From 04e243c85cab89fe16a07667122d5288e8ae9b59 Mon Sep 17 00:00:00 2001
From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Wed, 27 Dec 2017 14:24:27 -0800
Subject: [PATCH] Add handy functions for timeval manipulations. Obtained from
 FreeBSD.

---
 utils.c | 40 ++++++++++++++++++++++++++++++++++++++++
 utils.h |  8 ++++++++
 2 files changed, 48 insertions(+)

diff --git a/utils.c b/utils.c
index fc21b7f..294c1cd 100644
--- a/utils.c
+++ b/utils.c
@@ -531,3 +531,43 @@ valid_media_types(const char *path)
 
 	return ALL_MEDIA;
 }
+
+/*
+ * Add and subtract routines for timevals.
+ * N.B.: subtract routine doesn't deal with
+ * results which are before the beginning,
+ * it just gets very confused in this case.
+ * Caveat emptor.
+ */
+static void	timevalfix(struct timeval *);
+void
+timevaladd(struct timeval *t1, const struct timeval *t2)
+{
+
+	t1->tv_sec += t2->tv_sec;
+	t1->tv_usec += t2->tv_usec;
+	timevalfix(t1);
+}
+
+void
+timevalsub(struct timeval *t1, const struct timeval *t2)
+{
+
+	t1->tv_sec -= t2->tv_sec;
+	t1->tv_usec -= t2->tv_usec;
+	timevalfix(t1);
+}
+
+static void
+timevalfix(struct timeval *t1)
+{
+
+	if (t1->tv_usec < 0) {
+		t1->tv_sec--;
+		t1->tv_usec += 1000000;
+	}
+	if (t1->tv_usec >= 1000000) {
+		t1->tv_sec++;
+		t1->tv_usec -= 1000000;
+	}
+}
diff --git a/utils.h b/utils.h
index a200756..1cd7546 100644
--- a/utils.h
+++ b/utils.h
@@ -101,4 +101,12 @@ const char *mime_to_ext(const char * mime);
 int make_dir(char * path, mode_t mode);
 unsigned int DJBHash(uint8_t *data, int len);
 
+/* Timeval manipulations */
+void	timevaladd(struct timeval *t1, const struct timeval *t2);
+void	timevalsub(struct timeval *t1, const struct timeval *t2);
+#define	timevalcmp(tvp, uvp, cmp)					\
+	(((tvp)->tv_sec == (uvp)->tv_sec) ?				\
+	    ((tvp)->tv_usec cmp (uvp)->tv_usec) :			\
+	    ((tvp)->tv_sec cmp (uvp)->tv_sec))
+
 #endif