Function convert_rwcount

extlibs/fmt/src/os.cc:62–64

On Windows the count argument to read and write is unsigned, so convert it from size_t preventing integer overflow.

// On Windows the count argument to read and write is unsigned, so convert
// it from size_t preventing integer overflow.
inline unsigned convert_rwcount(std::size_t count) {
  return count <= UINT_MAX ? static_cast<unsigned>(count) : UINT_MAX;
}
#else
// Return type of read and write functions.
using RWResult = ssize_t;