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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 "Tar.h"
namespace Archive {
unsigned TarFileHeader::expected_checksum() const
{
auto checksum = 0u;
const u8* u8_this = reinterpret_cast<const u8*>(this);
const u8* u8_m_checksum = reinterpret_cast<const u8*>(&m_checksum);
for (auto i = 0u; i < sizeof(TarFileHeader); ++i) {
if (u8_this + i >= u8_m_checksum && u8_this + i < u8_m_checksum + sizeof(m_checksum)) {
checksum += ' ';
} else {
checksum += u8_this[i];
}
}
return checksum;
}
void TarFileHeader::calculate_checksum()
{
memset(m_checksum, ' ', sizeof(m_checksum));
VERIFY(String::formatted("{:06o}", expected_checksum()).copy_characters_to_buffer(m_checksum, sizeof(m_checksum)));
}
}
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