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eden/src/core/file_sys/fsmitm_romfsbuild.cpp

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// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <cstring>
#include <string_view>
#include "common/alignment.h"
#include "common/assert.h"
#include "core/file_sys/fsmitm_romfsbuild.h"
#include "core/file_sys/ips_layer.h"
#include "core/file_sys/vfs.h"
#include "core/file_sys/vfs_vector.h"
namespace FileSys {
constexpr u64 FS_MAX_PATH = 0x301;
constexpr u32 ROMFS_ENTRY_EMPTY = 0xFFFFFFFF;
constexpr u32 ROMFS_FILEPARTITION_OFS = 0x200;
// Types for building a RomFS.
struct RomFSHeader {
u64 header_size;
u64 dir_hash_table_ofs;
u64 dir_hash_table_size;
u64 dir_table_ofs;
u64 dir_table_size;
u64 file_hash_table_ofs;
u64 file_hash_table_size;
u64 file_table_ofs;
u64 file_table_size;
u64 file_partition_ofs;
};
static_assert(sizeof(RomFSHeader) == 0x50, "RomFSHeader has incorrect size.");
struct RomFSDirectoryEntry {
u32 parent;
u32 sibling;
u32 child;
u32 file;
u32 hash;
u32 name_size;
};
static_assert(sizeof(RomFSDirectoryEntry) == 0x18, "RomFSDirectoryEntry has incorrect size.");
struct RomFSFileEntry {
u32 parent;
u32 sibling;
u64 offset;
u64 size;
u32 hash;
u32 name_size;
};
static_assert(sizeof(RomFSFileEntry) == 0x20, "RomFSFileEntry has incorrect size.");
struct RomFSBuildFileContext;
struct RomFSBuildDirectoryContext {
std::string path;
u32 cur_path_ofs = 0;
u32 path_len = 0;
u32 entry_offset = 0;
std::shared_ptr<RomFSBuildDirectoryContext> parent;
std::shared_ptr<RomFSBuildDirectoryContext> child;
std::shared_ptr<RomFSBuildDirectoryContext> sibling;
std::shared_ptr<RomFSBuildFileContext> file;
};
struct RomFSBuildFileContext {
std::string path;
u32 cur_path_ofs = 0;
u32 path_len = 0;
u32 entry_offset = 0;
u64 offset = 0;
u64 size = 0;
std::shared_ptr<RomFSBuildDirectoryContext> parent;
std::shared_ptr<RomFSBuildFileContext> sibling;
VirtualFile source;
};
static u32 romfs_calc_path_hash(u32 parent, std::string_view path, u32 start,
std::size_t path_len) {
u32 hash = parent ^ 123456789;
for (u32 i = 0; i < path_len; i++) {
hash = (hash >> 5) | (hash << 27);
hash ^= path[start + i];
}
return hash;
}
static u64 romfs_get_hash_table_count(u64 num_entries) {
if (num_entries < 3) {
return 3;
}
if (num_entries < 19) {
return num_entries | 1;
}
u64 count = num_entries;
while (count % 2 == 0 || count % 3 == 0 || count % 5 == 0 || count % 7 == 0 ||
count % 11 == 0 || count % 13 == 0 || count % 17 == 0) {
count++;
}
return count;
}
void RomFSBuildContext::VisitDirectory(VirtualDir romfs_dir, VirtualDir ext_dir,
std::shared_ptr<RomFSBuildDirectoryContext> parent) {
std::vector<std::shared_ptr<RomFSBuildDirectoryContext>> child_dirs;
const auto entries = romfs_dir->GetEntries();
for (const auto& kv : entries) {
if (kv.second == VfsEntryType::Directory) {
const auto child = std::make_shared<RomFSBuildDirectoryContext>();
// Set child's path.
child->cur_path_ofs = parent->path_len + 1;
child->path_len = child->cur_path_ofs + static_cast<u32>(kv.first.size());
child->path = parent->path + "/" + kv.first;
if (ext_dir != nullptr && ext_dir->GetFile(kv.first + ".stub") != nullptr) {
continue;
}
// Sanity check on path_len
ASSERT(child->path_len < FS_MAX_PATH);
if (AddDirectory(parent, child)) {
child_dirs.push_back(child);
}
} else {
const auto child = std::make_shared<RomFSBuildFileContext>();
// Set child's path.
