From 569c6676a6ddb0ff73821d7693b5e18ddef809b9 Mon Sep 17 00:00:00 2001
From: Hans-Christoph Steiner <hans@eds.org>
Date: Thu, 16 Oct 2014 22:51:35 -0400
Subject: Imported Upstream version 3.2.0

---
 src/random.c | 65 +++++++++++++++++++++---------------------------------------
 1 file changed, 23 insertions(+), 42 deletions(-)

(limited to 'src/random.c')

diff --git a/src/random.c b/src/random.c
index 234ebdf..b825665 100644
--- a/src/random.c
+++ b/src/random.c
@@ -28,24 +28,11 @@ static SQLITE_WSD struct sqlite3PrngType {
 } 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.
+** Return N random bytes.
 */
-static u8 randomByte(void){
+void sqlite3_randomness(int N, void *pBuf){
   unsigned char t;
-
+  unsigned char *zBuf = pBuf;
 
   /* The "wsdPrng" macro will resolve to the pseudo-random number generator
   ** state vector.  If writable static data is unsupported on the target,
@@ -60,6 +47,16 @@ static u8 randomByte(void){
 # 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
@@ -88,29 +85,16 @@ static u8 randomByte(void){
     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();
-  }
+  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);
 }
 
@@ -139,7 +123,4 @@ void sqlite3PrngRestoreState(void){
     sizeof(sqlite3Prng)
   );
 }
-void sqlite3PrngResetState(void){
-  GLOBAL(struct sqlite3PrngType, sqlite3Prng).isInit = 0;
-}
 #endif /* SQLITE_OMIT_BUILTIN_TEST */
-- 
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