From 732e40dcfaa6a6c1be1b482f703790dc239f0ab8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Fri, 14 Apr 2023 20:06:26 +0200
Subject: [PATCH] gtimer: Avoid doing anything on g_usleep (0)

It's unlikely to happen, but still could be the case, so avoid do
anything.
---
 glib/gtimer.c      |  3 +++
 glib/tests/timer.c | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/glib/gtimer.c b/glib/gtimer.c
index d2d259918..dde502a15 100644
--- a/glib/gtimer.c
+++ b/glib/gtimer.c
@@ -269,6 +269,9 @@ g_timer_is_active (GTimer *timer)
 void
 g_usleep (gulong microseconds)
 {
+  if G_UNLIKELY (microseconds == 0)
+    return;
+
 #ifdef G_OS_WIN32
   /* Round up to the next millisecond */
   Sleep (microseconds ? (1 + (microseconds - 1) / 1000) : 0);
diff --git a/glib/tests/timer.c b/glib/tests/timer.c
index 3a2d1019c..be4cb957b 100644
--- a/glib/tests/timer.c
+++ b/glib/tests/timer.c
@@ -346,6 +346,29 @@ test_timeval_to_iso8601_overflow (void)
   g_assert_null (out);
 }
 
+static void
+test_usleep_with_zero_wait (void)
+{
+  GTimer *timer;
+  gdouble elapsed0, elapsed1;
+
+  timer = g_timer_new ();
+
+  g_timer_start (timer);
+  g_usleep (0);
+  elapsed0 = g_timer_elapsed (timer, NULL);
+  g_timer_stop (timer);
+
+  g_timer_start (timer);
+  g_usleep (1);
+  elapsed1 = g_timer_elapsed (timer, NULL);
+  g_timer_stop (timer);
+
+  g_assert_cmpfloat (elapsed0, <=, elapsed1);
+
+  g_clear_pointer (&timer, g_timer_destroy);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -360,6 +383,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/timeval/from-iso8601", test_timeval_from_iso8601);
   g_test_add_func ("/timeval/to-iso8601", test_timeval_to_iso8601);
   g_test_add_func ("/timeval/to-iso8601/overflow", test_timeval_to_iso8601_overflow);
+  g_test_add_func ("/usleep/with-zero-wait", test_usleep_with_zero_wait);
 
   return g_test_run ();
 }