ext/kgio/broken_system_compat.h

   1 /*
   2  * this header includes functions to support broken systems
   3  * without clock_gettime() or CLOCK_MONOTONIC
   4  */
   5
   6 #ifndef HAVE_TYPE_CLOCKID_T
   7 typedef int clockid_t;
   8 #endif
   9
  10 #ifndef HAVE_CLOCK_GETTIME
  11 #  ifndef CLOCK_REALTIME
  12 #    define CLOCK_REALTIME 0 /* whatever */
  13 #  endif
  14 static int fake_clock_gettime(clockid_t clk_id, struct timespec *res)
  15 {
  16         struct timeval tv;
  17         int r = gettimeofday(&tv, NULL);
  18
  19         assert(0 == r && "gettimeofday() broke!?");
  20         res->tv_sec = tv.tv_sec;
  21         res->tv_nsec = tv.tv_usec * 1000;
  22
  23         return r;
  24 }
  25 #  define clock_gettime fake_clock_gettime
  26 #endif /* broken systems w/o clock_gettime() */
  27
  28 /*
  29  * UGH
  30  * CLOCK_MONOTONIC is not guaranteed to be a macro, either
  31  */
  32 #ifndef CLOCK_MONOTONIC
  33 #  if (!defined(_POSIX_MONOTONIC_CLOCK) || !defined(HAVE_CLOCK_MONOTONIC))
  34 #    define CLOCK_MONOTONIC CLOCK_REALTIME
  35 #  endif
  36 #endif
  37
  38 /*
  39  * Availability of a monotonic clock needs to be detected at runtime
  40  * since we could've been built on a different system than we're run
  41  * under.
  42  */
  43 static clockid_t hopefully_CLOCK_MONOTONIC;
  44
  45 static int check_clock(void)
  46 {
  47         struct timespec now;
  48
  49         hopefully_CLOCK_MONOTONIC = CLOCK_MONOTONIC;
  50
  51         /* we can't check this reliably at compile time */
  52         if (clock_gettime(CLOCK_MONOTONIC, &now) == 0)
  53                 return 1;
  54
  55         if (clock_gettime(CLOCK_REALTIME, &now) == 0) {
  56                 hopefully_CLOCK_MONOTONIC = CLOCK_REALTIME;
  57                 rb_warn("CLOCK_MONOTONIC not available, "
  58                         "falling back to CLOCK_REALTIME");
  59                 return 2;
  60         }
  61         return -1;
  62 }