Add xdg mime support on Linux.

base/third_party/xdg_mime/xdgmime.c

+/* -*- mode: C; c-file-style: "gnu" -*- */
+/* xdgmime.c: XDG Mime Spec mime resolver.  Based on version 0.11 of the spec.
+ *
+ * More info can be found at http://www.freedesktop.org/standards/
+ * 
+ * Copyright (C) 2003,2004  Red Hat, Inc.
+ * Copyright (C) 2003,2004  Jonathan Blandford <jrb@alum.mit.edu>
+ *
+ * Licensed under the Academic Free License version 2.0
+ * Or under the following terms:
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "xdgmime.h"
+#include "xdgmimeint.h"
+#include "xdgmimeglob.h"
+#include "xdgmimemagic.h"
+#include "xdgmimealias.h"
+#include "xdgmimeicon.h"
+#include "xdgmimeparent.h"
+#include "xdgmimecache.h"
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <assert.h>
+
+typedef struct XdgDirTimeList XdgDirTimeList;
+typedef struct XdgCallbackList XdgCallbackList;
+
+static int need_reread = TRUE;
+static time_t last_stat_time = 0;
+
+static XdgGlobHash *global_hash = NULL;
+static XdgMimeMagic *global_magic = NULL;
+static XdgAliasList *alias_list = NULL;
+static XdgParentList *parent_list = NULL;
+static XdgDirTimeList *dir_time_list = NULL;
+static XdgCallbackList *callback_list = NULL;
+static XdgIconList *icon_list = NULL;
+static XdgIconList *generic_icon_list = NULL;
+
+XdgMimeCache **_caches = NULL;
+static int n_caches = 0;
+
+const char xdg_mime_type_unknown[] = "application/octet-stream";
+
+
+enum
+{
+  XDG_CHECKED_UNCHECKED,
+  XDG_CHECKED_VALID,
+  XDG_CHECKED_INVALID
+};
+
+struct XdgDirTimeList
+{
+  time_t mtime;
+  char *directory_name;
+  int checked;
+  XdgDirTimeList *next;
+};
+
+struct XdgCallbackList
+{
+  XdgCallbackList *next;
+  XdgCallbackList *prev;
+  int              callback_id;
+  XdgMimeCallback  callback;
+  void            *data;
+  XdgMimeDestroy   destroy;
+};
+
+/* Function called by xdg_run_command_on_dirs.  If it returns TRUE, further
+ * directories aren't looked at */
+typedef int (*XdgDirectoryFunc) (const char *directory,
+                                 void       *user_data);
+
+static void
+xdg_dir_time_list_add (char   *file_name, 
+                       time_t  mtime)
+{
+  XdgDirTimeList *list;
+
+  for (list = dir_time_list; list; list = list->next) 
+    {
+      if (strcmp (list->directory_name, file_name) == 0)
+        {
+          free (file_name);
+          return;
+        }
+    }
+  
+  list = calloc (1, sizeof (XdgDirTimeList));
+  list->checked = XDG_CHECKED_UNCHECKED;
+  list->directory_name = file_name;
+  list->mtime = mtime;
+  list->next = dir_time_list;
+  dir_time_list = list;
+}
+ 
+static void
+xdg_dir_time_list_free (XdgDirTimeList *list)
+{
+  XdgDirTimeList *next;
+
+  while (list)
+    {
+      next = list->next;
+      free (list->directory_name);
+      free (list);
+      list = next;
+    }
+}
+
+static int
+xdg_mime_init_from_directory (const char *directory)
+{
+  char *file_name;
+  struct stat st;
+
+  assert (directory != NULL);
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/mime.cache") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/mime.cache");
+  if (stat (file_name, &st) == 0)
+    {
+      XdgMimeCache *cache = _xdg_mime_cache_new_from_file (file_name);
+
+      if (cache != NULL)
+        {
+          xdg_dir_time_list_add (file_name, st.st_mtime);
+
+          _caches = realloc (_caches, sizeof (XdgMimeCache *) * (n_caches + 2));
+          _caches[n_caches] = cache;
+          _caches[n_caches + 1] = NULL;
+          n_caches++;
+
+          return FALSE;
+        }
+    }
+  free (file_name);
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/globs2") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/globs2");
+  if (stat (file_name, &st) == 0)
+    {
+      _xdg_mime_glob_read_from_file (global_hash, file_name);
