ladybird/Libraries/LibTar/TarStream.cpp
2020-10-04 00:16:40 +02:00

134 lines
3.9 KiB
C++

/*
* Copyright (c) 2020, Peter Elliott <pelliott@ualberta.ca>
* 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 <AK/LogStream.h>
#include <LibTar/TarStream.h>
namespace Tar {
TarFileStream::TarFileStream(TarStream& 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
ASSERT(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
ASSERT(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
ASSERT(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
ASSERT(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);
}
TarStream::TarStream(InputStream& stream)
: m_stream(stream)
{
if (!m_stream.read_or_error(Bytes(&m_header, sizeof(m_header)))) {
m_finished = true;
return;
}
ASSERT(m_stream.discard_or_error(block_size - sizeof(Header)));
}
static constexpr unsigned long block_ceiling(unsigned long offset)
{
return block_size * (1 + ((offset - 1) / block_size));
}
void TarStream::advance()
{
if (m_finished)
return;
m_generation++;
ASSERT(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;
}
ASSERT(m_stream.discard_or_error(block_size - sizeof(Header)));
}
bool TarStream::valid() const
{
return header().magic() == ustar_magic;
}
TarFileStream TarStream::file_contents()
{
ASSERT(!m_finished);
return TarFileStream(*this);
}
}