Ensure the launched commands are not terminated by the stop of xremap. (#214)

* Ensure the launched commands are not terminated by the stop of xremap.

Fix #213.

Signed-off-by: Kai Xia <kaix+github@fastmail.com>

* also stop child processes on unhappy path.

Signed-off-by: Kai Xia <kaix+github@fastmail.com>

* fix fmt

Signed-off-by: Kai Xia <kaix+github@fastmail.com>

Signed-off-by: Kai Xia <kaix+github@fastmail.com>

Cargo.lock

@@ -311,6 +311,15 @@ version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
+[[package]]
+name = "fork"
+version = "0.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9788ce090af4bf8d6e8f43d3f7d12305c787456387bd2d88856fcda3aa1f0dca"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "funty"
 version = "2.0.0"
@@ -1153,6 +1162,7 @@ dependencies = [
  "derive-where",
  "env_logger",
  "evdev",
+ "fork",
  "indoc",
  "lazy_static",
  "log",

Cargo.toml

@@ -13,6 +13,7 @@ clap_complete = "3.2.5"
 derive-where = "1.0.0"
 env_logger = "0.9.1"
 evdev = "0.12.0"
+fork = "0.1"
 indoc = "1.0"
 lazy_static = "1.4.0"
 log = "0.4.17"

src/action_dispatcher.rs

@@ -1,11 +1,12 @@
 use std::thread;
 
 use evdev::{uinput::VirtualDevice, EventType, InputEvent, Key};
+use fork::{fork, setsid, Fork};
 use log::debug;
 use log::error;
 use nix::sys::signal;
 use nix::sys::signal::{sigaction, SaFlags, SigAction, SigHandler, SigSet};
-use std::process::{Command, Stdio};
+use std::process::{exit, Command, Stdio};
 
 use crate::{action::Action, event::KeyEvent};
 
@@ -58,15 +59,40 @@ impl ActionDispatcher {
         }
 
         debug!("Running command: {:?}", command);
-        match Command::new(&command[0])
-            .args(&command[1..])
-            .stdin(Stdio::null())
-            .stdout(Stdio::null())
-            .stderr(Stdio::null())
-            .spawn()
-        {
-            Ok(child) => debug!("Process spawned: {:?}, pid {}", command, child.id()),
-            Err(e) => error!("Error running command: {:?}", e),
+        match fork() {
+            Ok(Fork::Child) => {
+                // Child process should fork again, and the parent should exit 0, while the child
+                // should spawn the user command then exit as well.
+                match fork() {
+                    Ok(Fork::Child) => {
+                        setsid().expect("Failed to setsid.");
+                        match Command::new(&command[0])
+                            .args(&command[1..])
+                            .stdin(Stdio::null())
+                            .stdout(Stdio::null())
+                            .stderr(Stdio::null())
+                            .spawn()
+                        {
+                            Ok(child) => {
+                                debug!("Process started: {:?}, pid {}", command, child.id());
+                                exit(0);
+                            }
+                            Err(e) => {
+                                error!("Error running command: {:?}", e);
+                                exit(1);
+                            }
+                        }
+                    }
+                    Ok(Fork::Parent(_)) => exit(0),
+                    Err(e) => {
+                        error!("Error spawning process: {:?}", e);
+                        exit(1);
+                    }
+                }
+            }
+            // Parent should simply continue.
+            Ok(Fork::Parent(_)) => (),
+            Err(e) => error!("Error spawning process: {:?}", e),
         }
     }
 }