mainloop.c

/*
 * Power debug tool (powerdebug)
 *
 * Copyright (C) 2016, Linaro Limited.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/epoll.h>
#include "mainloop.h"

static int epfd = -1;
static unsigned short nrhandler;

struct mainloop_data {
	mainloop_callback_t cb;
	void *data;
	int fd;
};

struct mainloop_data **mds;

#define MAX_EVENTS 10

int mainloop(unsigned int timeout)
{
        int i, nfds;
        struct epoll_event events[MAX_EVENTS];
	struct mainloop_data *md;

	if (epfd < 0)
		return -1;

	for (;;) {

                nfds = epoll_wait(epfd, events, MAX_EVENTS, timeout);
                if (nfds < 0) {
                        if (errno == EINTR)
                                continue;
                        return -1;
                }

		/* 
		 * A timeout occured. Let's send to ourself a SIGWINCH
		 * so the window get refreshed automatically. No need
		 * to use exported functions and this code stay self
		 * contained.
		 */
		if (!nfds) {
			kill(getpid(), SIGWINCH);
			continue;
		}

                for (i = 0; i < nfds; i++) {
			md = events[i].data.ptr;

			if (md->cb(md->fd, md->data) > 0)
				return 0;
		}

	}
}

int mainloop_add(int fd, mainloop_callback_t cb, void *data)
{
	struct epoll_event ev = {
		.events = EPOLLIN,
	};

	struct mainloop_data *md;

	if (fd >= nrhandler) {
		mds = realloc(mds, sizeof(*mds) * (fd + 1));
		if (!mds)
			return -1;
		nrhandler = fd + 1;
	}

	md = malloc(sizeof(*md));
	if (!md)
		return -1;

	md->data = data;
	md->cb = cb;
	md->fd = fd;

	mds[fd] = md;
	ev.data.ptr = md;

        if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev) < 0) {
		free(md);
		return -1;
	}

	return 0;
}

int mainloop_del(int fd)
{
	if (fd >= nrhandler)
		return -1;

        if (epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL) < 0)
		return -1;

	free(mds[fd]);

	return 0;
}

int mainloop_init(void)
{
        epfd = epoll_create(2);
        if (epfd < 0)
                return -1;

        return 0;
}

void mainloop_fini(void)
{
	close(epfd);
}