Re: [gtk-list] glib problem

[David Benson <daveb idealab com>]

In order to *sometimes* read from a socket, I think you must use
g_source_add and g_main_add_poll.  Very briefly, something like:



GPollFD poll_fd;

gboolean needs_input;		/* indicates whether the fd should be
                                 * read from. */

static gboolean prepare(gpointer  source_data,
                        GTimeVal* curtime,
                        gint*     timeout,
                        gpointer  user_data)
{
	if (needs_input)
		poll_fd.events = G_IO_IN;
	else
		poll_fd.events = 0;
	return FALSE;
}

static gboolean check(gpointer  source_data,
                        GTimeVal* curtime,
                        gpointer  user_data)
{
	return poll_fd.revents == 0 ? FALSE : TRUE;
}

static gboolean dispatch(gpointer  source_data,
                         GTimeVal* curtime,
                         gpointer  user_data)
{
	/* Do stuff... (you can look at poll_fd.revents for exactly
	 *              which IO conditions apply) */
}


void init_poll_fd(int fd)
{
	poll_fd.fd = fd;
	g_main_add_poll(&poll_fd, G_PRIORITY_DEFAULT);
	g_source_add(G_PRIORITY_DEFAULT, FALSE,
	             &source_funcs, NULL, NULL, NULL);
}


Of course, don't use globals in real code :)

- Dave


On Tue, 15 Feb 2000, Giaslas Georgios wrote:

> hi guys, i have the following problem:
> 
> i want to create a socket and call a function whenever there is something
> to read, using glib. When GIOFunc is set to return FALSE, there is no
> problem with the code, but i don't want the event source to be removed.
> So, i set myfunc to return TRUE but when there is something to read,
> GIOFunc is called once and then i get a segmentation fault.
> Can you help me with this, or suggest something else?
> 
> Here is a part of my code:
> after the creation of the socket i use the following code:
> --------------------------------------------------------
>   myloop=g_main_new(FALSE);
>   mychannel=g_io_channel_unix_new(sockfd);
>   buff="something";
>   g_io_channel_write(mychannel,buff,9,written);
>   eventid=g_io_add_watch(mychannel,G_IO_IN,&myfunc,NULL);
>   g_main_run(myloop);
>   g_io_channel_close(mychannel);
> ---------------------------------------------------------
> gboolean myfunc(GIOChannel *source, GIOCondition condition, gpointer data)
> {
>   gchar *buff;
>   guint *readden;
> 
>   buff=g_malloc(512);
>   if (g_io_channel_read(source,buff,100,readden)!=G_IO_ERROR_NONE) g_print("failed to read\n");
>   g_print("read : %s\n",buff);
>   if (buff=="something") g_main_quit(myloop);
>   return TRUE;
> }
> 
> 
> Thanx in advance
> 
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