3 files changed, 95 insertions, 23 deletions

diff --git a/src/eval.c b/src/eval.c
index 6e9fffd..d632e7c 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -137,11 +137,9 @@ static const struct bfs_stat *eval_stat(struct bfs_eval *state) {
  * Get the difference (in seconds) between two struct timespecs.
  */
 static time_t timespec_diff(const struct timespec *lhs, const struct timespec *rhs) {
-	time_t ret = lhs->tv_sec - rhs->tv_sec;
-	if (lhs->tv_nsec < rhs->tv_nsec) {
-		--ret;
-	}
-	return ret;
+	struct timespec diff = *lhs;
+	timespec_sub(&diff, rhs);
+	return diff.tv_sec;
 }
 
 bool bfs_expr_cmp(const struct bfs_expr *expr, long long n) {
@@ -260,8 +258,7 @@ bool eval_newer(const struct bfs_expr *expr, struct bfs_eval *state) {
 		return false;
 	}
 
-	return time->tv_sec > expr->reftime.tv_sec
-		|| (time->tv_sec == expr->reftime.tv_sec && time->tv_nsec > expr->reftime.tv_nsec);
+	return timespec_cmp(time, &expr->reftime) > 0;
 }
 
 /**
@@ -1047,21 +1044,6 @@ static int eval_gettime(struct bfs_eval *state, struct timespec *ts) {
 }
 
 /**
- * Record an elapsed time.
- */
-static void timespec_elapsed(struct timespec *elapsed, const struct timespec *start, const struct timespec *end) {
-	elapsed->tv_sec += end->tv_sec - start->tv_sec;
-	elapsed->tv_nsec += end->tv_nsec - start->tv_nsec;
-	if (elapsed->tv_nsec < 0) {
-		elapsed->tv_nsec += 1000000000L;
-		--elapsed->tv_sec;
-	} else if (elapsed->tv_nsec >= 1000000000L) {
-		elapsed->tv_nsec -= 1000000000L;
-		++elapsed->tv_sec;
-	}
-}
-
-/**
  * Evaluate an expression.
  */
 static bool eval_expr(struct bfs_expr *expr, struct bfs_eval *state) {
@@ -1079,7 +1061,8 @@ static bool eval_expr(struct bfs_expr *expr, struct bfs_eval *state) {
 
 	if (time) {
 		if (eval_gettime(state, &end) == 0) {
-			timespec_elapsed(&expr->elapsed, &start, &end);
+			timespec_sub(&end, &start);
+			timespec_add(&expr->elapsed, &end);
 		}
 	}
 
diff --git a/src/xtime.c b/src/xtime.c
index 49d7c36..6b8a141 100644
--- a/src/xtime.c
+++ b/src/xtime.c
@@ -354,6 +354,59 @@ error:
 	return -1;
 }
 
+/** One nanosecond. */
+static const long NS = 1000L * 1000 * 1000;
+
+void timespec_add(struct timespec *lhs, const struct timespec *rhs) {
+	lhs->tv_sec += rhs->tv_sec;
+	lhs->tv_nsec += rhs->tv_nsec;
+	if (lhs->tv_nsec >= NS) {
+		lhs->tv_nsec -= NS;
+		lhs->tv_sec += 1;
+	}
+}
+
+void timespec_sub(struct timespec *lhs, const struct timespec *rhs) {
+	lhs->tv_sec -= rhs->tv_sec;
+	lhs->tv_nsec -= rhs->tv_nsec;
+	if (lhs->tv_nsec < 0) {
+		lhs->tv_nsec += NS;
+		lhs->tv_sec -= 1;
+	}
+}
+
+int timespec_cmp(const struct timespec *lhs, const struct timespec *rhs) {
+	if (lhs->tv_sec < rhs->tv_sec) {
+		return -1;
+	} else if (lhs->tv_sec > rhs->tv_sec) {
+		return 1;
+	}
+
+	if (lhs->tv_nsec < rhs->tv_nsec) {
+		return -1;
+	} else if (lhs->tv_nsec > rhs->tv_nsec) {
+		return 1;
+	}
+
+	return 0;
+}
+
+void timespec_min(struct timespec *dest, const struct timespec *src) {
+	if (timespec_cmp(src, dest) < 0) {
+		*dest = *src;
+	}
+}
+
+void timespec_max(struct timespec *dest, const struct timespec *src) {
+	if (timespec_cmp(src, dest) > 0) {
+		*dest = *src;
+	}
+}
+
+double timespec_ns(const struct timespec *ts) {
+	return 1.0e9 * ts->tv_sec + ts->tv_nsec;
+}
+
 #if defined(_POSIX_TIMERS) && BFS_HAS_TIMER_CREATE
 #  define BFS_POSIX_TIMERS _POSIX_TIMERS
 #else
diff --git a/src/xtime.h b/src/xtime.h
index 2927a2e..b76fef2 100644
--- a/src/xtime.h
+++ b/src/xtime.h
@@ -47,6 +47,42 @@ int xtimegm(struct tm *tm, time_t *timep);
 int xgetdate(const char *str, struct timespec *result);
 
 /**
+ * Add to a timespec.
+ */
+void timespec_add(struct timespec *lhs, const struct timespec *rhs);
+
+/**
+ * Subtract from a timespec.
+ */
+void timespec_sub(struct timespec *lhs, const struct timespec *rhs);
+
+/**
+ * Compare two timespecs.
+ *
+ * @return
+ *         An integer with the sign of (*lhs - *rhs).
+ */
+int timespec_cmp(const struct timespec *lhs, const struct timespec *rhs);
+
+/**
+ * Update a minimum timespec.
+ */
+void timespec_min(struct timespec *dest, const struct timespec *src);
+
+/**
+ * Update a maximum timespec.
+ */
+void timespec_max(struct timespec *dest, const struct timespec *src);
+
+/**
+ * Convert a timespec to floating point.
+ *
+ * @return
+ *         The value in nanoseconds.
+ */
+double timespec_ns(const struct timespec *ts);
+
+/**
  * A timer.
  */
 struct timer;