+      xdg_dir_time_list_add (file_name, st.st_mtime);
+    }
+  else
+    {
+      free (file_name);
+      file_name = malloc (strlen (directory) + strlen ("/mime/globs") + 1);
+      strcpy (file_name, directory); strcat (file_name, "/mime/globs");
+      if (stat (file_name, &st) == 0)
+        {
+          _xdg_mime_glob_read_from_file (global_hash, file_name);
+          xdg_dir_time_list_add (file_name, st.st_mtime);
+        }
+      else
+        {
+          free (file_name);
+        }
+    }
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/magic") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/magic");
+  if (stat (file_name, &st) == 0)
+    {
+      _xdg_mime_magic_read_from_file (global_magic, file_name);
+      xdg_dir_time_list_add (file_name, st.st_mtime);
+    }
+  else
+    {
+      free (file_name);
+    }
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/aliases") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/aliases");
+  _xdg_mime_alias_read_from_file (alias_list, file_name);
+  free (file_name);
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/subclasses") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/subclasses");
+  _xdg_mime_parent_read_from_file (parent_list, file_name);
+  free (file_name);
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/icons") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/icons");
+  _xdg_mime_icon_read_from_file (icon_list, file_name);
+  free (file_name);
+
+  file_name = malloc (strlen (directory) + strlen ("/mime/generic-icons") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/generic-icons");
+  _xdg_mime_icon_read_from_file (generic_icon_list, file_name);
+  free (file_name);
+
+  return FALSE; /* Keep processing */
+}
+
+/* Runs a command on all the directories in the search path */
+static void
+xdg_run_command_on_dirs (XdgDirectoryFunc  func,
+                         void             *user_data)
+{
+  const char *xdg_data_home;
+  const char *xdg_data_dirs;
+  const char *ptr;
+
+  xdg_data_home = getenv ("XDG_DATA_HOME");
+  if (xdg_data_home)
+    {
+      if ((func) (xdg_data_home, user_data))
+        return;
+    }
+  else
+    {
+      const char *home;
+
+      home = getenv ("HOME");
+      if (home != NULL)
+        {
+          char *guessed_xdg_home;
+          int stop_processing;
+
+          guessed_xdg_home = malloc (strlen (home) + strlen ("/.local/share/") + 1);
+          strcpy (guessed_xdg_home, home);
+          strcat (guessed_xdg_home, "/.local/share/");
+          stop_processing = (func) (guessed_xdg_home, user_data);
+          free (guessed_xdg_home);
+
+          if (stop_processing)
+            return;
+        }
+    }
+
+  xdg_data_dirs = getenv ("XDG_DATA_DIRS");
+  if (xdg_data_dirs == NULL)
+    xdg_data_dirs = "/usr/local/share/:/usr/share/";
+
+  ptr = xdg_data_dirs;
+
+  while (*ptr != '\000')
+    {
+      const char *end_ptr;
+      char *dir;
+      int len;
+      int stop_processing;
+
+      end_ptr = ptr;
+      while (*end_ptr != ':' && *end_ptr != '\000')
+        end_ptr ++;
+
+      if (end_ptr == ptr)
+        {
+          ptr++;
+          continue;
+        }
+
+      if (*end_ptr == ':')
+        len = end_ptr - ptr;
+      else
+        len = end_ptr - ptr + 1;
+      dir = malloc (len + 1);
+      strncpy (dir, ptr, len);
+      dir[len] = '\0';
+      stop_processing = (func) (dir, user_data);
+      free (dir);
+
+      if (stop_processing)
+        return;
+
+      ptr = end_ptr;
+    }
+}
+
+/* Checks file_path to make sure it has the same mtime as last time it was
+ * checked.  If it has a different mtime, or if the file doesn't exist, it
+ * returns FALSE.
+ *
+ * FIXME: This doesn't protect against permission changes.
