Drupal 7 - Add a cancel button on node forms

modulename.module

<?php

/**
 * Implements hook_form_alter().
 */
function modulename_form_alter(&$form, &$form_state, $form_id) {
  // You might want to filter by content type.
  if ($form_id == 'ctype_node_form') {
    // Add a cancel button.
    $form['actions']['cancel'] = array(
      '#type'   => 'submit',
      '#value'  => t('Cancel'),
      '#access' => TRUE,
      '#weight' => 15,
      '#submit' => array('modulename_form_cancel', 'node_form_submit_build_node'),
      '#limit_validation_errors' => array(),
    );
  }
}

/**
 * Custom cancel button callback.
 */
function modulename_form_cancel($form, &$form_state) {
  $url = $_GET['destination'] ? $_GET['destination'] : 'choose/your/path';
  drupal_goto($url);
}

function modulename_form_alter(&$form, &$form_state, $form_id) {
  // You might want to filter by content type.
  if ($form_id == 'ctype_node_form') {
    if (!isset($form_state['ajax'])){
      // Add a cancel button.
      $form['actions']['cancel'] = array(
        '#type'   => 'submit',
        '#value'  => t('Cancel'),
        '#access' => TRUE,
        '#weight' => 15,
        '#submit' => array('modulename_form_cancel', 'node_form_submit_build_node'),
        '#limit_validation_errors' => array(),
      );
    }

    else {
      $form['actions']['cancel'] = array(
        '#weight' => 15,
        '#markup' => l(t('Cancel'), '#',
          array(
            'attributes' => array(
              'class' => 'ctools-close-modal button'
              ),
            'external' => TRUE
          )
        )
      );
    }
  }
}

/**
 * Custom cancel button callback.
 */
function modulename_form_cancell($form, &$form_state) {
  $fallback_destinaton = 'choose/your/path';
  // If edit, use the node itself as fallback.
  if (!empty($form['#node'])) {
    if (!empty($form['#node']->nid)) {
      $nid                 = $form['#node']->nid;
      $node                = node_load($nid);
      $node_uri            = node_uri($node);
      $fallback_destinaton = $node_uri['path'];
    }
  }
  // Go to destination or fallback.
  $url = isset($_GET['destination']) ? $_GET['destination'] : $fallback_destinaton;
  drupal_goto($url);
}

Would it be possible for me to repurpose your code to be able to place a button next to a field in content form that I've created?
Essentially, I'd like the button to be able to generate a random MD5 hash value and place it in the adjacent text field? Thanks!

dS.

Thanks a ton !!!! That was very helpful