Re: flock(2): locking against itself?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> I may be missing something in your curses non-blocking case, but
> can't you work around the issue by setting up an independent file
> descriptor, and hence tty structure, by performing a dup2(2) on stdin
> and then closing the original stdin file descriptor?

No.  dup2, like dup, creates another file descriptor reference to the
original open file table entry.  (Something very much like that is how
stdin and stdout got set up to begin with.)

Furthermore, in the case of non-blocking I/O, it is the underlying
object (the tty, here) that is nonblocking, not the open file table
entry and definitely not the file descriptor.  As Taylor R Campbell
said, nonblocking really _should_ be a property of the operation, not
of the descriptor, not of the open file table entry, and _definitely_
not of the object.

The only way I've thought of to work around this is to fork a helper
process which reads - blockingly - from stdin and writes the data to a
pipe; that pipe is then set nonblocking in the main process and is
independent of everything else.  I might need a third process to make
the reader process die reliably....

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