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OpenMW is an open implementation of the Morrowind engine
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This file (bsafile.cpp) is part of the OpenMW package.
OpenMW is distributed as free software: you can redistribute it and/or modify it under the terms of the GNU General Public License version 3, as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License version 3 along with this program. If not, see https://www.gnu.org/licenses/ .
*/
#include "bsafile.hpp"
#include <algorithm>#include <cassert>#include <cerrno>#include <cstring>#include <filesystem>#include <format>#include <fstream>#include <istream>#include <system_error>
#include <components/esm/fourcc.hpp>#include <components/files/constrainedfilestream.hpp>#include <components/files/utils.hpp>
using namespace Bsa;
/// Error handling[[noreturn]] void BSAFile::fail(const std::string& msg) const{ throw std::runtime_error("BSA Error: " + msg + "\nArchive: " + Files::pathToUnicodeString(mFilepath));}
// the getHash code is from bsapack from ghostwheel// the code is also the same as in// https://github.com/arviceblot/bsatool_rs/commit/67cb59ec3aaeedc0849222ea387f031c33e48c81BSAFile::Hash getHash(const std::string& name){ BSAFile::Hash hash; unsigned l = (static_cast<unsigned>(name.size()) >> 1); unsigned sum, off, temp, i, n;
for (sum = off = i = 0; i < l; i++) { sum ^= (((unsigned)(name[i])) << (off & 0x1F)); off += 8; } hash.mLow = sum;
for (sum = off = 0; i < name.size(); i++) { temp = (((unsigned)(name[i])) << (off & 0x1F)); sum ^= temp; n = temp & 0x1F; sum = std::rotr(sum, n); // binary "rotate right" off += 8; } hash.mHigh = sum; return hash;}
/// Read header information from the input sourcevoid BSAFile::readHeader(std::istream& input){ /* * The layout of a BSA archive is as follows: * * - 12 bytes header, contains 3 ints: * id number - equal to 0x100 * dirsize - size of the directory block (see below) * numfiles - number of files * * ---------- start of directory block ----------- * * - 8 bytes*numfiles, each record contains: * fileSize * offset into data buffer (see below) * * - 4 bytes*numfiles, each record is an offset into the following name buffer * * - name buffer, indexed by the previous table, each string is * null-terminated. Size is (dirsize - 12*numfiles). * * ---------- end of directory block ------------- * * - 8*filenum - hash table block, we currently ignore this * * ----------- start of data buffer -------------- * * - The rest of the archive is file data, indexed by the * offsets in the directory block. The offsets start at 0 at * the beginning of this buffer. * */ assert(!mIsLoaded);
// Total archive size const std::streamsize fsize = Files::getStreamSizeLeft(input);
if (fsize < 12) fail("File too small to be a valid BSA archive");
// Get essential header numbers std::streamsize dirsize; std::streamsize filenum; { // First 12 bytes uint32_t head[3];
input.read(reinterpret_cast<char*>(head), 12);
if (input.fail()) fail(std::format("Failed to read head: {}", std::generic_category().message(errno)));
if (head[0] != 0x100) fail("Unrecognized BSA header");
// Total number of bytes used in size/offset-table + filename // sections. dirsize = head[1];
// Number of files filenum = head[2]; }
// Each file must take up at least 21 bytes of data in the bsa. So // if files*21 overflows the file size then we are guaranteed that // the archive is corrupt. if (filenum * 21 > fsize - 12 || dirsize + 8 * filenum > fsize - 12) fail("Directory information larger than entire archive");