+ */
+static int
+xdg_check_file (const char *file_path,
+                int        *exists)
+{
+  struct stat st;
+
+  /* If the file exists */
+  if (stat (file_path, &st) == 0)
+    {
+      XdgDirTimeList *list;
+
+      if (exists)
+        *exists = TRUE;
+
+      for (list = dir_time_list; list; list = list->next)
+        {
+          if (! strcmp (list->directory_name, file_path))
+            {
+              if (st.st_mtime == list->mtime)
+                list->checked = XDG_CHECKED_VALID;
+              else 
+                list->checked = XDG_CHECKED_INVALID;
+
+              return (list->checked != XDG_CHECKED_VALID);
+            }
+        }
+      return TRUE;
+    }
+
+  if (exists)
+    *exists = FALSE;
+
+  return FALSE;
+}
+
+static int
+xdg_check_dir (const char *directory,
+               int        *invalid_dir_list)
+{
+  int invalid, exists;
+  char *file_name;
+
+  assert (directory != NULL);
+
+  /* Check the mime.cache file */
+  file_name = malloc (strlen (directory) + strlen ("/mime/mime.cache") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/mime.cache");
+  invalid = xdg_check_file (file_name, &exists);
+  free (file_name);
+  if (invalid)
+    {
+      *invalid_dir_list = TRUE;
+      return TRUE;
+    }
+  else if (exists)
+    {
+      return FALSE;
+    }
+
+  /* Check the globs file */
+  file_name = malloc (strlen (directory) + strlen ("/mime/globs") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/globs");
+  invalid = xdg_check_file (file_name, NULL);
+  free (file_name);
+  if (invalid)
+    {
+      *invalid_dir_list = TRUE;
+      return TRUE;
+    }
+
+  /* Check the magic file */
+  file_name = malloc (strlen (directory) + strlen ("/mime/magic") + 1);
+  strcpy (file_name, directory); strcat (file_name, "/mime/magic");
+  invalid = xdg_check_file (file_name, NULL);
+  free (file_name);
+  if (invalid)
+    {
+      *invalid_dir_list = TRUE;
+      return TRUE;
+    }
+
+  return FALSE; /* Keep processing */
+}
+
+/* Walks through all the mime files stat()ing them to see if they've changed.
+ * Returns TRUE if they have. */
+static int
+xdg_check_dirs (void)
+{
+  XdgDirTimeList *list;
+  int invalid_dir_list = FALSE;
+
+  for (list = dir_time_list; list; list = list->next)
+    list->checked = XDG_CHECKED_UNCHECKED;
+
+  xdg_run_command_on_dirs ((XdgDirectoryFunc) xdg_check_dir,
+                           &invalid_dir_list);
+
+  if (invalid_dir_list)
+    return TRUE;
+
+  for (list = dir_time_list; list; list = list->next)
+    {
+      if (list->checked != XDG_CHECKED_VALID)
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
+/* We want to avoid stat()ing on every single mime call, so we only look for
+ * newer files every 5 seconds.  This will return TRUE if we need to reread the
+ * mime data from disk.
+ */
+static int
+xdg_check_time_and_dirs (void)
+{
+  struct timeval tv;
+  time_t current_time;
+  int retval = FALSE;
+
+  gettimeofday (&tv, NULL);
+  current_time = tv.tv_sec;
+
+  if (current_time >= last_stat_time + 5)
+    {
+      retval = xdg_check_dirs ();
+      last_stat_time = current_time;
+    }
+
+  return retval;
+}
+
+/* Called in every public function.  It reloads the hash function if need be.
+ */
+static void
+xdg_mime_init (void)
+{
+  if (xdg_check_time_and_dirs ())
+    {
+      xdg_mime_shutdown ();
+    }
+
+  if (need_reread)
+    {
+      global_hash = _xdg_glob_hash_new ();
+      global_magic = _xdg_mime_magic_new ();
+      alias_list = _xdg_mime_alias_list_new ();
+      parent_list = _xdg_mime_parent_list_new ();
+      icon_list = _xdg_mime_icon_list_new ();
+      generic_icon_list = _xdg_mime_icon_list_new ();
+
+      xdg_run_command_on_dirs ((XdgDirectoryFunc) xdg_mime_init_from_directory,
+                               NULL);
+
+      need_reread = FALSE;
+    }
+}
+
+const char *
+xdg_mime_get_mime_type_for_data (const void *data,
+                                 size_t      len,
+                                 int        *result_prio)
+{
+  const char *mime_type;
+
+  xdg_mime_init ();
+
+  if (_caches)
+    return _xdg_mime_cache_get_mime_type_for_data (data, len, result_prio);
+
+  mime_type = _xdg_mime_magic_lookup_data (global_magic, data, len, result_prio, NULL, 0);
+
+  if (mime_type)
+    return mime_type;
+
+  return XDG_MIME_TYPE_UNKNOWN;
+}
+
+const char *
+xdg_mime_get_mime_type_for_file (const char  *file_name,
+                                 struct stat *statbuf)
+{
+  const char *mime_type;
+  /* currently, only a few globs occur twice, and none
+   * more often, so 5 seems plenty.
