timer: add ni_timeout_random() function

openSUSE · Jun 15, 2023 · 424a5b4 · 424a5b4
1 parent 4f405a3
commit 424a5b4
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Showing 2 changed files with 33 additions and 0 deletions.
diff --git a/include/wicked/time.h b/include/wicked/time.h
@@ -100,4 +100,6 @@ extern ni_timeout_t		ni_timeout_left(const struct timeval *, const struct timeva
 
 extern ni_bool_t		ni_timeval_add_timeout(struct timeval *, ni_timeout_t);
 
+extern ni_timeout_t		ni_timeout_random_range(ni_timeout_t min, ni_timeout_t max);
+
 #endif /* WICKED_TIME_H */
diff --git a/src/timer.c b/src/timer.c
@@ -430,6 +430,37 @@ ni_timeout_randomize(ni_timeout_t timeout, const ni_int_range_t *jitter)
 	return rtimeout;
 }
 
+ni_timeout_t
+ni_timeout_random_range(ni_timeout_t min, ni_timeout_t max)
+{
+	ni_timeout_t randval = 0;
+	ni_timeout_t range;
+
+	if (max <= min)
+		return min;
+
+	if (min >= NI_TIMEOUT_INFINITE || max >= NI_TIMEOUT_INFINITE)
+		return NI_TIMEOUT_INFINITE;
+
+	range = max - min + 1;
+
+	if (range > RAND_MAX) {
+		/*
+		 * Assume the largest number RAND_MAX is INT_MAX,
+		 * even random returns long int (64 or 32bit)...
+		 */
+		size_t count = sizeof(ni_timeout_t) / sizeof(int);
+		size_t i, bits = (sizeof(int) * 8) - 1;
+
+		for (i = 0; i < count; i++)
+			randval |= (ni_timeout_t)random() << (i * bits);
+	} else {
+		randval = (ni_timeout_t)random();
+	}
+
+	return min + (randval % range);
+}
+
 static ni_timeout_t
 ni_timeout_arm_randomized(struct timeval *deadline, ni_timeout_t timeout, const ni_int_range_t *jitter)
 {