Make epoll and inotify optional dependencies enabled by default with the epoll_inotify feature

Cargo.toml

@@ -32,5 +32,9 @@ lazy_static = "1.4.0"
 [target.'cfg(target_os="linux")'.dependencies]
 libc = "0.2.102"
 nix = "0.22.1"
-epoll = "4.3.1"
+epoll = { version = "4.3.1", optional = true }
-inotify = { version = "0.9.3", default-features = false, features = [] }
+inotify = { version = "0.9.3", default-features = false, features = [], optional = true }
+
+[features]
+default = ["epoll_inotify"]
+epoll_inotify = ["epoll", "inotify"]

src/linux/device/input_device.rs

@@ -5,9 +5,11 @@ use std::os::unix::io::AsRawFd;
 use std::os::unix::prelude::RawFd;
 use libc::{input_event, c_int};
 use nix::{ioctl_write_ptr, ioctl_read_buf};
-use epoll::ControlOptions::{EPOLL_CTL_ADD, EPOLL_CTL_DEL};
 use nix::fcntl::{OFlag, fcntl, FcntlArg};
 
+#[cfg(feature = "epoll_inotify")]
+use epoll::ControlOptions::{EPOLL_CTL_ADD, EPOLL_CTL_DEL};
+
 use crate::{Error,Result};
 use crate::linux::{EV_KEY, KEY_MAX, NAME, KEY_W, KEY_A, KEY_S, KEY_D};
 
@@ -105,6 +107,7 @@ impl InputDevice {
         Ok(())
     }
     
+    #[cfg(feature = "epoll_inotify")]
     pub fn epoll_add(mut self, epoll_fd: RawFd, data: u64) -> Result<Self> {
         if None != self.epoll_fd {
             return Err(Error::EpollAlreadyAdded);
@@ -122,6 +125,7 @@ impl InputDevice {
         Ok(self)
     }
 
+    #[cfg(feature = "epoll_inotify")]
     pub fn epoll_del(&mut self) -> Result<&mut Self> {
         if let Some(epoll_fd) = self.epoll_fd {
             // set this to None first, if we end up returning an Err early, we can't do anything else anyway...
@@ -137,6 +141,7 @@ impl Drop for InputDevice {
     fn drop(&mut self) {
         // ignore any errors here, what could we do anyhow?
         self.release().ok();
+        #[cfg(feature = "epoll_inotify")]
         self.epoll_del().ok();
     }
 }

src/linux/mod.rs

@@ -9,6 +9,7 @@ pub use device::{Device,InputDevice, Builder};
 use libc::input_event;
 use std::process::exit;
 use std::env;
+use std::collections::HashMap;
 
 const INPUT_FOLDER: &str = "/dev/input/";
 
@@ -18,12 +19,6 @@ const UP: i32 = 0;
 
 use getopts::Options;
 
-use inotify::{
-    Inotify,
-    WatchMask,
-};
-use std::collections::HashMap;
-
 const EV_KEY_U16: u16 = EV_KEY as u16;
 
 type LinuxKeyMaps = KeyMaps<Device, u16, input_event>;
@@ -127,6 +122,13 @@ pub fn main_res() -> Result<()> {
             send_event(&mut key_map, event, &device)?
         }
     } else {
+        #[cfg(not(feature = "epoll_inotify"))]
+        panic!("without epoll_inotify feature, only exactly 1 device is supported");
+
+        #[cfg(feature = "epoll_inotify")]
+            {
+                use inotify::{Inotify, WatchMask};
+
                 let epoll_fd = epoll::create(true)?;
                 const INOTIFY_DATA: u64 = u64::max_value();
 
@@ -218,6 +220,7 @@ pub fn main_res() -> Result<()> {
                 }
             }
     }
+}
 
 fn send_event(key_map: &mut LinuxKeyMaps, mut event: input_event, device: &Device) -> Result<()> {
     if event.type_ == EV_KEY_U16 {