notify.c

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/* 
   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/>.
*/

/*
  this is the change notify database. It implements mechanisms for
  storing current change notify waiters in a tdb, and checking if a
  given event matches any of the stored notify waiiters.
*/

#include "includes.h"
#include "system/filesys.h"
#include "lib/tdb/include/tdb.h"
#include "lib/util/util_tdb.h"
#include "messaging/messaging.h"
#include "tdb_wrap.h"
#include "lib/messaging/irpc.h"
#include "librpc/gen_ndr/ndr_notify.h"
#include "lib/util/dlinklist.h"
#include "ntvfs/common/ntvfs_common.h"
#include "ntvfs/sysdep/sys_notify.h"
#include "cluster/cluster.h"
#include "param/param.h"

struct notify_context {
	struct tdb_wrap *w;
	struct server_id server;
	struct messaging_context *messaging_ctx;
	struct notify_list *list;
	struct notify_array *array;
	int seqnum;
	struct sys_notify_context *sys_notify_ctx;
	struct smb_iconv_convenience *iconv_convenience;
};


struct notify_list {
	struct notify_list *next, *prev;
	void *private_data;
	void (*callback)(void *, const struct notify_event *);
	void *sys_notify_handle;
	int depth;
};

#define NOTIFY_KEY "notify array"

#define NOTIFY_ENABLE		"notify:enable"
#define NOTIFY_ENABLE_DEFAULT	true

static NTSTATUS notify_remove_all(struct notify_context *notify);
static void notify_handler(struct messaging_context *msg_ctx, void *private_data, 
			   uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);

/*
  destroy the notify context
*/
static int notify_destructor(struct notify_context *notify)
{
	messaging_deregister(notify->messaging_ctx, MSG_PVFS_NOTIFY, notify);
	notify_remove_all(notify);
	return 0;
}

/*
  Open up the notify.tdb database. You should close it down using
  talloc_free(). We need the messaging_ctx to allow for notifications
  via internal messages
*/
struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server, 
				   struct messaging_context *messaging_ctx,
				   struct loadparm_context *lp_ctx,
				   struct event_context *ev,
				   struct share_config *scfg)
{
	struct notify_context *notify;

	if (share_bool_option(scfg, NOTIFY_ENABLE, NOTIFY_ENABLE_DEFAULT) != true) {
		return NULL;
	}

	if (ev == NULL) {
		return NULL;
	}

	notify = talloc(mem_ctx, struct notify_context);
	if (notify == NULL) {
		return NULL;
	}

	notify->w = cluster_tdb_tmp_open(notify, lp_ctx, "notify.tdb", TDB_SEQNUM);
	if (notify->w == NULL) {
		talloc_free(notify);
		return NULL;
	}

	notify->server = server;
	notify->messaging_ctx = messaging_ctx;
	notify->list = NULL;
	notify->array = NULL;
	notify->iconv_convenience = lp_iconv_convenience(lp_ctx);
	notify->seqnum = tdb_get_seqnum(notify->w->tdb);

	talloc_set_destructor(notify, notify_destructor);

	/* register with the messaging subsystem for the notify
	   message type */
	messaging_register(notify->messaging_ctx, notify, 
			   MSG_PVFS_NOTIFY, notify_handler);

	notify->sys_notify_ctx = sys_notify_context_create(scfg, notify, ev);

	return notify;
}


/*
  lock the notify db
*/
static NTSTATUS notify_lock(struct notify_context *notify)
{
	if (tdb_lock_bystring(notify->w->tdb, NOTIFY_KEY) != 0) {
		return NT_STATUS_INTERNAL_DB_CORRUPTION;
	}
	return NT_STATUS_OK;
}

/*
  unlock the notify db
*/
static void notify_unlock(struct notify_context *notify)
{
	tdb_unlock_bystring(notify->w->tdb, NOTIFY_KEY);
}

/*
  load the notify array
*/
static NTSTATUS notify_load(struct notify_context *notify)
{
	TDB_DATA dbuf;
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;
	int seqnum;

	seqnum = tdb_get_seqnum(notify->w->tdb);

	if (seqnum == notify->seqnum && notify->array != NULL) {
		return NT_STATUS_OK;
	}

	notify->seqnum = seqnum;

	talloc_free(notify->array);
	notify->array = talloc_zero(notify, struct notify_array);
	NT_STATUS_HAVE_NO_MEMORY(notify->array);

	dbuf = tdb_fetch_bystring(notify->w->tdb, NOTIFY_KEY);
	if (dbuf.dptr == NULL) {
		return NT_STATUS_OK;
	}

	blob.data = dbuf.dptr;
	blob.length = dbuf.dsize;

	ndr_err = ndr_pull_struct_blob(&blob, notify->array, notify->iconv_convenience,
				       notify->array,
				       (ndr_pull_flags_fn_t)ndr_pull_notify_array);
	free(dbuf.dptr);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		return ndr_map_error2ntstatus(ndr_err);
	}

	return NT_STATUS_OK;
}

/*
  compare notify entries for sorting
*/
static int notify_compare(const void *p1, const void *p2)
{
	const struct notify_entry *e1 = p1, *e2 = p2;
	return strcmp(e1->path, e2->path);
}

