forked from dolphin-emu/dolphin
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Blob.cpp
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Blob.cpp
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// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include <algorithm>
#include <cstddef>
#include <limits>
#include <memory>
#include <string>
#include <utility>
#include "Common/CDUtils.h"
#include "Common/CommonTypes.h"
#include "Common/File.h"
#include "DiscIO/Blob.h"
#include "DiscIO/CISOBlob.h"
#include "DiscIO/CompressedBlob.h"
#include "DiscIO/DirectoryBlob.h"
#include "DiscIO/DriveBlob.h"
#include "DiscIO/FileBlob.h"
#include "DiscIO/TGCBlob.h"
#include "DiscIO/WIABlob.h"
#include "DiscIO/WbfsBlob.h"
namespace DiscIO
{
void SectorReader::SetSectorSize(int blocksize)
{
m_block_size = std::max(blocksize, 0);
for (auto& cache_entry : m_cache)
{
cache_entry.Reset();
cache_entry.data.resize(m_chunk_blocks * m_block_size);
}
}
void SectorReader::SetChunkSize(int block_cnt)
{
m_chunk_blocks = std::max(block_cnt, 1);
// Clear cache and resize the data arrays
SetSectorSize(m_block_size);
}
SectorReader::~SectorReader()
{
}
const SectorReader::Cache* SectorReader::FindCacheLine(u64 block_num)
{
auto itr = std::find_if(m_cache.begin(), m_cache.end(),
[&](const Cache& entry) { return entry.Contains(block_num); });
if (itr == m_cache.end())
return nullptr;
itr->MarkUsed();
return &*itr;
}
SectorReader::Cache* SectorReader::GetEmptyCacheLine()
{
Cache* oldest = &m_cache[0];
// Find the Least Recently Used cache line to replace.
std::for_each(m_cache.begin() + 1, m_cache.end(), [&](Cache& line) {
if (line.IsLessRecentlyUsedThan(*oldest))
{
oldest->ShiftLRU();
oldest = &line;
return;
}
line.ShiftLRU();
});
oldest->Reset();
return oldest;
}
const SectorReader::Cache* SectorReader::GetCacheLine(u64 block_num)
{
if (auto entry = FindCacheLine(block_num))
return entry;
// Cache miss. Fault in the missing entry.
Cache* cache = GetEmptyCacheLine();
// We only read aligned chunks, this avoids duplicate overlapping entries.
u64 chunk_idx = block_num / m_chunk_blocks;
u32 blocks_read = ReadChunk(cache->data.data(), chunk_idx);
if (!blocks_read)
return nullptr;
cache->Fill(chunk_idx * m_chunk_blocks, blocks_read);
// Secondary check for out-of-bounds read.
// If we got less than m_chunk_blocks, we may still have missed.
// We do this after the cache fill since the cache line itself is
// fine, the problem is being asked to read past the end of the disk.
return cache->Contains(block_num) ? cache : nullptr;
}
bool SectorReader::Read(u64 offset, u64 size, u8* out_ptr)
{
if (offset + size > GetDataSize())
return false;
u64 remain = size;
u64 block = 0;
u32 position_in_block = static_cast<u32>(offset % m_block_size);
while (remain > 0)
{
block = offset / m_block_size;
const Cache* cache = GetCacheLine(block);
if (!cache)
return false;
// Cache entries are aligned chunks, we may not want to read from the start
u32 read_offset = static_cast<u32>(block - cache->block_idx) * m_block_size + position_in_block;
u32 can_read = m_block_size * cache->num_blocks - read_offset;
u32 was_read = static_cast<u32>(std::min<u64>(can_read, remain));
std::copy(cache->data.begin() + read_offset, cache->data.begin() + read_offset + was_read,
out_ptr);
offset += was_read;
out_ptr += was_read;
remain -= was_read;
position_in_block = 0;
}
return true;
}
// Crap default implementation if not overridden.
bool SectorReader::ReadMultipleAlignedBlocks(u64 block_num, u64 cnt_blocks, u8* out_ptr)
{
for (u64 i = 0; i < cnt_blocks; ++i)
{
if (!GetBlock(block_num + i, out_ptr))
return false;
out_ptr += m_block_size;
}
return true;
}
u32 SectorReader::ReadChunk(u8* buffer, u64 chunk_num)
{
u64 block_num = chunk_num * m_chunk_blocks;
u32 cnt_blocks = m_chunk_blocks;
// If we are reading the end of a disk, there may not be enough blocks to
// read a whole chunk. We need to clamp down in that case.
u64 end_block = (GetDataSize() + m_block_size - 1) / m_block_size;
if (end_block)
cnt_blocks = static_cast<u32>(std::min<u64>(m_chunk_blocks, end_block - block_num));
if (ReadMultipleAlignedBlocks(block_num, cnt_blocks, buffer))
{
if (cnt_blocks < m_chunk_blocks)
{
std::fill(buffer + cnt_blocks * m_block_size, buffer + m_chunk_blocks * m_block_size, 0u);
}
return cnt_blocks;
}
// end_block may be zero on real disks if we fail to get the media size.
// We have to fallback to probing the disk instead.
if (!end_block)
{
for (u32 i = 0; i < cnt_blocks; ++i)
{
if (!GetBlock(block_num + i, buffer))
{
std::fill(buffer, buffer + (cnt_blocks - i) * m_block_size, 0u);
return i;
}
buffer += m_block_size;
}
return cnt_blocks;
}
return 0;
}
std::unique_ptr<BlobReader> CreateBlobReader(const std::string& filename)
{
if (Common::IsCDROMDevice(filename))
return DriveReader::Create(filename);
File::IOFile file(filename, "rb");
u32 magic;
if (!file.ReadArray(&magic, 1))
return nullptr;
// Conveniently, every supported file format (except for plain disc images and
// extracted discs) starts with a 4-byte magic number that identifies the format,
// so we just need a simple switch statement to create the right blob type. If the
// magic number doesn't match any known magic number and the directory structure
// doesn't match the directory blob format, we assume it's a plain disc image. If
// that assumption is wrong, the volume code that runs later will notice the error
// because the blob won't provide the right data when reading the GC/Wii disc header.
switch (magic)
{
case CISO_MAGIC:
return CISOFileReader::Create(std::move(file));
case GCZ_MAGIC:
return CompressedBlobReader::Create(std::move(file), filename);
case TGC_MAGIC:
return TGCFileReader::Create(std::move(file));
case WBFS_MAGIC:
return WbfsFileReader::Create(std::move(file), filename);
case WIA_MAGIC:
return WIAFileReader::Create(std::move(file), filename);
case RVZ_MAGIC:
return RVZFileReader::Create(std::move(file), filename);
default:
if (auto directory_blob = DirectoryBlobReader::Create(filename))
return std::move(directory_blob);
return PlainFileReader::Create(std::move(file));
}
}
} // namespace DiscIO