SQLite

Check-in [a221aa82bb]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Enhance sqlite3_randomness(N,P) such that it resets the internal PRNG if N is less than 1. Subsequent calls to sqlite3_randomness() will reinitialize the internal PRNG by calling the xRandomness() method of the default VFS.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: a221aa82bb5496885fd0bf76e4601443799511de
User & Date: drh 2014-01-01 14:00:13.905
References
2014-01-15
00:24
Merge recent fixes from trunk. Cherrypick of [c43b59dac1], [a221aa82bb], [e1eba1fb09], and [1e131094b5]. (check-in: c697d2f83c user: mistachkin tags: branch-3.8.2)
Context
2014-01-15
00:24
Merge recent fixes from trunk. Cherrypick of [c43b59dac1], [a221aa82bb], [e1eba1fb09], and [1e131094b5]. (check-in: c697d2f83c user: mistachkin tags: branch-3.8.2)
2014-01-01
15:18
Try to detect process ID changes due to fork() calls in os_unix.c and reset the PRNG when a process ID change is detected. (check-in: e1eba1fb09 user: drh tags: trunk)
14:00
Enhance sqlite3_randomness(N,P) such that it resets the internal PRNG if N is less than 1. Subsequent calls to sqlite3_randomness() will reinitialize the internal PRNG by calling the xRandomness() method of the default VFS. (check-in: a221aa82bb user: drh tags: trunk)
2013-12-24
12:04
Add -I. to the main.mk makefile for building sqlite3.o and speedtest1. (check-in: cc72c5aec7 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/main.c.
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111

    /*
    ** Reset the PRNG back to its uninitialized state.  The next call
    ** to sqlite3_randomness() will reseed the PRNG using a single call
    ** to the xRandomness method of the default VFS.
    */
    case SQLITE_TESTCTRL_PRNG_RESET: {
      sqlite3PrngResetState();
      break;
    }

    /*
    **  sqlite3_test_control(BITVEC_TEST, size, program)
    **
    ** Run a test against a Bitvec object of size.  The program argument







|







3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111

    /*
    ** Reset the PRNG back to its uninitialized state.  The next call
    ** to sqlite3_randomness() will reseed the PRNG using a single call
    ** to the xRandomness method of the default VFS.
    */
    case SQLITE_TESTCTRL_PRNG_RESET: {
      sqlite3_randomness(0,0);
      break;
    }

    /*
    **  sqlite3_test_control(BITVEC_TEST, size, program)
    **
    ** Run a test against a Bitvec object of size.  The program argument
Changes to src/random.c.
47
48
49
50
51
52
53






54
55
56
57
58
59
60
# define wsdPrng sqlite3Prng
#endif

#if SQLITE_THREADSAFE
  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
  sqlite3_mutex_enter(mutex);
#endif







  /* Initialize the state of the random number generator once,
  ** 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







>
>
>
>
>
>







47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
# define wsdPrng sqlite3Prng
#endif

#if SQLITE_THREADSAFE
  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PRNG);
  sqlite3_mutex_enter(mutex);
#endif

  if( N<=0 ){
    wsdPrng.isInit = 0;
    sqlite3_mutex_leave(mutex);
    return;
  }

  /* Initialize the state of the random number generator once,
  ** 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
75
76
77
78
79
80
81
82

83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
      t = wsdPrng.s[wsdPrng.j];
      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
      wsdPrng.s[i] = t;
    }
    wsdPrng.isInit = 1;
  }

  while( N-- ){

    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];
    *(zBuf++) = wsdPrng.s[t];
  }
  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







|
>







|







81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
      t = wsdPrng.s[wsdPrng.j];
      wsdPrng.s[wsdPrng.j] = wsdPrng.s[i];
      wsdPrng.s[i] = t;
    }
    wsdPrng.isInit = 1;
  }

  assert( N>0 );
  do{
    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];
    *(zBuf++) = wsdPrng.s[t];
  }while( --N );
  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
112
113
114
115
116
117
118
119
120
121
122
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 */







<
<
<

119
120
121
122
123
124
125



126
void sqlite3PrngRestoreState(void){
  memcpy(
    &GLOBAL(struct sqlite3PrngType, sqlite3Prng),
    &GLOBAL(struct sqlite3PrngType, sqlite3SavedPrng),
    sizeof(sqlite3Prng)
  );
}



#endif /* SQLITE_OMIT_BUILTIN_TEST */
Changes to src/sqlite.h.in.
2391
2392
2393
2394
2395
2396
2397

2398
2399
2400
2401

2402
2403
2404
2405
2406
2407
2408
2409
** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
** select random [ROWID | ROWIDs] when inserting new records into a table that
** already uses the largest possible [ROWID].  The PRNG is also used for
** the build-in random() and randomblob() SQL functions.  This interface allows
** applications to access the same PRNG for other purposes.
**
** ^A call to this routine stores N bytes of randomness into buffer P.

**
** ^The first time this routine is invoked (either internally or by
** the application) the PRNG is seeded using randomness obtained
** from the xRandomness method of the default [sqlite3_vfs] object.

** ^On all subsequent invocations, the pseudo-randomness is generated
** internally and without recourse to the [sqlite3_vfs] xRandomness
** method.
*/
void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks







>

|
|
|
>
|







2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
** select random [ROWID | ROWIDs] when inserting new records into a table that
** already uses the largest possible [ROWID].  The PRNG is also used for
** the build-in random() and randomblob() SQL functions.  This interface allows
** applications to access the same PRNG for other purposes.
**
** ^A call to this routine stores N bytes of randomness into buffer P.
** ^If N is less than one, then P can be a NULL pointer.
**
** ^If this routine has not been previously called or if the previous
** call had N less than one, then the PRNG is seeded using randomness
** obtained from the xRandomness method of the default [sqlite3_vfs] object.
** ^If the previous call to this routine had an N of 1 or more then
** the pseudo-randomness is generated
** internally and without recourse to the [sqlite3_vfs] xRandomness
** method.
*/
void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks
Changes to src/sqliteInt.h.
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
int sqlite3ExprImpliesExpr(Expr*, Expr*, int);
void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
int sqlite3FunctionUsesThisSrc(Expr*, SrcList*);
Vdbe *sqlite3GetVdbe(Parse*);
void sqlite3PrngSaveState(void);
void sqlite3PrngRestoreState(void);
void sqlite3PrngResetState(void);
void sqlite3RollbackAll(sqlite3*,int);
void sqlite3CodeVerifySchema(Parse*, int);
void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
void sqlite3BeginTransaction(Parse*, int);
void sqlite3CommitTransaction(Parse*);
void sqlite3RollbackTransaction(Parse*);
void sqlite3Savepoint(Parse*, int, Token*);







<







2968
2969
2970
2971
2972
2973
2974

2975
2976
2977
2978
2979
2980
2981
int sqlite3ExprImpliesExpr(Expr*, Expr*, int);
void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
int sqlite3FunctionUsesThisSrc(Expr*, SrcList*);
Vdbe *sqlite3GetVdbe(Parse*);
void sqlite3PrngSaveState(void);
void sqlite3PrngRestoreState(void);

void sqlite3RollbackAll(sqlite3*,int);
void sqlite3CodeVerifySchema(Parse*, int);
void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
void sqlite3BeginTransaction(Parse*, int);
void sqlite3CommitTransaction(Parse*);
void sqlite3RollbackTransaction(Parse*);
void sqlite3Savepoint(Parse*, int, Token*);