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/*
* Copyright (c) 2020, Peter Elliott <pelliott@ualberta.ca>
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibArchive/TarStream.h>
#include <string.h>
namespace Archive {
TarFileStream::TarFileStream(TarInputStream& tar_stream)
: m_tar_stream(tar_stream)
, m_generation(tar_stream.m_generation)
{
}
size_t TarFileStream::read(Bytes bytes)
{
// verify that the stream has not advanced
VERIFY(m_tar_stream.m_generation == m_generation);
if (has_any_error())
return 0;
auto to_read = min(bytes.size(), m_tar_stream.header().size() - m_tar_stream.m_file_offset);
auto nread = m_tar_stream.m_stream.read(bytes.trim(to_read));
m_tar_stream.m_file_offset += nread;
return nread;
}
bool TarFileStream::unreliable_eof() const
{
// verify that the stream has not advanced
VERIFY(m_tar_stream.m_generation == m_generation);
return m_tar_stream.m_stream.unreliable_eof()
|| m_tar_stream.m_file_offset >= m_tar_stream.header().size();
}
bool TarFileStream::read_or_error(Bytes bytes)
{
// verify that the stream has not advanced
VERIFY(m_tar_stream.m_generation == m_generation);
if (read(bytes) < bytes.size()) {
set_fatal_error();
return false;
}
return true;
}
bool TarFileStream::discard_or_error(size_t count)
{
// verify that the stream has not advanced
VERIFY(m_tar_stream.m_generation == m_generation);
if (count > m_tar_stream.header().size() - m_tar_stream.m_file_offset) {
return false;
}
m_tar_stream.m_file_offset += count;
return m_tar_stream.m_stream.discard_or_error(count);
}
TarInputStream::TarInputStream(InputStream& stream)
: m_stream(stream)
{
if (!m_stream.read_or_error(Bytes(&m_header, sizeof(m_header)))) {
m_finished = true;
m_stream.handle_any_error(); // clear out errors so we dont assert
return;
}
VERIFY(m_stream.discard_or_error(block_size - sizeof(TarFileHeader)));
}
static constexpr unsigned long block_ceiling(unsigned long offset)
{
return block_size * (1 + ((offset - 1) / block_size));
}
void TarInputStream::advance()
{
if (m_finished)
return;
m_generation++;
VERIFY(m_stream.discard_or_error(block_ceiling(m_header.size()) - m_file_offset));
m_file_offset = 0;
if (!m_stream.read_or_error(Bytes(&m_header, sizeof(m_header)))) {
m_finished = true;
return;
}
if (!valid()) {
m_finished = true;
return;
}
VERIFY(m_stream.discard_or_error(block_size - sizeof(TarFileHeader)));
}
bool TarInputStream::valid() const
{
auto& header_magic = header().magic();
auto& header_version = header().version();
if (!((header_magic == gnu_magic && header_version == gnu_version)
|| (header_magic == ustar_magic && header_version == ustar_version)
|| (header_magic == posix1_tar_magic && header_version == posix1_tar_version)))
return false;
// POSIX.1-1988 tar does not have magic numbers, so we also need to verify the header checksum.
return header().checksum() == header().expected_checksum();
}
TarFileStream TarInputStream::file_contents()
{
VERIFY(!m_finished);
return TarFileStream(*this);
}
TarOutputStream::TarOutputStream(OutputStream& stream)
: m_stream(stream)
{
}
void TarOutputStream::add_directory(const String& path, mode_t mode)
{
VERIFY(!m_finished);
TarFileHeader header;
memset(&header, 0, sizeof(header));
header.set_size(0);
header.set_filename(String::formatted("{}/", path)); // Old tar implementations assume directory names end with a /
header.set_type_flag(TarFileType::Directory);
header.set_mode(mode);
header.set_magic(gnu_magic);
header.set_version(gnu_version);
header.calculate_checksum();
VERIFY(m_stream.write_or_error(Bytes { &header, sizeof(header) }));
u8 padding[block_size] = { 0 };
VERIFY(m_stream.write_or_error(Bytes { &padding, block_size - sizeof(header) }));
}
void TarOutputStream::add_file(const String& path, mode_t mode, const ReadonlyBytes& bytes)
{
VERIFY(!m_finished);
TarFileHeader header;
memset(&header, 0, sizeof(header));
header.set_size(bytes.size());
header.set_filename(path);
header.set_type_flag(TarFileType::NormalFile);
header.set_mode(mode);
header.set_magic(gnu_magic);
header.set_version(gnu_version);
header.calculate_checksum();
VERIFY(m_stream.write_or_error(Bytes { &header, sizeof(header) }));
u8 padding[block_size] = { 0 };
VERIFY(m_stream.write_or_error(Bytes { &padding, block_size - sizeof(header) }));
size_t n_written = 0;
while (n_written < bytes.size()) {
n_written += m_stream.write(bytes.slice(n_written, min(bytes.size() - n_written, block_size)));
}
VERIFY(m_stream.write_or_error(Bytes { &padding, block_size - (n_written % block_size) }));
}
void TarOutputStream::finish()
{
VERIFY(!m_finished);
u8 padding[block_size] = { 0 };
m_stream.write_or_error(Bytes { &padding, block_size }); // 2 empty records that are used to signify the end of the archive
m_stream.write_or_error(Bytes { &padding, block_size });
m_finished = true;
}
}
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