1.1 --- a/extensions/sqlite/sqlite-source/random.c	Fri Jul 11 06:51:21 2008 +0000
     1.2 +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.3 @@ -1,103 +0,0 @@
     1.4 -/*
     1.5 -** 2001 September 15
     1.6 -**
     1.7 -** The author disclaims copyright to this source code.  In place of
     1.8 -** a legal notice, here is a blessing:
     1.9 -**
    1.10 -**    May you do good and not evil.
    1.11 -**    May you find forgiveness for yourself and forgive others.
    1.12 -**    May you share freely, never taking more than you give.
    1.13 -**
    1.14 -*************************************************************************
    1.15 -** This file contains code to implement a pseudo-random number
    1.16 -** generator (PRNG) for SQLite.
    1.17 -**
    1.18 -** Random numbers are used by some of the database backends in order
    1.19 -** to generate random integer keys for tables or random filenames.
    1.20 -**
    1.21 -** $Id$
    1.22 -*/
    1.23 -#include "sqliteInt.h"
    1.24 -
    1.25 -
    1.26 -/*
    1.27 -** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
    1.28 -** must be held while executing this routine.
    1.29 -**
    1.30 -** Why not just use a library random generator like lrand48() for this?
    1.31 -** Because the OP_NewRowid opcode in the VDBE depends on having a very
    1.32 -** good source of random numbers.  The lrand48() library function may
    1.33 -** well be good enough.  But maybe not.  Or maybe lrand48() has some
    1.34 -** subtle problems on some systems that could cause problems.  It is hard
    1.35 -** to know.  To minimize the risk of problems due to bad lrand48()
    1.36 -** implementations, SQLite uses this random number generator based
    1.37 -** on RC4, which we know works very well.
    1.38 -**
    1.39 -** (Later):  Actually, OP_NewRowid does not depend on a good source of
    1.40 -** randomness any more.  But we will leave this code in all the same.
    1.41 -*/
    1.42 -static int randomByte(void){
    1.43 -  unsigned char t;
    1.44 -
    1.45 -  /* All threads share a single random number generator.
    1.46 -  ** This structure is the current state of the generator.
    1.47 -  */
    1.48 -  static struct {
    1.49 -    unsigned char isInit;          /* True if initialized */
    1.50 -    unsigned char i, j;            /* State variables */
    1.51 -    unsigned char s[256];          /* State variables */
    1.52 -  } prng;
    1.53 -
    1.54 -  /* Initialize the state of the random number generator once,
    1.55 -  ** the first time this routine is called.  The seed value does
    1.56 -  ** not need to contain a lot of randomness since we are not
    1.57 -  ** trying to do secure encryption or anything like that...
    1.58 -  **
    1.59 -  ** Nothing in this file or anywhere else in SQLite does any kind of
    1.60 -  ** encryption.  The RC4 algorithm is being used as a PRNG (pseudo-random
    1.61 -  ** number generator) not as an encryption device.
    1.62 -  */
    1.63 -  if( !prng.isInit ){
    1.64 -    int i;
    1.65 -    char k[256];
    1.66 -    prng.j = 0;
    1.67 -    prng.i = 0;
    1.68 -    sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
    1.69 -    for(i=0; i<256; i++){
    1.70 -      prng.s[i] = i;
    1.71 -    }
    1.72 -    for(i=0; i<256; i++){
    1.73 -      prng.j += prng.s[i] + k[i];
    1.74 -      t = prng.s[prng.j];
    1.75 -      prng.s[prng.j] = prng.s[i];
    1.76 -      prng.s[i] = t;
    1.77 -    }
    1.78 -    prng.isInit = 1;
    1.79 -  }
    1.80 -
    1.81 -  /* Generate and return single random byte
    1.82 -  */
    1.83 -  prng.i++;
    1.84 -  t = prng.s[prng.i];
    1.85 -  prng.j += t;
    1.86 -  prng.s[prng.i] = prng.s[prng.j];
    1.87 -  prng.s[prng.j] = t;
    1.88 -  t += prng.s[prng.i];
    1.89 -  return prng.s[t];
    1.90 -}
    1.91 -
    1.92 -/*
    1.93 -** Return N random bytes.
    1.94 -*/
    1.95 -void sqlite3Randomness(int N, void *pBuf){
    1.96 -  unsigned char *zBuf = pBuf;
    1.97 -  static sqlite3_mutex *mutex = 0;
    1.98 -  if( mutex==0 ){
    1.99 -    mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PRNG);
   1.100 -  }
   1.101 -  sqlite3_mutex_enter(mutex);
   1.102 -  while( N-- ){
   1.103 -    *(zBuf++) = randomByte();
   1.104 -  }
   1.105 -  sqlite3_mutex_leave(mutex);
   1.106 -}