1 files changed, 46 insertions, 0 deletions
diff --git a/src/hid.rs b/src/hid.rs
index da70d81..6b09e98 100644
--- a/src/hid.rs
+++ b/src/hid.rs
@@ -10,6 +10,7 @@ use std::fs;
 use std::io;
 use std::os::fd::AsRawFd;
 use std::path::{Path, PathBuf};
+use std::time::{Duration, Instant};
 
 /// beyerdynamic USB vendor ID.
 pub const BEYERDYNAMIC_VID: u16 = 0x2e50;
@@ -198,6 +199,51 @@ impl Hidraw {
         self.file.read(buf)
     }
 
+    /// Wait up to `timeout` for one input report on the interrupt IN
+    /// endpoint. Returns `Ok(None)` if none arrived in time.
+    pub fn read_with_timeout(&mut self, timeout: Duration) -> io::Result<Option<Vec<u8>>> {
+        let deadline = Instant::now() + timeout;
+        loop {
+            let now = Instant::now();
+            if now >= deadline {
+                return Ok(None);
+            }
+            let mut set = unsafe { std::mem::zeroed::<libc::fd_set>() };
+            unsafe { libc::FD_ZERO(&mut set) };
+            unsafe { libc::FD_SET(self.file.as_raw_fd(), &mut set) };
+            let remaining = deadline.saturating_duration_since(now);
+            let mut tv = libc::timeval {
+                tv_sec: remaining.as_secs() as libc::time_t,
+                tv_usec: remaining.subsec_micros() as libc::suseconds_t,
+            };
+            let n = unsafe {
+                libc::select(
+                    self.file.as_raw_fd() + 1,
+                    &mut set,
+                    std::ptr::null_mut(),
+                    std::ptr::null_mut(),
+                    &mut tv,
+                )
+            };
+            if n < 0 {
+                let err = io::Error::last_os_error();
+                if err.kind() == io::ErrorKind::Interrupted {
+                    continue;
+                }
+                return Err(err);
+            }
+            if n == 0 {
+                return Ok(None);
+            }
+            let mut buf = [0u8; 256];
+            match self.read(&mut buf) {
+                Ok(len) => return Ok(Some(buf[..len].to_vec())),
+                Err(e) if e.kind() == io::ErrorKind::Interrupted => continue,
+                Err(e) => return Err(e),
+            }
+        }
+    }
+
     /// Write to the interrupt OUT endpoint.
     pub fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         use std::io::Write;