external/ibm-public/postfix/dist/src/util/myrand.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      myrand 3
   6 /* SUMMARY
   7 /*      rand wrapper
   8 /* SYNOPSIS
   9 /*      #include <myrand.h>
  10 /*
  11 /*      void    mysrand(seed)
  12 /*      int     seed;
  13 /*
  14 /*      int     myrand()
  15 /* DESCRIPTION
  16 /*      This module implements a wrapper for the portable, pseudo-random
  17 /*      number generator. The wrapper adds automatic initialization.
  18 /*
  19 /*      mysrand() performs initialization. This call may be skipped.
  20 /*
  21 /*      myrand() returns a pseudo-random number in the range [0, RAND_MAX].
  22 /*      If mysrand() was not called, it is invoked with the process ID
  23 /*      ex-or-ed with the time of day in seconds.
  24 /* LICENSE
  25 /* .ad
  26 /* .fi
  27 /*      The Secure Mailer license must be distributed with this software.
  28 /* WARNING
  29 /*      Do not use this code for generating unpredictable numbers.
  30 /* AUTHOR(S)
  31 /*      Wietse Venema
  32 /*      IBM T.J. Watson Research
  33 /*      P.O. Box 704
  34 /*      Yorktown Heights, NY 10598, USA
  35 /*--*/
  36
  37 /* System library. */
  38
  39 #include <sys_defs.h>
  40 #include <stdlib.h>
  41 #include <unistd.h>
  42 #include <time.h>
  43
  44 /* Utility library. */
  45
  46 #include <myrand.h>
  47
  48 static int myrand_initdone = 0;
  49
  50 /* mysrand - initialize */
  51
  52 void    mysrand(int seed)
  53 {
  54     srand(seed);
  55     myrand_initdone = 1;
  56 }
  57
  58 /* myrand - pseudo-random number */
  59
  60 int     myrand(void)
  61 {
  62     if (myrand_initdone == 0)
  63         mysrand(getpid() ^ time((time_t *) 0));
  64     return (rand());
  65 }