JavaScriptCore-903.5.tar.gz

[apple/javascriptcore.git] / wtf / RandomNumber.cpp

diff --git a/wtf/RandomNumber.cpp b/wtf/RandomNumber.cpp
index c94d5a4b900d697197d688bd34ad24108399ea66..490c5914a72373c30f63df4f4127c4bb72133be6 100644 (file)
--- a/wtf/RandomNumber.cpp
+++ b/wtf/RandomNumber.cpp
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
- *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
+ *           (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -27,6 +27,7 @@
 #include "config.h"
 #include "RandomNumber.h"
 
+#include "CryptographicallyRandomNumber.h"
 #include "RandomNumberSeed.h"
 
 #include <limits>
@@ -34,46 +35,53 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-namespace WTF {
+#if USE(MERSENNE_TWISTER_19937)
+extern "C" {
+#include "mt19937ar.c"
+}
+#endif
 
-double weakRandomNumber()
-{
-#if COMPILER(MSVC) && defined(_CRT_RAND_S)
-    // rand_s is incredibly slow on windows so we fall back on rand for Math.random
-    return (rand() + (rand() / (RAND_MAX + 1.0))) / (RAND_MAX + 1.0);
-#else
-    return randomNumber();
+#if PLATFORM(BREWMP)
+#include <AEEAppGen.h>
+#include <AEESource.h>
+#include <AEEStdLib.h>
+#include <wtf/brew/RefPtrBrew.h>
+#include <wtf/brew/ShellBrew.h>
 #endif
-}
+
+namespace WTF {
 
 double randomNumber()
 {
-#if !ENABLE(JSC_MULTIPLE_THREADS)
+#if USE(OS_RANDOMNESS)
+    uint32_t bits = cryptographicallyRandomNumber();
+    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
+#else
+    // Without OS_RANDOMNESS, we fall back to other random number generators
+    // that might not be cryptographically secure. Ideally, most ports would
+    // define USE(OS_RANDOMNESS).
+
+#if !ENABLE(WTF_MULTIPLE_THREADS)
     static bool s_initialized = false;
     if (!s_initialized) {
         initializeRandomNumberGenerator();
         s_initialized = true;
     }
 #endif
-    
-#if COMPILER(MSVC) && defined(_CRT_RAND_S)
+
+#if USE(MERSENNE_TWISTER_19937)
+    return genrand_res53();
+#elif PLATFORM(BREWMP)
     uint32_t bits;
-    rand_s(&bits);
-    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
-#elif PLATFORM(DARWIN)
-    uint32_t bits = arc4random();
-    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
-#elif PLATFORM(UNIX)
-    uint32_t part1 = random() & (RAND_MAX - 1);
-    uint32_t part2 = random() & (RAND_MAX - 1);
-    // random only provides 31 bits
-    uint64_t fullRandom = part1;
-    fullRandom <<= 31;
-    fullRandom |= part2;
+    // Is this a cryptographically strong source of random numbers? If so, we
+    // should move this into OSRandomSource.
+    // http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp851.pdf
+    // is slightly unclear on this point, although it seems to imply that it is
+    // secure.
+    RefPtr<ISource> randomSource = createRefPtrInstance<ISource>(AEECLSID_RANDOM);
+    ISOURCE_Read(randomSource.get(), reinterpret_cast<char*>(&bits), 4);
 
-    // Mask off the low 53bits
-    fullRandom &= (1LL << 53) - 1;
-    return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
+    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
 #else
     uint32_t part1 = rand() & (RAND_MAX - 1);
     uint32_t part2 = rand() & (RAND_MAX - 1);
@@ -89,6 +97,7 @@ double randomNumber()
     fullRandom &= (1LL << 53) - 1;
     return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
 #endif
+#endif
 }
 
 }