s3-dbwrap: Add dbwrap_record_watch_send/recv

With this API you can asynchronously wait for a record to be modified

2 files changed, 529 insertions, 0 deletions

diff --git a/source3/lib/dbwrap/dbwrap_watch.c b/source3/lib/dbwrap/dbwrap_watch.c
new file mode 100644
index 0000000000..db0d376e3c
--- /dev/null
+++ b/source3/lib/dbwrap/dbwrap_watch.c
@@ -0,0 +1,483 @@
+/*
+   Unix SMB/CIFS implementation.
+   Watch dbwrap record changes
+   Copyright (C) Volker Lendecke 2012
+
+   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/>.
+*/
+
+#include "includes.h"
+#include "system/filesys.h"
+#include "dbwrap.h"
+#include "dbwrap_watch.h"
+#include "dbwrap_open.h"
+#include "msg_channel.h"
+#include "lib/util/util_tdb.h"
+#include "lib/util/tevent_ntstatus.h"
+
+static struct db_context *dbwrap_record_watchers_db(void)
+{
+	static struct db_context *watchers_db;
+
+	if (watchers_db == NULL) {
+		watchers_db = db_open(NULL, lock_path("dbwrap_watchers.tdb"),
+				      0, TDB_CLEAR_IF_FIRST, O_RDWR|O_CREAT,
+				      0600, DBWRAP_LOCK_ORDER_3);
+	}
+	return watchers_db;
+}
+
+static TDB_DATA dbwrap_record_watchers_key(TALLOC_CTX *mem_ctx,
+					   struct db_context *db,
+					   struct db_record *rec,
+					   TDB_DATA *rec_key)
+{
+	const uint8_t *db_id;
+	size_t db_id_len;
+	TDB_DATA key, wkey;
+
+	dbwrap_db_id(db, &db_id, &db_id_len);
+	key = dbwrap_record_get_key(rec);
+
+	wkey.dsize = sizeof(uint32_t) + db_id_len + key.dsize;
+	wkey.dptr = talloc_array(mem_ctx, uint8_t, wkey.dsize);
+	if (wkey.dptr == NULL) {
+		return make_tdb_data(NULL, 0);
+	}
+	SIVAL(wkey.dptr, 0, db_id_len);
+	memcpy(wkey.dptr + sizeof(uint32_t), db_id, db_id_len);
+	memcpy(wkey.dptr + sizeof(uint32_t) + db_id_len, key.dptr, key.dsize);
+
+	if (rec_key != NULL) {
+		rec_key->dptr = wkey.dptr + sizeof(uint32_t) + db_id_len;
+		rec_key->dsize = key.dsize;
+	}
+
+	return wkey;
+}
+
+static bool dbwrap_record_watchers_key_parse(
+	TDB_DATA wkey, uint8_t **p_db_id, size_t *p_db_id_len, TDB_DATA *key)
+{
+	size_t db_id_len;
+
+	if (wkey.dsize < sizeof(uint32_t)) {
+		DEBUG(1, ("Invalid watchers key\n"));
+		return false;
+	}
+	db_id_len = IVAL(wkey.dptr, 0);
+	if (db_id_len > (wkey.dsize - sizeof(uint32_t))) {
+		DEBUG(1, ("Invalid watchers key, wkey.dsize=%d, "
+			  "db_id_len=%d\n", (int)wkey.dsize, (int)db_id_len));
+		return false;
+	}
+	*p_db_id = wkey.dptr + sizeof(uint32_t);
+	*p_db_id_len = db_id_len;
+	key->dptr = wkey.dptr + sizeof(uint32_t) + db_id_len;
+	key->dsize = wkey.dsize - sizeof(uint32_t) - db_id_len;
+	return true;
+}
+
+static NTSTATUS dbwrap_record_add_watcher(TDB_DATA w_key, struct server_id id)
+{
+	struct TALLOC_CTX *frame = talloc_stackframe();
+	struct db_context *db;
+	struct db_record *rec;
+	TDB_DATA value;
+	struct server_id *ids;
+	size_t num_ids;
+	NTSTATUS status;
+
+	db = dbwrap_record_watchers_db();
+	if (db == NULL) {
+		status = map_nt_error_from_unix(errno);
+		goto fail;
+	}
+	rec = dbwrap_fetch_locked(db, talloc_tos(), w_key);
+	if (rec == NULL) {
+		status = map_nt_error_from_unix(errno);
+		goto fail;
+	}
+	value = dbwrap_record_get_value(rec);
+
+	if ((value.dsize % sizeof(struct server_id)) != 0) {
+		status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+		goto fail;
+	}
+
+	ids = (struct server_id *)value.dptr;
+	num_ids = value.dsize / sizeof(struct server_id);
+
+	ids = talloc_realloc(talloc_tos(), ids, struct server_id,
+			     num_ids + 1);
+	if (ids == NULL) {
+		status = NT_STATUS_NO_MEMORY;
+		goto fail;
+	}