+   */
+  const char *mime_types[5];
+  FILE *file;
+  unsigned char *data;
+  int max_extent;
+  int bytes_read;
+  struct stat buf;
+  const char *base_name;
+  int n;
+
+  if (file_name == NULL)
+    return NULL;
+  if (! _xdg_utf8_validate (file_name))
+    return NULL;
+
+  xdg_mime_init ();
+
+  if (_caches)
+    return _xdg_mime_cache_get_mime_type_for_file (file_name, statbuf);
+
+  base_name = _xdg_get_base_name (file_name);
+  n = _xdg_glob_hash_lookup_file_name (global_hash, base_name, mime_types, 5);
+
+  if (n == 1)
+    return mime_types[0];
+
+  if (!statbuf)
+    {
+      if (stat (file_name, &buf) != 0)
+        return XDG_MIME_TYPE_UNKNOWN;
+
+      statbuf = &buf;
+    }
+
+  if (!S_ISREG (statbuf->st_mode))
+    return XDG_MIME_TYPE_UNKNOWN;
+
+  /* FIXME: Need to make sure that max_extent isn't totally broken.  This could
+   * be large and need getting from a stream instead of just reading it all
+   * in. */
+  max_extent = _xdg_mime_magic_get_buffer_extents (global_magic);
+  data = malloc (max_extent);
+  if (data == NULL)
+    return XDG_MIME_TYPE_UNKNOWN;
+        
+  file = fopen (file_name, "r");
+  if (file == NULL)
+    {
+      free (data);
+      return XDG_MIME_TYPE_UNKNOWN;
+    }
+
+  bytes_read = fread (data, 1, max_extent, file);
+  if (ferror (file))
+    {
+      free (data);
+      fclose (file);
+      return XDG_MIME_TYPE_UNKNOWN;
+    }
+
+  mime_type = _xdg_mime_magic_lookup_data (global_magic, data, bytes_read, NULL,
+                                           mime_types, n);
+
+  free (data);
+  fclose (file);
+
+  if (mime_type)
+    return mime_type;
+
+  return XDG_MIME_TYPE_UNKNOWN;
+}
+
+const char *
+xdg_mime_get_mime_type_from_file_name (const char *file_name)
+{
+  const char *mime_type;
+
+  xdg_mime_init ();
+
+  if (_caches)
+    return _xdg_mime_cache_get_mime_type_from_file_name (file_name);
+
+  if (_xdg_glob_hash_lookup_file_name (global_hash, file_name, &mime_type, 1))
+    return mime_type;
+  else
+    return XDG_MIME_TYPE_UNKNOWN;
+}
+
+int
+xdg_mime_get_mime_types_from_file_name (const char *file_name,
+                                        const char  *mime_types[],
+                                        int          n_mime_types)
+{
+  xdg_mime_init ();
+  
+  if (_caches)
+    return _xdg_mime_cache_get_mime_types_from_file_name (file_name, mime_types, n_mime_types);
+  
+  return _xdg_glob_hash_lookup_file_name (global_hash, file_name, mime_types, n_mime_types);
+}
+
+int
+xdg_mime_is_valid_mime_type (const char *mime_type)
+{
+  /* FIXME: We should make this a better test
+   */
+  return _xdg_utf8_validate (mime_type);
+}
+
+void
+xdg_mime_shutdown (void)
+{
+  XdgCallbackList *list;
+
+  /* FIXME: Need to make this (and the whole library) thread safe */
+  if (dir_time_list)
+    {
+      xdg_dir_time_list_free (dir_time_list);
+      dir_time_list = NULL;
+    }
+        
+  if (global_hash)
+    {
+      _xdg_glob_hash_free (global_hash);
+      global_hash = NULL;
+    }
+  if (global_magic)
+    {
+      _xdg_mime_magic_free (global_magic);
+      global_magic = NULL;
+    }
+
+  if (alias_list)
+    {
+      _xdg_mime_alias_list_free (alias_list);
