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         char devname[64];
  33
  34         if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
  35                 return -EINVAL;
  36         strncpy(devname, device + 5, sizeof(devname) - 1);
  37         strncpy(device_path, device, sizeof(device_path) - 1);
  38
  39         snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
  40                                 "/sys/block/%s/device/unload_heads", devname);
  41         return 0;
  42 }
  43
  44 static int valid_disk(void)
  45 {
  46         int fd = open(unload_heads_path, O_RDONLY);
  47
  48         if (fd < 0) {
  49                 perror(unload_heads_path);
  50                 return 0;
  51         }
  52
  53         close(fd);
  54         return 1;
  55 }
  56
  57 static void write_int(char *path, int i)
  58 {
  59         char buf[1024];
  60         int fd = open(path, O_RDWR);
  61
  62         if (fd < 0) {
  63                 perror("open");
  64                 exit(1);
  65         }
  66
  67         sprintf(buf, "%d", i);
  68
  69         if (write(fd, buf, strlen(buf)) != strlen(buf)) {
  70                 perror("write");
  71                 exit(1);
  72         }
  73
  74         close(fd);
  75 }
  76
  77 static void set_led(int on)
  78 {
  79         if (noled)
  80                 return;
  81         write_int("/sys/class/leds/hp::hddprotect/brightness", on);
  82 }
  83
  84 static void protect(int seconds)
  85 {
  86         const char *str = (seconds == 0) ? "Unparked" : "Parked";
  87
  88         write_int(unload_heads_path, seconds*1000);
  89         syslog(LOG_INFO, "%s %s disk head\n", str, device_path);
  90 }
  91
  92 static int on_ac(void)
  93 {
  94         /* /sys/class/power_supply/AC0/online */
  95         return 1;
  96 }
  97
  98 static int lid_open(void)
  99 {
 100         /* /proc/acpi/button/lid/LID/state */
 101         return 1;
 102 }
 103
 104 static void ignore_me(int signum)
 105 {
 106         protect(0);
 107         set_led(0);
 108 }
 109
 110 int main(int argc, char **argv)
 111 {
 112         int fd, ret;
 113         struct stat st;
 114         struct sched_param param;
 115
 116         if (argc == 1)
 117                 ret = set_unload_heads_path("/dev/sda");
 118         else if (argc == 2)
 119                 ret = set_unload_heads_path(argv[1]);
 120         else
 121                 ret = -EINVAL;
 122
 123         if (ret || !valid_disk()) {
 124                 fprintf(stderr, "usage: %s <device> (default: /dev/sda)\n",
 125                                 argv[0]);
 126                 exit(1);
 127         }
 128
 129         fd = open("/dev/freefall", O_RDONLY);
 130         if (fd < 0) {
 131                 perror("/dev/freefall");
 132                 return EXIT_FAILURE;
 133         }
 134
 135         if (stat("/sys/class/leds/hp::hddprotect/brightness", &st))
 136                 noled = 1;
 137
 138         if (daemon(0, 0) != 0) {
 139                 perror("daemon");
 140                 return EXIT_FAILURE;
 141         }
 142
 143         openlog(app_name, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
 144
 145         param.sched_priority = sched_get_priority_max(SCHED_FIFO);
 146         sched_setscheduler(0, SCHED_FIFO, &param);
 147         mlockall(MCL_CURRENT|MCL_FUTURE);
 148
 149         signal(SIGALRM, ignore_me);
 150
 151         for (;;) {
 152                 unsigned char count;
 153
 154                 ret = read(fd, &count, sizeof(count));
 155                 alarm(0);
 156                 if ((ret == -1) && (errno == EINTR)) {
 157                         /* Alarm expired, time to unpark the heads */
 158                         continue;
 159                 }
 160
 161                 if (ret != sizeof(count)) {
 162                         perror("read");
 163                         break;
 164                 }
 165
 166                 protect(21);
 167                 set_led(1);
 168                 if (1 || on_ac() || lid_open())
 169                         alarm(2);
 170                 else
 171                         alarm(20);
 172         }
 173
 174         closelog();
 175         close(fd);
 176         return EXIT_SUCCESS;
 177 }