/*
  save the notify array
*/
static NTSTATUS notify_save(struct notify_context *notify)
{
	TDB_DATA dbuf;
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;
	int ret;
	TALLOC_CTX *tmp_ctx;

	/* if possible, remove some depth arrays */
	while (notify->array->num_depths > 0 &&
	       notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
		notify->array->num_depths--;
	}

	/* we might just be able to delete the record */
	if (notify->array->num_depths == 0) {
		ret = tdb_delete_bystring(notify->w->tdb, NOTIFY_KEY);
		if (ret != 0) {
			return NT_STATUS_INTERNAL_DB_CORRUPTION;
		}
		return NT_STATUS_OK;
	}

	tmp_ctx = talloc_new(notify);
	NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);

	ndr_err = ndr_push_struct_blob(&blob, tmp_ctx, notify->iconv_convenience, notify->array,
				       (ndr_push_flags_fn_t)ndr_push_notify_array);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(tmp_ctx);
		return ndr_map_error2ntstatus(ndr_err);
	}

	dbuf.dptr = blob.data;
	dbuf.dsize = blob.length;
		
	ret = tdb_store_bystring(notify->w->tdb, NOTIFY_KEY, dbuf, TDB_REPLACE);
	talloc_free(tmp_ctx);
	if (ret != 0) {
		return NT_STATUS_INTERNAL_DB_CORRUPTION;
	}

	return NT_STATUS_OK;
}


/*
  handle incoming notify messages
*/
static void notify_handler(struct messaging_context *msg_ctx, void *private_data, 
			   uint32_t msg_type, struct server_id server_id, DATA_BLOB *data)
{
	struct notify_context *notify = talloc_get_type(private_data, struct notify_context);
	enum ndr_err_code ndr_err;
	struct notify_event ev;
	TALLOC_CTX *tmp_ctx = talloc_new(notify);
	struct notify_list *listel;

	if (tmp_ctx == NULL) {
		return;
	}

	ndr_err = ndr_pull_struct_blob(data, tmp_ctx, notify->iconv_convenience, &ev,
				      (ndr_pull_flags_fn_t)ndr_pull_notify_event);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(tmp_ctx);
		return;
	}

	for (listel=notify->list;listel;listel=listel->next) {
		if (listel->private_data == ev.private_data) {
			listel->callback(listel->private_data, &ev);
			break;
		}
	}

	talloc_free(tmp_ctx);	
}

/*
  callback from sys_notify telling us about changes from the OS
*/
static void sys_notify_callback(struct sys_notify_context *ctx, 
				void *ptr, struct notify_event *ev)
{
	struct notify_list *listel = talloc_get_type(ptr, struct notify_list);
	ev->private_data = listel;
	listel->callback(listel->private_data, ev);
}

/*
  add an entry to the notify array
*/
static NTSTATUS notify_add_array(struct notify_context *notify, struct notify_entry *e,
				 void *private_data, int depth)
{
	int i;
	struct notify_depth *d;
	struct notify_entry *ee;

	/* possibly expand the depths array */
	if (depth >= notify->array->num_depths) {
		d = talloc_realloc(notify->array, notify->array->depth, 
				   struct notify_depth, depth+1);
		NT_STATUS_HAVE_NO_MEMORY(d);
		for (i=notify->array->num_depths;i<=depth;i++) {
			ZERO_STRUCT(d[i]);
		}
		notify->array->depth = d;
		notify->array->num_depths = depth+1;
	}
	d = &notify->array->depth[depth];

	/* expand the entries array */
	ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
			    d->num_entries+1);
	NT_STATUS_HAVE_NO_MEMORY(ee);
	d->entries = ee;

	d->entries[d->num_entries] = *e;
	d->entries[d->num_entries].private_data = private_data;
	d->entries[d->num_entries].server = notify->server;
	d->entries[d->num_entries].path_len = strlen(e->path);
	d->num_entries++;

	d->max_mask |= e->filter;
	d->max_mask_subdir |= e->subdir_filter;

	if (d->num_entries > 1) {
		qsort(d->entries, d->num_entries, sizeof(d->entries[0]), notify_compare);
	}

	/* recalculate the maximum masks */
	d->max_mask = 0;
	d->max_mask_subdir = 0;