gdk_input_add() and GdkInputCondition mapping

[Emil Ong <onge mcs anl gov>]

Hi,

I'm working on an application that creates a display based on input from
standard in.  I'm using gdk_input_add() to get the input from standard in,
but I'm having a problem when piping to my application: when the left hand
side of the pipe closes its standard out (usually on exit), my handler
continues to be called.

I'll give an example that illustrates this:

#include <stdio.h>
#include <unistd.h>
#include <sys/poll.h>
#include <gtk/gtk.h>

void handle_input(gpointer data, gint source, GdkInputCondition condition)
{
    char buf[1024];
    struct pollfd ufds[1];
        
    ufds[0].fd = source;
    ufds[0].events = POLLIN;
    poll(ufds, 1, 1000);
    printf("0x%x\n", ufds[0]. revents);

    buf[0] = '\0';
    read(source, buf, 1024);

    printf(buf);
}

int main(int argc, char *argv[])
{
    gtk_init(&argc, &argv);

    (void)gdk_input_add(STDIN_FILENO, GDK_INPUT_READ, handle_input, NULL);

    gtk_main();
        
    return 0;
}

Now, when I compile this into polltest and run it...

$ echo test | ./polltest
0x11
test
0x10
0x10
0x10
0x10
0x10
...
^C

This effect appears to be freezing the GUI part of my app. I'm guessing
that this has something to do with the changes described in this message:

http://mail.gnome.org/archives/gtk-devel-list/1999-March/msg00089.html

where the GDK_INPUT_* mappings were changed.

My question is, is there a portable and efficient way to work around
this?  Right now I'm calling poll() in my handler to see if stdin has a
hangup, but this seems redundant and something that glib and/or gdk should
handle.

Thanks,
Emil