From: Matthias Kruk <m@m10k.eu>
Date: Tue, 20 Apr 2021 23:28:34 +0000 (+0900)
Subject: include/mutex: Prevent children from unlocking their parents' mutexes
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=97f5763dcd6c4669ff9d53af5df2ad7893aec9f5;p=toolbox

include/mutex: Prevent children from unlocking their parents' mutexes

The mutex_trylock() and mutex_unlock() functions use $$ to determine the
current process's PID. However, this variable always reflects the PID of
the original shell. This commit changes the functions to use $BASHPID to
determine the PID of the current shell.
---

diff --git a/include/mutex.sh b/include/mutex.sh
index 01f67ac..a72be4a 100644
--- a/include/mutex.sh
+++ b/include/mutex.sh
@@ -14,7 +14,7 @@ mutex_trylock() {
 
 	lock="$1"
 
-	if ! ln -s "$$" "$lock" &> /dev/null; then
+	if ! ln -s "$BASHPID" "$lock" &> /dev/null; then
 		return 1
 	fi
 
@@ -45,7 +45,7 @@ mutex_unlock() {
 		return 1
 	fi
 
-	if [ "$owner" -ne "$$" ]; then
+	if [ "$owner" -ne "$BASHPID" ]; then
 		return 2
 	fi