#include #include #include int main() { auto handle = (unsigned long long)_get_osfhandle(0); fprintf(stderr, "_get_osfhandle(0)=%llu\n", handle); // It look's like classic windows undocumented behaviour // https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/get-osfhandle // _get_osfhandle returns INVALID_HANDLE_VALUE - 1 without any sign of error if specified fd was closed. // Working with such handle will lead to future various errors. if (handle + 1 == (unsigned long long)INVALID_HANDLE_VALUE) { return 1; } return 0; }