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394 lines
12 KiB
C++
394 lines
12 KiB
C++
// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.
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#include "PakFilePrivatePCH.h"
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#include "IPlatformFilePak.h"
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#include "SecureHash.h"
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#include "FileManagerGeneric.h"
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#include "ModuleManager.h"
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#include "IPlatformFileModule.h"
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#include "IOBase.h"
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#include "BigInt.h"
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#include "SignedArchiveReader.h"
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#include "PublicKey.inl"
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DECLARE_CYCLE_STAT( TEXT( "FChunkCacheWorker.ProcessQueue" ), STAT_FChunkCacheWorker_ProcessQueue, STATGROUP_PakFile );
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DECLARE_CYCLE_STAT( TEXT( "FChunkCacheWorker.CheckSignature" ), STAT_FChunkCacheWorker_CheckSignature, STATGROUP_PakFile );
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DECLARE_CYCLE_STAT( TEXT( "FSignedArchiveReader.Serialize" ), STAT_SignedArchiveReader_Serialize, STATGROUP_PakFile );
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FChunkCacheWorker::FChunkCacheWorker(FArchive* InReader)
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: Reader(InReader)
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, QueuedRequestsEvent(NULL)
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{
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DecryptionKey.Exponent.Parse(DECRYPTION_KEY_EXPONENT);
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DecryptionKey.Modulus.Parse(DECYRPTION_KEY_MODULUS);
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// Public key should never be zero at this point. Check PublicKey.inl for more details.
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check(!DecryptionKey.Exponent.IsZero() && !DecryptionKey.Modulus.IsZero());
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QueuedRequestsEvent = FPlatformProcess::GetSynchEventFromPool();
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Thread = FRunnableThread::Create(this, TEXT("FChunkCacheWorker"), 0, TPri_BelowNormal);
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}
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FChunkCacheWorker::~FChunkCacheWorker()
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{
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delete Thread;
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Thread = NULL;
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FPlatformProcess::ReturnSynchEventToPool(QueuedRequestsEvent);
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QueuedRequestsEvent = nullptr;
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}
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bool FChunkCacheWorker::Init()
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{
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return true;
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}
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uint32 FChunkCacheWorker::Run()
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{
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while (StopTaskCounter.GetValue() == 0)
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{
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int32 ProcessedRequests = ProcessQueue();
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if (ProcessedRequests == 0)
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{
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QueuedRequestsEvent->Wait(500);
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}
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}
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return 0;
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}
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void FChunkCacheWorker::Stop()
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{
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StopTaskCounter.Increment();
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}
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FChunkBuffer* FChunkCacheWorker::GetCachedChunkBuffer(int32 ChunkIndex)
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{
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for (int32 BufferIndex = 0; BufferIndex < MaxCachedChunks; ++BufferIndex)
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{
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if (CachedChunks[BufferIndex].ChunkIndex == ChunkIndex)
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{
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// Update access info and lock
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CachedChunks[BufferIndex].LockCount++;
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CachedChunks[BufferIndex].LastAccessTime = FPlatformTime::Seconds();
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return &CachedChunks[BufferIndex];
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}
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}
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return NULL;
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}
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FChunkBuffer* FChunkCacheWorker::GetFreeBuffer()
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{
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// Find the least recently accessed, free buffer.