child->cur_path_ofs = parent->path_len + 1;
child->path_len = child->cur_path_ofs + static_cast<u32>(kv.first.size());
child->path = parent->path + "/" + kv.first;
if (ext_dir != nullptr && ext_dir->GetFile(kv.first + ".stub") != nullptr) {
continue;
}
// Sanity check on path_len
ASSERT(child->path_len < FS_MAX_PATH);
child->source = romfs_dir->GetFile(kv.first);
if (ext_dir != nullptr) {
if (const auto ips = ext_dir->GetFile(kv.first + ".ips")) {
if (auto patched = PatchIPS(child->source, ips)) {
child->source = std::move(patched);
}
}
}
child->size = child->source->GetSize();
AddFile(parent, child);
}
}
for (auto& child : child_dirs) {
auto subdir_name = std::string_view(child->path).substr(child->cur_path_ofs);
auto child_romfs_dir = romfs_dir->GetSubdirectory(subdir_name);
auto child_ext_dir = ext_dir != nullptr ? ext_dir->GetSubdirectory(subdir_name) : nullptr;
this->VisitDirectory(child_romfs_dir, child_ext_dir, child);
}
}
bool RomFSBuildContext::AddDirectory(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
std::shared_ptr<RomFSBuildDirectoryContext> dir_ctx) {
// Check whether it's already in the known directories.
const auto [it, is_new] = directories.emplace(dir_ctx->path, nullptr);
if (!is_new) {
return false;
}
// Add a new directory.
num_dirs++;
dir_table_size +=
sizeof(RomFSDirectoryEntry) + Common::AlignUp(dir_ctx->path_len - dir_ctx->cur_path_ofs, 4);
dir_ctx->parent = parent_dir_ctx;
it->second = dir_ctx;
return true;
}
bool RomFSBuildContext::AddFile(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
std::shared_ptr<RomFSBuildFileContext> file_ctx) {
// Check whether it's already in the known files.
const auto [it, is_new] = files.emplace(file_ctx->path, nullptr);
if (!is_new) {
return false;
}
// Add a new file.
num_files++;
file_table_size +=
sizeof(RomFSFileEntry) + Common::AlignUp(file_ctx->path_len - file_ctx->cur_path_ofs, 4);
file_ctx->parent = parent_dir_ctx;
it->second = file_ctx;
return true;
}
RomFSBuildContext::RomFSBuildContext(VirtualDir base_, VirtualDir ext_)
: base(std::move(base_)), ext(std::move(ext_)) {
root = std::make_shared<RomFSBuildDirectoryContext>();
root->path = "\0";
directories.emplace(root->path, root);
num_dirs = 1;
dir_table_size = 0x18;
VisitDirectory(base, ext, root);
}
RomFSBuildContext::~RomFSBuildContext() = default;
std::multimap<u64, VirtualFile> RomFSBuildContext::Build() {
const u64 dir_hash_table_entry_count = romfs_get_hash_table_count(num_dirs);
const u64 file_hash_table_entry_count = romfs_get_hash_table_count(num_files);
dir_hash_table_size = 4 * dir_hash_table_entry_count;
file_hash_table_size = 4 * file_hash_table_entry_count;
// Assign metadata pointers
RomFSHeader header{};
std::vector<u32> dir_hash_table(dir_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
std::vector<u32> file_hash_table(file_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
std::vector<u8> dir_table(dir_table_size);
std::vector<u8> file_table(file_table_size);
std::shared_ptr<RomFSBuildFileContext> cur_file;
// Determine file offsets.
u32 entry_offset = 0;
std::shared_ptr<RomFSBuildFileContext> prev_file = nullptr;
for (const auto& it : files) {
cur_file = it.second;
file_partition_size = Common::AlignUp(file_partition_size, 16);
cur_file->offset = file_partition_size;
file_partition_size += cur_file->size;
cur_file->entry_offset = entry_offset;
entry_offset +=
static_cast<u32>(sizeof(RomFSFileEntry) +
Common::AlignUp(cur_file->path_len - cur_file->cur_path_ofs, 4));
prev_file = cur_file;
}
// Assign deferred parent/sibling ownership.
for (auto it = files.rbegin(); it != files.rend(); ++it) {
cur_file = it->second;
cur_file->sibling = cur_file->parent->file;
cur_file->parent->file = cur_file;
}
std::shared_ptr<RomFSBuildDirectoryContext> cur_dir;
// Determine directory offsets.
entry_offset = 0;
for (const auto& it : directories) {
cur_dir = it.second;
cur_dir->entry_offset = entry_offset;
entry_offset +=
static_cast<u32>(sizeof(RomFSDirectoryEntry) +
Common::AlignUp(cur_dir->path_len - cur_dir->cur_path_ofs, 4));
}
// Assign deferred parent/sibling ownership.
