Re: again: x11 is eating one character from stdin pipe

[Petr M. <mi...@ph...>]

> Petr Mikulik and John Bollinger alerted me to the recurrence of an
> old problem.  When (1) gnuplot is run from a script and (2) mouse
> input is enabled, then characters are dropped from the input
> stream.
>
> I initially thought this was something I had broken with my X11
> initialization patches (revisions 1.71 - 1.74 of term/x11.trm).
> But after backing these out altogether, I still see the problem,
> although possibly with a lower frequency.
>
> After much poking about in the source code, I came
> across this bit in term/x11.trm
>
>             /* apparently multi-character inputs like escape sequences
>              * but also mouse-pasted text got buffered and therefore
>              * didn't trigger the select() function in X11_waitforinput().
>              * Switching to unbuffered input solved this (although I don't
>              * really like this solution 23 Jan 2002 (joze) */
>             setvbuf(stdin, (char *) 0, _IONBF, 0);
>
> Commenting out this one setvbuf() line solves 99% of the
> problem in my tests using the awk script below.
>
> With the setvbuf() in place, running the awk script causes the
> first 120+ plot commands to be lost in transit!!!!!!
>
> Without the setvbuf() command, only a single character is
> dropped - the first one following the first plot command.
>
> It would also be good to hear from Petr or some other Octave
> user as to whether removing the setvbuf()  line also fixes
> things in Octave.

I've tried it with Octave, but there is no change with or without setvbuf.
Gnuplot mostly looses the first character.

Probably, there was a thread on this topic around 23 Jan 2002, where
Johanness submitted his patch ...?

What I can confirm, is that I have this problem with gnuplot cvs'ed on June
21 2003 and newer. And, in the version of 21.6.2003, commenting out the
setvbuf command, only the first char written is lost; otherwise many of
them.

---
Petr Mikulik