| Index: third_party/sqlite/src/random.c
|
| ===================================================================
|
| --- third_party/sqlite/src/random.c (revision 56608)
|
| +++ third_party/sqlite/src/random.c (working copy)
|
| @@ -1,147 +0,0 @@
|
| -/*
|
| -** 2001 September 15
|
| -**
|
| -** The author disclaims copyright to this source code. In place of
|
| -** a legal notice, here is a blessing:
|
| -**
|
| -** May you do good and not evil.
|
| -** May you find forgiveness for yourself and forgive others.
|
| -** May you share freely, never taking more than you give.
|
| -**
|
| -*************************************************************************
|
| -** This file contains code to implement a pseudo-random number
|
| -** generator (PRNG) for SQLite.
|
| -**
|
| -** Random numbers are used by some of the database backends in order
|
| -** to generate random integer keys for tables or random filenames.
|
| -**
|
| -** $Id: random.c,v 1.29 2008/12/10 19:26:24 drh Exp $
|
| -*/
|
| -#include "sqliteInt.h"
|
| -
|
| -
|
| -/* All threads share a single random number generator.
|
| -** This structure is the current state of the generator.
|
| -*/
|
| -static SQLITE_WSD struct sqlite3PrngType {
|
| - unsigned char isInit; /* True if initialized */
|
| - unsigned char i, j; /* State variables */
|
| - unsigned char s[256]; /* State variables */
|
| -} sqlite3Prng;
|
| -
|
| -/*
|
| -** Get a single 8-bit random value from the RC4 PRNG. The Mutex
|
| -** must be held while executing this routine.
|
| -**
|
| -** Why not just use a library random generator like lrand48() for this?
|
| -** Because the OP_NewRowid opcode in the VDBE depends on having a very
|
| -** good source of random numbers. The lrand48() library function may
|
| -** well be good enough. But maybe not. Or maybe lrand48() has some
|
| -** subtle problems on some systems that could cause problems. It is hard
|
| -** to know. To minimize the risk of problems due to bad lrand48()
|
| -** implementations, SQLite uses this random number generator based
|
| -** on RC4, which we know works very well.
|
| -**
|
| -** (Later): Actually, OP_NewRowid does not depend on a good source of
|
| -** randomness any more. But we will leave this code in all the same.
|
| -*/
|
| -static u8 randomByte(void){
|
| - unsigned char t;
|
| -
|
| -
|
| - /* The "wsdPrng" macro will resolve to the pseudo-random number generator
|
| - ** state vector. If writable static data is unsupported on the target,
|
| - ** we have to locate the state vector at run-time. In the more common
|
| - ** case where writable static data is supported, wsdPrng can refer directly
|
| - ** to the "sqlite3Prng" state vector declared above.
|
| - */
|
| -#ifdef SQLITE_OMIT_WSD
|
| - struct sqlite3PrngType *p = &GLOBAL(struct sqlite3PrngType, sqlite3Prng);
|
| -# define wsdPrng p[0]
|
| -#else
|
| -# define wsdPrng sqlite3Prng
|
| -#endif
|
| -
|
| -
|
| - /* Initialize the state of the random number generator once,
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| - ** the first time this routine is called. The seed value does
|
| - ** not need to contain a lot of randomness since we are not
|
| - ** trying to do secure encryption or anything like that...
|
| - **
|
| - ** Nothing in this file or anywhere else in SQLite does any kind of
|
| - ** encryption. The RC4 algorithm is being used as a PRNG (pseudo-random
|
| - ** number generator) not as an encryption device.
|
| - */
|
| - if( !wsdPrng.isInit ){
|
| - int i;
|
| - char k[256];
|
| - wsdPrng.j = 0;
|
| - wsdPrng.i = 0;
|
| - sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
|
| - for(i=0; i<256; i++){
|
| - wsdPrng.s[i] = (u8)i;
|
| - }
|
| - for(i=0; i<256; i++){
|
| - wsdPrng.j += wsdPrng.s[i] + k[i];
|
| - t = wsdPrng.s[wsdPrng.j];
|
| - wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
|
| - wsdPrng.s[i] = t;
|
| - }
|
| - wsdPrng.isInit = 1;
|
| - }
|
| -
|
| - /* Generate and return single random byte
|
| - */
|
| - wsdPrng.i++;
|
| - t = wsdPrng.s[wsdPrng.i];
|
| - wsdPrng.j += t;
|
| - wsdPrng.s[wsdPrng.i] = wsdPrng.s[wsdPrng.j];
|
| - wsdPrng.s[wsdPrng.j] = t;
|
| - t += wsdPrng.s[wsdPrng.i];
|
| - return wsdPrng.s[t];
|
| -}
|
| -
|
| -/*
|
| -** Return N random bytes.
|
| -*/
|
| -void sqlite3_randomness(int N, void *pBuf){
|
| - unsigned char *zBuf = pBuf;
|
| -#if SQLITE_THREADSAFE
|
| - sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
|
| -#endif
|
| - sqlite3_mutex_enter(mutex);
|
| - while( N-- ){
|
| - *(zBuf++) = randomByte();
|
| - }
|
| - sqlite3_mutex_leave(mutex);
|
| -}
|
| -
|
| -#ifndef SQLITE_OMIT_BUILTIN_TEST
|
| -/*
|
| -** For testing purposes, we sometimes want to preserve the state of
|
| -** PRNG and restore the PRNG to its saved state at a later time, or
|
| -** to reset the PRNG to its initial state. These routines accomplish
|
| -** those tasks.
|
| -**
|
| -** The sqlite3_test_control() interface calls these routines to
|
| -** control the PRNG.
|
| -*/
|
| -static SQLITE_WSD struct sqlite3PrngType sqlite3SavedPrng;
|
| -void sqlite3PrngSaveState(void){
|
| - memcpy(
|
| - &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
|
| - &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
|
| - sizeof(sqlite3Prng)
|
| - );
|
| -}
|
| -void sqlite3PrngRestoreState(void){
|
| - memcpy(
|
| - &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
|
| - &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
|
| - sizeof(sqlite3Prng)
|
| - );
|
| -}
|
| -void sqlite3PrngResetState(void){
|
| - GLOBAL(struct sqlite3PrngType, sqlite3Prng).isInit = 0;
|
| -}
|
| -#endif /* SQLITE_OMIT_BUILTIN_TEST */
|
|
|