134 lines
3.4 KiB
C++
134 lines
3.4 KiB
C++
// Copyright 2017 PDFium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
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#include "core/fxcrt/fx_random.h"
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#include "build/build_config.h"
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#include "core/fxcrt/fx_memory.h"
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#include "core/fxcrt/fx_string.h"
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#include "core/fxcrt/fx_system.h"
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#define MT_N 848
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#define MT_M 456
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#define MT_Matrix_A 0x9908b0df
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#define MT_Upper_Mask 0x80000000
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#define MT_Lower_Mask 0x7fffffff
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#if defined(OS_WIN)
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#include <wincrypt.h>
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#else
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#include <sys/time.h>
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#include <unistd.h>
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#endif
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namespace {
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struct MTContext {
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uint32_t mti;
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uint32_t mt[MT_N];
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};
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bool g_bHaveGlobalSeed = false;
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uint32_t g_nGlobalSeed = 0;
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#if defined(OS_WIN)
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bool GenerateSeedFromCryptoRandom(uint32_t* pSeed) {
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HCRYPTPROV hCP = 0;
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if (!::CryptAcquireContext(&hCP, nullptr, nullptr, PROV_RSA_FULL, 0) ||
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!hCP) {
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return false;
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}
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::CryptGenRandom(hCP, sizeof(uint32_t), reinterpret_cast<uint8_t*>(pSeed));
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::CryptReleaseContext(hCP, 0);
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return true;
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}
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#endif
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uint32_t GenerateSeedFromEnvironment() {
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char c;
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uintptr_t p = reinterpret_cast<uintptr_t>(&c);
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uint32_t seed = ~static_cast<uint32_t>(p >> 3);
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#if defined(OS_WIN)
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SYSTEMTIME st;
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GetSystemTime(&st);
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seed ^= static_cast<uint32_t>(st.wSecond) * 1000000;
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seed ^= static_cast<uint32_t>(st.wMilliseconds) * 1000;
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seed ^= GetCurrentProcessId();
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#else
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struct timeval tv;
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gettimeofday(&tv, 0);
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seed ^= static_cast<uint32_t>(tv.tv_sec) * 1000000;
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seed ^= static_cast<uint32_t>(tv.tv_usec);
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seed ^= static_cast<uint32_t>(getpid());
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#endif
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return seed;
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}
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void* ContextFromNextGlobalSeed() {
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if (!g_bHaveGlobalSeed) {
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#if defined(OS_WIN)
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if (!GenerateSeedFromCryptoRandom(&g_nGlobalSeed))
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g_nGlobalSeed = GenerateSeedFromEnvironment();
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#else
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g_nGlobalSeed = GenerateSeedFromEnvironment();
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#endif
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g_bHaveGlobalSeed = true;
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}
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return FX_Random_MT_Start(++g_nGlobalSeed);
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}
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} // namespace
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void* FX_Random_MT_Start(uint32_t dwSeed) {
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MTContext* pContext = FX_Alloc(MTContext, 1);
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uint32_t* pBuf = pContext->mt;
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pBuf[0] = dwSeed;
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for (uint32_t i = 1; i < MT_N; i++)
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pBuf[i] = (1812433253UL * (pBuf[i - 1] ^ (pBuf[i - 1] >> 30)) + i);
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pContext->mti = MT_N;
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return pContext;
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}
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uint32_t FX_Random_MT_Generate(void* pContext) {
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MTContext* pMTC = static_cast<MTContext*>(pContext);
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uint32_t* pBuf = pMTC->mt;
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uint32_t v;
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if (pMTC->mti >= MT_N) {
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static const uint32_t mag[2] = {0, MT_Matrix_A};
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uint32_t kk;
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for (kk = 0; kk < MT_N - MT_M; kk++) {
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v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
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pBuf[kk] = pBuf[kk + MT_M] ^ (v >> 1) ^ mag[v & 1];
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}
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for (; kk < MT_N - 1; kk++) {
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v = (pBuf[kk] & MT_Upper_Mask) | (pBuf[kk + 1] & MT_Lower_Mask);
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pBuf[kk] = pBuf[kk + (MT_M - MT_N)] ^ (v >> 1) ^ mag[v & 1];
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}
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v = (pBuf[MT_N - 1] & MT_Upper_Mask) | (pBuf[0] & MT_Lower_Mask);
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pBuf[MT_N - 1] = pBuf[MT_M - 1] ^ (v >> 1) ^ mag[v & 1];
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pMTC->mti = 0;
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}
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v = pBuf[pMTC->mti++];
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v ^= (v >> 11);
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v ^= (v << 7) & 0x9d2c5680UL;
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v ^= (v << 15) & 0xefc60000UL;
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v ^= (v >> 18);
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return v;
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}
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void FX_Random_MT_Close(void* pContext) {
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FX_Free(pContext);
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}
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void FX_Random_GenerateMT(uint32_t* pBuffer, int32_t iCount) {
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void* pContext = ContextFromNextGlobalSeed();
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while (iCount-- > 0)
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*pBuffer++ = FX_Random_MT_Generate(pContext);
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FX_Random_MT_Close(pContext);
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}
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