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// 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_random.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 _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
#include <wincrypt.h>
#else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
#include <sys/time.h>
#include <unistd.h>
#endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
namespace {
struct MTContext {
uint32_t mti;
uint32_t mt[MT_N];
};
bool g_bHaveGlobalSeed = false;
uint32_t g_nGlobalSeed = 0;
#if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
bool GenerateSeedFromCryptoRandom(uint32_t* pSeed) {
HCRYPTPROV hCP = 0;
if (!::CryptAcquireContext(&hCP, nullptr, nullptr, PROV_RSA_FULL, 0) ||
!hCP) {
return false;
}
::CryptGenRandom(hCP, sizeof(uint32_t), reinterpret_cast<uint8_t*>(pSeed));
::CryptReleaseContext(hCP, 0);
return true;
}
#endif
uint32_t GenerateSeedFromEnvironment() {
char c;
uintptr_t p = reinterpret_cast<uintptr_t>(&c);
uint32_t seed = ~static_cast<uint32_t>(p >> 3);
#if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
SYSTEMTIME st;
GetSystemTime(&st);
seed ^= static_cast<uint32_t>(st.wSecond) * 1000000;
seed ^= static_cast<uint32_t>(st.wMilliseconds) * 1000;
seed ^= GetCurrentProcessId();
#else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
struct timeval tv;
gettimeofday(&tv, 0);
seed ^= static_cast<uint32_t>(tv.tv_sec) * 1000000;
seed ^= static_cast<uint32_t>(tv.tv_usec);
seed ^= static_cast<uint32_t>(getpid());
#endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
return seed;
}
void* ContextFromNextGlobalSeed() {
if (!g_bHaveGlobalSeed) {
#if _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
if (!GenerateSeedFromCryptoRandom(&g_nGlobalSeed))
g_nGlobalSeed = GenerateSeedFromEnvironment();
#else // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
g_nGlobalSeed = GenerateSeedFromEnvironment();
#endif // _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
g_bHaveGlobalSeed = true;
}
return FX_Random_MT_Start(++g_nGlobalSeed);
}
} // namespace
void* FX_Random_MT_Start(uint32_t dwSeed) {
MTContext* pContext = FX_Alloc(MTContext, 1);
uint32_t* pBuf = pContext->mt;
pBuf[0] = dwSeed;
for (uint32_t i = 1; i < MT_N; i++)
pBuf[i] = (1812433253UL * (pBuf[i - 1] ^ (pBuf[i - 1] >> 30)) + i);
pContext->mti = MT_N;
return pContext;
}
uint32_t FX_Random_MT_Generate(void* pContext) {
MTContext* pMTC = static_cast<MTContext*>(pContext);
uint32_t* pBuf = pMTC->mt;
uint32_t v;
if (pMTC->mti >= MT_N) {
static const uint32_t mag[2] = {0, MT_Matrix_A};
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];
pMTC->mti = 0;
}
v = pBuf[pMTC->mti++];
v ^= (v >> 11);
v ^= (v << 7) & 0x9d2c5680UL;
v ^= (v << 15) & 0xefc60000UL;
v ^= (v >> 18);
return v;
}
void FX_Random_MT_Close(void* pContext) {
FX_Free(pContext);
}
void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount) {
void* pContext = ContextFromNextGlobalSeed();
while (iCount-- > 0)
*pBuffer++ = FX_Random_MT_Generate(pContext);
FX_Random_MT_Close(pContext);
}
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