/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 2; tab-width: 8 -*- */

/* inotify-path.c - GVFS Monitor based on inotify.

   Copyright (C) 2006 John McCutchan

   Copyright (C) 2009 Codethink Limited

   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 2.1 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, see <http://www.gnu.org/licenses/>.

   Authors:

		 John McCutchan <john@johnmccutchan.com>

                 Ryan Lortie <desrt@desrt.ca>

*/

#include "config.h"

/* Don't put conflicting kernel types in the global namespace: */

#define __KERNEL_STRICT_NAMES

#include <sys/inotify.h>

#include <string.h>

#include <glib.h>

#include "inotify-kernel.h"

#include "inotify-path.h"

#include "inotify-missing.h"

#define IP_INOTIFY_DIR_MASK (IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_DELETE|IN_CREATE|IN_DELETE_SELF|IN_UNMOUNT|IN_MOVE_SELF|IN_CLOSE_WRITE)

#define IP_INOTIFY_FILE_MASK (IN_MODIFY|IN_ATTRIB|IN_CLOSE_WRITE)

/* Older libcs don't have this */

#ifndef IN_ONLYDIR

#define IN_ONLYDIR 0  

#endif

typedef struct ip_watched_file_s {

  gchar *filename;

  gchar *path;

  gint32 wd;

  GList *subs;

} ip_watched_file_t;

typedef struct ip_watched_dir_s {

  char *path;

  /* TODO: We need to maintain a tree of watched directories

   * so that we can deliver move/delete events to sub folders.

   * Or the application could do it...

   */

  struct ip_watched_dir_s* parent;

  GList*	 children;

  /* basename -> ip_watched_file_t

   * Maps basename to a ip_watched_file_t if the file is currently

   * being directly watched for changes (ie: 'hardlinks' mode).

   */

  GHashTable *files_hash;

  /* Inotify state */

  gint32 wd;

  /* List of inotify subscriptions */

  GList *subs;

} ip_watched_dir_t;

static gboolean     ip_debug_enabled = FALSE;

#define IP_W if (ip_debug_enabled) g_warning

/* path -> ip_watched_dir */

static GHashTable * path_dir_hash = NULL;

/* inotify_sub * -> ip_watched_dir *

 *

 * Each subscription is attached to a watched directory or it is on

 * the missing list

 */

static GHashTable * sub_dir_hash = NULL;

/* This hash holds GLists of ip_watched_dir_t *'s

 * We need to hold a list because symbolic links can share

 * the same wd

 */

static GHashTable * wd_dir_hash = NULL;

/* This hash holds GLists of ip_watched_file_t *'s

 * We need to hold a list because links can share

 * the same wd

 */

static GHashTable * wd_file_hash = NULL;

static ip_watched_dir_t *ip_watched_dir_new  (const char       *path,

					      int               wd);

static void              ip_watched_dir_free (ip_watched_dir_t *dir);

static gboolean          ip_event_callback   (ik_event_t       *event);

static gboolean (*event_callback)(ik_event_t *event, inotify_sub *sub, gboolean file_event);

gboolean

_ip_startup (gboolean (*cb)(ik_event_t *event, inotify_sub *sub, gboolean file_event))

{

  static gboolean initialized = FALSE;

  static gboolean result = FALSE;

  if (initialized == TRUE)

    return result;

  event_callback = cb;

  result = _ik_startup (ip_event_callback);

  if (!result)

    return FALSE;

  path_dir_hash = g_hash_table_new (g_str_hash, g_str_equal);

  sub_dir_hash = g_hash_table_new (g_direct_hash, g_direct_equal);

  wd_dir_hash = g_hash_table_new (g_direct_hash, g_direct_equal);

  wd_file_hash = g_hash_table_new (g_direct_hash, g_direct_equal);

  initialized = TRUE;

  return TRUE;

}

static void

ip_map_path_dir (const char       *path, 

                 ip_watched_dir_t *dir)

{

  g_assert (path && dir);

  g_hash_table_insert (path_dir_hash, dir->path, dir);

}

static void

ip_map_sub_dir (inotify_sub      *sub, 

                ip_watched_dir_t *dir)

