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inotify-path.c

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

/* inotify-helper.c - Gnome VFS Monitor based on inotify.

   Copyright (C) 2006 John McCutchan

   The Gnome Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The Gnome 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the Gnome Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.

   Authors: 
             John McCutchan <john@johnmccutchan.com>
*/

#include "config.h"

#include <sys/inotify.h>

#include <errno.h>
#include <string.h>
#include <glib.h>
#include "inotify-kernel.h"
#include "inotify-path.h"
#include "inotify-missing.h"

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

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;

      /* 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;
/* ih_sub_t * -> 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;

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 void                   ip_event_callback (ik_event_t *event);

static void (*event_callback)(ik_event_t *event, ih_sub_t *sub);

gboolean ip_startup (void (*cb)(ik_event_t *event, ih_sub_t *sub))
{
      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;
      }
      initialized = TRUE;

      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);

      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 (ih_sub_t *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)
{
      g_assert (wd >= 0 && dir);
      GList *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 gint32
ip_watch_parent (const char *path, guint mask, int *err, char **parent_path)
{
      gint32 wd;
      gchar *path_copy;
      gchar *p;

      path_copy = g_strdup (path);

        wd = -1;
        do
        {
                p = g_strrstr (path_copy, G_DIR_SEPARATOR_S);

                if (p == NULL)
                        return -1;

                if (p != &path_copy[0])
                        *p = '\0';

                wd = ik_watch (path_copy, mask, err);
        } 
        while (wd < 0 && errno == ENOENT);

        if (parent_path != NULL && wd >= 0)
                *parent_path = path_copy;
        else
                g_free (path_copy);

      return wd;
}

gboolean ip_start_watching (ih_sub_t *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)
      {
            IP_W("Already watching\n");
            goto out;
      }
      
      IP_W("Trying to add inotify watch ");
      wd = ik_watch (sub->dirname, IP_INOTIFY_MASK|IN_ONLYDIR|sub->extra_flags, &err);

        if (wd < 0 && errno == ENOENT)
        {
                char *parent_path;

            IP_W("Directory '%s' does not yet exist, finding and watching existing parent\n",
                     sub->dirname);

                parent_path = NULL;
            wd = ip_watch_parent (sub->dirname,
                                      IP_INOTIFY_MASK|IN_ONLYDIR|sub->extra_flags,
                                      &err, &parent_path);

            if (wd < 0)
            {
                        g_assert (parent_path == NULL);
                  IP_W("Failed\n");
                  return FALSE;
            }

            IP_W("Found parent '%s', will watch it for now until '%s' becomes available\n",
                     parent_path, sub->dirname);

                dir = ip_watched_dir_new (parent_path, wd);
                g_free (parent_path);

            ip_map_wd_dir (wd, dir);
            ip_map_path_dir (parent_path, dir);
        } else 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);
      }

out:
      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 (ih_sub_t *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);
}

static void
ip_unmap_all_subs (ip_watched_dir_t *dir)
{
      GList *l = NULL;

      for (l = dir->subs; l; l = l->next)
      {
            ih_sub_t *sub = l->data;
            g_hash_table_remove (sub_dir_hash, sub);
      }
      g_list_free (dir->subs);
      dir->subs = NULL;
}

gboolean ip_stop_watching  (ih_sub_t *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->wd = wd;

      return dir;
}

static void
ip_watched_dir_free (ip_watched_dir_t * dir)
{
      g_assert (dir->subs == 0);
      g_free(dir->path);
      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)
      {
            ih_sub_t *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 void ip_event_dispatch (GList *dir_list, GList *pair_dir_list, ik_event_t *event)
{
      GList *dirl;
        GList *subl, *resubscription_list;

      if (!event)
            return;

      /* TODO:
       *
       * Figure out how we will deliver move events
       */

        resubscription_list = NULL;
      for (dirl = dir_list; dirl; dirl = dirl->next)
      {
            ip_watched_dir_t *dir = dirl->data;
                char *event_path;

                event_path = g_build_filename (dir->path, event->name, NULL);



            for (subl = dir->subs; subl; subl = subl->next)
            {
                  ih_sub_t *sub = subl->data;

                  /* If the event and the subscription have a filename
                   * they need to match before the event could be delivered.
                   */
                  if (event->name && sub->filename) {

                               if (strcmp (event->name, sub->filename))
                                {
                              continue;
                                }

                  /* If the event doesn't have a filename, but the subscription does
                   * we shouldn't deliever the event */
                  } else if (sub->filename)
                        continue;

                        if (g_str_has_prefix (sub->dirname, event_path)) {

                            IP_W("Adding directory %s to resubscription list (because of event %s)", 
                                 sub->dirname, event_path);

                            resubscription_list = g_list_prepend (resubscription_list, sub);

                            if (strcmp (sub->dirname, event_path) == 0) {
                                        char *subscription_dir;

                                        IP_W("directory '%s' is now available!", 
                                             sub->dirname);

                                        /* Normally, the subscription directory name,
                                         * matches the directory getting watched.  This 
                                         * isn't necessarily true, though, if we're watching
                                         * a parent since the directory we're actually interested 
                                         * in doesn't exist anymore.  When the directory we *are*
                                         * interested in shows up, we find out relative to the
                                         * directory we're watching.  We need to fudge our subscription
                                         * temporarily to account for that.
                                         *
                                         * FIXME: This is a hack, we should send the dirname that the 
                                         * event came from, along with the subscription, or store a 
                                         * full path in the event structure
                                         */
                                        subscription_dir = sub->dirname;
                                        sub->dirname = dir->path;
                                        event_callback (event, sub);
                                        sub->dirname = subscription_dir;
                            }

                            continue;
                        }

                  event_callback (event, sub);
            }

                g_free (event_path);
      }

      if (event->pair)
      for (dirl = pair_dir_list; dirl; dirl = dirl->next)
      {
            ip_watched_dir_t *dir = dirl->data;

            for (subl = dir->subs; subl; subl = subl->next)
            {
                  ih_sub_t *sub = subl->data;

                  /* If the event and the subscription have a filename
                   * they need to match before the event could be delivered.
                   */
                  if (event->pair->name && sub->filename) {
                        if (strcmp (event->pair->name, sub->filename))
                              continue;
                  /* If the event doesn't have a filename, but the subscription does
                   * we shouldn't deliever the event */
                  } else if (sub->filename)
                        continue;

                  event_callback (event->pair, sub);
            }
      }

        for (subl = resubscription_list; subl; subl = subl->next)
        {
            ip_stop_watching (subl->data);
            ip_start_watching (subl->data);
        }
        g_list_free (resubscription_list);
}

static void
ip_event_callback (ik_event_t *event)
{
      GList *dir_list = NULL;
      GList *pair_dir_list = NULL;

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

      /* We can ignore IN_IGNORED events */
      if (event->mask & IN_IGNORED) {
            ik_event_free (event);
            return;
      }

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

      if (event->mask & IP_INOTIFY_MASK) {
            ip_event_dispatch (dir_list, pair_dir_list, event);
              dir_list = g_hash_table_lookup (wd_dir_hash, GINT_TO_POINTER(event->wd));
        }

      /* We have to manage the missing list when we get a DELETE event. */
      if (event->mask & IN_DELETE_SELF || event->mask & IN_MOVE_SELF)
      {
            /* 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);
}

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