// SPDX-License-Identifier: GPL-2.0-only
/*
 * Controller of read/write threads for virtio-trace
 *
 * Copyright (C) 2012 Hitachi, Ltd.
 * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
 *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 */

#define _GNU_SOURCE
#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "trace-agent.h"

#define HOST_MSG_SIZE           256
#define EVENT_WAIT_MSEC         100

static volatile sig_atomic_t global_signal_val;
bool global_sig_receive;        /* default false */
bool global_run_operation;      /* default false*/

/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
static void signal_handler(int sig)
{
        global_signal_val = sig;
}

int rw_ctl_init(const char *ctl_path)
{
        int ctl_fd;

        ctl_fd = open(ctl_path, O_RDONLY);
        if (ctl_fd == -1) {
                pr_err("Cannot open ctl_fd\n");
                goto error;
        }

        return ctl_fd;

error:
        exit(EXIT_FAILURE);
}

static int wait_order(int ctl_fd)
{
        struct pollfd poll_fd;
        int ret = 0;

        while (!global_sig_receive) {
                poll_fd.fd = ctl_fd;
                poll_fd.events = POLLIN;

                ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);

                if (global_signal_val) {
                        global_sig_receive = true;
                        pr_info("Receive interrupt %d\n", global_signal_val);

                        /* Wakes rw-threads when they are sleeping */
                        if (!global_run_operation)
                                pthread_cond_broadcast(&cond_wakeup);

                        ret = -1;
                        break;
                }

                if (ret < 0) {
                        pr_err("Polling error\n");
                        goto error;
                }

                if (ret)
                        break;
        }

        return ret;

error:
        exit(EXIT_FAILURE);
}

/*
 * contol read/write threads by handling global_run_operation
 */
void *rw_ctl_loop(int ctl_fd)
{
        ssize_t rlen;
        char buf[HOST_MSG_SIZE];
        int ret;

        /* Setup signal handlers */
        signal(SIGTERM, signal_handler);
        signal(SIGINT, signal_handler);
        signal(SIGQUIT, signal_handler);

        while (!global_sig_receive) {

                ret = wait_order(ctl_fd);
                if (ret < 0)
                        break;

                rlen = read(ctl_fd, buf, sizeof(buf));
                if (rlen < 0) {
                        pr_err("read data error in ctl thread\n");
                        goto error;
                }

                if (rlen == 2 && buf[0] == '1') {
                        /*
                         * If host writes '1' to a control path,
                         * this controller wakes all read/write threads.
                         */
                        global_run_operation = true;
                        pthread_cond_broadcast(&cond_wakeup);
                        pr_debug("Wake up all read/write threads\n");
                } else if (rlen == 2 && buf[0] == '0') {
                        /*
                         * If host writes '0' to a control path, read/write
                         * threads will wait for notification from Host.
                         */
                        global_run_operation = false;
                        pr_debug("Stop all read/write threads\n");
                } else
                        pr_info("Invalid host notification: %s\n", buf);
        }

        return NULL;

error:
        exit(EXIT_FAILURE);
}