summaryrefslogtreecommitdiff
path: root/mysys/my_rnd.c
blob: 1c8de9dd7a567db6c40546c4fbf2730e03203911 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
/* Copyright (C) 2007 MySQL AB & Michael Widenius

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "mysys_priv.h"
#include <my_rnd.h>
#include <m_string.h>

/*
  Initialize random generator

  NOTES
    MySQL's password checks depends on this, so don't do any changes
    that changes the random numbers that are generated!
*/

void my_rnd_init(struct my_rnd_struct *rand_st, ulong seed1, ulong seed2)
{
#ifdef HAVE_valgrind
  bzero((char*) rand_st,sizeof(*rand_st));      /* Avoid UMC varnings */
#endif
  rand_st->max_value= 0x3FFFFFFFL;
  rand_st->max_value_dbl=(double) rand_st->max_value;
  rand_st->seed1=seed1%rand_st->max_value ;
  rand_st->seed2=seed2%rand_st->max_value;
}


/*
  Generate random number.

  SYNOPSIS
    my_rnd()
    rand_st    INOUT  Structure used for number generation
    
  RETURN VALUE
    generated pseudo random number
*/

double my_rnd(struct my_rnd_struct *rand_st)
{
  rand_st->seed1=(rand_st->seed1*3+rand_st->seed2) % rand_st->max_value;
  rand_st->seed2=(rand_st->seed1+rand_st->seed2+33) % rand_st->max_value;
  return (((double) rand_st->seed1)/rand_st->max_value_dbl);
}


/**
  Generate a random number using the OpenSSL/yaSSL supplied
  random number generator if available.

  @param rand_st [INOUT] Structure used for number generation
                         only if none of the SSL libraries are
                         available.

  @retval                Generated random number.
*/

double my_rnd_ssl(struct my_rnd_struct *rand_st)
{

#if defined(HAVE_YASSL) || defined(HAVE_OPENSSL)
  int rc;
  unsigned int res;

#if defined(HAVE_YASSL)
  rc= yaSSL::RAND_bytes((unsigned char *) &res, sizeof (unsigned int));
#else
  rc= RAND_bytes((unsigned char *) &res, sizeof (unsigned int));
#endif /* HAVE_YASSL */

  if (rc)
    return (double)res / (double)UINT_MAX;
#endif /* defined(HAVE_YASSL) || defined(HAVE_OPENSSL) */

  return my_rnd(rand_st);
}

#ifdef __cplusplus
}
#endif