lib/maxfd.c

   1 #include "./maxfd.h"
   2 #include <errno.h>
   3
   4 long mp_open_max(void) {
   5         long maxfd = 0L;
   6         /* Try sysconf(_SC_OPEN_MAX) first, as it can be higher than OPEN_MAX.
   7          * If that fails and the macro isn't defined, we fall back to an educated
   8          * guess. There's no guarantee that our guess is adequate and the program
   9          * will die with SIGSEGV if it isn't and the upper boundary is breached. */
  10
  11 #ifdef _SC_OPEN_MAX
  12         errno = 0;
  13         if ((maxfd = sysconf(_SC_OPEN_MAX)) < 0) {
  14                 if (errno == 0)
  15                         maxfd = DEFAULT_MAXFD; /* it's indeterminate */
  16                 else
  17                         die(STATE_UNKNOWN, _("sysconf error for _SC_OPEN_MAX\n"));
  18         }
  19 #elif defined(OPEN_MAX)
  20         return OPEN_MAX
  21 #else /* sysconf macro unavailable, so guess (may be wildly inaccurate) */
  22         return DEFAULT_MAXFD;
  23 #endif
  24
  25         return (maxfd);
  26 }