path: root/src/util/container_meta_data.c

/*
     This file is part of GNUnet.
     (C) 2003, 2004, 2005, 2006, 2008, 2009, 2010 Christian Grothoff (and other contributing authors)

     GNUnet 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, or (at your
     option) any later version.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file util/container_meta_data.c
 * @brief Storing of meta data
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_common.h"
#include "gnunet_container_lib.h"
#include "gnunet_strings_lib.h"
#include "gnunet_time_lib.h"
#include <extractor.h>
#include <zlib.h>

#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)

/**
 * Meta data item.
 */
struct MetaItem
{
  /**
   * This is a doubly linked list.
   */
  struct MetaItem *next;

  /**
   * This is a doubly linked list.
   */
  struct MetaItem *prev;

  /**
   * Name of the extracting plugin.
   */
  char *plugin_name;

  /**
   * Mime-type of data.
   */
  char *mime_type;

  /**
   * The actual meta data.
   */
  char *data;

  /**
   * Number of bytes in 'data'.
   */
  size_t data_size;

  /**
   * Type of the meta data.
   */
  enum EXTRACTOR_MetaType type;

  /**
   * Format of the meta data.
   */
  enum EXTRACTOR_MetaFormat format;

};

/**
 * Meta data to associate with a file, directory or namespace.
 */
struct GNUNET_CONTAINER_MetaData
{
  /**
   * Head of linked list of the meta data items.
   */
  struct MetaItem *items_head;

  /**
   * Tail of linked list of the meta data items.
   */
  struct MetaItem *items_tail;

  /**
   * Complete serialized and compressed buffer of the items.
   * NULL if we have not computed that buffer yet.
   */
  char *sbuf;

  /**
   * Number of bytes in 'sbuf'. 0 if the buffer is stale.
   */
  size_t sbuf_size;

  /**
   * Number of items in the linked list.
   */
  unsigned int item_count;

};


/**
 * Create a fresh struct CONTAINER_MetaData token.
 *
 * @return empty meta-data container
 */
struct GNUNET_CONTAINER_MetaData *
GNUNET_CONTAINER_meta_data_create ()
{
  return GNUNET_malloc (sizeof (struct GNUNET_CONTAINER_MetaData));
}


/**
 * Free meta data item.
 *
 * @param mi item to free
 */
static void
meta_item_free (struct MetaItem *mi)
{
  GNUNET_free_non_null (mi->plugin_name);
  GNUNET_free_non_null (mi->mime_type);
  GNUNET_free_non_null (mi->data);
  GNUNET_free (mi);
}


/**
 * The meta data has changed, invalidate its serialization
 * buffer.
 *
 * @param md meta data that changed
 */
static void
invalidate_sbuf (struct GNUNET_CONTAINER_MetaData *md)
{
  if (NULL == md->sbuf)
    return;
  GNUNET_free (md->sbuf);
  md->sbuf = NULL;
  md->sbuf_size = 0;
}


/**
 * Free meta data.
 *
 * @param md what to free
 */
void
GNUNET_CONTAINER_meta_data_destroy (struct GNUNET_CONTAINER_MetaData *md)
{
  struct MetaItem *pos;

  if (NULL == md)
    return;
  while (NULL != (pos = md->items_head))
  {
    GNUNET_CONTAINER_DLL_remove (md->items_head, md->items_tail, pos);
    meta_item_free (pos);
  }
  GNUNET_free_non_null (md->sbuf);
  GNUNET_free (md);
}


/**
 * Remove all items in the container.
 *
 * @param md metadata to manipulate
 */
void
GNUNET_CONTAINER_meta_data_clear (struct GNUNET_CONTAINER_MetaData *md)
{
  struct MetaItem *mi;

  if (NULL == md)
    return;
  while (NULL != (mi = md->items_head))
  {
    GNUNET_CONTAINER_DLL_remove (md->items_head, md->items_tail, mi);
    meta_item_free (mi);
  }
  GNUNET_free_non_null (md->sbuf);
  memset (md, 0, sizeof (struct GNUNET_CONTAINER_MetaData));
}


/**
 * Test if two MDs are equal.  We consider them equal if
 * the meta types, formats and content match (we do not
 * include the mime types and plugins names in this
 * consideration).
 *
 * @param md1 first value to check
 * @param md2 other value to check
 * @return GNUNET_YES if they are equal
 */
int
GNUNET_CONTAINER_meta_data_test_equal (const struct GNUNET_CONTAINER_MetaData
                                       *md1,
                                       const struct GNUNET_CONTAINER_MetaData
                                       *md2)