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Zip.cpp
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Zip.cpp
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/*
* Copyright (c) 2021, Idan Horowitz <[email protected]>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibArchive/Zip.h>
namespace Archive {
OutputStream& operator<<(OutputStream& stream, ZipCompressionMethod method)
{
return stream << to_underlying(method);
}
bool Zip::find_end_of_central_directory_offset(ReadonlyBytes buffer, size_t& offset)
{
for (size_t backwards_offset = 0; backwards_offset <= UINT16_MAX; backwards_offset++) // the file may have a trailing comment of an arbitrary 16 bit length
{
if (buffer.size() < (sizeof(EndOfCentralDirectory) - sizeof(u8*)) + backwards_offset)
return false;
auto const signature_offset = (buffer.size() - (sizeof(EndOfCentralDirectory) - sizeof(u8*)) - backwards_offset);
if (auto signature = ReadonlyBytes { buffer.data() + signature_offset, EndOfCentralDirectory::signature.size() };
signature == EndOfCentralDirectory::signature) {
offset = signature_offset;
return true;
}
}
return false;
}
Optional<Zip> Zip::try_create(ReadonlyBytes buffer)
{
size_t end_of_central_directory_offset;
if (!find_end_of_central_directory_offset(buffer, end_of_central_directory_offset))
return {};
EndOfCentralDirectory end_of_central_directory {};
if (!end_of_central_directory.read(buffer.slice(end_of_central_directory_offset)))
return {};
if (end_of_central_directory.disk_number != 0 || end_of_central_directory.central_directory_start_disk != 0 || end_of_central_directory.disk_records_count != end_of_central_directory.total_records_count)
return {}; // TODO: support multi-volume zip archives
size_t member_offset = end_of_central_directory.central_directory_offset;
for (size_t i = 0; i < end_of_central_directory.total_records_count; i++) {
CentralDirectoryRecord central_directory_record {};
if (member_offset > buffer.size())
return {};
if (!central_directory_record.read(buffer.slice(member_offset)))
return {};
if (central_directory_record.general_purpose_flags & 1)
return {}; // TODO: support encrypted zip members
if (central_directory_record.general_purpose_flags & 3)
return {}; // TODO: support zip data descriptors
if (central_directory_record.compression_method != ZipCompressionMethod::Store && central_directory_record.compression_method != ZipCompressionMethod::Deflate)
return {}; // TODO: support obsolete zip compression methods
if (central_directory_record.compression_method == ZipCompressionMethod::Store && central_directory_record.uncompressed_size != central_directory_record.compressed_size)
return {};
if (central_directory_record.start_disk != 0)
return {}; // TODO: support multi-volume zip archives
if (memchr(central_directory_record.name, 0, central_directory_record.name_length) != nullptr)
return {};
LocalFileHeader local_file_header {};
if (central_directory_record.local_file_header_offset > buffer.size())
return {};
if (!local_file_header.read(buffer.slice(central_directory_record.local_file_header_offset)))
return {};
if (buffer.size() - (local_file_header.compressed_data - buffer.data()) < central_directory_record.compressed_size)
return {};
member_offset += central_directory_record.size();
}
return Zip {
end_of_central_directory.total_records_count,
end_of_central_directory.central_directory_offset,
buffer,
};
}
bool Zip::for_each_member(Function<IterationDecision(const ZipMember&)> callback)
{
size_t member_offset = m_members_start_offset;
for (size_t i = 0; i < m_member_count; i++) {
CentralDirectoryRecord central_directory_record {};
VERIFY(central_directory_record.read(m_input_data.slice(member_offset)));
LocalFileHeader local_file_header {};
VERIFY(local_file_header.read(m_input_data.slice(central_directory_record.local_file_header_offset)));
ZipMember member;
char null_terminated_name[central_directory_record.name_length + 1];
memcpy(null_terminated_name, central_directory_record.name, central_directory_record.name_length);
null_terminated_name[central_directory_record.name_length] = 0;
member.name = String { null_terminated_name };
member.compressed_data = { local_file_header.compressed_data, central_directory_record.compressed_size };
member.compression_method = central_directory_record.compression_method;
member.uncompressed_size = central_directory_record.uncompressed_size;
member.crc32 = central_directory_record.crc32;
member.is_directory = central_directory_record.external_attributes & zip_directory_external_attribute || member.name.ends_with('/'); // FIXME: better directory detection
if (callback(member) == IterationDecision::Break)
return false;
member_offset += central_directory_record.size();
}
return true;
}
ZipOutputStream::ZipOutputStream(OutputStream& stream)
: m_stream(stream)
{
}
static u16 minimum_version_needed(ZipCompressionMethod method)
{
// Deflate was added in PKZip 2.0
return method == ZipCompressionMethod::Deflate ? 20 : 10;
}
void ZipOutputStream::add_member(const ZipMember& member)
{
VERIFY(!m_finished);
VERIFY(member.name.length() <= UINT16_MAX);
VERIFY(member.compressed_data.size() <= UINT32_MAX);
m_members.append(member);
LocalFileHeader local_file_header {
.minimum_version = minimum_version_needed(member.compression_method),
.general_purpose_flags = 0,
.compression_method = static_cast<u16>(member.compression_method),
.modification_time = 0, // TODO: support modification time
.modification_date = 0,
.crc32 = member.crc32,
.compressed_size = static_cast<u32>(member.compressed_data.size()),
.uncompressed_size = member.uncompressed_size,
.name_length = static_cast<u16>(member.name.length()),
.extra_data_length = 0,
.name = reinterpret_cast<u8 const*>(member.name.characters()),
.extra_data = nullptr,
.compressed_data = member.compressed_data.data(),
};
local_file_header.write(m_stream);
}
void ZipOutputStream::finish()
{
VERIFY(!m_finished);
m_finished = true;
auto file_header_offset = 0u;
auto central_directory_size = 0u;
for (const ZipMember& member : m_members) {
auto zip_version = minimum_version_needed(member.compression_method);
CentralDirectoryRecord central_directory_record {
.made_by_version = zip_version,
.minimum_version = zip_version,
.general_purpose_flags = 0,
.compression_method = member.compression_method,
.modification_time = 0, // TODO: support modification time
.modification_date = 0,
.crc32 = member.crc32,
.compressed_size = static_cast<u32>(member.compressed_data.size()),
.uncompressed_size = member.uncompressed_size,
.name_length = static_cast<u16>(member.name.length()),
.extra_data_length = 0,
.comment_length = 0,
.start_disk = 0,
.internal_attributes = 0,
.external_attributes = member.is_directory ? zip_directory_external_attribute : 0,
.local_file_header_offset = file_header_offset, // FIXME: we assume the wrapped output stream was never written to before us
.name = reinterpret_cast<u8 const*>(member.name.characters()),
.extra_data = nullptr,
.comment = nullptr,
};
file_header_offset += sizeof(LocalFileHeader::signature) + (sizeof(LocalFileHeader) - (sizeof(u8*) * 3)) + member.name.length() + member.compressed_data.size();
central_directory_record.write(m_stream);
central_directory_size += central_directory_record.size();
}
EndOfCentralDirectory end_of_central_directory {
.disk_number = 0,
.central_directory_start_disk = 0,
.disk_records_count = static_cast<u16>(m_members.size()),
.total_records_count = static_cast<u16>(m_members.size()),
.central_directory_size = central_directory_size,
.central_directory_offset = file_header_offset,
.comment_length = 0,
.comment = nullptr,
};
end_of_central_directory.write(m_stream);
}
}