From aed0b2f64d44cf444a733ca96304a689f003ad30 Mon Sep 17 00:00:00 2001
From: Matthias Kruk <m@m10k.eu>
Date: Mon, 26 Sep 2022 17:58:53 +0900
Subject: [PATCH] include/sem: Implement sem_trywait() using sem_wait() with 0
 timeout

Because sem_trywait() does not unlock the waitlock if the counter is
greater than 1, the next caller will be left waiting until sem_post()
is executed.

This commit changes sem_trywait() to call sem_wait() with a timeout
of 0 seconds, since this issue does not affect sem_wait().
---
 include/sem.sh | 23 ++---------------------
 1 file changed, 2 insertions(+), 21 deletions(-)

diff --git a/include/sem.sh b/include/sem.sh
index 7189ab7..2fdfbaa 100644
--- a/include/sem.sh
+++ b/include/sem.sh
@@ -227,27 +227,8 @@ sem_wait() {
 sem_trywait() {
 	local name="$1"
 
-	local waitlock
-	local countlock
-	local counter
-	local err
-
-	waitlock=$(_sem_get_waitlock "$name")
-	countlock=$(_sem_get_countlock "$name")
-	counter=$(_sem_get_counter "$name")
-	err=1
-
-	if ! wmutex_trylock "$waitlock"; then
-		return 1
-	fi
-
-	if mutex_lock "$countlock"; then
-		_sem_counter_dec "$counter"
-		mutex_unlock "$countlock"
-		err=0
-	fi
-
-	return "$err"
+	sem_wait "$name" 0
+	return "$?"
 }
 
 sem_post() {
-- 
2.47.3