Re: g_spawn_async_with_pipes and g_io_add_watch problem

["Ole C." <oles lists gmail com>]

Hello all again,
I can't really seem to hack this, so I guess I give it another shot
providing some code.

The first spawn starts a c program that takes stdout from the perl
script as input.

The next spawn starts a perl script that reads a file, changes it and
puts it on stdout.

The callback functions are listed below that. The problem is that the
program does a few calls to the pipe_to_mkukoa callback function and
then hangs in the first g_io_channel_write_chars call.

Ideas anyone? I have stared myself blind on this now I think.

 GIOChannel *iocfinalp1 = g_io_channel_new_file (s_p1finalpath, "w+", NULL);
  gint ok = g_spawn_async_with_pipes (NULL, s_removelfProgString, NULL, 0,
                                      NULL,
                                      NULL,
                                      NULL,
                                      &rlfsin,
                                      &rlfsout,
                                      &rlfserr,
                                      &errormk);

  /*set up the channels */
  /*This channel will be written to from stdout from the perl script */
  GIOChannel *iocrlfsin = g_io_channel_unix_new (rlfsin);
  /*this channel will output to the final file */
  GIOChannel *iocrlfsout = g_io_channel_unix_new (rlfsout);

  /*Spawn the p1edit program */
  gint okrlf = g_spawn_async_with_pipes (NULL,
                                         s_extProgString,
                                         NULL,
                                         0,
                                         NULL,
                                         NULL,
                                         NULL,
                                         NULL,  /*no stdin, filename as parameter */
                                         &p1usout,      
                                         &p1userr,
                                         &errorp1);

  GIOChannel *iocstdout = g_io_channel_unix_new (p1usout);
  g_io_add_watch (iocstdout, G_IO_IN | G_IO_HUP, pipe_output_to_mkukoa,
                  iocrlfsin);

  /*The standard out from those files should then be directed to the
final file */
  g_io_add_watch (iocrlfsout, G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_NVAL,
                  pipe_output_to_file, iocfinalp1);

gboolean
pipe_output_to_mkukoa (GIOChannel * ioc, GIOCondition condition,
                       gpointer data)
{
  gchar *buffer;
  GIOChannel *iocrlf = (GIOChannel *) data;
  gsize bytes;
   buffer = malloc (g_io_channel_get_buffer_size (ioc)+1);
  if (condition & G_IO_IN)
    {
       if (g_io_channel_read_chars (ioc, buffer,
g_io_channel_get_buffer_size(ioc), &bytes, NULL)
          != G_IO_STATUS_ERROR && bytes > 0)
        {
          GIOStatus retur =
            g_io_channel_write_chars (iocrlf, buffer, bytes, NULL, NULL);
        }
.
.//misc other stuff here, but it hangs on the write_chars above
.
.

gboolean
pipe_output_to_file (GIOChannel * ioc, GIOCondition condition, gpointer data)
{
  gchar *buffer = malloc (g_io_channel_get_buffer_size (ioc));
  GIOChannel *iocfh = (GIOChannel *) data;
  gsize bytes;
  if (condition & G_IO_IN)
    {
        if (g_io_channel_read_chars (ioc, buffer,
g_io_channel_get_buffer_size (ioc), &bytes, NULL)
                                      != G_IO_STATUS_ERROR && bytes > 0) 

        {

          GIOStatus retur =
            g_io_channel_write_chars (iocfh, buffer, bytes, NULL, NULL);
        }
      if (condition & G_IO_HUP)
        {
          while (g_io_channel_read_chars (iocfh, buffer,
g_io_channel_get_buffer_size (ioc), &bytes, NULL)
                                  != G_IO_STATUS_ERROR && bytes > 0)
            {
              GIOStatus retur =
                g_io_channel_write_chars (iocfh, buffer, bytes, NULL, NULL);
            }

          return FALSE;
        }
    }

  if (condition & (G_IO_HUP | G_IO_ERR | G_IO_NVAL))
    {
      g_io_channel_unref (ioc);
      g_io_channel_shutdown (ioc, TRUE, NULL);
    }

  return TRUE;
}


On Mar 17, 2005 1:41 AM, Tim Müller <zen18864 zen co uk> wrote:
> On Wednesday 16 March 2005 21:55, Ole C. wrote:
>
> >  (snip a lot)
>
> I have to admit I have only quickly looked over your text and not read it in
> much detail, but it sounds like you might not be checking the condition in
> the g_io_add_watch() callback on a per-flag basis. Your callback could be
> called with condition = G_IO_IN | G_IO_HUP at the end, so if you just check
> with if (condition == G_IO_IN) etc. instead of if ((condition & G_IO_IN)) you
> won't catch that case properly.
>
> Just a thought. If that's not it, I'd recommend you post some code somewhere
> for people to look at (the shorter, the better).
>
> Cheers
> -Tim