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/*
* Copyright (c) 2020-2022, Peter Elliott <pelliott@serenityos.org>
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/String.h>
#include <AK/StringView.h>
#include <string.h>
#include <sys/types.h>
// glibc before 2.28 defines these from sys/types.h, but we don't want
// TarFileHeader::major() and TarFileHeader::minor() to use those macros
#ifdef minor
# undef minor
#endif
#ifdef major
# undef major
#endif
namespace Archive {
enum class TarFileType : char {
NormalFile = '0',
AlternateNormalFile = '\0',
HardLink = '1',
SymLink = '2',
CharacterSpecialFile = '3',
BlockSpecialFile = '4',
Directory = '5',
FIFO = '6',
ContiguousFile = '7',
GlobalExtendedHeader = 'g',
ExtendedHeader = 'x',
// GNU extensions
LongName = 'L',
};
constexpr size_t block_size = 512;
constexpr StringView gnu_magic = "ustar "sv; // gnu format magic
constexpr StringView gnu_version = " "sv; // gnu format version
constexpr StringView ustar_magic = "ustar"sv; // ustar format magic
constexpr StringView ustar_version = "00"sv; // ustar format version
constexpr StringView posix1_tar_magic = ""sv; // POSIX.1-1988 format magic
constexpr StringView posix1_tar_version = ""sv; // POSIX.1-1988 format version
template<size_t N>
static ErrorOr<size_t> get_field_as_integral(char const (&field)[N])
{
size_t value = 0;
for (size_t i = 0; i < N; ++i) {
if (field[i] == 0 || field[i] == ' ')
break;
if (field[i] < '0' || field[i] > '7')
return Error::from_string_literal("Passed a non-octal value");
value *= 8;
value += field[i] - '0';
}
return value;
}
template<size_t N>
static StringView get_field_as_string_view(char const (&field)[N])
{
return { field, min(__builtin_strlen(field), N) };
}
template<size_t N, class TSource>
static void set_field(char (&field)[N], TSource&& source)
{
VERIFY(N >= source.length());
memcpy(field, StringView(source).characters_without_null_termination(), source.length());
if (N > source.length())
field[source.length()] = 0;
}
template<class TSource, size_t N>
static void set_octal_field(char (&field)[N], TSource&& source)
{
set_field(field, String::formatted("{:o}", forward<TSource>(source)));
}
class [[gnu::packed]] TarFileHeader {
public:
StringView filename() const { return get_field_as_string_view(m_filename); }
ErrorOr<mode_t> mode() const { return TRY(get_field_as_integral(m_mode)); }
ErrorOr<uid_t> uid() const { return TRY(get_field_as_integral(m_uid)); }
ErrorOr<gid_t> gid() const { return TRY(get_field_as_integral(m_gid)); }
// FIXME: support 2001-star size encoding
ErrorOr<size_t> size() const { return TRY(get_field_as_integral(m_size)); }
ErrorOr<time_t> timestamp() const { return TRY(get_field_as_integral(m_timestamp)); }
ErrorOr<unsigned> checksum() const { return TRY(get_field_as_integral(m_checksum)); }
TarFileType type_flag() const { return TarFileType(m_type_flag); }
StringView link_name() const { return { m_link_name, strlen(m_link_name) }; }
StringView magic() const { return get_field_as_string_view(m_magic); }
StringView version() const { return get_field_as_string_view(m_version); }
StringView owner_name() const { return get_field_as_string_view(m_owner_name); }
StringView group_name() const { return get_field_as_string_view(m_group_name); }
ErrorOr<int> major() const { return TRY(get_field_as_integral(m_major)); }
ErrorOr<int> minor() const { return TRY(get_field_as_integral(m_minor)); }
// FIXME: support ustar filename prefix
StringView prefix() const { return get_field_as_string_view(m_prefix); }
void set_filename(StringView filename) { set_field(m_filename, filename); }
void set_mode(mode_t mode) { set_octal_field(m_mode, mode); }
void set_uid(uid_t uid) { set_octal_field(m_uid, uid); }
void set_gid(gid_t gid) { set_octal_field(m_gid, gid); }
void set_size(size_t size) { set_octal_field(m_size, size); }
void set_timestamp(time_t timestamp) { set_octal_field(m_timestamp, timestamp); }
void set_type_flag(TarFileType type) { m_type_flag = to_underlying(type); }
void set_link_name(StringView link_name) { set_field(m_link_name, link_name); }
// magic doesn't necessarily include a null byte
void set_magic(StringView magic) { set_field(m_magic, magic); }
// version doesn't necessarily include a null byte
void set_version(StringView version) { set_field(m_version, version); }
void set_owner_name(StringView owner_name) { set_field(m_owner_name, owner_name); }
void set_group_name(StringView group_name) { set_field(m_group_name, group_name); }
void set_major(int major) { set_octal_field(m_major, major); }
void set_minor(int minor) { set_octal_field(m_minor, minor); }
void set_prefix(StringView prefix) { set_field(m_prefix, prefix); }
unsigned expected_checksum() const;
void calculate_checksum();
bool is_zero_block() const;
bool content_is_like_extended_header() const;
void set_filename_and_prefix(StringView filename);
private:
char m_filename[100] { 0 };
char m_mode[8] { 0 };
char m_uid[8] { 0 };
char m_gid[8] { 0 };
char m_size[12] { 0 };
char m_timestamp[12] { 0 };
char m_checksum[8] { 0 }; // an uninitialized header's checksum is filled with spaces
char m_type_flag { 0 };
char m_link_name[100] { 0 };
char m_magic[6] { 0 };
char m_version[2] { 0 };
char m_owner_name[32] { 0 };
char m_group_name[32] { 0 };
char m_major[8] { 0 };
char m_minor[8] { 0 };
char m_prefix[155] { 0 }; // zero out the prefix for archiving
};
}
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