From 7003a2457da6a6e3ad4c316e19f0951fc682a67f Mon Sep 17 00:00:00 2001
From: ionutboangiu <ionut.boangiu@itsyscom.com>
Date: Thu, 28 Jul 2022 17:00:26 +0300
Subject: [PATCH] Fix issue where fib function overflows

---
 utils/consts.go    |  9 +++++++++
 utils/coreutils.go | 11 +++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/utils/consts.go b/utils/consts.go
index ba4e54c8c..9585a2436 100644
--- a/utils/consts.go
+++ b/utils/consts.go
@@ -2784,6 +2784,15 @@ const (
 	HSuffix  = "h"
 )
 
+// Go type limits
+const (
+	AbsoluteMaxUint     = ^uint(0)
+	AbsoluteMinUint     = 0
+	AbsoluteMaxInt      = int(AbsoluteMaxUint >> 1)
+	AbsoluteMinInt      = -AbsoluteMaxInt - 1
+	AbsoluteMaxDuration = time.Duration(AbsoluteMaxInt)
+)
+
 func buildCacheInstRevPrefixes() {
 	CachePrefixToInstance = make(map[string]string)
 	for k, v := range CacheInstanceToPrefix {
diff --git a/utils/coreutils.go b/utils/coreutils.go
index db8822a88..2197ece29 100644
--- a/utils/coreutils.go
+++ b/utils/coreutils.go
@@ -483,7 +483,9 @@ func copyFile(rc io.ReadCloser, path string, fm os.FileMode) (err error) {
 func Fib() func() int {
 	a, b := 0, 1
 	return func() int {
-		a, b = b, a+b
+		if b > 0 {
+			a, b = b, a+b
+		}
 		return a
 	}
 }
@@ -493,7 +495,12 @@ func Fib() func() int {
 func FibDuration(durationUnit, maxDuration time.Duration) func() time.Duration {
 	fib := Fib()
 	return func() time.Duration {
-		fibNrAsDuration := time.Duration(fib()) * durationUnit
+		fibNrAsDuration := time.Duration(fib())
+		if fibNrAsDuration > (AbsoluteMaxDuration / durationUnit) { // check if the current fibonacci nr. in the sequence would exceed the absolute maximum duration if multiplied by the duration unit value
+			fibNrAsDuration = AbsoluteMaxDuration
+		} else {
+			fibNrAsDuration *= durationUnit
+		}
 		if maxDuration > 0 && maxDuration < fibNrAsDuration {
 			return maxDuration
 		}