From 4a2b0b9881f4753d24597eccfe98db65e531d962 Mon Sep 17 00:00:00 2001
From: Federico Terzi <federicoterzi96@gmail.com>
Date: Sat, 14 Sep 2019 00:38:45 +0200
Subject: [PATCH] Add lock file to prevent multiple instances from running. Add
 status subcommand. Fix #5. Fix #22

---
 Cargo.lock  | 11 +++++++++++
 Cargo.toml  |  1 +
 src/main.rs | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 800cedc..6752f52 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -228,6 +228,7 @@ dependencies = [
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "cmake 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.99 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -268,6 +269,15 @@ dependencies = [
  "miniz_oxide 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "fs2"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "fuchsia-cprng"
 version = "0.1.1"
@@ -733,6 +743,7 @@ dependencies = [
 "checksum failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "795bd83d3abeb9220f257e597aa0080a508b27533824adf336529648f6abf7e2"
 "checksum failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "ea1063915fd7ef4309e222a5a07cf9c319fb9c7836b1f89b85458672dbb127e1"
 "checksum flate2 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)" = "2adaffba6388640136149e18ed080b77a78611c1e1d6de75aedcdf78df5d4682"
+"checksum fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9564fc758e15025b46aa6643b1b77d047d1a56a1aea6e01002ac0c7026876213"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 "checksum getrandom 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "473a1265acc8ff1e808cd0a1af8cee3c2ee5200916058a2ca113c29f2d903571"
 "checksum lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
diff --git a/Cargo.toml b/Cargo.toml
index 4c772b3..ba7b325 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,7 @@ regex = "1.3.1"
 log = "0.4.8"
 simplelog = "0.7.1"
 zip = "0.5.3"
+fs2 = "0.4.3"
 
 [dev-dependencies]
 tempfile = "3.1.0"
diff --git a/src/main.rs b/src/main.rs
index 73f09c9..c00b4b0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,6 +15,8 @@ use log::{info, error, LevelFilter};
 use simplelog::{CombinedLogger, TermLogger, TerminalMode, SharedLogger};
 use std::process::exit;
 use std::time::Duration;
+use std::fs::{File, OpenOptions};
+use fs2::FileExt;
 
 mod ui;
 mod event;
@@ -50,6 +52,8 @@ fn main() {
             .about("Tool to detect current window properties, to simplify filters creation."))
         .subcommand(SubCommand::with_name("daemon")
             .about("Start the daemon without spawning a new process."))
+        .subcommand(SubCommand::with_name("status")
+            .about("Check if the espanso daemon is running or not."))
         .get_matches();
 
 
@@ -102,9 +106,21 @@ fn main() {
         daemon_main(config_set);
         return;
     }
+
+    if let Some(matches) = matches.subcommand_matches("status") {
+        status_main();
+        return;
+    }
 }
 
 fn daemon_main(config_set: ConfigSet) {
+    // Try to acquire lock file
+    let lock_file = acquire_lock();
+    if lock_file.is_none() {
+        error!("espanso is already running.");
+        exit(3);
+    }
+
     info!("starting daemon...");
 
     let (send_channel, receive_channel) = mpsc::channel();
@@ -148,6 +164,17 @@ fn daemon_background(receive_channel: Receiver<Event>, config_set: ConfigSet) {
     event_manager.eventloop();
 }
 
+fn status_main() {
+    let lock_file = acquire_lock();
+    if let Some(lock_file) = lock_file {
+        println!("espanso is not running");
+
+        release_lock(lock_file);
+    }else{
+        println!("espanso is running");
+    }
+}
+
 /// Cli tool used to analyze active windows to extract useful information
 /// to create configuration filters.
 fn detect_main() {
@@ -180,4 +207,27 @@ fn detect_main() {
 
         thread::sleep(Duration::from_millis(500));
     }
+}
+
+fn acquire_lock() -> Option<File> {
+    let espanso_dir = context::get_data_dir();
+    let lock_file_path = espanso_dir.join("espanso.lock");
+    let file = OpenOptions::new()
+        .read(true)
+        .write(true)
+        .create(true)
+        .open(lock_file_path)
+        .expect("Cannot create reference to lock file.");
+
+    let res = file.try_lock_exclusive();
+
+    if let Ok(_) = res {
+        return Some(file)
+    }
+
+    None
+}
+
+fn release_lock(lock_file: File) {
+    lock_file.unlock().unwrap()
 }
\ No newline at end of file