From: stockton AT bcm DOT tmc DOT edu (David Stockton)
Message-Id: <199612192326.RAA15234@ginger.imgen.bcm.tmc.edu>
Subject: Re: SIGINT handling & stdio
To: feeley AT raptor DOT IRO DOT UMontreal DOT CA (Marc Feeley)
Date: Thu, 19 Dec 1996 23:26:38 +0000 (GMT)
Cc: djgpp AT delorie DOT com (DJGPP Mail List)
In-Reply-To: <q6d8wf6bvh.fsf@raptor.IRO.UMontreal.CA> from "Marc Feeley" at Dec 12, 96 10:06:10 am
Reply-to: stockton AT bcm DOT tmc DOT edu
Organization: Molecular and Human Genetics, Baylor College of Medicine
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Marc,
   I ran your program on djgpp version 2.0 and Windows 95 and it pretty
much worked as expected.  The interupt handler was not called until a
carriage return (That is if I typed "hello^Cthere" I would get "interrupt
got 116, got 104, got 101, got 114, got 101, got 10").  If I tried putting
a printf in user_signal_handler() it somehow ended up putting the printed
characters in my input stream, which I do not understand.  But as far as
the interrupt being serviced it worked almost as expected.
						- David
> 
> I want to port a program that uses stdio and handles ctrl-c interrupts
> with signal(SIGINT,...).  The program below is a small example.  It
> seems that when getchar is called, a ctrl-c will NOT call the signal
> handler; the program simply terminates.  This is strange because if I
> replace getchar with getkey then the program works fine.
> Unfortunately I can't use getkey in my program because the input is
> not necessarily from the console (it might be a redirection).
> 
> Any suggestions?  I'm sure this problem must have come up before but
> I can't find a suitable answer in the FAQ or the DJGPP doc.
> 
> Marc
> 
> 
> #include <stdio.h>
> #include <signal.h>
> 
> int intr = 0;
> 
> void user_signal_handler (void) { intr = 1; }
> 
> void main (void)
> {
>   int c;
>   signal (SIGINT, user_signal_handler);
>   while ((c=getchar()) != 'q')
>     {
>       if (intr) { printf ("interrupt\n"); intr = 0; }
>       printf ("got %d\n", c);
>     }
> }
> 
> 
Marc,
   I ran your program on djgpp version 2.0 and Windows 95 and it pretty
much worked as expected.  The interupt handler was not called until a
carriage return (That is if I typed "hello^Cthere" I would get "interrupt
got 116, got 104, got 101, got 114, got 101, got 10").  If I tried putting
a printf in user_signal_handler() it somehow ended up putting the printed
characters in my input stream, which I do not understand.  But as far as
the interrupt being serviced it worked almost as expected.
						- David