1 files changed, 68 insertions, 0 deletions
diff --git a/third_party/rust/alsa/src/poll.rs b/third_party/rust/alsa/src/poll.rs
new file mode 100644
index 0000000000..3e9191164e
--- /dev/null
+++ b/third_party/rust/alsa/src/poll.rs
@@ -0,0 +1,68 @@
+//! Tiny poll ffi
+//!
+//! A tiny wrapper around libc's poll system call.
+
+use libc;
+use super::error::*;
+use std::io;
+pub use libc::pollfd;
+
+
+bitflags! {
+    pub struct Flags: ::libc::c_short {
+        const IN  = ::libc::POLLIN;
+        const PRI = ::libc::POLLPRI;
+        const OUT = ::libc::POLLOUT;
+        const ERR = ::libc::POLLERR;
+        const HUP = ::libc::POLLHUP;
+        const NVAL = ::libc::POLLNVAL;
+    }
+}
+
+pub trait Descriptors {
+    fn count(&self) -> usize;
+    fn fill(&self, _: &mut [pollfd]) -> Result<usize>;
+    fn revents(&self, _: &[pollfd]) -> Result<Flags>;
+
+    /// Wrapper around count and fill - returns an array of pollfds
+    fn get(&self) -> Result<Vec<pollfd>> {
+        let mut v = vec![pollfd { fd: 0, events: 0, revents: 0 }; self.count()];
+        if self.fill(&mut v)? != v.len() { Err(Error::unsupported("did not fill the poll descriptors array")) }
+        else { Ok(v) }
+    }
+}
+
+impl Descriptors for pollfd {
+    fn count(&self) -> usize { 1 }
+    fn fill(&self, a: &mut [pollfd]) -> Result<usize> { a[0] = *self; Ok(1) }
+    fn revents(&self, a: &[pollfd]) -> Result<Flags> { Ok(Flags::from_bits_truncate(a[0].revents)) }
+}
+
+/// Wrapper around the libc poll call.
+pub fn poll(fds: &mut[pollfd], timeout: i32) -> Result<usize> {
+    let r = unsafe { libc::poll(fds.as_mut_ptr(), fds.len() as libc::nfds_t, timeout as libc::c_int) };
+    if r >= 0 { Ok(r as usize) } else {
+         from_code("poll", -io::Error::last_os_error().raw_os_error().unwrap()).map(|_| unreachable!())
+    }
+}
+
+/// Builds a pollfd array, polls it, and returns the poll descriptors which have non-zero revents.
+pub fn poll_all<'a>(desc: &[&'a dyn Descriptors], timeout: i32) -> Result<Vec<(&'a dyn Descriptors, Flags)>> {
+
+    let mut pollfds: Vec<pollfd> = vec!();
+    let mut indices = vec!();
+    for v2 in desc.iter().map(|q| q.get()) {
+        let v = v2?;
+        indices.push(pollfds.len() .. pollfds.len()+v.len());
+        pollfds.extend(v);
+    };
+
+    poll(&mut pollfds, timeout)?;
+
+    let mut res = vec!();
+    for (i, r) in indices.into_iter().enumerate() {
+        let z = desc[i].revents(&pollfds[r])?;
+        if !z.is_empty() { res.push((desc[i], z)); }
+    }
+    Ok(res)
+}