From 2e7c74ebbb4bc17b774644ecba791c625c050431 Mon Sep 17 00:00:00 2001
From: Blinningjr <nicke.l@telia.com>
Date: Tue, 15 Dec 2020 16:27:39 +0100
Subject: [PATCH] D
---
cargo_klee_examples/examples/array.rs | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/cargo_klee_examples/examples/array.rs b/cargo_klee_examples/examples/array.rs
index 83777a8..feeabe1 100644
--- a/cargo_klee_examples/examples/array.rs
+++ b/cargo_klee_examples/examples/array.rs
@@ -8,11 +8,11 @@
use klee_sys::klee_make_symbolic;
use panic_klee as _;
-fn sum_first_elements(arr: &[u8], index: usize) -> u8 {
- let mut acc = 0;
+fn sum_first_elements(arr: &[u8], index: usize) -> u16 {
+ let mut acc: u16 = 0;
for i in 0..index {
if index < arr.len() {
- acc += arr[i as usize];
+ acc += arr[i as usize] as u16;
} else {
break;
}
@@ -45,7 +45,7 @@ fn main() {
// [your answer here]]
// The diffrence is that debug test all 10 possible paths and release only checks 2. This is becaus
// 9 of the paths are basicly the same. These are the path were index is 0..8, the last path is
-// diffrent because then the index is out side of the array(index = 255), thus there will be an error.
+// diffrent because then the index is out side of the array(index = 255), thus there will be an error/panic.
//
//
// Debug:
@@ -80,11 +80,15 @@ fn main() {
// Explain what caused the error.
//
// [your answer here]
+// acc = 255 and arr[i as usize] = 127 in the secound loop in sum_first_elements, test4. Thus acc
+// is a u8 variable that will overflow and cause a panic.
//
// E) Make a sensible fix to the code.
// Motivate your choice.
//
// [your answer here]
+// I made acc a u16 instead of a u8 because the maximum sum of arr is 8 * 255, which will easily
+// fit in a u16. And thus will avoid the overflow problem.
//
// [Git commit "D"]
//
--
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