From ec7f1772ddae642e71931bbb5b7e48dcd713dd75 Mon Sep 17 00:00:00 2001
From: Federico Terzi <federicoterzi96@gmail.com>
Date: Mon, 1 Nov 2021 21:57:32 +0100
Subject: [PATCH] fix(detect): unregister device from epoll when removed on
 Wayland. #836

---
 espanso-detect/src/evdev/device.rs | 15 ++++++++++----
 espanso-detect/src/evdev/mod.rs    | 32 +++++++++++++++++++++++++++---
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/espanso-detect/src/evdev/device.rs b/espanso-detect/src/evdev/device.rs
index 818578d..5723ccc 100644
--- a/espanso-detect/src/evdev/device.rs
+++ b/espanso-detect/src/evdev/device.rs
@@ -2,7 +2,7 @@
 // https://github.com/xkbcommon/libxkbcommon/blob/master/tools/interactive-evdev.c
 
 use anyhow::Result;
-use libc::{input_event, size_t, ssize_t, EWOULDBLOCK, O_CLOEXEC, O_NONBLOCK, O_RDONLY};
+use libc::{input_event, size_t, ssize_t, ENODEV, EWOULDBLOCK, O_CLOEXEC, O_NONBLOCK, O_RDONLY};
 use log::trace;
 use scopeguard::ScopeGuard;
 use std::collections::HashMap;
@@ -127,7 +127,11 @@ impl Device {
     }
 
     if len < 0 && unsafe { *errno_ptr } != EWOULDBLOCK {
-      return Err(DeviceError::BlockingReadOperation().into());
+      if unsafe { *errno_ptr } == ENODEV {
+        return Err(DeviceError::FailedReadNoSuchDevice.into());
+      }
+
+      return Err(DeviceError::FailedRead(unsafe { *errno_ptr }).into());
     }
 
     Ok(events)
@@ -322,6 +326,9 @@ pub enum DeviceError {
   #[error("no devices found")]
   NoDevicesFound(),
 
-  #[error("read operation can't block device")]
-  BlockingReadOperation(),
+  #[error("read operation failed with code: `{0}`")]
+  FailedRead(i32),
+
+  #[error("read operation failed: ENODEV No such device")]
+  FailedReadNoSuchDevice,
 }
diff --git a/espanso-detect/src/evdev/mod.rs b/espanso-detect/src/evdev/mod.rs
index d7d6337..4f5f5c3 100644
--- a/espanso-detect/src/evdev/mod.rs
+++ b/espanso-detect/src/evdev/mod.rs
@@ -38,8 +38,9 @@ use keymap::Keymap;
 use lazycell::LazyCell;
 use libc::{
   __errno_location, close, epoll_ctl, epoll_event, epoll_wait, EINTR, EPOLLIN, EPOLL_CTL_ADD,
+  EPOLL_CTL_DEL,
 };
-use log::{debug, error, info, trace};
+use log::{debug, error, info, trace, warn};
 use thiserror::Error;
 
 use crate::event::{InputEvent, Key, KeyboardEvent, Variant};
@@ -204,7 +205,9 @@ impl Source for EVDEVSource {
         }
       }
 
-      for ev in evs.iter() {
+      #[allow(clippy::needless_range_loop)]
+      for i in 0usize..(ret as usize) {
+        let ev = evs[i];
         let device = &self.devices[ev.u64 as usize];
         match device.read() {
           Ok(events) if !events.is_empty() => {
@@ -226,7 +229,30 @@ impl Source for EVDEVSource {
             });
           }
           Ok(_) => { /* SKIP EMPTY */ }
-          Err(err) => error!("Can't read from device {}: {}", device.get_path(), err),
+          Err(err) => {
+            if let Some(DeviceError::FailedReadNoSuchDevice) = err.downcast_ref::<DeviceError>() {
+              warn!("Can't read from device {}, this error usually means the device has been disconnected, removing from epoll.", device.get_path());
+
+              if unsafe {
+                epoll_ctl(
+                  *epfd,
+                  EPOLL_CTL_DEL,
+                  device.get_raw_fd(),
+                  std::ptr::null_mut(),
+                )
+              } != 0
+              {
+                error!(
+                  "Could not remove {} from epoll, errno {}",
+                  device.get_path(),
+                  unsafe { *errno_ptr }
+                );
+                return Err(EVDEVSourceError::Internal().into());
+              }
+            } else {
+              error!("Can't read from device {}: {}", device.get_path(), err)
+            }
+          }
         }
       }
     }