scripts: Ignore database locks if the process that locked the database no longer exists in makepkg and pacman-db-upgrade

scripts/libmakepkg/util/lock.sh.in

@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+#   lock.sh - functions to handle pacman locking
+#
+#   Copyright (c) 2024 Pacman Development Team <pacman-dev@lists.archlinux.org>
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; either version 2 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+is_pacman_locked() {
+	local lockfile="$(pacman-conf DBPath)/db.lck"
+	if [[ -f $lockfile ]]; then
+		local pid=$(<"$lockfile")
+		# Check if the pid is valid and the process is still running
+		if [[ -n $pid && $pid =~ ^[0-9]+$ && -d /proc/$pid ]]; then
+			return 0
+		fi
+	fi
+	return 1
+}

scripts/libmakepkg/util/meson.build

@@ -5,6 +5,7 @@ sources = [
   'config.sh.in',
   'dirsize.sh.in',
   'error.sh.in',
+  'lock.sh.in',
   'message.sh.in',
   'option.sh.in',
   'parseopts.sh.in',

scripts/makepkg.sh.in

@@ -247,14 +247,11 @@ run_pacman() {
 		else
 			cmd=(su root -c "$cmdescape")
 		fi
-		local lockfile="$(pacman-conf DBPath)/db.lck"
-		while [[ -f $lockfile ]]; do
-			local timer=0
+		local timer=0
+		while is_pacman_locked && (( timer < 10 )); do
+			(( ++timer ))
 			msg "$(gettext "Pacman is currently in use, please wait...")"
-			while [[ -f $lockfile ]] && (( timer < 10 )); do
-				(( ++timer ))
-				sleep 3
-			done
+			sleep 3
 		done
 	fi
 	"${cmd[@]}"

scripts/pacman-db-upgrade.sh.in

@@ -30,6 +30,7 @@ declare -r myver='@PACKAGE_VERSION@'
 MAKEPKG_LIBRARY=${MAKEPKG_LIBRARY:-'@libmakepkgdir@'}
 
 # Import libmakepkg
+source "$MAKEPKG_LIBRARY"/util/lock.sh
 source "$MAKEPKG_LIBRARY"/util/message.sh
 source "$MAKEPKG_LIBRARY"/util/parseopts.sh
 
@@ -132,15 +133,18 @@ fi
 
 # strip any trailing slash from our dbroot
 dbroot="${dbroot%/}"
+
+# make sure pacman isn't running
+if is_pacman_locked; then
+	die "$(gettext "Pacman lock file was found. Cannot run while pacman is running.")"
+fi
+
 # form the path to our lockfile location
 lockfile="${dbroot}/db.lck"
 
-# make sure pacman isn't running
-if [[ -f $lockfile ]]; then
-	die "$(gettext "Pacman lock file was found. Cannot run while pacman is running.")"
-fi
 # do not let pacman run while we do this
-touch "$lockfile"
+# write our pid to the lockfile
+echo $$ > "$lockfile"
 
 if [[ -f "${dbroot}"/local/ALPM_DB_VERSION ]]; then
 	db_version=$(cat "${dbroot}"/local/ALPM_DB_VERSION)