{

  /* Associate subscription and directory */

  g_assert (dir && sub);

  g_hash_table_insert (sub_dir_hash, sub, dir);

  dir->subs = g_list_prepend (dir->subs, sub);

}

static void

ip_map_wd_dir (gint32            wd, 

               ip_watched_dir_t *dir)

{

  GList *dir_list;

  g_assert (wd >= 0 && dir);

  dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));

  dir_list = g_list_prepend (dir_list, dir);

  g_hash_table_replace (wd_dir_hash, GINT_TO_POINTER (dir->wd), dir_list);

}

static void

ip_map_wd_file (gint32             wd,

                ip_watched_file_t *file)

{

  GList *file_list;

  g_assert (wd >= 0 && file);

  file_list = g_hash_table_lookup (wd_file_hash, GINT_TO_POINTER (wd));

  file_list = g_list_prepend (file_list, file);

  g_hash_table_replace (wd_file_hash, GINT_TO_POINTER (wd), file_list);

}

static void

ip_unmap_wd_file (gint32             wd,

                  ip_watched_file_t *file)

{

  GList *file_list = g_hash_table_lookup (wd_file_hash, GINT_TO_POINTER (wd));

  if (!file_list)

    return;

  g_assert (wd >= 0 && file);

  file_list = g_list_remove (file_list, file);

  if (file_list == NULL)

    g_hash_table_remove (wd_file_hash, GINT_TO_POINTER (wd));

  else

    g_hash_table_replace (wd_file_hash, GINT_TO_POINTER (wd), file_list);

}

static ip_watched_file_t *

ip_watched_file_new (const gchar *dirname,

                     const gchar *filename)

{

  ip_watched_file_t *file;

  file = g_new0 (ip_watched_file_t, 1);

  file->path = g_strjoin ("/", dirname, filename, NULL);

  file->filename = g_strdup (filename);

  file->wd = -1;

  return file;

}

static void

ip_watched_file_free (ip_watched_file_t *file)

{

  g_assert (file->subs == NULL);

  g_free (file->filename);

  g_free (file->path);

}

static void

ip_watched_file_add_sub (ip_watched_file_t *file,

                         inotify_sub       *sub)

{

  file->subs = g_list_prepend (file->subs, sub);

}

static void

ip_watched_file_start (ip_watched_file_t *file)

{

  if (file->wd < 0)

    {

      gint err;

      file->wd = _ik_watch (file->path,

                            IP_INOTIFY_FILE_MASK,

                            &err;;

      if (file->wd >= 0)

        ip_map_wd_file (file->wd, file);

    }

}

static void

ip_watched_file_stop (ip_watched_file_t *file)

{

  if (file->wd >= 0)

    {

      _ik_ignore (file->path, file->wd);

      ip_unmap_wd_file (file->wd, file);

      file->wd = -1;

    }

}

gboolean

_ip_start_watching (inotify_sub *sub)

{

  gint32 wd;

  int err;

  ip_watched_dir_t *dir;

  g_assert (sub);

  g_assert (!sub->cancelled);

  g_assert (sub->dirname);

  IP_W ("Starting to watch %s\n", sub->dirname);

  dir = g_hash_table_lookup (path_dir_hash, sub->dirname);

  if (dir == NULL)

    {

      IP_W ("Trying to add inotify watch ");

      wd = _ik_watch (sub->dirname, IP_INOTIFY_DIR_MASK|IN_ONLYDIR, &err;;

      if (wd < 0)

        {

          IP_W ("Failed\n");

          return FALSE;

        }

      else

        {

          /* Create new watched directory and associate it with the

           * wd hash and path hash

           */

          IP_W ("Success\n");

          dir = ip_watched_dir_new (sub->dirname, wd);

          ip_map_wd_dir (wd, dir);

          ip_map_path_dir (sub->dirname, dir);

        }

    }

  else

    IP_W ("Already watching\n");

  if (sub->hardlinks)

    {

      ip_watched_file_t *file;

      file = g_hash_table_lookup (dir->files_hash, sub->filename);

      if (file == NULL)