+	ids[num_ids] = id;
+	num_ids += 1;
+
+	status = dbwrap_record_store(
+		rec, make_tdb_data((uint8_t *)ids, talloc_get_size(ids)), 0);
+fail:
+	TALLOC_FREE(frame);
+	return status;
+}
+
+static NTSTATUS dbwrap_record_del_watcher(TDB_DATA w_key, struct server_id id)
+{
+	struct TALLOC_CTX *frame = talloc_stackframe();
+	struct db_context *db;
+	struct db_record *rec;
+	struct server_id *ids;
+	size_t i, num_ids;
+	TDB_DATA value;
+	NTSTATUS status;
+
+	db = dbwrap_record_watchers_db();
+	if (db == NULL) {
+		status = map_nt_error_from_unix(errno);
+		goto fail;
+	}
+	rec = dbwrap_fetch_locked(db, talloc_tos(), w_key);
+	if (rec == NULL) {
+		status = map_nt_error_from_unix(errno);
+		goto fail;
+	}
+	value = dbwrap_record_get_value(rec);
+
+	if ((value.dsize % sizeof(struct server_id)) != 0) {
+		status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+		goto fail;
+	}
+
+	ids = (struct server_id *)value.dptr;
+	num_ids = value.dsize / sizeof(struct server_id);
+
+	for (i=0; i<num_ids; i++) {
+		if (procid_equal(&id, &ids[i])) {
+			ids[i] = ids[num_ids-1];
+			value.dsize -= sizeof(struct server_id);
+			break;
+		}
+	}
+	if (value.dsize == 0) {
+		status = dbwrap_record_delete(rec);
+		goto done;
+	}
+	status = dbwrap_record_store(rec, value, 0);
+fail:
+done:
+	TALLOC_FREE(frame);
+	return status;
+}
+
+static NTSTATUS dbwrap_record_get_watchers(struct db_context *db,
+					   struct db_record *rec,
+					   TALLOC_CTX *mem_ctx,
+					   struct server_id **p_ids,
+					   size_t *p_num_ids)
+{
+	struct db_context *w_db;
+	TDB_DATA key = { 0, };
+	TDB_DATA value = { 0, };
+	struct server_id *ids;
+	NTSTATUS status;
+
+	key = dbwrap_record_watchers_key(talloc_tos(), db, rec, NULL);
+	if (key.dptr == NULL) {
+		status = NT_STATUS_NO_MEMORY;
+		goto fail;
+	}
+	w_db = dbwrap_record_watchers_db();
+	if (w_db == NULL) {
+		status = NT_STATUS_INTERNAL_ERROR;
+		goto fail;
+	}
+	status = dbwrap_fetch(w_db, mem_ctx, key, &value);
+	TALLOC_FREE(key.dptr);
+	if (!NT_STATUS_IS_OK(status)) {
+		goto fail;
+	}
+	if ((value.dsize % sizeof(struct server_id)) != 0) {
+		status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+		goto fail;
+	}
+	ids = (struct server_id *)value.dptr;
+	*p_ids = talloc_move(mem_ctx, &ids);
+	*p_num_ids = value.dsize / sizeof(struct server_id);
+	return NT_STATUS_OK;
+fail:
+	TALLOC_FREE(key.dptr);
+	TALLOC_FREE(value.dptr);
+	return status;
+}
+
+struct dbwrap_record_watch_state {
+	struct tevent_context *ev;
+	struct db_context *db;
+	struct tevent_req *req;
+	struct messaging_context *msg;
+	struct msg_channel *channel;
+	TDB_DATA key;
+	TDB_DATA w_key;
+};
+
+static void dbwrap_record_watch_done(struct tevent_req *subreq);
+static int dbwrap_record_watch_state_destructor(
+	struct dbwrap_record_watch_state *state);
+
+struct tevent_req *dbwrap_record_watch_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct db_record *rec,
+					    struct messaging_context *msg)
+{
+	struct tevent_req *req, *subreq;
+	struct dbwrap_record_watch_state *state;
+	struct db_context *watchers_db;
+	NTSTATUS status;
+	int ret;
+
+	req = tevent_req_create(mem_ctx, &state,
+				struct dbwrap_record_watch_state);
+	if (req == NULL) {
+		return NULL;
+	}
+	state->db = dbwrap_record_get_db(rec);
+	state->ev = ev;
+	state->req = req;
+	state->msg = msg;
+
+	watchers_db = dbwrap_record_watchers_db();
+	if (watchers_db == NULL) {
+		tevent_req_nterror(req, map_nt_error_from_unix(errno));
+		return tevent_req_post(req, ev);
+	}
+
