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vfs_concat: Rewrite and fix ConcatenatedVfsFile

This commit is contained in:
Zach Hilman 2018-09-19 22:00:44 -04:00
parent 3e5c3d0f16
commit 44fdac334c
2 changed files with 59 additions and 14 deletions

View File

@ -5,10 +5,22 @@
#include <algorithm>
#include <utility>
#include "common/assert.h"
#include "core/file_sys/vfs_concat.h"
namespace FileSys {
bool VerifyConcatenationMap(std::map<u64, VirtualFile> map) {
for (auto iter = map.begin(); iter != --map.end();) {
const auto old = iter++;
if (old->first + old->second->GetSize() != iter->first) {
return false;
}
}
return map.begin()->first == 0;
}
VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name) {
if (files.empty())
return nullptr;
@ -27,7 +39,10 @@ ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::s
}
}
ConcatenatedVfsFile::~ConcatenatedVfsFile() = default;
ConcatenatedVfsFile::ConcatenatedVfsFile(std::map<u64, VirtualFile> files_, std::string name)
: files(std::move(files_)), name(std::move(name)) {
ASSERT(VerifyConcatenationMap(files));
}
std::string ConcatenatedVfsFile::GetName() const {
if (files.empty())
@ -62,28 +77,25 @@ bool ConcatenatedVfsFile::IsReadable() const {
}
std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
auto entry = files.end();
std::pair<u64, VirtualFile> entry = *files.rbegin();
for (auto iter = files.begin(); iter != files.end(); ++iter) {
if (iter->first > offset) {
entry = --iter;
entry = *--iter;
break;
}
}
// Check if the entry should be the last one. The loop above will make it end().
if (entry == files.end() && offset < files.rbegin()->first + files.rbegin()->second->GetSize())
--entry;
if (entry == files.end())
if (entry.first + entry.second->GetSize() <= offset)
return 0;
const auto remaining = entry->second->GetSize() + offset - entry->first;
if (length > remaining) {
return entry->second->Read(data, remaining, offset - entry->first) +
Read(data + remaining, length - remaining, offset + remaining);
const auto read_in =
std::min(entry.first + entry.second->GetSize() - offset, entry.second->GetSize());
if (length > read_in) {
return entry.second->Read(data, read_in, offset - entry.first) +
Read(data + read_in, length - read_in, offset + read_in);
}
return entry->second->Read(data, length, offset - entry->first);
return entry.second->Read(data, std::min(read_in, length), offset - entry.first);
}
std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {
@ -93,4 +105,5 @@ std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::
bool ConcatenatedVfsFile::Rename(std::string_view name) {
return false;
}
} // namespace FileSys

View File

@ -4,22 +4,54 @@
#pragma once
#include <map>
#include <memory>
#include <string_view>
#include <boost/container/flat_map.hpp>
#include "core/file_sys/vfs.h"
#include "core/file_sys/vfs_static.h"
namespace FileSys {
class ConcatenatedVfsFile;
// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name = "");
// Convenience function that turns a map of offsets to files into a concatenated file, filling gaps
// with template parameter.
template <u8 filler_byte>
VirtualFile ConcatenateFiles(std::map<u64, VirtualFile> files, std::string name = "") {
if (files.empty())
return nullptr;
if (files.size() == 1)
return files.begin()->second;
for (auto iter = files.begin(); iter != --files.end();) {
const auto old = iter++;
if (old->first + old->second->GetSize() != iter->first) {
files.emplace(old->first + old->second->GetSize(),
std::make_shared<StaticVfsFile<filler_byte>>(iter->first - old->first -
old->second->GetSize()));
}
}
if (files.begin()->first != 0)
files.emplace(0, std::make_shared<StaticVfsFile<filler_byte>>(files.begin()->first));
return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
}
// Class that wraps multiple vfs files and concatenates them, making reads seamless. Currently
// read-only.
class ConcatenatedVfsFile : public VfsFile {
friend VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name);
template <u8 filler_byte>
friend VirtualFile ConcatenateFiles(std::map<u64, VirtualFile> files, std::string name);
ConcatenatedVfsFile(std::vector<VirtualFile> files, std::string name);
ConcatenatedVfsFile(std::map<u64, VirtualFile> files, std::string name);
public:
~ConcatenatedVfsFile() override;
@ -36,7 +68,7 @@ public:
private:
// Maps starting offset to file -- more efficient.
boost::container::flat_map<u64, VirtualFile> files;
std::map<u64, VirtualFile> files;
std::string name;
};