xdgmime.c

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/* -*- 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 <[e-mail]>
 *
 * 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 "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;

XdgMimeCache **_xdg_mime_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;
  XdgMimeCache *cache;
};

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 XdgDirTimeList *
xdg_dir_time_list_new (void)
{
  XdgDirTimeList *retval;

  retval = calloc (1, sizeof (XdgDirTimeList));
  retval->checked = XDG_CHECKED_UNCHECKED;

  return retval;
}

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;
  XdgDirTimeList *list;

  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)
	{
	  list = xdg_dir_time_list_new ();
	  list->directory_name = file_name;
	  list->mtime = st.st_mtime;
	  list->next = dir_time_list;
	  list->cache = cache;
	  dir_time_list = list;

	  _xdg_mime_caches = realloc (_xdg_mime_caches, sizeof (XdgMimeCache *) * (n_caches + 2));
	  _xdg_mime_caches[n_caches] = cache;
          _xdg_mime_caches[n_caches + 1] = NULL;
	  n_caches++;

	  return FALSE;
	}
    }
  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);

      list = xdg_dir_time_list_new ();
      list->directory_name = file_name;
      list->mtime = st.st_mtime;
      list->next = dir_time_list;
      dir_time_list = list;
    }
  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);

      list = xdg_dir_time_list_new ();
      list->directory_name = file_name;
      list->mtime = st.st_mtime;
      list->next = dir_time_list;
      dir_time_list = list;
    }
  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);

  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;
    }
}

static XdgMimeCache *
xdg_lookup_cache_for_file (const char *file_path)
{
  XdgDirTimeList *list;

  for (list = dir_time_list; list; list = list->next)
      if (! strcmp (list->directory_name, file_path))
	 return list->cache;

  return NULL;
}

/* 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)
{
  struct stat st;

  /* If the file exists */
  if (stat (file_path, &st) == 0)
    {
      XdgDirTimeList *list;

      for (list = dir_time_list; list; list = list->next)
	{
	  if (! strcmp (list->directory_name, file_path) &&
	      st.st_mtime == list->mtime)
	    {
	      if (list->checked == XDG_CHECKED_UNCHECKED)
		list->checked = XDG_CHECKED_VALID;
	      else if (list->checked == XDG_CHECKED_VALID)
		list->checked = XDG_CHECKED_INVALID;

	      return (list->checked != XDG_CHECKED_VALID);
	    }
	}
      return TRUE;
    }

  return FALSE;
}

static int
xdg_check_dir (const char *directory,
	       int        *invalid_dir_list)
{
  int invalid, has_cache;
  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);
  has_cache = xdg_lookup_cache_for_file (file_name) != NULL;
  free (file_name);

  if (has_cache)
    {
      if (invalid)
	{
	  *invalid_dir_list = TRUE;
	  return TRUE;
	}

      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);
  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);
  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 ();
    }