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/*
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibArchive/Zip.h>
namespace Archive {
bool Zip::find_end_of_central_directory_offset(const 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 signature_offset = (buffer.size() - (sizeof(EndOfCentralDirectory) - sizeof(u8*)) - backwards_offset);
if (memcmp(buffer.data() + signature_offset, end_of_central_directory_signature, sizeof(end_of_central_directory_signature)) == 0) {
offset = signature_offset;
return true;
}
}
return false;
}
Optional<Zip> Zip::try_create(const 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 (!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 (!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();
}
Zip zip;
zip.m_input_data = buffer;
zip.member_count = end_of_central_directory.total_records_count;
zip.members_start_offset = end_of_central_directory.central_directory_offset;
return zip;
}
bool Zip::for_each_member(Function<IterationDecision(const ZipMember&)> callback)
{
size_t member_offset = members_start_offset;
for (size_t i = 0; i < 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 = static_cast<ZipCompressionMethod>(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;
}
}
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