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buffer.h: incorrect RandRange results

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'low' was promoted to unsigned, triggering a ubsan warning

Change-Id: Id49340079d39c105da93cf13e96cf852a93a94ba
This commit is contained in:
Johann 2017-07-01 08:52:18 -07:00 committed by James Zern
parent c2044fda1d
commit 6cb3178192
1 changed files with 13 additions and 3 deletions
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16
test/buffer.h
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@ -73,8 +73,10 @@ class Buffer {
void Set(ACMRandom *rand_class, T (ACMRandom::*rand_func)());
// Set the buffer (excluding padding) to the output of ACMRandom function
// 'RandRange' with range 'low' to 'high' which must be within
// testing::internal::Random::kMaxRange (1u << 31).
// 'RandRange' with range 'low' to 'high' which typically must be within
// testing::internal::Random::kMaxRange (1u << 31). However, because we want
// to allow negative low (and high) values, it is restricted to INT32_MAX
// here.
void Set(ACMRandom *rand_class, const int32_t low, const int32_t high);
// Copy the contents of Buffer 'a' (excluding padding).
@ -176,6 +178,7 @@ void Buffer<T>::Set(ACMRandom *rand_class, T (ACMRandom::*rand_func)()) {
}
}
// TODO(johannkoenig): Use T for low/high.
template <typename T>
void Buffer<T>::Set(ACMRandom *rand_class, const int32_t low,
const int32_t high) {
@ -184,11 +187,18 @@ void Buffer<T>::Set(ACMRandom *rand_class, const int32_t low,
EXPECT_LE(low, high);
EXPECT_GE(low, std::numeric_limits<T>::min());
EXPECT_LE(high, std::numeric_limits<T>::max());
EXPECT_LE(static_cast<int64_t>(high) - low,
std::numeric_limits<int32_t>::max());
T *src = TopLeftPixel();
for (int height = 0; height < height_; ++height) {
for (int width = 0; width < width_; ++width) {
src[width] = static_cast<T>((*rand_class).RandRange(high - low) + low);
// 'low' will be promoted to unsigned given the return type of RandRange.
// Store the value as an int to avoid unsigned overflow warnings when
// 'low' is negative.
const int32_t value =
static_cast<int32_t>((*rand_class).RandRange(high - low));
src[width] = static_cast<T>(value + low);
}
src += stride_;
}