gimp/app/config/gimpxmlparser.c

/* The GIMP -- an image manipulation program
 * Copyright (C) 1995-1997 Spencer Kimball and Peter Mattis
 *
 * GimpXmlParser
 * Copyright (C) 2003  Sven Neumann <sven@gimp.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <string.h>

#include <glib-object.h>

#include "config-types.h"

#include "gimpxmlparser.h"


struct _GimpXmlParser
{
  GMarkupParseContext *context;
};


static gchar * parse_encoding (const gchar *text,
                               gint         text_len);


/**
 * gimp_xml_parser_new:
 * @markup_parser: a #GMarkupParser
 * @user_data: user data to pass to #GMarkupParser functions
 *
 * GimpXmlParser is a thin wrapper around GMarkupParser. This function
 * creates one for you and sets up a GMarkupParseContext.
 *
 * Return value: a new #GimpXmlParser
 **/
GimpXmlParser *
gimp_xml_parser_new (const GMarkupParser *markup_parser,
                     gpointer             user_data)
{
  GimpXmlParser *parser;

  g_return_val_if_fail (markup_parser != NULL, NULL);

  parser = g_new (GimpXmlParser, 1);

  parser->context = g_markup_parse_context_new (markup_parser,
                                                0, user_data, NULL);

  return parser;
}

/**
 * gimp_xml_parser_parse_file:
 * @parser: a #GimpXmlParser
 * @filename: name of a file to parse
 * @error: return location for possible errors
 *
 * This function creates a GIOChannel for @filename and calls
 * gimp_xml_parser_parse_io_channel() for you.
 *
 * Return value: %TRUE on success, %FALSE otherwise
 **/
gboolean
gimp_xml_parser_parse_file (GimpXmlParser  *parser,
                            const gchar    *filename,
                            GError        **error)
{
  GIOChannel *io;
  gboolean    success;

  g_return_val_if_fail (parser != NULL, FALSE);
  g_return_val_if_fail (filename != NULL, FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  io = g_io_channel_new_file (filename, "r", error);
  if (!io)
    return FALSE;

  success = gimp_xml_parser_parse_io_channel (parser, io, error);

  g_io_channel_unref (io);

  return success;
}

/**
 * gimp_xml_parser_parse_io_channel:
 * @parser: a #GimpXmlParser
 * @io: a #GIOChannel
 * @error: return location for possible errors
 *
 * Makes @parser read from the specified @io channel. This function
 * returns when the GIOChannel becomes empty (end of file) or an
 * error occurs, either reading from @io or parsing the read data.
 *
 * This function tries to determine the character encoding from the
 * XML header and converts the content to UTF-8 for you.
 *
 * Return value: %TRUE on success, %FALSE otherwise
 **/
gboolean
gimp_xml_parser_parse_io_channel (GimpXmlParser  *parser,
                                  GIOChannel     *io,
                                  GError        **error)
{
  GIOStatus    status;
  guchar       buffer[8196];
  gsize        len = 0;
  gsize        bytes;
  const gchar *io_encoding;
  gchar       *encoding = NULL;

  g_return_val_if_fail (parser != NULL, FALSE);
  g_return_val_if_fail (io != NULL, FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  io_encoding = g_io_channel_get_encoding (io);
  if (io_encoding && strcmp (io_encoding, "UTF-8"))
    {
      g_warning ("gimp_xml_parser_parse_io_channel():\n"
                 "The encoding has already been set on this GIOChannel!");
      return FALSE;
    }

  /* try to determine the encoding */
  while (len < sizeof (buffer) && !encoding)
    {
      status = g_io_channel_read_chars (io,
                                        buffer + len, 1, &bytes, error);
      len += bytes;

      if (status == G_IO_STATUS_ERROR)
        return FALSE;
      if (status == G_IO_STATUS_EOF)
        break;

      encoding = parse_encoding (buffer, len);
    }

  if (encoding)
    {
      if (!g_io_channel_set_encoding (io, encoding, error))
        return FALSE;

      g_free (encoding);
    }

  while (TRUE)
    {
      if (!g_markup_parse_context_parse (parser->context, buffer, len, error))
        return FALSE;

      status = g_io_channel_read_chars (io,
                                        buffer, sizeof (buffer), &len, error);

      switch (status)
        {
        case G_IO_STATUS_ERROR:
          return FALSE;
        case G_IO_STATUS_EOF:
          return g_markup_parse_context_end_parse (parser->context, error);
        case G_IO_STATUS_NORMAL:
        case G_IO_STATUS_AGAIN:
          break;
        }
    }
}

/**
 * gimp_xml_parser_free:
 * @parser: a #GimpXmlParser
 *
 * Frees the resources allocated for @parser. You must not access
 * @parser after calling this function.
 **/
void
gimp_xml_parser_free (GimpXmlParser *parser)
{
  g_return_if_fail (parser != NULL);

  g_markup_parse_context_free (parser->context);
  g_free (parser);
}


static gchar *
parse_encoding (const gchar *text,
                gint         text_len)
{
  const gchar *start;
  const gchar *end;
  gint         i;

  g_return_val_if_fail (text, NULL);

  if (text_len < 20)
    return NULL;

  start = g_strstr_len (text, text_len, "<?xml");
  if (!start)
    return NULL;

  end = g_strstr_len (start, text_len - (start - text), "?>");
  if (!end)
    return NULL;

  text_len = end - start;
  if (text_len < 12)
    return NULL;

  start = g_strstr_len (start + 1, text_len - 1, "encoding=");
  if (!start)
    return NULL;

  start += 9;
  if (*start != '\"' && *start != '\'')
    return NULL;

  text_len = end - start;
  if (text_len < 1)
    return NULL;

  for (i = 1; i < text_len; i++)
    if (start[i] == start[0])
      break;

  if (i == text_len || i < 3)
    return NULL;

  return g_strndup (start + 1, i - 1);
}