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FChunkBuffer* LeastRecentFreeBuffer = NULL;
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for (int32 BufferIndex = 0; BufferIndex < MaxCachedChunks; ++BufferIndex)
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{
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if (CachedChunks[BufferIndex].LockCount == 0 &&
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(LeastRecentFreeBuffer == NULL || LeastRecentFreeBuffer->LastAccessTime > CachedChunks[BufferIndex].LastAccessTime))
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{
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LeastRecentFreeBuffer = &CachedChunks[BufferIndex];
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}
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}
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if (LeastRecentFreeBuffer)
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{
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// Update access info and lock
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LeastRecentFreeBuffer->LockCount++;
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LeastRecentFreeBuffer->LastAccessTime = FPlatformTime::Seconds();
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}
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return LeastRecentFreeBuffer;
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}
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void FChunkCacheWorker::ReleaseBuffer(int32 ChunkIndex)
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{
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for (int32 BufferIndex = 0; BufferIndex < MaxCachedChunks; ++BufferIndex)
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{
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if (CachedChunks[BufferIndex].ChunkIndex == ChunkIndex)
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{
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CachedChunks[BufferIndex].LockCount--;
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check(CachedChunks[BufferIndex].LockCount >= 0);
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}
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}
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}
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int32 FChunkCacheWorker::ProcessQueue()
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{
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SCOPE_CYCLE_COUNTER( STAT_FChunkCacheWorker_ProcessQueue );
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// Add the queue to the active requests list
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{
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FScopeLock LockQueue(&QueueLock);
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ActiveRequests.Append(RequestQueue);
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RequestQueue.Empty();
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}
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// Keep track how many request have been process this loop
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int32 ProcessedRequests = ActiveRequests.Num();
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for (int32 RequestIndex = 0; RequestIndex < ActiveRequests.Num(); ++RequestIndex)
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{
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FChunkRequest& Request = *ActiveRequests[RequestIndex];
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if (Request.RefCount.GetValue() == 0)
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{
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// ChunkRequest is no longer used by anything. Add it to the free requests lists
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// and release the associated buffer.
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ReleaseBuffer(Request.Index);
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ActiveRequests.RemoveAt(RequestIndex--);
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FreeChunkRequests.Push(&Request);
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}
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else if (Request.Buffer == NULL)
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{
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// See if the requested chunk is already cached.
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FChunkBuffer* CachedBuffer = GetCachedChunkBuffer(Request.Index);
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if (!CachedBuffer)
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{
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// This chunk is not cached. Get a free buffer if possible.
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CachedBuffer = GetFreeBuffer();
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if (!!CachedBuffer)
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{
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// Load and verify.
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CachedBuffer->ChunkIndex = Request.Index;
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Request.Buffer = CachedBuffer;
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CheckSignature(Request);
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}
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}
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else
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{
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Request.Buffer = CachedBuffer;
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}
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if (!!CachedBuffer)
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{
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check(Request.Buffer == CachedBuffer);
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// Chunk is cached and trusted. We no longer need the request handle on this thread.
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// Let the other thread know the chunk is ready to read.
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Request.RefCount.Decrement();
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Request.IsTrusted.Increment();
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}
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}
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}
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return ProcessedRequests;
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}
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void FChunkCacheWorker::Decrypt(uint8* DecryptedData, const int256* Data, const int64 DataLength)
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{
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for (int64 Index = 0; Index < DataLength; ++Index)
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{
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int256 DecryptedByte = FEncryption::ModularPow(Data[Index], DecryptionKey.Exponent, DecryptionKey.Modulus);
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DecryptedData[Index] = (uint8)DecryptedByte.ToInt();
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}
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}
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bool FChunkCacheWorker::CheckSignature(const FChunkRequest& ChunkInfo)
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{
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SCOPE_CYCLE_COUNTER( STAT_FChunkCacheWorker_CheckSignature );
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FSignature Signature;
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Reader->Seek(ChunkInfo.Offset);
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Reader->Serialize(ChunkInfo.Buffer->Data, ChunkInfo.Size);
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Signature.Serialize(*Reader);
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// Hash data
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uint8 Hash[20];
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FSHA1::HashBuffer(ChunkInfo.Buffer->Data, ChunkInfo.Size, Hash);
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// Decrypt serialized hash
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uint8 DecryptedHash[20];
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Decrypt(DecryptedHash, Signature.Data, ARRAY_COUNT(DecryptedHash));
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// Compare hashes
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if (FMemory::Memcmp(Hash, DecryptedHash, sizeof(DecryptedHash)) != 0)
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{
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UE_LOG(LogPakFile, Fatal, TEXT("Pak file has been tampered with."));
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}
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return true;
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}
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FChunkRequest& FChunkCacheWorker::RequestChunk(int32 ChunkIndex, int64 StartOffset, int64 ChunkSize)
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{
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FChunkRequest* NewChunk = FreeChunkRequests.Pop();
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if (NewChunk == NULL)
