Split random code from fx_extension.h

This CL moves the code invovled in random number generation into
fx_rand.h from fx_extension.h.

Change-Id: I6c644d7ec0323f32ef6e23c2e2548a9c792e3a72
Reviewed-on: https://pdfium-review.googlesource.com/13070
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 141 insertions, 0 deletions

diff --git a/core/fxcrt/fx_rand.cpp b/core/fxcrt/fx_rand.cpp
new file mode 100644
index 0000000000..7a0c3e4d9b
--- /dev/null
+++ b/core/fxcrt/fx_rand.cpp
@@ -0,0 +1,141 @@
+// Copyright 2017 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "core/fxcrt/fx_rand.h"
+
+#include "core/fxcrt/fx_memory.h"
+#include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/fx_system.h"
+
+#define MT_N 848
+#define MT_M 456
+#define MT_Matrix_A 0x9908b0df
+#define MT_Upper_Mask 0x80000000
+#define MT_Lower_Mask 0x7fffffff
+
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+#include <wincrypt.h>
+#else  // _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+#include <ctime>
+#endif  // _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+
+namespace {
+
+struct MTContext {
+  MTContext() {
+    mti = MT_N + 1;
+    bHaveSeed = false;
+  }
+
+  uint32_t mti;
+  bool bHaveSeed;
+  uint32_t mt[MT_N];
+};
+
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+bool GenerateCryptoRandom(uint32_t* pBuffer, int32_t iCount) {
+  HCRYPTPROV hCP = 0;
+  if (!::CryptAcquireContext(&hCP, nullptr, nullptr, PROV_RSA_FULL, 0) ||
+      !hCP) {
+    return false;
+  }
+  ::CryptGenRandom(hCP, iCount * sizeof(uint32_t),
+                   reinterpret_cast<uint8_t*>(pBuffer));
+  ::CryptReleaseContext(hCP, 0);
+  return true;
+}
+#endif
+
+}  // namespace
+
+void* FX_Random_MT_Start(uint32_t dwSeed) {
+  MTContext* pContext = FX_Alloc(MTContext, 1);
+  pContext->mt[0] = dwSeed;
+  uint32_t& i = pContext->mti;
+  uint32_t* pBuf = pContext->mt;
+  for (i = 1; i < MT_N; i++)
+    pBuf[i] = (1812433253UL * (pBuf[i - 1] ^ (pBuf[i - 1] >> 30)) + i);
+
+  pContext->bHaveSeed = true;
+  return pContext;
+}
+
+uint32_t FX_Random_MT_Generate(void* pContext) {
+  ASSERT(pContext);
+
+  MTContext* pMTC = static_cast<MTContext*>(pContext);
+  uint32_t v;
+  static uint32_t mag[2] = {0, MT_Matrix_A};
+  uint32_t& mti = pMTC->mti;
+  uint32_t* pBuf = pMTC->mt;
+  if ((int)mti < 0 || mti >= MT_N) {
+    if (mti > MT_N && !pMTC->bHaveSeed)
+      return 0;
+
+    uint32_t kk;
+    for (kk = 0; kk < MT_N - MT_M; kk++) {
+      v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
+      pBuf[kk] = pBuf[kk + MT_M] ^ (v >> 1) ^ mag[v & 1];
+    }
+    for (; kk < MT_N - 1; kk++) {
+      v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
+      pBuf[kk] = pBuf[kk + (MT_M - MT_N)] ^ (v >> 1) ^ mag[v & 1];
+    }
+    v = (pBuf[MT_N - 1] & MT_Upper_Mask) | (pBuf[0] & MT_Lower_Mask);
+    pBuf[MT_N - 1] = pBuf[MT_M - 1] ^ (v >> 1) ^ mag[v & 1];
+    mti = 0;
+  }
+  v = pBuf[mti++];
+  v ^= (v >> 11);
+  v ^= (v << 7) & 0x9d2c5680UL;
+  v ^= (v << 15) & 0xefc60000UL;
+  v ^= (v >> 18);
+  return v;
+}
+
+void FX_Random_MT_Close(void* pContext) {
+  ASSERT(pContext);
+  FX_Free(pContext);
+}
+
+void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount) {
+  uint32_t dwSeed;
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+  if (!GenerateCryptoRandom(&dwSeed, 1))
+    FX_Random_GenerateBase(&dwSeed, 1);
+#else
+  FX_Random_GenerateBase(&dwSeed, 1);
+#endif
+  void* pContext = FX_Random_MT_Start(dwSeed);
+  while (iCount-- > 0)
+    *pBuffer++ = FX_Random_MT_Generate(pContext);
+
+  FX_Random_MT_Close(pContext);
+}
+
+void FX_Random_GenerateBase(uint32_t* pBuffer, int32_t iCount) {
+#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
+  SYSTEMTIME st1, st2;
+  ::GetSystemTime(&st1);
+  do {
+    ::GetSystemTime(&st2);
+  } while (memcmp(&st1, &st2, sizeof(SYSTEMTIME)) == 0);
+  uint32_t dwHash1 =
+      FX_HashCode_GetA(CFX_ByteStringC((uint8_t*)&st1, sizeof(st1)), true);
+  uint32_t dwHash2 =
+      FX_HashCode_GetA(CFX_ByteStringC((uint8_t*)&st2, sizeof(st2)), true);
+  ::srand((dwHash1 << 16) | (uint32_t)dwHash2);
+#else
+  time_t tmLast = time(nullptr);
+  time_t tmCur;
+  while ((tmCur = time(nullptr)) == tmLast)
+    continue;
+
+  ::srand((tmCur << 16) | (tmLast & 0xFFFF));
+#endif
+  while (iCount-- > 0)
+    *pBuffer++ = static_cast<uint32_t>((::rand() << 16) | (::rand() & 0xFFFF));
+}