,
+) -> Result<usize, Errno> {
+    let timeout = if user_timespec.is_null() {
+        zx::Duration::INFINITE
+    } else {
+        let ts = current_task.mm.read_object(user_timespec)?;
+        duration_from_timespec(ts)?
+    };
+    do_epoll_pwait(current_task, epfd, events, max_events, timeout, user_sigmask)
+}
+
 struct ReadyPollItem {
     index: usize,
     events: u32,

src/proc/bin/starnix/syscalls/decls.rs

@@ -368,6 +368,7 @@ macro_rules! for_each_syscall {
             pidfd_getfd,
             faccessat2,
             process_madvise,
+            epoll_pwait2,
         }
     }
 }

src/proc/bin/starnix/syscalls/table.rs

@@ -79,6 +79,7 @@ pub fn dispatch_syscall(
         epoll_create[1],
         epoll_ctl[4],
         epoll_pwait[5],
+        epoll_pwait2[5],
         epoll_wait[4],
         eventfd2[2],
         eventfd[1],

src/proc/tests/android/gvisor/meta/epoll_test.cml

@@ -5,6 +5,6 @@
     include: [ "//src/proc/tests/android/gvisor/meta/gvisor.shard.cml" ],
     program: {
         binary: "data/tests/epoll_test",
-        args: [ "--gunit_filter=-*.EpollPwait2Timeout:*.DoubleEpollOneShot:*.CloseFile:*.DoubleLayerEpoll" ],
+        args: [ "--gunit_filter=-*.DoubleEpollOneShot:*.CloseFile:*.DoubleLayerEpoll" ],
     },
 }