+      alias_list = NULL;
+    }
+
+  if (parent_list)
+    {
+      _xdg_mime_parent_list_free (parent_list);
+      parent_list = NULL;
+    }
+
+  if (icon_list)
+    {
+      _xdg_mime_icon_list_free (icon_list);
+      icon_list = NULL;
+    }
+
+  if (generic_icon_list)
+    {
+      _xdg_mime_icon_list_free (generic_icon_list);
+      generic_icon_list = NULL;
+    }
+  
+  if (_caches)
+    {
+      int i;
+
+      for (i = 0; i < n_caches; i++)
+        _xdg_mime_cache_unref (_caches[i]);
+      free (_caches);
+      _caches = NULL;
+      n_caches = 0;
+    }
+
+  for (list = callback_list; list; list = list->next)
+    (list->callback) (list->data);
+
+  need_reread = TRUE;
+}
+
+int
+xdg_mime_get_max_buffer_extents (void)
+{
+  xdg_mime_init ();
+  
+  if (_caches)
+    return _xdg_mime_cache_get_max_buffer_extents ();
+
+  return _xdg_mime_magic_get_buffer_extents (global_magic);
+}
+
+const char *
+_xdg_mime_unalias_mime_type (const char *mime_type)
+{
+  const char *lookup;
+
+  if (_caches)
+    return _xdg_mime_cache_unalias_mime_type (mime_type);
+
+  if ((lookup = _xdg_mime_alias_list_lookup (alias_list, mime_type)) != NULL)
+    return lookup;
+
+  return mime_type;
+}
+
+const char *
+xdg_mime_unalias_mime_type (const char *mime_type)
+{
+  xdg_mime_init ();
+
+  return _xdg_mime_unalias_mime_type (mime_type);
+}
+
+int
+_xdg_mime_mime_type_equal (const char *mime_a,
+                           const char *mime_b)
+{
+  const char *unalias_a, *unalias_b;
+
+  unalias_a = _xdg_mime_unalias_mime_type (mime_a);
+  unalias_b = _xdg_mime_unalias_mime_type (mime_b);
+
+  if (strcmp (unalias_a, unalias_b) == 0)
+    return 1;
+
+  return 0;
+}
+
+int
+xdg_mime_mime_type_equal (const char *mime_a,
+                          const char *mime_b)
+{
+  xdg_mime_init ();
+
+  return _xdg_mime_mime_type_equal (mime_a, mime_b);
+}
+
+int
+xdg_mime_media_type_equal (const char *mime_a,
+                           const char *mime_b)
+{
+  char *sep;
+
+  sep = strchr (mime_a, '/');
+  
+  if (sep && strncmp (mime_a, mime_b, sep - mime_a + 1) == 0)
+    return 1;
+
+  return 0;
+}
+
+#if 1
+static int
+xdg_mime_is_super_type (const char *mime)
+{
+  int length;
+  const char *type;
+
+  length = strlen (mime);
+  type = &(mime[length - 2]);
+
+  if (strcmp (type, "/*") == 0)
+    return 1;
+
+  return 0;
+}
+#endif
+
+int
+_xdg_mime_mime_type_subclass (const char *mime,
+                              const char *base)
+{
+  const char *umime, *ubase;
+  const char **parents;
+
+  if (_caches)
+    return _xdg_mime_cache_mime_type_subclass (mime, base);
+
+  umime = _xdg_mime_unalias_mime_type (mime);
+  ubase = _xdg_mime_unalias_mime_type (base);
+
+  if (strcmp (umime, ubase) == 0)
+    return 1;
+
+#if 1  
+  /* Handle supertypes */
+  if (xdg_mime_is_super_type (ubase) &&
+      xdg_mime_media_type_equal (umime, ubase))
+    return 1;
+#endif
+
+  /*  Handle special cases text/plain and application/octet-stream */
+  if (strcmp (ubase, "text/plain") == 0 && 
+      strncmp (umime, "text/", 5) == 0)
+    return 1;
+
+  if (strcmp (ubase, "application/octet-stream") == 0)
+    return 1;
+  
+  parents = _xdg_mime_parent_list_lookup (parent_list, umime);