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{
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NewChunk = new FChunkRequest();
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}
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NewChunk->Index = ChunkIndex;
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NewChunk->Offset = StartOffset;
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NewChunk->Size = ChunkSize;
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NewChunk->Buffer = NULL;
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NewChunk->IsTrusted.Set(0);
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// At this point both worker and the archive use this chunk so increase ref count
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NewChunk->RefCount.Set(2);
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QueueLock.Lock();
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RequestQueue.Add(NewChunk);
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QueueLock.Unlock();
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QueuedRequestsEvent->Trigger();
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return *NewChunk;
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}
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void FChunkCacheWorker::ReleaseChunk(FChunkRequest& Chunk)
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{
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Chunk.RefCount.Decrement();
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}
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FSignedArchiveReader::FSignedArchiveReader(FArchive* InPakReader, FChunkCacheWorker* InSignatureChecker)
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: SignatureSize(FSignature::Size())
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, ChunkCount(0)
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, PakReader(InPakReader)
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, SizeOnDisk(0)
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, PakSize(0)
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, PakOffset(0)
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, SignatureChecker(InSignatureChecker)
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{
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// Cache global info about the archive
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const int64 MaxChunkSize = FPakInfo::MaxChunkDataSize + SignatureSize;
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SizeOnDisk = PakReader->TotalSize();
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ChunkCount = SizeOnDisk / MaxChunkSize + ((SizeOnDisk % MaxChunkSize) ? 1 : 0);
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PakSize = SizeOnDisk - ChunkCount * SignatureSize;
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}
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FSignedArchiveReader::~FSignedArchiveReader()
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{
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delete PakReader;
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PakReader = NULL;
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}
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int64 FSignedArchiveReader::CalculateChunkSize(int64 ChunkIndex) const
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{
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if (ChunkIndex == (ChunkCount - 1))
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{
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const int64 MaxChunkSize = FPakInfo::MaxChunkDataSize + SignatureSize;
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int64 Slack = SizeOnDisk % MaxChunkSize;
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if (!Slack)
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{
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return FPakInfo::MaxChunkDataSize;
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}
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else
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{
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Slack -= SignatureSize;
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check(Slack > 0);
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return Slack;
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}
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}
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else
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{
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return FPakInfo::MaxChunkDataSize;
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}
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}
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void FSignedArchiveReader::PrecacheChunks(TArray<FSignedArchiveReader::FReadInfo>& Chunks, int64 Length)
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{
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// Request all the chunks that are needed to complete this read
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int64 DataOffset;
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int64 DestOffset = 0;
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int32 FirstChunkIndex = CalculateChunkIndex(PakOffset);
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int64 ChunkStartOffset = CalculateChunkOffset(PakOffset, DataOffset);
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int32 NumChunks = (DataOffset - ChunkStartOffset + Length) / FPakInfo::MaxChunkDataSize + 1;
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int64 RemainingLength = Length;
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int64 ArchiveOffset = PakOffset;
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// And then try to precache 'PrecacheLength' more chunks because it's likely
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// we're going to try to read them next
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if ((NumChunks + FirstChunkIndex + PrecacheLength - 1) < ChunkCount)
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{
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NumChunks += PrecacheLength;
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}
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Chunks.Empty(NumChunks);
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for (int32 ChunkIndexOffset = 0; ChunkIndexOffset < NumChunks; ++ChunkIndexOffset)
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{
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ChunkStartOffset = CalculateChunkOffset(ArchiveOffset, DataOffset);
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int64 SizeToReadFromBuffer = RemainingLength;
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if (DataOffset + SizeToReadFromBuffer > ChunkStartOffset + FPakInfo::MaxChunkDataSize)
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{
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SizeToReadFromBuffer = ChunkStartOffset + FPakInfo::MaxChunkDataSize - DataOffset;
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}
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FReadInfo ChunkInfo;
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ChunkInfo.SourceOffset = DataOffset - ChunkStartOffset;
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ChunkInfo.DestOffset = DestOffset;
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ChunkInfo.Size = SizeToReadFromBuffer;
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const int32 ChunkIndex = ChunkIndexOffset + FirstChunkIndex;
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if (LastCachedChunk.ChunkIndex == ChunkIndex)
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{
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ChunkInfo.Request = NULL;
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ChunkInfo.PreCachedChunk = &LastCachedChunk;
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}
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else
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{
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const int64 ChunkSize = CalculateChunkSize(ChunkIndex);
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ChunkInfo.Request = &SignatureChecker->RequestChunk(ChunkIndex, ChunkStartOffset, ChunkSize);
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ChunkInfo.PreCachedChunk = NULL;
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}
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Chunks.Add(ChunkInfo);
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ArchiveOffset += SizeToReadFromBuffer;
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DestOffset += SizeToReadFromBuffer;
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RemainingLength -= SizeToReadFromBuffer;
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}
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}
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void FSignedArchiveReader::Serialize(void* Data, int64 Length)
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{
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SCOPE_CYCLE_COUNTER( STAT_SignedArchiveReader_Serialize );
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// First make sure the chunks we're going to read are actually cached.
