Cannot load large ULog file (2.5 GB)

[JacobCrabill]

Problem description

ULog files larger than ~2.5 GB (not sure the exact limit) fail to open (tested on the latest version of master, in addition to a custom branch from ~1yr ago). The issue is actually within QFile - the call to file.readAll() returns an empty QByteArray, which later causes ULogParser::readFileHeader() to fail, which results in the error message "ULog: wrong header". file.size() shows the proper size after opening the file; it's only the subsequent call to file.readAll() that fails.

Based on the file size, and the fact that I can load a 1.5GB ULog file with no issues, I'm suspecting that the Qt libraries for QFile or QByteArray are using signed 32-bit integers somewhere; I don't know enough about Qt to dig deeper though.

Steps to reproduce (important)

• Ubuntu 20.04 64-bit, 'vanilla' Qt dependencies installed via apt just last week
• 2.5GB ULog file capable of being opened with PyULog
• Adding the following after the call to file.readAll(): qDebug() << "Error Message:" << file.errorString() << endl; shows the error message "Unknown error"