On 2020-03-12 02:08, Norton Allen wrote: > Correct me if I am wrong, but O_NDELAY is not the same as O_NONBLOCK At least for cygwin those two are exactly the same... I think... #define _FNONBLOCK 0x4000 /* non blocking I/O (POSIX style) */ #define _FNDELAY _FNONBLOCK /* non blocking I/O (4.2 style) */