// SPDX-License-Identifier: GPL-2.0-only
/* Disk protection for HP/DELL machines.
 *
 * Copyright 2008 Eric Piel
 * Copyright 2009 Pavel Machek <pavel@ucw.cz>
 * Copyright 2012 Sonal Santan
 * Copyright 2014 Pali Rohár <pali@kernel.org>
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <signal.h>
#include <sys/mman.h>
#include <sched.h>
#include <syslog.h>

static int noled;
static char unload_heads_path[64];
static char device_path[32];
static const char app_name[] = "FREE FALL";

static int set_unload_heads_path(char *device)
{
        if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
                return -EINVAL;
        strncpy(device_path, device, sizeof(device_path) - 1);

        snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
                                "/sys/block/%s/device/unload_heads", device+5);
        return 0;
}

static int valid_disk(void)
{
        int fd = open(unload_heads_path, O_RDONLY);

        if (fd < 0) {
                perror(unload_heads_path);
                return 0;
        }

        close(fd);
        return 1;
}

static void write_int(char *path, int i)
{
        char buf[1024];
        int fd = open(path, O_RDWR);

        if (fd < 0) {
                perror("open");
                exit(1);
        }

        sprintf(buf, "%d", i);

        if (write(fd, buf, strlen(buf)) != strlen(buf)) {
                perror("write");
                exit(1);
        }

        close(fd);
}

static void set_led(int on)
{
        if (noled)
                return;
        write_int("/sys/class/leds/hp::hddprotect/brightness", on);
}

static void protect(int seconds)
{
        const char *str = (seconds == 0) ? "Unparked" : "Parked";

        write_int(unload_heads_path, seconds*1000);
        syslog(LOG_INFO, "%s %s disk head\n", str, device_path);
}

static int on_ac(void)
{
        /* /sys/class/power_supply/AC0/online */
        return 1;
}

static int lid_open(void)
{
        /* /proc/acpi/button/lid/LID/state */
        return 1;
}

static void ignore_me(int signum)
{
        protect(0);
        set_led(0);
}

int main(int argc, char **argv)
{
        int fd, ret;
        struct stat st;
        struct sched_param param;

        if (argc == 1)
                ret = set_unload_heads_path("/dev/sda");
        else if (argc == 2)
                ret = set_unload_heads_path(argv[1]);
        else
                ret = -EINVAL;

        if (ret || !valid_disk()) {
                fprintf(stderr, "usage: %s <device> (default: /dev/sda)\n",
                                argv[0]);
                exit(1);
        }

        fd = open("/dev/freefall", O_RDONLY);
        if (fd < 0) {
                perror("/dev/freefall");
                return EXIT_FAILURE;
        }

        if (stat("/sys/class/leds/hp::hddprotect/brightness", &st))
                noled = 1;

        if (daemon(0, 0) != 0) {
                perror("daemon");
                return EXIT_FAILURE;
        }

        openlog(app_name, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);

        param.sched_priority = sched_get_priority_max(SCHED_FIFO);
        sched_setscheduler(0, SCHED_FIFO, &param);
        mlockall(MCL_CURRENT|MCL_FUTURE);

        signal(SIGALRM, ignore_me);

        for (;;) {
                unsigned char count;

                ret = read(fd, &count, sizeof(count));
                alarm(0);
                if ((ret == -1) && (errno == EINTR)) {
                        /* Alarm expired, time to unpark the heads */
                        continue;
                }

                if (ret != sizeof(count)) {
                        perror("read");
                        break;
                }

                protect(21);
                set_led(1);
                if (1 || on_ac() || lid_open())
                        alarm(2);
                else
                        alarm(20);
        }

        closelog();
        close(fd);
        return EXIT_SUCCESS;
}