+	state->w_key = dbwrap_record_watchers_key(state, state->db, rec,
+						  &state->key);
+	if (tevent_req_nomem(state->w_key.dptr, req)) {
+		return tevent_req_post(req, ev);
+	}
+
+	ret = msg_channel_init(state, state->msg, MSG_DBWRAP_MODIFIED,
+			       &state->channel);
+	if (ret != 0) {
+		tevent_req_nterror(req, map_nt_error_from_unix(ret));
+		return tevent_req_post(req, ev);
+	}
+
+	status = dbwrap_record_add_watcher(
+		state->w_key, messaging_server_id(state->msg));
+	if (tevent_req_nterror(req, status)) {
+		return tevent_req_post(req, ev);
+	}
+	talloc_set_destructor(state, dbwrap_record_watch_state_destructor);
+
+	subreq = msg_read_send(state, state->ev, state->channel);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+	tevent_req_set_callback(subreq, dbwrap_record_watch_done, req);
+	return req;
+}
+
+static int dbwrap_record_watch_state_destructor(
+	struct dbwrap_record_watch_state *s)
+{
+	if (s->msg != NULL) {
+		dbwrap_record_del_watcher(
+			s->w_key, messaging_server_id(s->msg));
+	}
+	return 0;
+}
+
+static void dbwrap_watch_record_stored(struct db_context *db,
+				       struct db_record *rec,
+				       void *private_data)
+{
+	struct messaging_context *msg = talloc_get_type_abort(
+		private_data, struct messaging_context);
+	struct server_id *ids = NULL;
+	size_t num_ids = 0;
+	TDB_DATA w_key = { 0, };
+	DATA_BLOB w_blob;
+	NTSTATUS status;
+	uint32_t i;
+
+	status = dbwrap_record_get_watchers(db, rec, talloc_tos(),
+					    &ids, &num_ids);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(1, ("dbwrap_record_get_watchers failed: %s\n",
+			  nt_errstr(status)));
+		goto done;
+	}
+	w_key = dbwrap_record_watchers_key(talloc_tos(), db, rec, NULL);
+	if (w_key.dptr == NULL) {
+		DEBUG(1, ("dbwrap_record_watchers_key failed\n"));
+		goto done;
+	}
+	w_blob.data = w_key.dptr;
+	w_blob.length = w_key.dsize;
+
+	for (i=0; i<num_ids; i++) {
+		status = messaging_send(msg, ids[i], MSG_DBWRAP_MODIFIED,
+					&w_blob);
+		if (!NT_STATUS_IS_OK(status)) {
+			char *str = procid_str_static(&ids[i]);
+			DEBUG(1, ("messaging_send to %s failed: %s\n",
+				  str, nt_errstr(status)));
+			TALLOC_FREE(str);
+		}
+	}
+done:
+	TALLOC_FREE(w_key.dptr);
+	TALLOC_FREE(ids);
+	return;
+}
+
+void dbwrap_watch_db(struct db_context *db, struct messaging_context *msg)
+{
+	dbwrap_set_stored_callback(db, dbwrap_watch_record_stored, msg);
+}
+
+static void dbwrap_record_watch_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct dbwrap_record_watch_state *state = tevent_req_data(
+		req, struct dbwrap_record_watch_state);
+	struct messaging_rec *rec;
+	int ret;
+
+	ret = msg_read_recv(subreq, talloc_tos(), &rec);
+	TALLOC_FREE(subreq);
+	if (ret != 0) {
+		tevent_req_nterror(req, map_nt_error_from_unix(ret));
+		return;
+	}
+
+	if ((rec->buf.length == state->w_key.dsize) &&
+	    (memcmp(rec->buf.data, state->w_key.dptr, rec->buf.length) == 0)) {
+		tevent_req_done(req);
+		return;
+	}
+
+	/*
+	 * Not our record, wait for the next one
+	 */
+	subreq = msg_read_send(state, state->ev, state->channel);
+	if (tevent_req_nomem(subreq, req)) {
+		return;
+	}
+	tevent_req_set_callback(subreq, dbwrap_record_watch_done, req);
+}
+
+NTSTATUS dbwrap_record_watch_recv(struct tevent_req *req,
+				  TALLOC_CTX *mem_ctx,
+				  struct db_record **prec)
+{
+	struct dbwrap_record_watch_state *state = tevent_req_data(
+		req, struct dbwrap_record_watch_state);
+	NTSTATUS status;
+	struct db_record *rec;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		return status;
