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 01f67ac06d1029b59d24ebe5a74ae2c2c92125f8..a72be4a998d61019f9b12c0cc7ed0a2571e0d4db 100644 (file)
--- 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