CI_Upload::do_upload PHP Method

    public function do_upload($field = 'userfile')
    {
        // Is $_FILES[$field] set? If not, no reason to continue.
        if (isset($_FILES[$field])) {
            $_file = $_FILES[$field];
        } elseif (($c = preg_match_all('/(?:^[^\\[]+)|\\[[^]]*\\]/', $field, $matches)) > 1) {
            $_file = $_FILES;
            for ($i = 0; $i < $c; $i++) {
                // We can't track numeric iterations, only full field names are accepted
                if (($field = trim($matches[0][$i], '[]')) === '' or !isset($_file[$field])) {
                    $_file = NULL;
                    break;
                }
                $_file = $_file[$field];
            }
        }
        if (!isset($_file)) {
            $this->set_error('upload_no_file_selected', 'debug');
            return FALSE;
        }
        // Is the upload path valid?
        if (!$this->validate_upload_path()) {
            // errors will already be set by validate_upload_path() so just return FALSE
            return FALSE;
        }
        // Was the file able to be uploaded? If not, determine the reason why.
        if (!is_uploaded_file($_file['tmp_name'])) {
            $error = isset($_file['error']) ? $_file['error'] : 4;
            switch ($error) {
                case UPLOAD_ERR_INI_SIZE:
                    $this->set_error('upload_file_exceeds_limit', 'info');
                    break;
                case UPLOAD_ERR_FORM_SIZE:
                    $this->set_error('upload_file_exceeds_form_limit', 'info');
                    break;
                case UPLOAD_ERR_PARTIAL:
                    $this->set_error('upload_file_partial', 'debug');
                    break;
                case UPLOAD_ERR_NO_FILE:
                    $this->set_error('upload_no_file_selected', 'debug');
                    break;
                case UPLOAD_ERR_NO_TMP_DIR:
                    $this->set_error('upload_no_temp_directory', 'error');
                    break;
                case UPLOAD_ERR_CANT_WRITE:
                    $this->set_error('upload_unable_to_write_file', 'error');
                    break;
                case UPLOAD_ERR_EXTENSION:
                    $this->set_error('upload_stopped_by_extension', 'debug');
                    break;
                default:
                    $this->set_error('upload_no_file_selected', 'debug');
                    break;
            }
            return FALSE;
        }
        // Set the uploaded data as class variables
        $this->file_temp = $_file['tmp_name'];
        $this->file_size = $_file['size'];
        // Skip MIME type detection?
        if ($this->detect_mime !== FALSE) {
            $this->_file_mime_type($_file);
        }
        $this->file_type = preg_replace('/^(.+?);.*$/', '\\1', $this->file_type);
        $this->file_type = strtolower(trim(stripslashes($this->file_type), '"'));
        $this->file_name = $this->_prep_filename($_file['name']);
        $this->file_ext = $this->get_extension($this->file_name);
        $this->client_name = $this->file_name;
        // Is the file type allowed to be uploaded?
        if (!$this->is_allowed_filetype()) {
            $this->set_error('upload_invalid_filetype', 'debug');
            return FALSE;
        }
        // if we're overriding, let's now make sure the new name and type is allowed
        if ($this->_file_name_override !== '') {
            $this->file_name = $this->_prep_filename($this->_file_name_override);
            // If no extension was provided in the file_name config item, use the uploaded one
            if (strpos($this->_file_name_override, '.') === FALSE) {
                $this->file_name .= $this->file_ext;
            } else {
                // An extension was provided, let's have it!
                $this->file_ext = $this->get_extension($this->_file_name_override);
            }
            if (!$this->is_allowed_filetype(TRUE)) {
                $this->set_error('upload_invalid_filetype', 'debug');
                return FALSE;
            }
        }
        // Convert the file size to kilobytes
        if ($this->file_size > 0) {
            $this->file_size = round($this->file_size / 1024, 2);
        }
        // Is the file size within the allowed maximum?
        if (!$this->is_allowed_filesize()) {
            $this->set_error('upload_invalid_filesize', 'info');
            return FALSE;
        }
        // Are the image dimensions within the allowed size?
        // Note: This can fail if the server has an open_basedir restriction.
        if (!$this->is_allowed_dimensions()) {
            $this->set_error('upload_invalid_dimensions', 'info');
            return FALSE;
        }
        // Sanitize the file name for security
        $this->file_name = $this->_CI->security->sanitize_filename($this->file_name);
        // Truncate the file name if it's too long
        if ($this->max_filename > 0) {
            $this->file_name = $this->limit_filename_length($this->file_name, $this->max_filename);
        }
        // Remove white spaces in the name
        if ($this->remove_spaces === TRUE) {
            $this->file_name = preg_replace('/\\s+/', '_', $this->file_name);
        }
        if ($this->file_ext_tolower && ($ext_length = strlen($this->file_ext))) {
            // file_ext was previously lower-cased by a get_extension() call
            $this->file_name = substr($this->file_name, 0, -$ext_length) . $this->file_ext;
        }
        /*
         * Validate the file name
         * This function appends an number onto the end of
         * the file if one with the same name already exists.
         * If it returns false there was a problem.
         */
        $this->orig_name = $this->file_name;
        if (FALSE === ($this->file_name = $this->set_filename($this->upload_path, $this->file_name))) {
            return FALSE;
        }
        /*
         * Run the file through the XSS hacking filter
         * This helps prevent malicious code from being
         * embedded within a file. Scripts can easily
         * be disguised as images or other file types.
         */
        if ($this->xss_clean && $this->do_xss_clean() === FALSE) {
            $this->set_error('upload_unable_to_write_file', 'error');
            return FALSE;
        }
        /*
         * Move the file to the final destination
         * To deal with different server configurations
         * we'll attempt to use copy() first. If that fails
         * we'll use move_uploaded_file(). One of the two should
         * reliably work in most environments
         */
        if (!@copy($this->file_temp, $this->upload_path . $this->file_name)) {
            if (!@move_uploaded_file($this->file_temp, $this->upload_path . $this->file_name)) {
                $this->set_error('upload_destination_error', 'error');
                return FALSE;
            }
        }
        /*
         * Set the finalized image dimensions
         * This sets the image width/height (assuming the
         * file was an image). We use this information
         * in the "data" function.
         */
        $this->set_image_properties($this->upload_path . $this->file_name);
        return TRUE;
    }

 function do_upload($_FILES = '', $field = 'userfile')
 {
     if (empty($_FILES[$field])) {
         $this->set_error('upload_no_file_selected');
         return FALSE;
     } else {
         if (count($_FILES[$field]['name']) > 1) {
             foreach ($_FILES[$field]['name'] as $index => $name) {
                 if (!empty($name)) {
                     $this->do_xupload($_FILES, $field, $index);
                     $temp = parent::data();
                     $this->set_dataArray($temp, $index);
                 }
             }
             return true;
         } else {
             if ($field == 'proimg') {
                 $this->do_xupload($_FILES, $field);
                 $temp = parent::data();
                 $this->set_dataArray($temp, 0);
                 return true;
             } else {
                 parent::do_upload($_FILES, $field);
                 return parent::data();
             }
         }
     }
 }