        {

          file = ip_watched_file_new (sub->dirname, sub->filename);

          g_hash_table_insert (dir->files_hash, file->filename, file);

        }

      ip_watched_file_add_sub (file, sub);

      ip_watched_file_start (file);

    }

  ip_map_sub_dir (sub, dir);

  return TRUE;

}

static void

ip_unmap_path_dir (const char       *path, 

                   ip_watched_dir_t *dir)

{

  g_assert (path && dir);

  g_hash_table_remove (path_dir_hash, dir->path);

}

static void

ip_unmap_wd_dir (gint32            wd, 

                 ip_watched_dir_t *dir)

{

  GList *dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));

  if (!dir_list)

    return;

  g_assert (wd >= 0 && dir);

  dir_list = g_list_remove (dir_list, dir);

  if (dir_list == NULL) 

    g_hash_table_remove (wd_dir_hash, GINT_TO_POINTER (dir->wd));

  else

    g_hash_table_replace (wd_dir_hash, GINT_TO_POINTER (dir->wd), dir_list);

}

static void

ip_unmap_wd (gint32 wd)

{

  GList *dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));

  if (!dir_list)

    return;

  g_assert (wd >= 0);

  g_hash_table_remove (wd_dir_hash, GINT_TO_POINTER (wd));

  g_list_free (dir_list);

}

static void

ip_unmap_sub_dir (inotify_sub      *sub,

                  ip_watched_dir_t *dir)

{

  g_assert (sub && dir);

  g_hash_table_remove (sub_dir_hash, sub);

  dir->subs = g_list_remove (dir->subs, sub);

  if (sub->hardlinks)

    {

      ip_watched_file_t *file;

      file = g_hash_table_lookup (dir->files_hash, sub->filename);

      file->subs = g_list_remove (file->subs, sub);

      if (file->subs == NULL)

        {

          g_hash_table_remove (dir->files_hash, sub->filename);

          ip_watched_file_stop (file);

          ip_watched_file_free (file);

        }

    }

 }

static void

ip_unmap_all_subs (ip_watched_dir_t *dir)

{

  while (dir->subs != NULL)

    ip_unmap_sub_dir (dir->subs->data, dir);

}

gboolean

_ip_stop_watching (inotify_sub *sub)

{

  ip_watched_dir_t *dir = NULL;

  dir = g_hash_table_lookup (sub_dir_hash, sub);

  if (!dir) 

    return TRUE;

  ip_unmap_sub_dir (sub, dir);

  /* No one is subscribing to this directory any more */

  if (dir->subs == NULL)

    {

      _ik_ignore (dir->path, dir->wd);

      ip_unmap_wd_dir (dir->wd, dir);

      ip_unmap_path_dir (dir->path, dir);

      ip_watched_dir_free (dir);

    }

  return TRUE;

}

static ip_watched_dir_t *

ip_watched_dir_new (const char *path, 

                    gint32      wd)

{

  ip_watched_dir_t *dir = g_new0 (ip_watched_dir_t, 1);

  dir->path = g_strdup (path);

  dir->files_hash = g_hash_table_new (g_str_hash, g_str_equal);

  dir->wd = wd;

  return dir;

}

static void

ip_watched_dir_free (ip_watched_dir_t *dir)

{

  g_assert_cmpint (g_hash_table_size (dir->files_hash), ==, 0);

  g_assert (dir->subs == NULL);

  g_free (dir->path);

  g_hash_table_unref (dir->files_hash);

  g_free (dir);

}

static void

ip_wd_delete (gpointer data, 

              gpointer user_data)

{

  ip_watched_dir_t *dir = data;

  GList *l = NULL;

  for (l = dir->subs; l; l = l->next)

    {

      inotify_sub *sub = l->data;

      /* Add subscription to missing list */

      _im_add (sub);

    }

  ip_unmap_all_subs (dir);

  /* Unassociate the path and the directory */

  ip_unmap_path_dir (dir->path, dir);

  ip_watched_dir_free (dir);

}

static gboolean

ip_event_dispatch (GList      *dir_list, 

                   GList      *file_list,

                   ik_event_t *event)

{

  gboolean interesting = FALSE;

  GList *l;

  if (!event)

    return FALSE;

  for (l = dir_list; l; l = l->next)

    {

      GList *subl;

      ip_watched_dir_t *dir = l->data;

      for (subl = dir->subs; subl; subl = subl->next)

	{

	  inotify_sub *sub = subl->data;

	  /* If the subscription and the event

	   * contain a filename and they don't

	   * match, we don't deliver this event.

