From de2603ab5ff7d049194fc02fc03992f975441f3f Mon Sep 17 00:00:00 2001
From: Project Nayuki <me@nayuki.io>
Date: Tue, 28 Aug 2018 05:08:03 +0000
Subject: [PATCH] Simplified some C code for overflow-safe calculation.
---
c/qrcodegen.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/c/qrcodegen.c b/c/qrcodegen.c
index cd759c7..715cb78 100644
--- a/c/qrcodegen.c
+++ b/c/qrcodegen.c
@@ -984,7 +984,7 @@ bool qrcodegen_encodeSegmentsAdvanced(const struct qrcodegen_Segment segs[], siz
testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version) {
assert(segs != NULL || len == 0);
assert(qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX);
- int result = 0;
+ long result = 0;
for (size_t i = 0; i < len; i++) {
int numChars = segs[i].numChars;
int bitLength = segs[i].bitLength;
@@ -995,13 +995,12 @@ testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int
// Fail if segment length value doesn't fit in the length field's bit-width
if (numChars >= (1L << ccbits))
return -1;
- long temp = 4L + ccbits + bitLength;
- if (temp > INT16_MAX - result)
+ result += 4L + ccbits + bitLength;
+ if (result > INT16_MAX)
return -1;
- result += temp;
}
assert(0 <= result && result <= INT16_MAX);
- return result;
+ return (int)result;
}