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TArray<FReadInfo> QueuedChunks;
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PrecacheChunks(QueuedChunks, Length);
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// Read data from chunks.
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int64 RemainingLength = Length;
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uint8* DestData = (uint8*)Data;
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int32 ChunksToRead = QueuedChunks.Num() - PrecacheLength;
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const int32 LastRequestIndex = ChunksToRead - 1;
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do
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{
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int32 ChunksReadThisLoop = 0;
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// Try to read cached chunks. If a chunk is not yet ready, skip to the next chunk - it's possible
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// that it has already been precached in one of the previous reads.
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for (int32 QueueIndex = 0; QueueIndex <= LastRequestIndex; ++QueueIndex)
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{
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FReadInfo& ChunkInfo = QueuedChunks[QueueIndex];
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if (ChunkInfo.Request && ChunkInfo.Request->IsReady())
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{
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// Read
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FMemory::Memcpy(DestData + ChunkInfo.DestOffset, ChunkInfo.Request->Buffer->Data + ChunkInfo.SourceOffset, ChunkInfo.Size);
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// Is this the last chunk? if so, copy it to pre-cache
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if (LastRequestIndex == QueueIndex && ChunkInfo.Request->Index != LastCachedChunk.ChunkIndex)
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{
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LastCachedChunk.ChunkIndex = ChunkInfo.Request->Index;
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FMemory::Memcpy(LastCachedChunk.Data, ChunkInfo.Request->Buffer->Data, FPakInfo::MaxChunkDataSize);
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}
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// Let the worker know we're done with this chunk for now.
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SignatureChecker->ReleaseChunk(*ChunkInfo.Request);
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ChunkInfo.Request = NULL;
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// One less chunk remaining
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ChunksToRead--;
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ChunksReadThisLoop++;
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}
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else if (ChunkInfo.PreCachedChunk)
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{
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// Copy directly from the pre-cached chunk.
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FMemory::Memcpy(DestData + ChunkInfo.DestOffset, ChunkInfo.PreCachedChunk->Data + ChunkInfo.SourceOffset, ChunkInfo.Size);
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ChunkInfo.PreCachedChunk = NULL;
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// One less chunk remaining
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ChunksToRead--;
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ChunksReadThisLoop++;
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}
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}
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if (ChunksReadThisLoop == 0)
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{
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// No chunks read, avoid tight spinning loops and give up some time to the other threads
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FPlatformProcess::Sleep(0.0f);
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}
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}
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while (ChunksToRead > 0);
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PakOffset += Length;
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// Free precached chunks (they will still get precached but simply marked as not used by anything)
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for (int32 QueueIndex = QueuedChunks.Num() - PrecacheLength; QueueIndex < QueuedChunks.Num(); ++QueueIndex)
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{
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FReadInfo& CachedChunk = QueuedChunks[QueueIndex];
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SignatureChecker->ReleaseChunk(*CachedChunk.Request);
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}
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}
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