/*

   Unix SMB/CIFS implementation.

   Copyright (C) Andrew Tridgell 2006

   This program 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 3 of the License, or

   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

*/

/*

  notify implementation using inotify

*/

#include "includes.h"

#include "../librpc/gen_ndr/notify.h"

#include "smbd/smbd.h"

#include "lib/util/sys_rw.h"

#include "smbd/globals.h"

#include <sys/inotify.h>

/* glibc < 2.5 headers don't have these defines */

#ifndef IN_ONLYDIR

#define IN_ONLYDIR 0x01000000

#endif

#ifndef IN_MASK_ADD

#define IN_MASK_ADD 0x20000000

#endif

struct inotify_private {

  struct sys_notify_context *ctx;

  int fd;

  struct inotify_watch_context *watches;

};

struct inotify_watch_context {

  struct inotify_watch_context *next, *prev;

  struct inotify_private *in;

  int wd;

  void (*callback)(struct sys_notify_context *ctx,

       void *private_data,

       struct notify_event *ev,

       uint32_t filter);

  void *private_data;

  uint32_t mask; /* the inotify mask */

  uint32_t filter; /* the windows completion filter */

  const char *path;

  char *last_mkdir;

  struct inotify_event *moved_from_event;

};

/*

  map from a change notify mask to a inotify mask. Remove any bits

  which we can handle

*/

static const struct {

  uint32_t notify_mask;

  uint32_t inotify_mask;

} inotify_mapping[] = {

  {FILE_NOTIFY_CHANGE_FILE_NAME,   IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},

  {FILE_NOTIFY_CHANGE_DIR_NAME,    IN_CREATE|IN_DELETE|IN_MOVED_FROM|IN_MOVED_TO},

  {FILE_NOTIFY_CHANGE_ATTRIBUTES,  IN_ATTRIB|IN_MOVED_TO|IN_MOVED_FROM|IN_MODIFY},

  {FILE_NOTIFY_CHANGE_LAST_WRITE,  IN_ATTRIB},

  {FILE_NOTIFY_CHANGE_LAST_ACCESS, IN_ATTRIB},

  {FILE_NOTIFY_CHANGE_EA,          IN_ATTRIB},

  {FILE_NOTIFY_CHANGE_SECURITY,    IN_ATTRIB}

};

static uint32_t inotify_map(uint32_t *filter)

{

  size_t i;

  uint32_t out=0;

  for (i=0;i<ARRAY_SIZE(inotify_mapping);i++) {

    if (inotify_mapping[i].notify_mask & *filter) {

      out |= inotify_mapping[i].inotify_mask;

      *filter &= ~inotify_mapping[i].notify_mask;

    }

  }

  return out;

}

/*

 * Map inotify mask back to filter. This returns all filters that

 * could have created the inotify watch.

 */

static uint32_t inotify_map_mask_to_filter(uint32_t mask)

{

  size_t i;

  uint32_t filter = 0;

  for (i = 0; i < ARRAY_SIZE(inotify_mapping); i++) {

    if (inotify_mapping[i].inotify_mask & mask) {

      filter |= inotify_mapping[i].notify_mask;

    }

  }

  if (mask & IN_ISDIR) {

    filter &= ~FILE_NOTIFY_CHANGE_FILE_NAME;

  } else {

    filter &= ~FILE_NOTIFY_CHANGE_DIR_NAME;

  }

  return filter;

}

/*

  destroy the inotify private context

*/

static int inotify_destructor(struct inotify_private *in)

{

  close(in->fd);

  return 0;

}

/*

  see if a particular event from inotify really does match a requested

  notify event in SMB

*/

static bool filter_match(struct inotify_watch_context *w,

       struct inotify_event *e)

{

  bool ok;

  DEBUG(10, ("filter_match: e->mask=%x, w->mask=%x, w->filter=%x\n",

       e->mask, w->mask, w->filter));

  if ((e->mask & w->mask) == 0) {

    /* this happens because inotify_add_watch() coalesces watches on the same

       path, oring their masks together */

    return False;

  }

  /* SMB separates the filters for files and directories */

  if (e->mask & IN_ISDIR) {

    ok = ((w->filter & FILE_NOTIFY_CHANGE_DIR_NAME) != 0);

    return ok;

