return 1;

    }

  *distrenjob = dj;

  dj->next = NULL;

  dj->name = (char *)NULL;

  dj->submitter = (char *)NULL;

  dj->jobnum = 0; /*< @todo there should be a central jobnum allocator and a way to save the maximum jobnumber allocated */

  dj->priority = 0;

  dj->width = 0;

  dj->height = 0;

  dj->completed_frames = 0;

  dj->assigned_frames = 0;

  dj->total_render_time = 0;

  dj->hibernate = 0;

  dj->prev_frame_index = -1;

  dj->assigned_render_power = 0;

  dj->watchdog_forgiveness = 3600; // initialize watchdog forgiveness at 1 hour

  dj->frameset = (struct frameset *)NULL; /*< @todo does frameset need to be initialized here? */

  return 0;

}

/**

   read an unsigned integer property from an xmlNode

   convenience function for distrenjob_unserialize()

   @param xmlnode may be NULL for convenience

   @return 0 on success, other on error

 */

int _distrenjob_xml_readuint(xmlNodePtr xmlnode, xmlChar *propname, unsigned int *num)

{

  xmlChar *string;

  if(!xmlnode)

    return 1;

  string = xmlGetProp(xmlnode, propname);

  if(!string)

    return 1;

  *num = (unsigned int)strtoul((char *)string, (char **)NULL, 10);

#ifndef NDEBUG

  fprintf(stderr, "_distrenjob_xml_readuint(%zx, \"%s\", *(%zx)=%u): read %s=\"%d\"\n",

	  (size_t)xmlnode, propname, (size_t)num, *num, propname, *num);

#endif

  xmlFree(string);

  return 0;

}

/**

   Loads a distrenjob that was serialized with distrenjob_serialize()

   @see distrenjob_serialize()

   @param pathtoxml path to XML file

   @param distrenjob will be set to a pointer

*/

int distrenjob_unserialize(struct distrenjob **distrenjob, char *pathtoxml)

{

  struct distrenjob *dj;

  struct frameset *fs;

  unsigned int start_frame;

  unsigned int end_frame;

  unsigned int counter;

  struct tm tm;

  xmlDocPtr xmldoc;

  xmlNodePtr xmlnode;

  xmlChar *xmlchar;

  xmlXPathContextPtr xmlxpathcontext;

  int tmp;

  if(distrenjob_new(distrenjob))

    return 1;

  dj = *distrenjob;

  xmldoc = xmlReadFile(pathtoxml, NULL, XML_PARSE_PEDANTIC);

  if(!xmldoc)

    {

      /**

	 @todo are we able to depend on libxml2's printed errors or

	 channel them into syslog output (eventually)? Currently,

	 this error is repetitious of a libxml2 error printed on stderr

	 for us.

       */

      fprintf(stderr, "error reading XML file ``%s''\n", pathtoxml);

      distrenjob_free(distrenjob);

      return 2;

    }

  xmlxpathcontext = xmlXPathNewContext(xmldoc);

  xmlnode = xml_quickxpath(xmlxpathcontext, (xmlChar *)"/job");

  if(!xmlnode)

    {

      distrenjob_free(distrenjob);

      return 3;

    }

  /*< @todo should we use xmlChar everywhere too? */

  dj->name = (char *)xmlGetProp(xmlnode, (xmlChar *)"name");

  if(!dj->name)

    {

      distrenjob_free(distrenjob);

      return 4;

    }

  /*< @todo validation needs to be done on usernames. e.g., currently, they shouldn't contain the '"' char  */

  dj->submitter = (char *)xmlGetProp(xmlnode, (xmlChar *)"submitter");

  if(!dj->submitter)

    {

      distrenjob_free(distrenjob);

      return 5;

    }

  tmp = _distrenjob_xml_readuint(xmlnode, (xmlChar *)"priority", &dj->priority);

  if(tmp)

    {

      distrenjob_free(distrenjob);

      return 6;

    }

  dj->output_format = (char *)xmlGetProp(xmlnode, (xmlChar *)"output_format");

  if(!dj->output_format)

    {

      distrenjob_free(distrenjob);

      return 6;

    }

  xmlnode = xml_quickxpath(xmlxpathcontext, (xmlChar *)"/job/resolution");

  tmp = _distrenjob_xml_readuint(xmlnode, (xmlChar *)"width"   , &dj->width   );

  tmp += _distrenjob_xml_readuint(xmlnode, (xmlChar *)"height"  , &dj->height  );

  xmlnode = xml_quickxpath(xmlxpathcontext, (xmlChar *)"/job/video");

  tmp += _distrenjob_xml_readuint(xmlnode, (xmlChar *)"start_frame", &start_frame);

  tmp += _distrenjob_xml_readuint(xmlnode, (xmlChar *)"end_frame", &end_frame);

  if(tmp)

