fcntl() versus ioctl()

[Guy Harris]

> Isn't it a dubious feature that the PARENT should suffer if a CHILD decides
> to set the FNDELAY flag of stdin?

Arguably.

> It's an FCNTL() we're talking about, not an IOCTL()!

The problem is that there are two sets of "file descriptor" flags: those stored
per-process, and those stored per "file table entry".  The "file table entry"
is shared by file descriptors passed to children, or created by "dup"; it holds
the seek pointer.

Unfortunately, the no-delay flag is a "file table entry" flag, not a
per-process flag.  The only per-process flag is the "close on exec" flag.
There exist "fcntl"s to manipulate both.