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         devname[sizeof(devname) - 1] = '\0';
  38         strncpy(device_path, device, sizeof(device_path) - 1);
  39
  40         snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
  41                                 "/sys/block/%s/device/unload_heads", devname);
  42         return 0;
  43 }
  44
  45 static int valid_disk(void)
  46 {
  47         int fd = open(unload_heads_path, O_RDONLY);
  48
  49         if (fd < 0) {
  50                 perror(unload_heads_path);
  51                 return 0;
  52         }
  53
  54         close(fd);
  55         return 1;
  56 }
  57
  58 static void write_int(char *path, int i)
  59 {
  60         char buf[1024];
  61         int fd = open(path, O_RDWR);
  62
  63         if (fd < 0) {
  64                 perror("open");
  65                 exit(1);
  66         }
  67
  68         sprintf(buf, "%d", i);
  69
  70         if (write(fd, buf, strlen(buf)) != strlen(buf)) {
  71                 perror("write");
  72                 exit(1);
  73         }
  74
  75         close(fd);
  76 }
  77
  78 static void set_led(int on)
  79 {
  80         if (noled)
  81                 return;
  82         write_int("/sys/class/leds/hp::hddprotect/brightness", on);
  83 }
  84
  85 static void protect(int seconds)
  86 {
  87         const char *str = (seconds == 0) ? "Unparked" : "Parked";
  88
  89         write_int(unload_heads_path, seconds*1000);
  90         syslog(LOG_INFO, "%s %s disk head\n", str, device_path);
  91 }
  92
  93 static int on_ac(void)
  94 {
  95         /* /sys/class/power_supply/AC0/online */
  96         return 1;
  97 }
  98
  99 static int lid_open(void)
 100 {
 101         /* /proc/acpi/button/lid/LID/state */
 102         return 1;
 103 }
 104
 105 static void ignore_me(int signum)
 106 {
 107         protect(0);
 108         set_led(0);
 109 }
 110
 111 int main(int argc, char **argv)
 112 {
 113         int fd, ret;
 114         struct stat st;
 115         struct sched_param param;
 116
 117         if (argc == 1)
 118                 ret = set_unload_heads_path("/dev/sda");
 119         else if (argc == 2)
 120                 ret = set_unload_heads_path(argv[1]);
 121         else
 122                 ret = -EINVAL;
 123
 124         if (ret || !valid_disk()) {
 125                 fprintf(stderr, "usage: %s <device> (default: /dev/sda)\n",
 126                                 argv[0]);
 127                 exit(1);
 128         }
 129
 130         fd = open("/dev/freefall", O_RDONLY);
 131         if (fd < 0) {
 132                 perror("/dev/freefall");
 133                 return EXIT_FAILURE;
 134         }
 135
 136         if (stat("/sys/class/leds/hp::hddprotect/brightness", &st))
 137                 noled = 1;
 138
 139         if (daemon(0, 0) != 0) {
 140                 perror("daemon");
 141                 return EXIT_FAILURE;
 142         }
 143
 144         openlog(app_name, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
 145
 146         param.sched_priority = sched_get_priority_max(SCHED_FIFO);
 147         sched_setscheduler(0, SCHED_FIFO, &param);
 148         mlockall(MCL_CURRENT|MCL_FUTURE);
 149
 150         signal(SIGALRM, ignore_me);
 151
 152         for (;;) {
 153                 unsigned char count;
 154
 155                 ret = read(fd, &count, sizeof(count));
 156                 alarm(0);
 157                 if ((ret == -1) && (errno == EINTR)) {
 158                         /* Alarm expired, time to unpark the heads */
 159                         continue;
 160                 }
 161
 162                 if (ret != sizeof(count)) {
 163                         perror("read");
 164                         break;
 165                 }
 166
 167                 protect(21);
 168                 set_led(1);
 169                 if (1 || on_ac() || lid_open())
 170                         alarm(2);
 171                 else
 172                         alarm(20);
 173         }
 174
 175         closelog();
 176         close(fd);
 177         return EXIT_SUCCESS;
 178 }