+  for (; parents && *parents; parents++)
+    {
+      if (_xdg_mime_mime_type_subclass (*parents, ubase))
+        return 1;
+    }
+
+  return 0;
+}
+
+int
+xdg_mime_mime_type_subclass (const char *mime,
+                             const char *base)
+{
+  xdg_mime_init ();
+
+  return _xdg_mime_mime_type_subclass (mime, base);
+}
+
+char **
+xdg_mime_list_mime_parents (const char *mime)
+{
+  const char **parents;
+  char **result;
+  int i, n;
+
+  if (_caches)
+    return _xdg_mime_cache_list_mime_parents (mime);
+
+  parents = xdg_mime_get_mime_parents (mime);
+
+  if (!parents)
+    return NULL;
+
+  for (i = 0; parents[i]; i++) ;
+  
+  n = (i + 1) * sizeof (char *);
+  result = (char **) malloc (n);
+  memcpy (result, parents, n);
+
+  return result;
+}
+
+const char **
+xdg_mime_get_mime_parents (const char *mime)
+{
+  const char *umime;
+
+  xdg_mime_init ();
+
+  umime = _xdg_mime_unalias_mime_type (mime);
+
+  return _xdg_mime_parent_list_lookup (parent_list, umime);
+}
+
+void 
+xdg_mime_dump (void)
+{
+  xdg_mime_init();
+
+  printf ("*** ALIASES ***\n\n");
+  _xdg_mime_alias_list_dump (alias_list);
+  printf ("\n*** PARENTS ***\n\n");
+  _xdg_mime_parent_list_dump (parent_list);
+  printf ("\n*** CACHE ***\n\n");
+  _xdg_glob_hash_dump (global_hash);
+  printf ("\n*** GLOBS ***\n\n");
+  _xdg_glob_hash_dump (global_hash);
+  printf ("\n*** GLOBS REVERSE TREE ***\n\n");
+  _xdg_mime_cache_glob_dump ();
+}
+
+
+/* Registers a function to be called every time the mime database reloads its files
+ */
+int
+xdg_mime_register_reload_callback (XdgMimeCallback  callback,
+                                   void            *data,
+                                   XdgMimeDestroy   destroy)
+{
+  XdgCallbackList *list_el;
+  static int callback_id = 1;
+
+  /* Make a new list element */
+  list_el = calloc (1, sizeof (XdgCallbackList));
+  list_el->callback_id = callback_id;
+  list_el->callback = callback;
+  list_el->data = data;
+  list_el->destroy = destroy;
+  list_el->next = callback_list;
+  if (list_el->next)
+    list_el->next->prev = list_el;
+
+  callback_list = list_el;
+  callback_id ++;
+
+  return callback_id - 1;
+}
+
+void
+xdg_mime_remove_callback (int callback_id)
+{
+  XdgCallbackList *list;
+
+  for (list = callback_list; list; list = list->next)
+    {
+      if (list->callback_id == callback_id)
+        {
+          if (list->next)
+            list->next = list->prev;
+
+          if (list->prev)
+            list->prev->next = list->next;
+          else
+            callback_list = list->next;
+
+          /* invoke the destroy handler */
+          (list->destroy) (list->data);
+          free (list);
+          return;
+        }
+    }
+}
+
+const char *
+xdg_mime_get_icon (const char *mime)
+{
+  xdg_mime_init ();
+  
+  if (_caches)
+    return _xdg_mime_cache_get_icon (mime);
+
+  return _xdg_mime_icon_list_lookup (icon_list, mime);
+}
+
+const char *
+xdg_mime_get_generic_icon (const char *mime)
+{
+  xdg_mime_init ();
+  
+  if (_caches)
+    return _xdg_mime_cache_get_generic_icon (mime);
+
+  return _xdg_mime_icon_list_lookup (generic_icon_list, mime);
+}