Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 76 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/wtf/RandomNumber.cpp b/Source/JavaScriptCore/wtf/RandomNumber.cpp
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+++ b/Source/JavaScriptCore/wtf/RandomNumber.cpp
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+/*
+ * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
+ *           (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
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#include "config.h"
+#include "RandomNumber.h"
+
+#include "CryptographicallyRandomNumber.h"
+#include "RandomNumberSeed.h"
+
+#include <limits>
+#include <limits.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#if USE(MERSENNE_TWISTER_19937)
+extern "C" {
+#include "mt19937ar.c"
+}
+#endif
+
+namespace WTF {
+
+double randomNumber()
+{
+#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 USE(MERSENNE_TWISTER_19937)
+    return genrand_res53();
+#else
+    uint32_t part1 = rand() & (RAND_MAX - 1);
+    uint32_t part2 = rand() & (RAND_MAX - 1);
+    // rand only provides 31 bits, and the low order bits of that aren't very random
+    // so we take the high 26 bits of part 1, and the high 27 bits of part2.
+    part1 >>= 5; // drop the low 5 bits
+    part2 >>= 4; // drop the low 4 bits
+    uint64_t fullRandom = part1;
+    fullRandom <<= 27;
+    fullRandom |= part2;
+
+    // Mask off the low 53bits
+    fullRandom &= (1LL << 53) - 1;
+    return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
+#endif
+#endif
+}
+
+}