// Read the offset info into a temporary buffer std::vector<uint32_t> offsets(3 * filenum); input.read(reinterpret_cast<char*>(offsets.data()), 12 * filenum);
if (input.fail()) fail(std::format("Failed to read offsets: {}", std::generic_category().message(errno)));
// Read the string table mStringBuf.resize(dirsize - 12 * filenum); input.read(mStringBuf.data(), mStringBuf.size());
if (input.fail()) fail(std::format("Failed to read string table: {}", std::generic_category().message(errno)));
// Check our position assert(input.tellg() == std::streampos(12 + dirsize)); std::vector<Hash> hashes(filenum); static_assert(sizeof(Hash) == 8); input.read(reinterpret_cast<char*>(hashes.data()), 8 * filenum);
if (input.fail()) fail(std::format("Failed to read hashes: {}", std::generic_category().message(errno)));
// Calculate the offset of the data buffer. All file offsets are // relative to this. 12 header bytes + directory + hash table // (skipped) const std::streamsize fileDataOffset = 12 + dirsize + 8 * filenum;
// Set up the the FileStruct table mFiles.reserve(filenum); size_t endOfNameBuffer = 0; for (std::streamsize i = 0; i < filenum; i++) { const uint32_t fileSize = offsets[i * 2]; const std::streamsize offset = static_cast<std::streamsize>(offsets[i * 2 + 1]) + fileDataOffset;
if (fileSize + offset > fsize) fail(std::format("Archive contains offsets outside itself: {} + {} > {}", fileSize, offset, fsize));
if (offset > std::numeric_limits<uint32_t>::max()) fail(std::format( "Absolute file {} offset is too large: {} > {}", i, offset, std::numeric_limits<uint32_t>::max()));
const uint32_t nameOffset = offsets[2 * filenum + i];
if (nameOffset >= mStringBuf.size()) fail("Archive contains names offset outside itself");
const char* const begin = mStringBuf.data() + nameOffset; const char* const end = reinterpret_cast<const char*>(std::memchr(begin, '\0', mStringBuf.size() - nameOffset));
if (end == nullptr) fail("Archive contains non-zero terminated string");
const std::size_t nameSize = end - begin;
FileStruct fs;
fs.mFileSize = fileSize; fs.mOffset = static_cast<uint32_t>(offset); fs.mHash = hashes[i]; fs.mNameOffset = nameOffset; fs.mNameSize = static_cast<uint32_t>(nameSize); fs.mNamesBuffer = &mStringBuf;
mFiles.push_back(fs);
endOfNameBuffer = std::max(endOfNameBuffer, nameOffset + nameSize + 1); assert(endOfNameBuffer <= mStringBuf.size()); } mStringBuf.resize(endOfNameBuffer);
std::sort(mFiles.begin(), mFiles.end(), [](const FileStruct& left, const FileStruct& right) { return left.mOffset < right.mOffset; });}
/// Write header information to the output sinkvoid Bsa::BSAFile::writeHeader(){ std::fstream output(mFilepath, std::ios::binary | std::ios::in | std::ios::out);
uint32_t head[3]; head[0] = 0x100; uint64_t fileDataOffset = mFiles.empty() ? 12 : mFiles.front().mOffset; head[1] = static_cast<uint32_t>(fileDataOffset - 12 - 8 * mFiles.size());
output.seekp(0, std::ios_base::end);
head[2] = static_cast<uint32_t>(mFiles.size()); output.seekp(0); output.write(reinterpret_cast<char*>(head), 12);
std::sort(mFiles.begin(), mFiles.end(), [](const FileStruct& left, const FileStruct& right) { return std::make_pair(left.mHash.mLow, left.mHash.mHigh) < std::make_pair(right.mHash.mLow, right.mHash.mHigh); });
