wechat_qrcode crash in zxing detector

[BerylLuo]

crash backtrace:
thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x27fc00008)
frame #0: 0x0000000101443870 void std::__1::__sort<zxing::qrcode::(anonymous namespace)::XComparator&, zxing::Ref<zxing::qrcode::FinderPattern>*>(zxing::Ref<zxing::qrcode::FinderPattern>*, zxing::Ref<zxing::qrcode::FinderPattern>*, zxing::qrcode::(anonymous namespace)::XComparator&) + 1808 frame #1: 0x000000010143185c zxing::qrcode::FinderPatternFinder::selectBestPatterns(zxing::ErrorHandler&) + 1544
frame #2: 0x000000010142e1b0 zxing::qrcode::FinderPatternFinder::getPatternInfosFileMode(zxing::DecodeHints const&, zxing::ErrorHandler&) + 492 frame #3: 0x000000010142d398 zxing::qrcode::FinderPatternFinder::find(zxing::DecodeHints const&, zxing::ErrorHandler&) + 1556
frame #4: 0x000000010145fb3c zxing::qrcode::Detector::detect(zxing::DecodeHints const&, zxing::ErrorHandler&) + 220 frame #5: 0x00000001014a8ea8 zxing::qrcode::QRCodeReader::decodeMore(zxing::Refzxing::BinaryBitmap, zxing::Refzxing::BitMatrix, zxing::DecodeHints, zxing::ErrorHandler&) + 408
frame #6: 0x00000001014a8ac8 zxing::qrcode::QRCodeReader::decode(zxing::Ref<zxing::BinaryBitmap>, zxing::DecodeHints) + 520 frame #7: 0x0000000101485fd8 wechat_qrcode::DecoderMgr::TryDecode(zxing::Refzxing::LuminanceSource, zxing::Refzxing::Result&) + 340
frame #8: 0x0000000101485b60 `wechat_qrcode::DecoderMgr::decodeImage(Justice::JTMat&, std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator >&) + 656

I modified if(!isnan(x)) to if(!isnan(x) && x >= 0.0) in line 1125 and line 1130 to solved this problem.
Just woderiny why isnan() function doesn't work.

opencv_contrib/modules/wechat_qrcode/src/zxing/qrcode/detector/finder_pattern_finder.cpp

Line 1125 in b8e4061

if (!isnan(ccj)) {

[asmorkalov]

Could you provide the image that generates crash and sample code to reproduce the issue?

[BerylLuo]

Sorry, the source project is too complicated so I can't extract the sample code. The weird thing is that crash appears when decoding images asynchronously, but not when decoding single one image.

Follow the backtrace I try to print a->getX() and b->getX() in line113, both of it is "nan". I guess the reason is isnan() in line 1125 and 1130 doesn't work, so pushed nan coordinate in possibleCenters_ . After I modify the if-condition according to line 1089 and 1116, the crash no longer occurs.

opencv_contrib/modules/wechat_qrcode/src/zxing/qrcode/detector/finder_pattern_finder.cpp

Line 113 in b8e4061

bool operator()(Ref<FinderPattern> a, Ref<FinderPattern> b) { return a->getX() < b->getX(); }

opencv_contrib/modules/wechat_qrcode/src/zxing/qrcode/detector/finder_pattern_finder.cpp

Line 1116 in b8e4061

if (!isnan(cJ) && cJ >= 0.0) {