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QR-Code-generator
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Simplified some C code for overflow-safe calculation.

This commit is contained in:
Project Nayuki 2018-08-28 05:08:03 +00:00
parent f1a1ab189b
commit de2603ab5f
1 changed files with 4 additions and 5 deletions
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9
c/qrcodegen.c
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@ -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) { testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version) {
assert(segs != NULL || len == 0); assert(segs != NULL || len == 0);
assert(qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX); assert(qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX);
int result = 0; long result = 0;
for (size_t i = 0; i < len; i++) { for (size_t i = 0; i < len; i++) {
int numChars = segs[i].numChars; int numChars = segs[i].numChars;
int bitLength = segs[i].bitLength; 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 // Fail if segment length value doesn't fit in the length field's bit-width
if (numChars >= (1L << ccbits)) if (numChars >= (1L << ccbits))
return -1; return -1;
long temp = 4L + ccbits + bitLength; result += 4L + ccbits + bitLength;
if (temp > INT16_MAX - result) if (result > INT16_MAX)
return -1; return -1;
result += temp;
} }
assert(0 <= result && result <= INT16_MAX); assert(0 <= result && result <= INT16_MAX);
return result; return (int)result;
} }