Re: Monitoring IO

[David Helder <dhelder umich edu>]

Or call fileno(file) to get the fd of the file.

David



On Wed, 6 Dec 2000, Erik Mouw wrote:

> Hi Chris,
>
> I didn't expect you on this list... ;-)
>
> On Wed, Dec 06, 2000 at 12:44:41PM -0500, Chris Blazie wrote:
> >     I'm working on some applications that need to monitor and interact
> > with arbitrary external IO (for now, the serial port).  For starters
> > (since I'm new to GTK development), I wrote a tiny app that instantiates a
> > GtkText widget, registers a GIO Channel via the gtk_input_add_full()
> > wrapper, and writes to the GtkText box from the input callback:
> >
> > s_port = fopen( "/dev/ttyS0", "r" );
> >
> > off = gtk_input_add_full( (gint) s_port, GDK_INPUT_READ,
> >                             (GdkInputFunction) input_callback,
> >                             NULL, data, NULL );
> >
> > The input_callback function looks like this:
> >
> > void input_callback( gpointer          data, gint              source, 
> >                      GdkInputCondition condition )
> > {
> >     gtk_text_insert( GTK_TEXT(textedit), NULL, NULL, NULL, "data
> > added\n", -1 );
> >
> > }
> >
> >     For some reason the input_callback function never gets called.
> > I suspect I'm not using the FILE pointer correctly, but I don't know how.
> > Can someone tell me what I'm missing here?
>
> gtk_input_add_full() needs a file descriptor, not a FILE pointer. Open
> the serial port with:
>
>   int s_port;
>
>   s_port = open("/dev/ttyS0", O_RDONLY);
>
> Hope this helps,
>
>
> Erik

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