B20.1 under NT4.0, non blocking I/O

J. J. Farrell jjf@hal.com
Wed Mar 31 19:45:00 GMT 1999

> From: michele_liberi@it.ibm.com
> In the UNIX world the statement
> "fcntl(fd,F_SETFL,FNDELAY|fcntl(fd,F_GETFL,0));" may be used to set "non
> blocking io" flag on a given file descriptor.

This is true of some parts of the UNIX world, but it's not the
Standard way to do it. The preferred name for the FNDELAY flag
in user-level code is O_NDELAY, but the Standard way to achieve
this effect is to use O_NONBLOCK. There are usually small
differences between the meaning of O_NDELAY and O_NONBLOCK in
implementations which support both, but O_NONBLOCK is the only
one you can reasonably expect to be supported on all UNIX-like

> In cygwin B20.1 under NT4.0
> it is completely inoperative.

Having said that, I've no idea if O_NONBLOCK works any better
than O_NDELAY under cygwin!

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