Documentation/laptops/freefall.c

   1 /* Disk protection for HP/DELL machines.
   2  *
   3  * Copyright 2008 Eric Piel
   4  * Copyright 2009 Pavel Machek <pavel@ucw.cz>
   5  * Copyright 2012 Sonal Santan
   6  * Copyright 2014 Pali Rohár <pali.rohar@gmail.com>
   7  *
   8  * GPLv2.
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <unistd.h>
  14 #include <fcntl.h>
  15 #include <sys/stat.h>
  16 #include <sys/types.h>
  17 #include <string.h>
  18 #include <stdint.h>
  19 #include <errno.h>
  20 #include <signal.h>
  21 #include <sys/mman.h>
  22 #include <sched.h>
  23 #include <syslog.h>
  24
  25 static int noled;
  26 static char unload_heads_path[64];
  27 static char device_path[32];
  28 static const char app_name[] = "FREE FALL";
  29
  30 static int set_unload_heads_path(char *device)
  31 {
  32         if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
  33                 return -EINVAL;
  34         strncpy(device_path, device, sizeof(device_path) - 1);
  35
  36         snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
  37                                 "/sys/block/%s/device/unload_heads", device+5);
  38         return 0;
  39 }
  40
  41 static int valid_disk(void)
  42 {
  43         int fd = open(unload_heads_path, O_RDONLY);
  44
  45         if (fd < 0) {
  46                 perror(unload_heads_path);
  47                 return 0;
  48         }
  49
  50         close(fd);
  51         return 1;
  52 }
  53
  54 static void write_int(char *path, int i)
  55 {
  56         char buf[1024];
  57         int fd = open(path, O_RDWR);
  58
  59         if (fd < 0) {
  60                 perror("open");
  61                 exit(1);
  62         }
  63
  64         sprintf(buf, "%d", i);
  65
  66         if (write(fd, buf, strlen(buf)) != strlen(buf)) {
  67                 perror("write");
  68                 exit(1);
  69         }
  70
  71         close(fd);
  72 }
  73
  74 static void set_led(int on)
  75 {
  76         if (noled)
  77                 return;
  78         write_int("/sys/class/leds/hp::hddprotect/brightness", on);
  79 }
  80
  81 static void protect(int seconds)
  82 {
  83         const char *str = (seconds == 0) ? "Unparked" : "Parked";
  84
  85         write_int(unload_heads_path, seconds*1000);
  86         syslog(LOG_INFO, "%s %s disk head\n", str, device_path);
  87 }
  88
  89 static int on_ac(void)
  90 {
  91         /* /sys/class/power_supply/AC0/online */
  92         return 1;
  93 }
  94
  95 static int lid_open(void)
  96 {
  97         /* /proc/acpi/button/lid/LID/state */
  98         return 1;
  99 }
 100
 101 static void ignore_me(int signum)
 102 {
 103         protect(0);
 104         set_led(0);
 105 }
 106
 107 int main(int argc, char **argv)
 108 {
 109         int fd, ret;
 110         struct stat st;
 111         struct sched_param param;
 112
 113         if (argc == 1)
 114                 ret = set_unload_heads_path("/dev/sda");
 115         else if (argc == 2)
 116                 ret = set_unload_heads_path(argv[1]);
 117         else
 118                 ret = -EINVAL;
 119
 120         if (ret || !valid_disk()) {
 121                 fprintf(stderr, "usage: %s <device> (default: /dev/sda)\n",
 122                                 argv[0]);
 123                 exit(1);
 124         }
 125
 126         fd = open("/dev/freefall", O_RDONLY);
 127         if (fd < 0) {
 128                 perror("/dev/freefall");
 129                 return EXIT_FAILURE;
 130         }
 131
 132         if (stat("/sys/class/leds/hp::hddprotect/brightness", &st))
 133                 noled = 1;
 134
 135         if (daemon(0, 0) != 0) {
 136                 perror("daemon");
 137                 return EXIT_FAILURE;
 138         }
 139
 140         openlog(app_name, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
 141
 142         param.sched_priority = sched_get_priority_max(SCHED_FIFO);
 143         sched_setscheduler(0, SCHED_FIFO, &param);
 144         mlockall(MCL_CURRENT|MCL_FUTURE);
 145
 146         signal(SIGALRM, ignore_me);
 147
 148         for (;;) {
 149                 unsigned char count;
 150
 151                 ret = read(fd, &count, sizeof(count));
 152                 alarm(0);
 153                 if ((ret == -1) && (errno == EINTR)) {
 154                         /* Alarm expired, time to unpark the heads */
 155                         continue;
 156                 }
 157
 158                 if (ret != sizeof(count)) {
 159                         perror("read");
 160                         break;
 161                 }
 162
 163                 protect(21);
 164                 set_led(1);
 165                 if (1 || on_ac() || lid_open())
 166                         alarm(2);
 167                 else
 168                         alarm(20);
 169         }
 170
 171         closelog();
 172         close(fd);
 173         return EXIT_SUCCESS;
 174 }