lib/nanosleep.c

   1 /* Provide a replacement for the POSIX nanosleep function.
   2
   3    Copyright (C) 1999-2000, 2002, 2004-2020 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* written by Jim Meyering
  19    and Bruno Haible for the native Windows part */
  20
  21 #include <config.h>
  22
  23 #include <time.h>
  24
  25 #include "intprops.h"
  26 #include "sig-handler.h"
  27 #include "verify.h"
  28
  29 #include <stdbool.h>
  30 #include <stdio.h>
  31 #include <sys/types.h>
  32 #include <sys/select.h>
  33 #include <signal.h>
  34
  35 #include <sys/time.h>
  36 #include <errno.h>
  37
  38 #include <unistd.h>
  39
  40
  41 enum { BILLION = 1000 * 1000 * 1000 };
  42
  43 #if HAVE_BUG_BIG_NANOSLEEP
  44
  45 int
  46 nanosleep (const struct timespec *requested_delay,
  47            struct timespec *remaining_delay)
  48 # undef nanosleep
  49 {
  50   /* nanosleep mishandles large sleeps due to internal overflow problems.
  51      The worst known case of this is Linux 2.6.9 with glibc 2.3.4, which
  52      can't sleep more than 24.85 days (2^31 milliseconds).  Similarly,
  53      cygwin 1.5.x, which can't sleep more than 49.7 days (2^32 milliseconds).
  54      Solve this by breaking the sleep up into smaller chunks.  */
  55
  56   if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
  57     {
  58       errno = EINVAL;
  59       return -1;
  60     }
  61
  62   {
  63     /* Verify that time_t is large enough.  */
  64     verify (TYPE_MAXIMUM (time_t) / 24 / 24 / 60 / 60);
  65     const time_t limit = 24 * 24 * 60 * 60;
  66     time_t seconds = requested_delay->tv_sec;
  67     struct timespec intermediate;
  68     intermediate.tv_nsec = requested_delay->tv_nsec;
  69
  70     while (limit < seconds)
  71       {
  72         int result;
  73         intermediate.tv_sec = limit;
  74         result = nanosleep (&intermediate, remaining_delay);
  75         seconds -= limit;
  76         if (result)
  77           {
  78             if (remaining_delay)
  79               remaining_delay->tv_sec += seconds;
  80             return result;
  81           }
  82         intermediate.tv_nsec = 0;
  83       }
  84     intermediate.tv_sec = seconds;
  85     return nanosleep (&intermediate, remaining_delay);
  86   }
  87 }
  88
  89 #elif defined _WIN32 && ! defined __CYGWIN__
  90 /* Native Windows platforms.  */
  91
  92 # define WIN32_LEAN_AND_MEAN
  93 # include <windows.h>
  94
  95 /* The Windows API function Sleep() has a resolution of about 15 ms and takes
  96    at least 5 ms to execute.  We use this function for longer time periods.
  97    Additionally, we use busy-looping over short time periods, to get a
  98    resolution of about 0.01 ms.  In order to measure such short timespans,
  99    we use the QueryPerformanceCounter() function.  */
 100
 101 int
 102 nanosleep (const struct timespec *requested_delay,
 103            struct timespec *remaining_delay)
 104 {
 105   static bool initialized;
 106   /* Number of performance counter increments per nanosecond,
 107      or zero if it could not be determined.  */
 108   static double ticks_per_nanosecond;
 109
 110   if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
 111     {
 112       errno = EINVAL;
 113       return -1;
 114     }
 115
 116   /* For requested delays of one second or more, 15ms resolution is
 117      sufficient.  */
 118   if (requested_delay->tv_sec == 0)
 119     {
 120       if (!initialized)
 121         {
 122           /* Initialize ticks_per_nanosecond.  */
 123           LARGE_INTEGER ticks_per_second;
 124
 125           if (QueryPerformanceFrequency (&ticks_per_second))
 126             ticks_per_nanosecond =
 127               (double) ticks_per_second.QuadPart / 1000000000.0;
 128
 129           initialized = true;
 130         }
 131       if (ticks_per_nanosecond)
 132         {
 133           /* QueryPerformanceFrequency worked.  We can use
 134              QueryPerformanceCounter.  Use a combination of Sleep and
 135              busy-looping.  */
 136           /* Number of milliseconds to pass to the Sleep function.
