qnapd/signals.c

/***************************************************************************
 *   Copyright (C) 05/2009 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   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; version 2 of the License                *
 *                                                                         *
 *   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 <stdlib.h>
#include <unistd.h>

#include <fcntl.h>
#include <signal.h>

#include "event.h"
#include "list.h"
#include "logging.h"
#include "signals.h"

struct signal_entry {
	struct list_head list;
	int signum;
	int deleted;

	void (*callback)(void *privdata);
	void *privdata;
};

static LIST_HEAD(callback_list);
static int sig_pipe[2];

static void sig_handler(int signal)
{
	unsigned char signum = (signal & 0xFF);
	write(sig_pipe[1], &signum, 1);
}

int signal_remove_callback(int signum, int type)
{
	/* mark all old handler for deletion */
	struct signal_entry *search;
	list_for_each_entry(search, &callback_list, list) {
		if (search->signum == signum)
			search->deleted = 1;
	}

	struct sigaction sig_action;

	switch (type) {
	case SIG_IGNORE:
		sig_action.sa_handler = SIG_IGN;
		break;

	default:
	case SIG_DEFAULT:
		sig_action.sa_handler = SIG_DFL;
		break;
	}

	if (sigaction(signum, &sig_action, NULL) < 0) {
		log_print(LOG_WARN, "%s(): sigaction(%d)", __FUNCTION__, signum);
		return -1;
	}

	/* trigger remove */
	sig_handler(0);
	return 0;
}

int signal_add_callback(int signum, void (*callback)(void *privdata), void *privdata)
{
	struct signal_entry *entry = malloc(sizeof(struct signal_entry));
	if (entry == NULL) {
		log_print(LOG_WARN, "%s(): out of memory", __FUNCTION__);
		return -1;
	}

	entry->signum = signum;
	entry->deleted = 0;
	entry->callback = callback;
	entry->privdata = privdata;
	list_add_tail(&entry->list, &callback_list);

	struct sigaction sig_action = {
		.sa_handler = sig_handler,
	};

	if (sigaction(signum, &sig_action, NULL) < 0) {
		log_print(LOG_WARN, "%s(): sigaction(%d)", __FUNCTION__, signum);
		list_del(&entry->list);
		free(entry);
		return -1;
	}

	return 0;
}

static int sig_event(int fd, void *privdata)
{
	unsigned char signum;
	int len = read(fd, &signum, 1);
	if (len <= 0) {
		log_print(LOG_WARN, "%s(): read()", __FUNCTION__);
		return -1;
	}

	struct signal_entry *search, *tmp;
	list_for_each_entry_safe(search, tmp, &callback_list, list) {
		if (search->deleted) {
			list_del(&search->list);
			free(search);
			continue;
		}

		if (search->signum == signum)
			search->callback(search->privdata);
	}

	return 0;
}

int signal_init(void)
{
	if (pipe(sig_pipe) < 0) {
		log_print(LOG_ERROR, "%s(): pipe()", __FUNCTION__);
		return -1;
	}

	if (fcntl(sig_pipe[0], F_SETFD, FD_CLOEXEC) < 0) {
		log_print(LOG_WARN, "%s(): fcntl(FD_CLOEXEC)", __FUNCTION__);
		return -1;
	}

	if (fcntl(sig_pipe[1], F_SETFD, FD_CLOEXEC) < 0) {
		log_print(LOG_WARN, "%s(): fcntl(FD_CLOEXEC)", __FUNCTION__);
		return -1;
	}

	event_add_readfd(NULL, sig_pipe[0], sig_event, NULL);
	return 0;
}