From 493586cbca340e631e7d68a3e8ade41016783d34 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 12 Nov 2017 07:09:36 -0800
Subject: [PATCH] Fix overflow check

---
 fmt/format.h | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/fmt/format.h b/fmt/format.h
index f28c467f..bd99746a 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -3758,17 +3758,19 @@ template <typename Char>
 unsigned parse_nonnegative_int(const Char *&s) {
   assert('0' <= *s && *s <= '9');
   unsigned value = 0;
-  do {
-    unsigned new_value = value * 10 + (*s++ - '0');
-    // Check if value wrapped around.
-    if (new_value < value) {
-      value = (std::numeric_limits<unsigned>::max)();
-      break;
-    }
-    value = new_value;
-  } while ('0' <= *s && *s <= '9');
   // Convert to unsigned to prevent a warning.
   unsigned max_int = (std::numeric_limits<int>::max)();
+  unsigned big = max_int / 10;
+  do {
+    // Check for overflow.
+    if (value > big) {
+      value = max_int + 1;
+      break;
+    }
+    value = value * 10 + (*s - '0');
+    ++s;
+  } while ('0' <= *s && *s <= '9');
+  // Convert to unsigned to prevent a warning.
   if (value > max_int)
     FMT_THROW(FormatError("number is too big"));
   return value;