[libmicrohttpd] Understanding minimal_example.c

[arnuld uttre]

This is some part of the code from minimal_example.c that is
distributed with the libmicrohttpd source. I have some questions over
it which manual does not explain:



static int
ahc_echo (void *cls,
          struct MHD_Connection *connection,
          const char *url,
          const char *method,
          const char *version,
          const char *upload_data, size_t *upload_data_size, void **ptr)
{
  static int aptr;
  const char *me = cls;
  struct MHD_Response *response;
  int ret;

  
printf("--------------------------------------------------------------------------------\n");
  printf("upload_datae = %s\n", upload_data);


  if (0 != strcmp (method, "GET"))
    return MHD_NO;              /* unexpected method */
  if (&aptr != *ptr)
    {
      /* do never respond on first call */
      *ptr = &aptr;
      return MHD_YES;
    }
  *ptr = NULL;                  /* reset when done */
  response = MHD_create_response_from_data (strlen (me),
                                            (void *) me, MHD_NO, MHD_NO);
  ret = MHD_queue_response (connection, MHD_HTTP_OK, response);
  MHD_destroy_response (response);
  return ret;
}
-------------------------------------------------------------

> if (0 != strcmp (method, "GET"))
>   return MHD_NO;              /* unexpected method */

why we are returning with MHD_NO when the method is GET and not for
other methods ?


>      /* do never respond on first call */
>      *ptr = &aptr;
>      return MHD_YES;
>     }
>   *ptr = NULL;                  /* reset when done */


Why never respond to the first attempt of the client ?  I am, in my
software, not using any check for GET method. I also respond to the
very first call and just set the pointer to some value and then I
never set it to NULL again. What harm I am doing to my program ?


Last, *ptr = &aptr and aptr is not initialized with some value. Can't
it produce Segfault ?




-- 
http://uttre.wordpress.com/2008/05/14/the-lost-love-of-mine/