for (auto it = directories.rbegin(); it->second != root; ++it) {
cur_dir = it->second;
cur_dir->sibling = cur_dir->parent->child;
cur_dir->parent->child = cur_dir;
}
std::multimap<u64, VirtualFile> out;
// Populate file tables.
for (const auto& it : files) {
cur_file = it.second;
RomFSFileEntry cur_entry{};
cur_entry.parent = cur_file->parent->entry_offset;
cur_entry.sibling =
cur_file->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_file->sibling->entry_offset;
cur_entry.offset = cur_file->offset;
cur_entry.size = cur_file->size;
const auto name_size = cur_file->path_len - cur_file->cur_path_ofs;
const auto hash = romfs_calc_path_hash(cur_file->parent->entry_offset, cur_file->path,
cur_file->cur_path_ofs, name_size);
cur_entry.hash = file_hash_table[hash % file_hash_table_entry_count];
file_hash_table[hash % file_hash_table_entry_count] = cur_file->entry_offset;
cur_entry.name_size = name_size;
out.emplace(cur_file->offset + ROMFS_FILEPARTITION_OFS, cur_file->source);
std::memcpy(file_table.data() + cur_file->entry_offset, &cur_entry, sizeof(RomFSFileEntry));
std::memset(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry), 0,
Common::AlignUp(cur_entry.name_size, 4));
std::memcpy(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry),
cur_file->path.data() + cur_file->cur_path_ofs, name_size);
}
// Populate dir tables.
for (const auto& it : directories) {
cur_dir = it.second;
RomFSDirectoryEntry cur_entry{};
cur_entry.parent = cur_dir == root ? 0 : cur_dir->parent->entry_offset;
cur_entry.sibling =
cur_dir->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->sibling->entry_offset;
cur_entry.child =
cur_dir->child == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->child->entry_offset;
cur_entry.file = cur_dir->file == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->file->entry_offset;
const auto name_size = cur_dir->path_len - cur_dir->cur_path_ofs;
const auto hash = romfs_calc_path_hash(cur_dir == root ? 0 : cur_dir->parent->entry_offset,
cur_dir->path, cur_dir->cur_path_ofs, name_size);
cur_entry.hash = dir_hash_table[hash % dir_hash_table_entry_count];
dir_hash_table[hash % dir_hash_table_entry_count] = cur_dir->entry_offset;
cur_entry.name_size = name_size;
std::memcpy(dir_table.data() + cur_dir->entry_offset, &cur_entry,
sizeof(RomFSDirectoryEntry));
std::memset(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry), 0,
Common::AlignUp(cur_entry.name_size, 4));
std::memcpy(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry),
cur_dir->path.data() + cur_dir->cur_path_ofs, name_size);
}
// Set header fields.
header.header_size = sizeof(RomFSHeader);
header.file_hash_table_size = file_hash_table_size;
header.file_table_size = file_table_size;
header.dir_hash_table_size = dir_hash_table_size;
header.dir_table_size = dir_table_size;
header.file_partition_ofs = ROMFS_FILEPARTITION_OFS;
header.dir_hash_table_ofs = Common::AlignUp(header.file_partition_ofs + file_partition_size, 4);
header.dir_table_ofs = header.dir_hash_table_ofs + header.dir_hash_table_size;
header.file_hash_table_ofs = header.dir_table_ofs + header.dir_table_size;
header.file_table_ofs = header.file_hash_table_ofs + header.file_hash_table_size;
std::vector<u8> header_data(sizeof(RomFSHeader));
std::memcpy(header_data.data(), &header, header_data.size());
out.emplace(0, std::make_shared<VectorVfsFile>(std::move(header_data)));
std::vector<u8> metadata(file_hash_table_size + file_table_size + dir_hash_table_size +
dir_table_size);
std::size_t index = 0;
std::memcpy(metadata.data(), dir_hash_table.data(), dir_hash_table.size() * sizeof(u32));
index += dir_hash_table.size() * sizeof(u32);
std::memcpy(metadata.data() + index, dir_table.data(), dir_table.size());
index += dir_table.size();
std::memcpy(metadata.data() + index, file_hash_table.data(),
file_hash_table.size() * sizeof(u32));
index += file_hash_table.size() * sizeof(u32);
std::memcpy(metadata.data() + index, file_table.data(), file_table.size());
out.emplace(header.dir_hash_table_ofs, std::make_shared<VectorVfsFile>(std::move(metadata)));
return out;
}
} // namespace FileSys
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