Method fill_events

src/uinput.rs:376–392

Read a maximum of `num` events into the internal buffer. If the underlying fd is not O_NONBLOCK, this will block. Returns the number of events that were read, or an error.

(&mut self)

    ///
    /// Returns the number of events that were read, or an error.
    pub(crate) fn fill_events(&mut self) -> io::Result<usize> {
        let fd = self.fd.as_raw_fd();
        self.event_buf.reserve(crate::EVENT_BATCH_SIZE);

        let spare_capacity = self.event_buf.spare_capacity_mut();
        let spare_capacity_size = std::mem::size_of_val(spare_capacity);

        // use libc::read instead of nix::unistd::read b/c we need to pass an uninitialized buf
        let res = unsafe { libc::read(fd, spare_capacity.as_mut_ptr() as _, spare_capacity_size) };
        let bytes_read = nix::errno::Errno::result(res)?;
        let num_read = bytes_read as usize / std::mem::size_of::<input_event>();
        unsafe {
            let len = self.event_buf.len();
            self.event_buf.set_len(len + num_read);
        }
        Ok(num_read)
    }

    /// Fetches and returns events from the kernel ring buffer without doing synchronization on
    /// SYN_DROPPED.