+	}
+	rec = dbwrap_fetch_locked(state->db, mem_ctx, state->key);
+	if (req == NULL) {
+		return NT_STATUS_INTERNAL_DB_ERROR;
+	}
+	*prec = rec;
+	return NT_STATUS_OK;
+}
+
+struct dbwrap_watchers_traverse_read_state {
+	int (*fn)(const uint8_t *db_id, size_t db_id_len, const TDB_DATA key,
+		  const struct server_id *watchers, size_t num_watchers,
+		  void *private_data);
+	void *private_data;
+};
+
+static int dbwrap_watchers_traverse_read_callback(
+	struct db_record *rec, void *private_data)
+{
+	struct dbwrap_watchers_traverse_read_state *state =
+		(struct dbwrap_watchers_traverse_read_state *)private_data;
+	uint8_t *db_id;
+	size_t db_id_len;
+	TDB_DATA w_key, key, w_data;
+	int res;
+
+	w_key = dbwrap_record_get_key(rec);
+	w_data = dbwrap_record_get_value(rec);
+
+	if (!dbwrap_record_watchers_key_parse(w_key, &db_id, &db_id_len,
+					      &key)) {
+		return 0;
+	}
+	if ((w_data.dsize % sizeof(struct server_id)) != 0) {
+		return 0;
+	}
+	res = state->fn(db_id, db_id_len, key,
+			(struct server_id *)w_data.dptr,
+			w_data.dsize / sizeof(struct server_id),
+			state->private_data);
+	return res;
+}
+
+void dbwrap_watchers_traverse_read(
+	int (*fn)(const uint8_t *db_id, size_t db_id_len, const TDB_DATA key,
+		  const struct server_id *watchers, size_t num_watchers,
+		  void *private_data),
+	void *private_data)
+{
+	struct dbwrap_watchers_traverse_read_state state;
+	struct db_context *db;
+
+	db = dbwrap_record_watchers_db();
+	if (db == NULL) {
+		return;
+	}
+	state.fn = fn;
+	state.private_data = private_data;
+	dbwrap_traverse_read(db, dbwrap_watchers_traverse_read_callback,
+			     &state, NULL);
+}
+
+static int dbwrap_wakeall_cb(const uint8_t *db_id, size_t db_id_len,
+			     const TDB_DATA key,
+			     const struct server_id *watchers,
+			     size_t num_watchers,
+			     void *private_data)
+{
+	struct messaging_context *msg = talloc_get_type_abort(
+		private_data, struct messaging_context);
+	uint32_t i;
+	DATA_BLOB blob;
+
+	blob.data = key.dptr;
+	blob.length = key.dsize;
+
+	for (i=0; i<num_watchers; i++) {
+		messaging_send(msg, watchers[i], MSG_DBWRAP_MODIFIED, &blob);
+	}
+	return 0;
+}
+
+void dbwrap_watchers_wakeall(struct messaging_context *msg)
+{
+	dbwrap_watchers_traverse_read(dbwrap_wakeall_cb, msg);
+}
diff --git a/source3/lib/dbwrap/dbwrap_watch.h b/source3/lib/dbwrap/dbwrap_watch.h
new file mode 100644
index 0000000000..e242fa188a
--- /dev/null
+++ b/source3/lib/dbwrap/dbwrap_watch.h
@@ -0,0 +1,46 @@
+/*
+   Unix SMB/CIFS implementation.
+   Watch dbwrap record changes
+   Copyright (C) Volker Lendecke 2012
+
+   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/>.
+*/
+
+#ifndef __DBWRAP_WATCH_H__
+#define __DBWRAP_WATCH_H__
+
+#include <tevent.h>
+#include "dbwrap.h"
+#include "messages.h"
+
+void dbwrap_watch_db(struct db_context *db, struct messaging_context *msg);
+
+struct tevent_req *dbwrap_record_watch_send(TALLOC_CTX *mem_ctx,
+					    struct tevent_context *ev,
+					    struct db_record *rec,
+					    struct messaging_context *msg);
+NTSTATUS dbwrap_record_watch_recv(struct tevent_req *req,
+				  TALLOC_CTX *mem_ctx,
+				  struct db_record **prec);
+
+void dbwrap_watchers_traverse_read(
+	int (*fn)(const uint8_t *db_id, size_t db_id_len, const TDB_DATA key,
+		  const struct server_id *watchers, size_t num_watchers,
+		  void *private_data),
+	void *private_data);
+
+void dbwrap_watchers_wakeall(struct messaging_context *msg);
+
+
+#endif /* __DBWRAP_H__ */