Thanks for hint.
In my case io_write() is the function g_io_unix_write() from giounix.c:
----- snip -----
static GIOStatus
g_io_unix_write (GIOChannel *channel,
const gchar *buf,
gsize count,
gsize *bytes_written,
GError **err)
{
GIOUnixChannel *unix_channel = (GIOUnixChannel *)channel;
gssize result;
retry:
result = write (unix_channel->fd, buf, count);
if (result < 0)
{
*bytes_written = 0;
switch (errno)
{
#ifdef EINTR
case EINTR:
goto retry;
#endif
#ifdef EAGAIN
case EAGAIN:
return G_IO_STATUS_AGAIN;
#endif
default:
g_set_error (err, G_IO_CHANNEL_ERROR,
g_io_channel_error_from_errno (errno),
g_strerror (errno));
return G_IO_STATUS_ERROR;
}
}
*bytes_written = result;
return G_IO_STATUS_NORMAL;
}
--------- snip ----------
(this code is from svn-trunk)
The function above has no special handling for the case that write()
returns 0. It regards this situation as G_IO_STATUS_NORMAL. However,
g_io_channel_flush() has a different opinion about that - see
g_assert(this_time > 0).
So one of these functions should change its philosophy!
The write()-manpage does not clearly mention what it means if write()
returns 0. In my understanding, if writing data is not possible, it
returns -1 and sets errno to EINTR or EAGAIN .. but maybe this is wrong
and write() returns 0 when there is a EINTR or EAGAIN situation.
I guess this problem should be filed as a bug. Please confirm ..
Christian
On Tue, 2007-12-18 at 09:56 -0800, Peter Long wrote:
> The assert only happens if io_write returns a successful status code AND the total bytes_written are less that the bytes in the buffer. So io_write() wrote nothing while there was data to write but did not report an error. That does sound like a bug to me. I bet the bug is in io_write(). It should return an error status if it could not write any more data.
>
> Peter Long
>
> ----- Original Message ----
> From: Christian Bünnig <masala@xxxxxx>
> To: "gtk-list@xxxxxxxxx" <gtk-list@xxxxxxxxx>
> Sent: Tuesday, December 18, 2007 11:52:57 AM
> Subject: IO Channel Flush - Assertion Failure
>
>
> Hi,
>
> for data communication between 2 Bluetooth devices I have created IO
> channels on the corresponding sockets. This works well the most time.
> However, sometimes (I could not determine the exact occurrence yet)
> flushing the channel with g_io_channel_flush() fails in that it raises
> an assertion error. The failure happens in the line
> g_assert (this_time > 0);
> in the function below (from giochannel.c)
>
> ------ snip -------
>
> GIOStatus
> g_io_channel_flush (GIOChannel *channel, GError **error)
> {
> GIOStatus status;
> gsize this_time = 1, bytes_written = 0;
>
> g_return_val_if_fail (channel != NULL, G_IO_STATUS_ERROR);
> g_return_val_if_fail ((error == NULL) || (*error == NULL),
> G_IO_STATUS_ERROR);
>
> if (channel->write_buf == NULL || channel->write_buf->len == 0)
> return G_IO_STATUS_NORMAL;
>
> do
> {
> g_assert (this_time > 0); /// THIS ASSERTION FAILS ///
>
> status = channel->funcs->io_write(channel,
> channel->write_buf->str +
> bytes_written,
> channel->write_buf->len -
> bytes_written,
> &this_time, error);
> bytes_written += this_time;
> }
> while ((bytes_written < channel->write_buf->len)
> && (status == G_IO_STATUS_NORMAL));
>
> g_string_erase (channel->write_buf, 0, bytes_written);
>
> return status;
> }
>
> ------- snip --------
>
> Afaik. assertions are used to detect bugs .. why is it considered as a
> bug if channel->funcs->io_write() writes no data (this_time == 0)? And
> who is responsible for that assertion failure?
>
> Thanks for some advice,
>
> Christian
>
> _______________________________________________
> gtk-list mailing list
> gtk-list@xxxxxxxxx
> http://mail.gnome.org/mailman/listinfo/gtk-list
>
>
>
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