  }

  if ((e->mask & IN_ATTRIB) &&

      (w->filter & (FILE_NOTIFY_CHANGE_ATTRIBUTES|

        FILE_NOTIFY_CHANGE_LAST_WRITE|

        FILE_NOTIFY_CHANGE_LAST_ACCESS|

        FILE_NOTIFY_CHANGE_EA|

        FILE_NOTIFY_CHANGE_SECURITY))) {

    return True;

  }

  if ((e->mask & IN_MODIFY) &&

      (w->filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)) {

    return True;

  }

  ok = ((w->filter & FILE_NOTIFY_CHANGE_FILE_NAME) != 0);

  return ok;

}

static void trigger_orphaned_moved_from(struct inotify_watch_context *w)

{

  struct notify_event ne = {};

  struct inotify_event *e = w->moved_from_event;

  ne = (struct notify_event){

    .action = NOTIFY_ACTION_REMOVED,

    .path = e->name,

    .dir = w->path,

  };

  w->callback(w->in->ctx,

        w->private_data,

        &ne,

        inotify_map_mask_to_filter(e->mask));

}

static void moved_from_timeout(struct tevent_context *ev,

             struct tevent_timer *te,

             struct timeval now,

             void *private_data)

{

  struct inotify_watch_context *w = talloc_get_type_abort(

    private_data, struct inotify_watch_context);

  trigger_orphaned_moved_from(w);

  TALLOC_FREE(w->moved_from_event);

}

static void save_moved_from(struct tevent_context *ev,

          struct inotify_watch_context *w,

          struct inotify_event *e)

{

  if (w->moved_from_event != NULL) {

    trigger_orphaned_moved_from(w);

    TALLOC_FREE(w->moved_from_event);

  }

  w->moved_from_event = talloc_memdup(

    w, e, sizeof(struct inotify_event) + e->len);

  if (w->moved_from_event == NULL) {

    /*

     * Not much we can do here

     */

    return;

  }

  tevent_add_timer(ev,

       w->moved_from_event,

       tevent_timeval_current_ofs(0, 100000),

       moved_from_timeout,

       w);

}

static bool handle_local_rename(struct inotify_watch_context *w,

        struct inotify_event *to)

{

  struct inotify_private *in = w->in;

  struct inotify_event *from = w->moved_from_event;

  struct notify_event ne = {};

  uint32_t filter;

  if ((w->last_mkdir != NULL) && (w->moved_from_event != NULL) &&

      IS_SMBD_TMPNAME(w->moved_from_event->name, NULL))

  {

    if (strcmp(to->name, w->last_mkdir) == 0) {

      /*

       * Assume this is a rename() from smbd after a

       * mkdir of the real target directory. See the

       * comment about RENAME_NOREPLACE in

       * mkdir_internals(). We have already sent out

       * the mkdir notify event, this MOVED_FROM/TO

       * pair is just internal fluff that the client

       * should not get wind of via notify.

       */

      TALLOC_FREE(w->last_mkdir);

      TALLOC_FREE(w->moved_from_event);

      return true;

    }

    if (strcmp(w->moved_from_event->name, w->last_mkdir) == 0) {

      /*

       * Assume this is a renameat2() from smbd's

       * mkdir_internal().

       */

      TALLOC_FREE(w->last_mkdir);

      TALLOC_FREE(w->moved_from_event);

      /*

       * Pretend this is not a rename but a new

       * directory.

       */

      to->mask = IN_ISDIR | IN_CREATE;

      return false;

    }

  }

  ne = (struct notify_event){

    .action = NOTIFY_ACTION_OLD_NAME,

    .path = from->name,

    .dir = w->path,

  };

  if (filter_match(w, from)) {

    filter = inotify_map_mask_to_filter(to->mask);

    w->callback(in->ctx, w->private_data, &ne, filter);

  }

  ne = (struct notify_event){

    .action = NOTIFY_ACTION_NEW_NAME,

    .path = to->name,

    .dir = w->path,

  };

  filter = inotify_map_mask_to_filter(to->mask);

  if (filter_match(w, to)) {

    w->callback(in->ctx, w->private_data, &ne, filter);

  }

  if (to->mask & IN_ISDIR) {

    return true;

  }

  if ((w->filter & FILE_NOTIFY_CHANGE_CREATION) == 0) {

    return true;

  }

  /*

   * SMB expects a file rename to generate three events, two for

   * the rename and the other for a modify of the

   * destination. Strange!

