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>

6 files changed, 163 insertions, 133 deletions

diff --git a/BUILD.gn b/BUILD.gn
index e4800a6374..59804a7c7d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -843,6 +843,8 @@ static_library("fxcrt") {
     "core/fxcrt/fx_extension.h",
     "core/fxcrt/fx_memory.cpp",
     "core/fxcrt/fx_memory.h",
+    "core/fxcrt/fx_rand.cpp",
+    "core/fxcrt/fx_rand.h",
     "core/fxcrt/fx_safe_types.h",
     "core/fxcrt/fx_stream.cpp",
     "core/fxcrt/fx_stream.h",
diff --git a/core/fpdfapi/edit/cpdf_creator.cpp b/core/fpdfapi/edit/cpdf_creator.cpp
index 4c25f372ac..7d9f2d0cc8 100644
--- a/core/fpdfapi/edit/cpdf_creator.cpp
+++ b/core/fpdfapi/edit/cpdf_creator.cpp
@@ -19,6 +19,7 @@
 #include "core/fpdfapi/parser/cpdf_string.h"
 #include "core/fpdfapi/parser/fpdf_parser_decode.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/fx_rand.h"
 
 namespace {
 
diff --git a/core/fxcrt/fx_extension.cpp b/core/fxcrt/fx_extension.cpp
index 2d485490ca..35a8442f40 100644
--- a/core/fxcrt/fx_extension.cpp
+++ b/core/fxcrt/fx_extension.cpp
@@ -9,46 +9,7 @@
 #include <algorithm>
 #include <cwctype>
 
-#if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
-#include <wincrypt.h>
-#else
-#include <ctime>
-#endif
-
-#define MT_N 848
-#define MT_M 456
-#define MT_Matrix_A 0x9908b0df
-#define MT_Upper_Mask 0x80000000
-#define MT_Lower_Mask 0x7fffffff
-
-namespace {
-
-struct FX_MTRANDOMCONTEXT {
-  FX_MTRANDOMCONTEXT() {
-    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
+#include "core/fxcrt/fx_rand.h"
 
 float FXSYS_wcstof(const wchar_t* pwsStr, int32_t iLength, int32_t* pUsedLen) {
   ASSERT(pwsStr);
@@ -163,94 +124,6 @@ size_t FXSYS_ToUTF16BE(uint32_t unicode, char* buf) {
   return 8;
 }
 
-void* FX_Random_MT_Start(uint32_t dwSeed) {
-  FX_MTRANDOMCONTEXT* pContext = FX_Alloc(FX_MTRANDOMCONTEXT, 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);
-  FX_MTRANDOMCONTEXT* pMTC = static_cast<FX_MTRANDOMCONTEXT*>(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));
-}
-
 #ifdef PDF_ENABLE_XFA
 void FX_GUID_CreateV4(FX_GUID* pGUID) {
   FX_Random_GenerateMT((uint32_t*)pGUID, 4);
diff --git a/core/fxcrt/fx_extension.h b/core/fxcrt/fx_extension.h
index bd20b3969e..365ab4d692 100644
--- a/core/fxcrt/fx_extension.h
+++ b/core/fxcrt/fx_extension.h
@@ -86,11 +86,6 @@ void FXSYS_IntToFourHexChars(uint16_t c, char* buf);
 
 size_t FXSYS_ToUTF16BE(uint32_t unicode, char* buf);
 
-void* FX_Random_MT_Start(uint32_t dwSeed);
-void FX_Random_MT_Close(void* pContext);
-uint32_t FX_Random_MT_Generate(void* pContext);
-void FX_Random_GenerateBase(uint32_t* pBuffer, int32_t iCount);
-void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount);
 
 #ifdef PDF_ENABLE_XFA
 struct FX_GUID {
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));
+}
diff --git a/core/fxcrt/fx_rand.h b/core/fxcrt/fx_rand.h
new file mode 100644
index 0000000000..db5f48fee3
--- /dev/null
+++ b/core/fxcrt/fx_rand.h
@@ -0,0 +1,18 @@
+// 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
+
+#ifndef CORE_FXCRT_FX_RAND_H_
+#define CORE_FXCRT_FX_RAND_H_
+
+#include <stdint.h>
+
+void* FX_Random_MT_Start(uint32_t dwSeed);
+void FX_Random_MT_Close(void* pContext);
+uint32_t FX_Random_MT_Generate(void* pContext);
+void FX_Random_GenerateBase(uint32_t* pBuffer, int32_t iCount);
+void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount);
+
+#endif  // CORE_FXCRT_FX_RAND_H_