Re: Executing external process goes into infinite loop

["Ardhan Madras" <ajhwb knac com>]

In execute_input() i can't see a code to make a infinite loop, If you are curious, see codes of 
gdk_input_add() and find out why the GdkInputFunction recalled, btw have you try g_io_add_watch() instead by 
making a call to gdk_input_add() the deprecated one?.

--- ajhwb


--- rgasch gmail com wrote:

From: RNG <rgasch gmail com>
To: gtk-app-devel-list gnome org
Subject: Executing external process goes into infinite loop
Date: Mon, 4 May 2009 08:52:56 +0200

Hi,

I have inherited an old version of a glade-based program which I am
trying to clean up. I have applied some fixes and for the most part
things are going well, but 1 function in particular is giving me
trouble and I will readily admit that I don't quite understand how
this is working and how it should work.

The function in question calls a rendering process (povray) by calling
the execute_command() function. This works but upon completion of the
rendering process, my program goes into an infinite loop, continually
calling the execute_input() function as if the end of the povray
process is never detected. Below is the relevant code, I would be
grateful as to any ideas what might be wrong here because as stated
above, I am stumped.

Thanks
Robert


-------------------------------------------------------------------------


typedef struct ExecData ExecData;
struct ExecData
{
  int           input;
  gchar        *text;
  gchar        *error_message;
  FinishedFunc  finish_func;
  gpointer      user_data;
  gint          pid;
  gint          input_id;
};

static ExecData *
exec_data_new (int           in,
               gchar        *error_msg,
               FinishedFunc  func,
               gpointer      user_data,
               int           pid)
{
  ExecData *data;

  data = g_new0 (ExecData, 1);
  data->input = in;
  data->text = g_strdup ("");
  data->error_message = g_strdup (error_msg);
  data->finish_func = func;
  data->user_data = user_data;
  data->pid = pid;

  return data;
}

static void
exec_data_free (ExecData *data)
{
  close (data->input);
  g_free (data->error_message);
  g_free (data->text);
  g_free (data);
}

static void
execute_input (gpointer          user_data,
               gint              source_fd,
               GdkInputCondition condition)
{
  ExecData *data = (ExecData*) user_data;
  gchar     buf[1025];
  gint      length;

  fcntl (data->input, F_SETFL, O_NONBLOCK);
  length = read (data->input, buf, 1024);
  fcntl (data->input, F_SETFL, 0);
  if (length <= 0)
    {
      if (length == 0 && errno != EAGAIN)
        {
          gchar *open_paren;
          gint   status;

          open_paren = strrchr (data->text, '(');
          status = -1;
          if (open_paren != NULL)
          if (sscanf (&open_paren[1], "%i", &status) != 1)
            status = -1;

          /* POV-Ray returns 512 on an aborted trace.
             Don't popup an error dialog box. */
          if (status != 0 && status != 512)
            {
              GtkWidget *window;

              window = create_execution_error_window ();

              set_text (window, "error_label", data->error_message);
              set_text (window, "error_text", data->text);
              gtk_widget_show (window);
            }

          if (data->finish_func != NULL)
            data->finish_func (data->user_data);

          waitpid (data->pid, NULL, 0);

          gdk_input_remove (data->input_id);
          close (data->input);
          exec_data_free (data);
        }
    }
  else
    {
      buf[length] = '\0';
      data->text =
        g_renew (gchar, data->text, length + strlen (data->text) + 1);
      strcat (data->text, buf);
    }
}

void
execute_command (gchar        *command,
                 gchar        *error_message,
                 FinishedFunc  func,
                 gpointer      user_data)
{
  int       in;
  ExecData *data;
  int       pid;

  in = proc_open (command, &pid);
  data = exec_data_new (in, error_message, func, user_data, pid);

  g_free (data->text);
  data->text = g_strdup_printf ("Executing the command: '%s'\n\n", command);

  data->input_id =
    gdk_input_add (in,
                   GDK_INPUT_READ,
                   (GdkInputFunction) execute_input,
                   (gpointer) data);
}
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