	   */

	  if (sub->filename &&

	      event->name &&

	      strcmp (sub->filename, event->name) &&

              (!event->pair || !event->pair->name || strcmp (sub->filename, event->pair->name)))

	    continue;

	  /* If the subscription has a filename

	   * but this event doesn't, we don't

	   * deliver this event.

	   */

	  if (sub->filename && !event->name)

	    continue;

	  /* If we're also watching the file directly

	   * don't report events that will also be

	   * reported on the file itself.

	   */

	  if (sub->hardlinks)

	    {

	      event->mask &= ~IP_INOTIFY_FILE_MASK;

	      if (!event->mask)

		continue;

	    }

	  /* FIXME: We might need to synthesize

	   * DELETE/UNMOUNT events when

	   * the filename doesn't match

	   */

	  interesting |= event_callback (event, sub, FALSE);

          if (sub->hardlinks)

            {

              ip_watched_file_t *file;

              file = g_hash_table_lookup (dir->files_hash, sub->filename);

              if (file != NULL)

                {

                  if (event->mask & (IN_MOVED_FROM | IN_DELETE))

                    ip_watched_file_stop (file);

                  if (event->mask & (IN_MOVED_TO | IN_CREATE))

                    ip_watched_file_start (file);

                }

            }

        }

    }

  for (l = file_list; l; l = l->next)

    {

      ip_watched_file_t *file = l->data;

      GList *subl;

      for (subl = file->subs; subl; subl = subl->next)

        {

	  inotify_sub *sub = subl->data;

	  interesting |= event_callback (event, sub, TRUE);

        }

    }

  return interesting;

}

static gboolean

ip_event_callback (ik_event_t *event)

{

  gboolean interesting = FALSE;

  GList* dir_list = NULL;

  GList *file_list = NULL;

  /* We can ignore the IGNORED events. Likewise, if the event queue overflowed,

   * there is not much we can do to recover. */

  if (event->mask & (IN_IGNORED | IN_Q_OVERFLOW))

    {

      _ik_event_free (event);

      return TRUE;

    }

  dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (event->wd));

  file_list = g_hash_table_lookup (wd_file_hash, GINT_TO_POINTER (event->wd));

  if (event->mask & IP_INOTIFY_DIR_MASK)

    interesting |= ip_event_dispatch (dir_list, file_list, event);

  /* Only deliver paired events if the wds are separate */

  if (event->pair && event->pair->wd != event->wd)

    {

      dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (event->pair->wd));

      file_list = g_hash_table_lookup (wd_file_hash, GINT_TO_POINTER (event->pair->wd));

      if (event->pair->mask & IP_INOTIFY_DIR_MASK)

        interesting |= ip_event_dispatch (dir_list, file_list, event->pair);

    }

  /* We have to manage the missing list

   * when we get an event that means the

   * file has been deleted/moved/unmounted.

   */

  if (event->mask & IN_DELETE_SELF ||

      event->mask & IN_MOVE_SELF ||

      event->mask & IN_UNMOUNT)

    {

      /* Add all subscriptions to missing list */

      g_list_foreach (dir_list, ip_wd_delete, NULL);

      /* Unmap all directories attached to this wd */

      ip_unmap_wd (event->wd);

    }

  _ik_event_free (event);

  return interesting;

}

const char *

_ip_get_path_for_wd (gint32 wd)

{

  GList *dir_list;

  ip_watched_dir_t *dir;

  g_assert (wd >= 0);

  dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER (wd));

  if (dir_list)

    {

      dir = dir_list->data;

      if (dir)

	return dir->path;

    }

  return NULL;

}