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/*
Watch code for Xen Store Daemon.
Copyright (C) 2005 Rusty Russell IBM Corporation
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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <stdio.h>
#include <sys/types.h>
#include <stdarg.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <assert.h>
#include "talloc.h"
#include "list.h"
#include "xenstored_watch.h"
#include "xenstore_lib.h"
#include "utils.h"
#include "xenstored_domain.h"
extern int quota_nb_watch_per_domain;
struct watch
{
/* Watches on this connection */
struct list_head list;
/* Current outstanding events applying to this watch. */
struct list_head events;
/* Is this relative to connnection's implicit path? */
const char *relative_path;
char *token;
char *node;
};
static void add_event(struct connection *conn,
struct watch *watch,
const char *name)
{
/* Data to send (node\0token\0). */
unsigned int len;
char *data;
if (!check_event_node(name)) {
/* Can this conn load node, or see that it doesn't exist? */
struct node *node = get_node(conn, name, XS_PERM_READ);
/*
* XXX We allow EACCES here because otherwise a non-dom0
* backend driver cannot watch for disappearance of a frontend
* xenstore directory. When the directory disappears, we
* revert to permissions of the parent directory for that path,
* which will typically disallow access for the backend.
* But this breaks device-channel teardown!
* Really we should fix this better...
*/
if (!node && errno != ENOENT && errno != EACCES)
return;
}
if (watch->relative_path) {
name += strlen(watch->relative_path);
if (*name == '/') /* Could be "" */
name++;
}
len = strlen(name) + 1 + strlen(watch->token) + 1;
data = talloc_array(watch, char, len);
strcpy(data, name);
strcpy(data + strlen(name) + 1, watch->token);
send_reply(conn, XS_WATCH_EVENT, data, len);
talloc_free(data);
}
void fire_watches(struct connection *conn, const char *name, bool recurse)
{
struct connection *i;
struct watch *watch;
/* During transactions, don't fire watches. */
if (conn && conn->transaction)
return;
/* Create an event for each watch. */
list_for_each_entry(i, &connections, list) {
list_for_each_entry(watch, &i->watches, list) {
if (is_child(name, watch->node))
add_event(i, watch, name);
else if (recurse && is_child(watch->node, name))
add_event(i, watch, watch->node);
}
}
}
static int destroy_watch(void *_watch)
{
trace_destroy(_watch, "watch");
return 0;
}
void do_watch(struct connection *conn, struct buffered_data *in)
{
struct watch *watch;
char *vec[2];
bool relative;
if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec)) {
send_error(conn, EINVAL);
return;
}
if (strstarts(vec[0], "@")) {
relative = false;
if (strlen(vec[0]) > XENSTORE_REL_PATH_MAX) {
send_error(conn, EINVAL);
return;
}
/* check if valid event */
} else {
relative = !strstarts(vec[0], "/");
vec[0] = canonicalize(conn, vec[0]);
if (!is_valid_nodename(vec[0])) {
send_error(conn, EINVAL);
return;
}
}
/* Check for duplicates. */
list_for_each_entry(watch, &conn->watches, list) {
if (streq(watch->node, vec[0]) &&
streq(watch->token, vec[1])) {
send_error(conn, EEXIST);
return;
}
}
if (domain_watch(conn) > quota_nb_watch_per_domain) {
send_error(conn, E2BIG);
return;
}
watch = talloc(conn, struct watch);
watch->node = talloc_strdup(watch, vec[0]);
watch->token = talloc_strdup(watch, vec[1]);
if (relative)
watch->relative_path = get_implicit_path(conn);
else
watch->relative_path = NULL;
INIT_LIST_HEAD(&watch->events);
domain_watch_inc(conn);
list_add_tail(&watch->list, &conn->watches);
trace_create(watch, "watch");
talloc_set_destructor(watch, destroy_watch);
send_ack(conn, XS_WATCH);
/* We fire once up front: simplifies clients and restart. */
add_event(conn, watch, watch->node);
}
void do_unwatch(struct connection *conn, struct buffered_data *in)
{
struct watch *watch;
char *node, *vec[2];
if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec)) {
send_error(conn, EINVAL);
return;
}
node = canonicalize(conn, vec[0]);
list_for_each_entry(watch, &conn->watches, list) {
if (streq(watch->node, node) && streq(watch->token, vec[1])) {
list_del(&watch->list);
talloc_free(watch);
domain_watch_dec(conn);
send_ack(conn, XS_UNWATCH);
return;
}
}
send_error(conn, ENOENT);
}
void conn_delete_all_watches(struct connection *conn)
{
struct watch *watch;
while ((watch = list_top(&conn->watches, struct watch, list))) {
list_del(&watch->list);
talloc_free(watch);
domain_watch_dec(conn);
}
}
/*
* Local variables:
* c-file-style: "linux"
* indent-tabs-mode: t
* c-indent-level: 8
* c-basic-offset: 8
* tab-width: 8
* End:
*/
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