utils: add round_up/down() helper functions

src/libstrongswan/tests/test_utils.c

@@ -165,6 +165,28 @@ START_TEST(test_untoh)
 }
 END_TEST
 
+/*******************************************************************************
+ * round_up/down
+ */
+
+START_TEST(test_round)
+{
+	ck_assert_int_eq(round_up(0, 4), 0);
+	ck_assert_int_eq(round_up(1, 4), 4);
+	ck_assert_int_eq(round_up(2, 4), 4);
+	ck_assert_int_eq(round_up(3, 4), 4);
+	ck_assert_int_eq(round_up(4, 4), 4);
+	ck_assert_int_eq(round_up(5, 4), 8);
+
+	ck_assert_int_eq(round_down(0, 4), 0);
+	ck_assert_int_eq(round_down(1, 4), 0);
+	ck_assert_int_eq(round_down(2, 4), 0);
+	ck_assert_int_eq(round_down(3, 4), 0);
+	ck_assert_int_eq(round_down(4, 4), 4);
+	ck_assert_int_eq(round_down(5, 4), 4);
+}
+END_TEST
+
 /*******************************************************************************
  * memxor
  */
@@ -416,6 +438,10 @@ Suite *utils_suite_create()
 	tcase_add_test(tc, test_untoh);
 	suite_add_tcase(s, tc);
 
+	tc = tcase_create("round");
+	tcase_add_test(tc, test_round);
+	suite_add_tcase(s, tc);
+
 	tc = tcase_create("memxor");
 	tcase_add_test(tc, test_memxor);
 	tcase_add_test(tc, test_memxor_aligned);

src/libstrongswan/utils/utils.h

@@ -670,6 +670,29 @@ static inline u_int64_t untoh64(void *network)
 #endif
 }
 
+/**
+ * Round up size to be multiple of alignement
+ */
+static inline size_t round_up(size_t size, int alignement)
+{
+	int remainder;
+
+	remainder = size % alignement;
+	if (remainder)
+	{
+		size += alignement - remainder;
+	}
+	return size;
+}
+
+/**
+ * Round down size to be a multiple of alignement
+ */
+static inline size_t round_down(size_t size, int alignement)
+{
+	return size - (size % alignement);
+}
+
 /**
  * Special type to count references
  */