   */

  ne.action = NOTIFY_ACTION_MODIFIED;

  to->mask = IN_ATTRIB;

  if (filter_match(w, to)) {

    w->callback(in->ctx, w->private_data, &ne, filter);

  }

  return true;

}

/*

  dispatch one inotify event

  the cookies are used to correctly handle renames

*/

static void inotify_dispatch(struct tevent_context *ev,

           struct inotify_private *in,

           struct inotify_event *e)

{

  struct inotify_watch_context *w, *next;

  struct notify_event ne;

  uint32_t filter;

  DBG_DEBUG("called with mask=%x, name=[%s]\n",

      e->mask, e->len ? e->name : "");

  /* ignore extraneous events, such as unmount and IN_IGNORED events */

  if ((e->mask & (IN_ATTRIB|IN_MODIFY|IN_CREATE|IN_DELETE|

      IN_MOVED_FROM|IN_MOVED_TO)) == 0) {

    return;

  }

  if (e->mask & IN_MOVED_FROM) {

    for (w = in->watches; w != NULL; w = w->next) {

      if (e->wd != w->wd) {

        continue;

      }

      save_moved_from(ev, w, e);

    }

    return;

  }

  if (e->mask & IN_MOVED_TO) {

    for (w = in->watches; w != NULL; w = w->next) {

      if ((w->wd == e->wd) &&

          (w->moved_from_event != NULL) &&

          (w->moved_from_event->cookie == e->cookie))

      {

        bool handled = handle_local_rename(w, e);

        if (handled) {

          return;

        }

      }

    }

  }

  if ((e->mask & IN_CREATE) && (e->mask & IN_ISDIR)) {

    for (w = in->watches; w != NULL; w = w->next) {

      if (w->wd != e->wd) {

        continue;

      }

      TALLOC_FREE(w->last_mkdir);

      w->last_mkdir = talloc_strdup(w, e->name);

    }

    if (IS_SMBD_TMPNAME(e->name, NULL)) {

      return;

    }

  }

  if (e->mask & IN_CREATE) {

    ne.action = NOTIFY_ACTION_ADDED;

  } else if (e->mask & IN_DELETE) {

    ne.action = NOTIFY_ACTION_REMOVED;

  } else if (e->mask & IN_MOVED_TO) {

    ne.action = NOTIFY_ACTION_ADDED;

  } else {

    ne.action = NOTIFY_ACTION_MODIFIED;

  }

  ne.path = e->name;

  filter = inotify_map_mask_to_filter(e->mask);

  DBG_DEBUG("ne.action = %d, ne.path = %s, filter = %d\n",

      ne.action, ne.path, filter);

  /* find any watches that have this watch descriptor */

  for (w=in->watches;w;w=next) {

    next = w->next;

    if (w->wd == e->wd && filter_match(w, e)) {

      ne.dir = w->path;

      w->callback(in->ctx, w->private_data, &ne, filter);

    }

  }

}

/*

  called when the kernel has some events for us

*/

static void inotify_handler(struct tevent_context *ev, struct tevent_fd *fde,

          uint16_t flags, void *private_data)

{

  struct inotify_private *in = talloc_get_type(private_data,

                 struct inotify_private);

  char buf[sizeof(struct inotify_event) + NAME_MAX + 1];

  int bufsize = 0;

  struct inotify_event *e = NULL;

  ssize_t ret;

  ret = sys_read(in->fd, buf, sizeof(buf));

  if (ret == -1) {

    DEBUG(0, ("Failed to read all inotify data - %s\n",

        strerror(errno)));

    /* the inotify fd will now be out of sync,

     * can't keep reading data off it */

    TALLOC_FREE(fde);

    return;

  }

  bufsize = ret;

  e = (struct inotify_event *)buf;

  /* we can get more than one event in the buffer */

  while (bufsize >= sizeof(struct inotify_event)) {

    size_t e_len = sizeof(struct inotify_event) + e->len;

    if ((e_len < sizeof(struct inotify_event)) ||

        (e_len > bufsize))

    {

      DBG_ERR("Invalid data from inotify\n");

      TALLOC_FREE(fde);

      return;

