eventscript.c

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/* 
   event script handling

   Copyright (C) Andrew Tridgell  2007

   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 "system/wait.h"
#include "../include/ctdb_private.h"
#include "lib/events/events.h"

/*
  run the event script - varargs version
 */
static int ctdb_event_script_v(struct ctdb_context *ctdb, const char *fmt, va_list ap)
{
	char *options, *cmdstr;
	int ret;
	va_list ap2;
	struct stat st;

	if (stat(ctdb->takeover.event_script, &st) != 0 && 
	    errno == ENOENT) {
		DEBUG(0,("No event script found at '%s'\n", ctdb->takeover.event_script));
		return 0;
	}

	va_copy(ap2, ap);
	options  = talloc_vasprintf(ctdb, fmt, ap2);
	va_end(ap2);
	CTDB_NO_MEMORY(ctdb, options);

	cmdstr = talloc_asprintf(ctdb, "%s %s", ctdb->takeover.event_script, options);
	CTDB_NO_MEMORY(ctdb, cmdstr);

	ret = system(cmdstr);
	if (ret != -1) {
		ret = WEXITSTATUS(ret);
	}

	talloc_free(cmdstr);
	talloc_free(options);

	return ret;
}

/*
  run the event script
 */
int ctdb_event_script(struct ctdb_context *ctdb, const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	ret = ctdb_event_script_v(ctdb, fmt, ap);
	va_end(ap);

	return ret;
}


struct ctdb_event_script_state {
	struct ctdb_context *ctdb;
	pid_t child;
	void (*callback)(struct ctdb_context *, int, void *);
	int fd[2];
	void *private_data;
};

/* called when child is finished */
static void ctdb_event_script_handler(struct event_context *ev, struct fd_event *fde, 
				      uint16_t flags, void *p)
{
	struct ctdb_event_script_state *state = 
		talloc_get_type(p, struct ctdb_event_script_state);
	int status = -1;
	void (*callback)(struct ctdb_context *, int, void *) = state->callback;
	void *private_data = state->private_data;
	struct ctdb_context *ctdb = state->ctdb;

	waitpid(state->child, &status, 0);
	if (status != -1) {
		status = WEXITSTATUS(status);
	}
	talloc_set_destructor(state, NULL);
	talloc_free(state);
	callback(ctdb, status, private_data);
}


/* called when child times out */
static void ctdb_event_script_timeout(struct event_context *ev, struct timed_event *te, 
				      struct timeval t, void *p)
{
	struct ctdb_event_script_state *state = talloc_get_type(p, struct ctdb_event_script_state);
	void (*callback)(struct ctdb_context *, int, void *) = state->callback;
	void *private_data = state->private_data;
	struct ctdb_context *ctdb = state->ctdb;

	DEBUG(0,("event script timed out\n"));
	talloc_free(state);
	callback(ctdb, -1, private_data);
}

/*
  destroy a running event script
 */
static int event_script_destructor(struct ctdb_event_script_state *state)
{
	kill(state->child, SIGKILL);
	waitpid(state->child, NULL, 0);
	return 0;
}

/*
  run the event script in the background, calling the callback when 
  finished
 */
int ctdb_event_script_callback(struct ctdb_context *ctdb, 
			       struct timeval timeout,
			       TALLOC_CTX *mem_ctx,
			       void (*callback)(struct ctdb_context *, int, void *),
			       void *private_data,
			       const char *fmt, ...)
{
	struct ctdb_event_script_state *state;
	va_list ap;
	int ret;

	state = talloc(mem_ctx, struct ctdb_event_script_state);
	CTDB_NO_MEMORY(ctdb, state);

	state->ctdb = ctdb;
	state->callback = callback;
	state->private_data = private_data;
	
	ret = pipe(state->fd);
	if (ret != 0) {
		talloc_free(state);
		return -1;
	}

	state->child = fork();

	if (state->child == (pid_t)-1) {
		close(state->fd[0]);
		close(state->fd[1]);
		talloc_free(state);
		return -1;
	}

	if (state->child == 0) {
		close(state->fd[0]);
		ctdb_set_realtime(false);
		set_close_on_exec(state->fd[1]);
		va_start(ap, fmt);
		ret = ctdb_event_script_v(ctdb, fmt, ap);
		va_end(ap);
		_exit(ret);
	}

	talloc_set_destructor(state, event_script_destructor);

	close(state->fd[1]);

	event_add_fd(ctdb->ev, state, state->fd[0], EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
		     ctdb_event_script_handler, state);

	if (!timeval_is_zero(&timeout)) {
		event_add_timed(ctdb->ev, state, timeout, ctdb_event_script_timeout, state);
	}

	return 0;
}