size_t filenum = mFiles.size(); std::vector<uint32_t> offsets(3 * filenum); std::vector<Hash> hashes(filenum); for (size_t i = 0; i < filenum; i++) { auto& f = mFiles[i]; offsets[i * 2] = f.mFileSize; offsets[i * 2 + 1] = static_cast<uint32_t>(f.mOffset - fileDataOffset); offsets[2 * filenum + i] = f.mNameOffset; hashes[i] = f.mHash; } output.write(reinterpret_cast<char*>(offsets.data()), sizeof(uint32_t) * offsets.size()); output.write(reinterpret_cast<char*>(mStringBuf.data()), mStringBuf.size()); output.seekp(fileDataOffset - 8 * mFiles.size(), std::ios_base::beg); output.write(reinterpret_cast<char*>(hashes.data()), sizeof(Hash) * hashes.size());}
/// Open an archive file.void BSAFile::open(const std::filesystem::path& file){ if (mIsLoaded) close();
mFilepath = file; if (std::filesystem::exists(file)) { std::ifstream input(mFilepath, std::ios_base::binary); readHeader(input); mIsLoaded = true; } else { { std::fstream(mFilepath, std::ios::binary | std::ios::out); } writeHeader(); mIsLoaded = true; }}
/// Close the archive, write the updated headers to the filevoid Bsa::BSAFile::close(){ if (mHasChanged) writeHeader();
mFiles.clear(); mStringBuf.clear(); mIsLoaded = false;}
Files::IStreamPtr Bsa::BSAFile::getFile(const FileStruct* file){ return Files::openConstrainedFileStream(mFilepath, file->mOffset, file->mFileSize);}
void Bsa::BSAFile::addFile(const std::string& filename, std::istream& file){ if (!mIsLoaded) fail("Unable to add file " + filename + " the archive is not opened");
auto newStartOfDataBuffer = 12 + (12 + 8) * (mFiles.size() + 1) + mStringBuf.size() + filename.size() + 1; if (mFiles.empty()) std::filesystem::resize_file(mFilepath, newStartOfDataBuffer);
std::fstream stream(mFilepath, std::ios::binary | std::ios::in | std::ios::out);
FileStruct newFile; file.seekg(0, std::ios::end); newFile.mFileSize = static_cast<uint32_t>(file.tellg()); newFile.mHash = getHash(filename);
if (mFiles.empty()) newFile.mOffset = static_cast<uint64_t>(newStartOfDataBuffer); else { std::vector<char> buffer; while (mFiles.front().mOffset < newStartOfDataBuffer) { FileStruct& firstFile = mFiles.front(); buffer.resize(firstFile.mFileSize);
stream.seekg(firstFile.mOffset, std::ios::beg); stream.read(buffer.data(), firstFile.mFileSize);
stream.seekp(0, std::ios::end); firstFile.mOffset = static_cast<uint64_t>(stream.tellp());
stream.write(buffer.data(), firstFile.mFileSize);
// ensure sort order is preserved std::rotate(mFiles.begin(), mFiles.begin() + 1, mFiles.end()); } stream.seekp(0, std::ios::end); newFile.mOffset = static_cast<uint64_t>(stream.tellp()); }
newFile.mNameOffset = static_cast<uint32_t>(mStringBuf.size()); newFile.mNameSize = static_cast<uint32_t>(filename.size()); newFile.mNamesBuffer = &mStringBuf;
mStringBuf.insert(mStringBuf.end(), filename.begin(), filename.end()); mStringBuf.push_back('\0');
mFiles.push_back(newFile);
mHasChanged = true;
stream.seekp(0, std::ios::end); file.seekg(0, std::ios::beg); stream << file.rdbuf();}
BsaVersion Bsa::BSAFile::detectVersion(const std::filesystem::path& filePath){ std::ifstream input(filePath, std::ios_base::binary);
// Get essential header numbers
// First 12 bytes uint32_t head[3];
input.read(reinterpret_cast<char*>(head), sizeof(head));
if (input.gcount() != sizeof(head)) return BsaVersion::Unknown;
if (head[0] == static_cast<uint32_t>(BsaVersion::Uncompressed)) { return BsaVersion::Uncompressed; }
if (head[0] == static_cast<uint32_t>(BsaVersion::Compressed)) { return BsaVersion::Compressed; }
if (head[0] == ESM::fourCC("BTDX")) { if (head[2] == ESM::fourCC("GNRL")) return BsaVersion::BA2GNRL; if (head[2] == ESM::fourCC("DX10")) return BsaVersion::BA2DX10; }
return BsaVersion::Unknown;}