    }

    inotify_dispatch(ev, in, e);

    e = (struct inotify_event *)((char *)e + e_len);

    bufsize -= e_len;

  }

}

/*

  setup the inotify handle - called the first time a watch is added on

  this context

*/

static int inotify_setup(struct sys_notify_context *ctx)

{

  struct inotify_private *in;

  struct tevent_fd *fde;

  in = talloc(ctx, struct inotify_private);

  if (in == NULL) {

    return ENOMEM;

  }

  in->fd = inotify_init();

  if (in->fd == -1) {

    int ret = errno;

    DEBUG(0, ("Failed to init inotify - %s\n", strerror(ret)));

    talloc_free(in);

    return ret;

  }

  in->ctx = ctx;

  in->watches = NULL;

  ctx->private_data = in;

  talloc_set_destructor(in, inotify_destructor);

  /* add a event waiting for the inotify fd to be readable */

  fde = tevent_add_fd(ctx->ev, in, in->fd, TEVENT_FD_READ,

          inotify_handler, in);

  if (fde == NULL) {

    ctx->private_data = NULL;

    TALLOC_FREE(in);

    return ENOMEM;

  }

  return 0;

}

/*

  destroy a watch

*/

static int watch_destructor(struct inotify_watch_context *w)

{

  struct inotify_private *in = w->in;

  int wd = w->wd;

  DLIST_REMOVE(w->in->watches, w);

  for (w=in->watches;w;w=w->next) {

    if (w->wd == wd) {

      /*

       * Another inotify_watch_context listens on this path,

       * leave the kernel level watch in place

       */

      return 0;

    }

  }

  DEBUG(10, ("Deleting inotify watch %d\n", wd));

  if (inotify_rm_watch(in->fd, wd) == -1) {

    DEBUG(1, ("inotify_rm_watch returned %s\n", strerror(errno)));

  }

  return 0;

}

/*

  add a watch. The watch is removed when the caller calls

  talloc_free() on *handle

*/

int inotify_watch(TALLOC_CTX *mem_ctx,

      struct sys_notify_context *ctx,

      const char *path,

      uint32_t *filter,

      uint32_t *subdir_filter,

      void (*callback)(struct sys_notify_context *ctx,

           void *private_data,

           struct notify_event *ev,

           uint32_t filter),

      void *private_data,

      void *handle_p)

{

  struct inotify_private *in;

  uint32_t mask;

  struct inotify_watch_context *w;

  uint32_t orig_filter = *filter;

  void **handle = (void **)handle_p;

  /* maybe setup the inotify fd */

  if (ctx->private_data == NULL) {

    int ret;

    ret = inotify_setup(ctx);

    if (ret != 0) {

      return ret;

    }

  }

  in = talloc_get_type(ctx->private_data, struct inotify_private);

  mask = inotify_map(filter);

  if (mask == 0) {

    /* this filter can't be handled by inotify */

    return EINVAL;

  }

  /* using IN_MASK_ADD allows us to cope with inotify() returning the same

     watch descriptor for multiple watches on the same path */

  mask |= (IN_MASK_ADD | IN_ONLYDIR);

  w = talloc(mem_ctx, struct inotify_watch_context);

  if (w == NULL) {

    *filter = orig_filter;

    return ENOMEM;

  }

  *w = (struct inotify_watch_context) {

    .in = in,

    .callback = callback,

    .private_data = private_data,

    .mask = mask,

    .filter = orig_filter,

    .path = talloc_strdup(w, path),

  };

  if (w->path == NULL) {

    *filter = orig_filter;

    TALLOC_FREE(w);

    return ENOMEM;

  }

  /* get a new watch descriptor for this path */

  w->wd = inotify_add_watch(in->fd, path, mask);

  if (w->wd == -1) {

    int err = errno;

    *filter = orig_filter;

    TALLOC_FREE(w);

    DEBUG(1, ("inotify_add_watch returned %s\n", strerror(err)));

    return err;

  }

  DEBUG(10, ("inotify_add_watch for %s mask %x returned wd %d\n",

       path, mask, w->wd));

  (*handle) = w;

  DLIST_ADD(in->watches, w);

  /* the caller frees the handle to stop watching */

  talloc_set_destructor(w, watch_destructor);

  return 0;

}