    {

      fprintf(stderr, "distrenjob_unserialize(): error reading integer values from ``%s''\n",

	      pathtoxml);

      distrenjob_free(distrenjob);

      return 7;

    }

  /**

     total_render_time and watchdog stuff doesn't need error

     checking, just good defaults

  */

  xmlnode = xml_quickxpath(xmlxpathcontext, (xmlChar *)"/job/stats");

  dj->total_render_time = 0;

  xmlchar = xmlGetProp(xmlnode, (xmlChar *)"total_render_time");

  if(xmlchar)

    {

      if(strptime((char *)xmlchar, "%D %T", &tm))

	dj->total_render_time = mktime(&tm);

      xmlFree(xmlchar);

    }

  xmlnode = xml_quickxpath(xmlxpathcontext, (xmlChar *)"/job/watchdog");

  dj->watchdog_forgiveness = 3600;

  tmp =_distrenjob_xml_readuint(xmlnode, (xmlChar *)"forgiveness", &dj->watchdog_forgiveness);

  if(tmp)

    fprintf(stderr, "distrenjob_unserialize(): warning: watchdog forgiveness is unspecified in ``%s'', defaulting to 3600\n", pathtoxml);

  xmlXPathFreeContext(xmlxpathcontext);

  xmlFreeDoc(xmldoc);

  /**

     reconstruct the frameset

  */

  dj->total_frames = end_frame - start_frame + 1;

 dj->frameset = malloc(sizeof(struct frameset) * dj->total_frames);

 if(!dj->frameset)

   {

     fprintf(stderr, "OOM!\n");

     distrenjob_free(distrenjob);

     return 8;

   }

 fs = dj->frameset;

 for(counter = start_frame; counter <= end_frame; counter ++)

   {

     fs->num = counter;

     fs->status = FRAMESETSTATUS_UNASSIGNED; /*< @todo job partial completion and resumption support */

     fs ++;

   }

  return 0;

}

int distrenjob_serialize(struct distrenjob *job, char *outfile)

{

  xmlTextWriterPtr writer;

  char *tmp;

  char *tmpfile;

  int tmprtn;

  /**

     transactional FS access for POSIX systems...

     (probably not implemented correctly)

   */

  _distren_asprintf(&tmpfile, "%s_", outfile);

  /* create xml document at the location tmp with no compression */

  writer = xmlNewTextWriterFilename(tmpfile, 0);

  xmlTextWriterStartDocument(writer, NULL, "utf-8", NULL);

  /**

     write distrenjob element and add its attributes */

  xmlTextWriterStartElement(writer, (xmlChar*)"job");

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"name", (xmlChar*)job->name);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"submitter", (xmlChar*)job->submitter);

  _distren_asprintf(&tmp, "%d", job->priority);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"priority", (xmlChar*)tmp);

  free(tmp);

  /**

     write resolution element and add its attributes */

  xmlTextWriterStartElement(writer, (xmlChar*)"resolution");

  _distren_asprintf(&tmp, "%d", job->width);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"width", (xmlChar*)tmp);

  free(tmp);

  _distren_asprintf(&tmp, "%d", job->height);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"height", (xmlChar*)tmp);

  free(tmp);

  xmlTextWriterEndElement(writer);

  /**

     write video element and its attributes */

  xmlTextWriterStartElement(writer, (xmlChar*)"video");

  _distren_asprintf(&tmp, "%d", job->frameset[0].num);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"start_frame", (xmlChar*)tmp);

  free(tmp);

  _distren_asprintf(&tmp, "%d", job->frameset[(job->total_frames - 1)].num);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"end_fame", (xmlChar*)tmp);

  free(tmp);

  xmlTextWriterWriteAttribute(writer, (xmlChar*)"output_format", (xmlChar*)job->output_format);

  xmlTextWriterEndElement(writer);

  /**

     write watchdog forgiveness element */

  _distren_asprintf(&tmp, "%d", job->watchdog_forgiveness);

  xmlTextWriterWriteElement(writer, (xmlChar*)"wd_forgiveness", (xmlChar*)tmp);

  free(tmp);

  /**

     end document */

  xmlTextWriterEndDocument(writer);

  /**

     free writer and save xml file to disk */

  xmlFreeTextWriter(writer);

  /**

     This is the key to transactioanl POSIX

     FS programming.

   */

  tmprtn = rename(tmpfile, outfile);

  if(tmprtn == -1)

    {

      fprintf(stderr, "%s:%d: Error renaming ``%s'' to ``%s''\n",

	      __FILE__, __LINE__,

	      tmpfile, outfile);

      perror("rename");

      tmprtn = 1;

    }

  free(tmpfile);

  return tmprtn;

}