 137              Since Sleep can take up to 8 ms less or 8 ms more than requested
 138              (or maybe more if the system is loaded), we subtract 10 ms.  */
 139           int sleep_millis = (int) requested_delay->tv_nsec / 1000000 - 10;
 140           /* Determine how many ticks to delay.  */
 141           LONGLONG wait_ticks = requested_delay->tv_nsec * ticks_per_nanosecond;
 142           /* Start.  */
 143           LARGE_INTEGER counter_before;
 144           if (QueryPerformanceCounter (&counter_before))
 145             {
 146               /* Wait until the performance counter has reached this value.
 147                  We don't need to worry about overflow, because the performance
 148                  counter is reset at reboot, and with a frequency of 3.6E6
 149                  ticks per second 63 bits suffice for over 80000 years.  */
 150               LONGLONG wait_until = counter_before.QuadPart + wait_ticks;
 151               /* Use Sleep for the longest part.  */
 152               if (sleep_millis > 0)
 153                 Sleep (sleep_millis);
 154               /* Busy-loop for the rest.  */
 155               for (;;)
 156                 {
 157                   LARGE_INTEGER counter_after;
 158                   if (!QueryPerformanceCounter (&counter_after))
 159                     /* QueryPerformanceCounter failed, but succeeded earlier.
 160                        Should not happen.  */
 161                     break;
 162                   if (counter_after.QuadPart >= wait_until)
 163                     /* The requested time has elapsed.  */
 164                     break;
 165                 }
 166               goto done;
 167             }
 168         }
 169     }
 170   /* Implementation for long delays and as fallback.  */
 171   Sleep (requested_delay->tv_sec * 1000 + requested_delay->tv_nsec / 1000000);
 172
 173  done:
 174   /* Sleep is not interruptible.  So there is no remaining delay.  */
 175   if (remaining_delay != NULL)
 176     {
 177       remaining_delay->tv_sec = 0;
 178       remaining_delay->tv_nsec = 0;
 179     }
 180   return 0;
 181 }
 182
 183 #else
 184 /* Unix platforms lacking nanosleep. */
 185
 186 /* Some systems (MSDOS) don't have SIGCONT.
 187    Using SIGTERM here turns the signal-handling code below
 188    into a no-op on such systems. */
 189 # ifndef SIGCONT
 190 #  define SIGCONT SIGTERM
 191 # endif
 192
 193 static sig_atomic_t volatile suspended;
 194
 195 /* Handle SIGCONT. */
 196
 197 static _GL_ASYNC_SAFE void
 198 sighandler (int sig)
 199 {
 200   suspended = 1;
 201 }
 202
 203 /* Suspend execution for at least *TS_DELAY seconds.  */
 204
 205 static int
 206 my_usleep (const struct timespec *ts_delay)
 207 {
 208   struct timeval tv_delay;
 209   tv_delay.tv_sec = ts_delay->tv_sec;
 210   tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
 211   if (tv_delay.tv_usec == 1000000)
 212     {
 213       if (tv_delay.tv_sec == TYPE_MAXIMUM (time_t))
 214         tv_delay.tv_usec = 1000000 - 1; /* close enough */
 215       else
 216         {
 217           tv_delay.tv_sec++;
 218           tv_delay.tv_usec = 0;
 219         }
 220     }
 221   return select (0, NULL, NULL, NULL, &tv_delay);
 222 }
 223
 224 /* Suspend execution for at least *REQUESTED_DELAY seconds.  The
 225    *REMAINING_DELAY part isn't implemented yet.  */
 226
 227 int
 228 nanosleep (const struct timespec *requested_delay,
 229            struct timespec *remaining_delay)
 230 {
 231   static bool initialized;
 232
 233   if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
 234     {
 235       errno = EINVAL;
 236       return -1;
 237     }
 238
 239   /* set up sig handler */
 240   if (! initialized)
 241     {
 242       struct sigaction oldact;
 243
 244       sigaction (SIGCONT, NULL, &oldact);
 245       if (get_handler (&oldact) != SIG_IGN)
 246         {
 247           struct sigaction newact;
 248
 249           newact.sa_handler = sighandler;
 250           sigemptyset (&newact.sa_mask);
 251           newact.sa_flags = 0;
 252           sigaction (SIGCONT, &newact, NULL);
 253         }
 254       initialized = true;
 255     }
 256
 257   suspended = 0;
 258
 259   if (my_usleep (requested_delay) == -1)
 260     {
 261       if (suspended)
 262         {
 263           /* Calculate time remaining.  */
 264           /* FIXME: the code in sleep doesn't use this, so there's no
 265              rush to implement it.  */
 266
 267           errno = EINTR;
 268         }
 269       return -1;
 270     }
 271
 272   /* FIXME: Restore sig handler?  */
 273
 274   return 0;
 275 }
 276 #endif