1 files changed, 24 insertions, 36 deletions

diff --git a/sumtimespec.c b/sumtimespec.c
index a359971..2b2e935 100644
--- a/sumtimespec.c
+++ b/sumtimespec.c
@@ -6,48 +6,36 @@
 int
 libsimple_sumtimespec(struct timespec *sum, const struct timespec *augend, const struct timespec *addend)
 {
-	long int ns = augend->tv_nsec + addend->tv_nsec;
 	time_t s;
-	int ret = 0;
-
-	s = augend->tv_sec + addend->tv_sec;
-	if ((augend->tv_sec < 0) == (addend->tv_sec < 0)) {
-		if (augend->tv_sec >= 0 && augend->tv_sec > TIME_MAX - addend->tv_sec) {
-			s = TIME_MAX;
-			ns = 999999999L;
-			errno = ERANGE;
-			ret = -1;
-		} else if (augend->tv_sec < 0 && augend->tv_sec < TIME_MIN - addend->tv_sec) {
-			s = TIME_MIN;
-			ns = 0;
-			errno = ERANGE;
-			ret = -1;
-		}
+
+	if (LIBSIMPLE_SADD_OVERFLOW(augend->tv_sec, addend->tv_sec, &s, TIME_MIN, TIME_MAX)) {
+		if (addend->tv_sec > 0)
+			goto too_large;
+		else
+			goto too_small;
 	}
 
-	if (ns < 0) {
-		if (s == TIME_MIN) {
-			ns = 0L;
-			errno = ERANGE;
-			ret = -1;
-		} else {
-			s -= 1;
-			ns += 1000000000L;
-		}
-	} else if (ns >= 1000000000L) {
-		if (s == TIME_MAX) {
-			ns = 999999999L;
-			errno = ERANGE;
-			ret = -1;
-		} else {
-			s += 1;
-			ns -= 1000000000L;
-		}
+	sum->tv_nsec = augend->tv_nsec + addend->tv_nsec;
+	if (sum->tv_nsec >= 1000000000L) {
+		if (LIBSIMPLE_SINCR_OVERFLOW(&s, TIME_MAX))
+			goto too_large;
+		sum->tv_nsec -= 1000000000L;
 	}
 
 	sum->tv_sec = s;
-	sum->tv_nsec = ns;
-	return ret;
+	return 0;
+
+too_large:
+	sum->tv_sec = TIME_MAX;
+	sum->tv_nsec = 999999999L;
+	errno = ERANGE;
+	return -1;
+
+too_small:
+	sum->tv_sec = TIME_MIN;
+	sum->tv_nsec = 0;
+	errno = ERANGE;
+	return -1;
 }