From 893e4fc46d31d1cc51c1e39481f5659a40152233 Mon Sep 17 00:00:00 2001
From: Sebastian Wick <sebastian.wick@redhat.com>
Date: Wed, 7 Feb 2024 18:53:16 +0100
Subject: [PATCH] timespec: Implement saturating timespec substraction

Signed-off-by: Sebastian Wick <sebastian.wick@redhat.com>
---
 src/timespec-util.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/timespec-util.h b/src/timespec-util.h
index d37568d2..d3c53bd7 100644
--- a/src/timespec-util.h
+++ b/src/timespec-util.h
@@ -290,4 +290,22 @@ timespec_add(struct timespec *r,
 	}
 }
 
+/**
+ * Saturating timespec subtraction
+ *
+ * \param r[out] result: max(a - b, 0)
+ * \param a[in] operand
+ * \param b[in] operand
+ */
+static inline void
+timespec_sub_saturate(struct timespec *r,
+                      const struct timespec *a, const struct timespec *b)
+{
+   timespec_sub(r, a, b);
+   if (r->tv_sec < 0) {
+      r->tv_sec = 0;
+      r->tv_nsec = 0;
+   }
+}
+
 #endif /* TIMESPEC_UTIL_H */