From fa9670a85b8dead29b01f395024000e54dcbd2b9 Mon Sep 17 00:00:00 2001
From: guinux <nuxgui@gmail.com>
Date: Sat, 13 May 2017 17:33:47 +0200
Subject: [PATCH] remove lockfile only if it's older than boot time

---
 src/daemon.vala | 67 +++++++++++++++++++++++++++++++++++--------------
 src/tray.vala   |  4 +--
 2 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/src/daemon.vala b/src/daemon.vala
index 3882dc1..1a20fa7 100644
--- a/src/daemon.vala
+++ b/src/daemon.vala
@@ -163,7 +163,7 @@ namespace Pamac {
 			timer = new Timer ();
 			extern_lock = false;
 			refresh_handle ();
-			Timeout.add (500, check_pacman_running);
+			Timeout.add (500, check_extern_lock);
 			create_thread_pool ();
 			cancellable = new Cancellable ();
 			curl = new Curl.Easy ();
@@ -226,7 +226,7 @@ namespace Pamac {
 			files_handle = alpm_config.get_files_handle ();
 		}
 
-		private bool check_pacman_running () {
+		private bool check_extern_lock () {
 			if (extern_lock) {
 				if (!lockfile.query_exists ()) {
 					extern_lock = false;
@@ -236,28 +236,57 @@ namespace Pamac {
 			} else {
 				if (lockfile.query_exists ()) {
 					if (databases_lock_mutex.trylock ()) {
-						// Functions trans_prepare, sysupgrade_prepare and refresh threads are blocked until unlock.
-						// An extern lock appears, check if pacman running.
+						extern_lock = true;
+						// Functions trans_init, build_prepare and refresh threads are blocked until unlock.
+						// An extern lock appears, check if it is not a too old lock.
 						int exit_status;
+						string output;
+						uint64 lockfile_time;
 						try {
-							Process.spawn_command_line_sync ("pidof pacman",
-														null,
-														null,
-														out exit_status);
+							// get lockfile modification time since epoch
+							Process.spawn_command_line_sync ("stat -c %Y %s".printf (alpm_handle.lockfile),
+															out output,
+															null,
+															out exit_status);
+							if (exit_status == 0) {
+								string[] splitted = output.split ("\n");
+								if (splitted.length == 2) {
+									if (uint64.try_parse (splitted[0], out lockfile_time)) {
+										uint64 boot_time;
+										// get boot time since epoch
+										Process.spawn_command_line_sync ("cat /proc/stat",
+																		out output,
+																		null,
+																		out exit_status);
+										if (exit_status == 0) {
+											splitted = output.split ("\n");
+											foreach (unowned string line in splitted) {
+												if ("btime" in line) {
+													string[] space_splitted = line.split (" ");
+													if (space_splitted.length == 2) {
+														if (uint64.try_parse (space_splitted[1], out boot_time)) {
+															// check if lock file is older than boot time
+															if (lockfile_time < boot_time) {
+																// remove the unneeded lock file.
+																try {
+																	lockfile.delete ();
+																} catch (Error e) {
+																	stderr.printf ("Error: %s\n", e.message);
+																}
+																extern_lock = false;
+																databases_lock_mutex.unlock ();
+															}
+														}
+													}
+												}
+											}
+										}
+									}
+								}
+							}
 						} catch (SpawnError e) {
 							stderr.printf ("Error: %s\n", e.message);
 						}
-						if (exit_status == 0) {
-							extern_lock = true;
-						} else {
-							// Pacman is not running: remove the unneeded lock file.
-							try {
-								lockfile.delete ();
-							} catch (Error e) {
-								stderr.printf ("Error: %s\n", e.message);
-							}
-							databases_lock_mutex.unlock ();
-						}
 					}
 				}
 			}
diff --git a/src/tray.vala b/src/tray.vala
index d47f85a..416ae3d 100644
--- a/src/tray.vala
+++ b/src/tray.vala
@@ -252,7 +252,7 @@ namespace Pamac {
 			return run;
 		}
 
-		bool check_pacman_running () {
+		bool check_extern_lock () {
 			if (extern_lock) {
 				if (!lockfile.query_exists ()) {
 					extern_lock = false;
@@ -309,7 +309,7 @@ namespace Pamac {
 				//try standard lock file
 				lockfile = GLib.File.new_for_path ("var/lib/pacman/db.lck");
 			}
-			Timeout.add (200, check_pacman_running);
+			Timeout.add (200, check_extern_lock);
 			start_refresh ();
 			launch_refresh_timeout (pamac_config.refresh_period);