Programmatic file migration in Drupal for existing nodes over HTTP using CCK filefield and nodeapi

gistfile1.php

<?php
/* Similar to the CCK migration thing I posted before I found a peculiarity dealing with filefield and nodeapi - for some reason, it didn't actually update the filefield until I ran a separate node_save().. */

function archivalcollection_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {
  if ($op == 'presave') {
    switch ($node->type) {
      case 'archivalcollection':
        if ((empty($node->field_arms_pdffile[0]['fid']) || $node->field_arms_pdffile[0]['fid'] == 0) 
          && !empty($node->field_arms_amat_printfindingaid[0]['value'])) {
          $pdfurl = $node->field_arms_amat_printfindingaid[0]['value'];
          $pdfpath = file_directory_path() .'/archivalcollections/pdf';
          $tmppath = file_directory_temp();
          $tmpfile = $tmppath.'/'.basename($pdfurl);
          if (!$pdfdata = file_get_contents($pdfurl)) {
            watchdog('AMAT Migration', "nid $node->nid - Could not read $pdfurl", NULL, WATCHDOG_ERROR);
          } elseif (!$tmppdf = file_save_data($pdfdata, $tmpfile)) {
            watchdog('AMAT Migration', "nid $node->nid - Could not write to $tmpfile", NULL, WATCHDOG_ERROR);
          } elseif (!$file = field_file_save_file($tmpfile, array(), $pdfpath)) {
            watchdog('AMAT Migration', "nid $node->nid - Could not create file object for file $tmpfile", NULL, WATCHDOG_ERROR);
          } else {
            $fc = $file;
            $fid = $fc['fid'];
            $file = field_file_save($node, $file);
            $node->field_arms_pdffile = array( 0 =>
              array(
                'fid' => $fc['fid'],
                'title' => basename($fc['filename']),
                'filename' => $fc['filename'],
                'filepath' => $fc['filepath'],
                'filesize' => $fc['filesize'],
                'mimetype' => $fc['filemime'],
                'data' => array('description' => ''),
                'list' => 1,
              ),
            );
            node_save($node);
          }
        }
        // }
        break;
    }
  }
}