lib/src/format.dart - external/github.com/simolus3/tar - Git at Google

 /// Holds the possible TAR formats that a file could take.
 ///
 /// This library supports the V7, USTAR, PAX, GNU, and STAR formats. The
 /// [MaybeTarFormat] class generally describes any combination of those formats
 /// and represents that we don't know the exact format yet. As soon as we do
 /// know, the [TarFormat] enum represents the exact format of a header.
 sealed class MaybeTarFormat {
   /// The TAR formats are encoded in powers of two in [_value], such that we
   /// can refine our guess via bit operations as we discover more information
   /// about the TAR file.
   /// A value of 0 means that the format is invalid.
   int get _value;

   factory MaybeTarFormat._(int value) {
     return switch (value) {
       1 => TarFormat.v7,
       2 => TarFormat.ustar,
       4 => TarFormat.pax,
       8 => TarFormat.gnu,
       16 => TarFormat.star,
       final other => _MaybeTarFormat(other),
     };
   }

   /// Returns a new [MaybeTarFormat] that signifies that it can be either
   /// `this` or [other]'s format.
   ///
   /// **Example:**
   /// ```dart
   /// TarFormat format = TarFormat.ustar | TarFormat.pax;
   /// ```
   ///
   /// The above code would signify that we have limited `format` to either
   /// the USTAR or PAX format, but need further information to refine the guess.
   MaybeTarFormat operator |(TarFormat other);

   /// Returns if [other] is a possible resolution of `this`.
   ///
   /// For example, a [TarFormat] with a value of 6 means that we do not have
   /// enough information to determine if it is [TarFormat.ustar] or
   /// [TarFormat.pax], so either of them could be possible resolutions of
   /// `this`.
   bool has(MaybeTarFormat other);

   /// Returns a new [TarFormat] that signifies that it can only be [other]'s
   /// format.
   ///
   /// **Example:**
   /// ```dart
   /// TarFormat format = TarFormat.PAX | TarFormat.USTAR;
   /// ...
   /// format = format.mayOnlyBe(TarFormat.USTAR);
   /// ```
   ///
   /// In the above example, we found that `format` could either be PAX or USTAR,
   /// but later learnt that it can only be the USTAR format.
   ///
   /// If `has(other) == false`, [mayOnlyBe] will result in an unknown
   /// [TarFormat].
   MaybeTarFormat mayOnlyBe(MaybeTarFormat other);

   /// Returns if this format might be valid.
   ///
   /// This returns true as well even if we have yet to fully determine what the
   /// format is.
   bool get valid;
 }

 /// A fully resolved tar format.
 ///
 /// When we know that a tar entry must use a specific format, this is represented
 /// with a value from this [TarFormat] enum.
 enum TarFormat implements MaybeTarFormat {
   /// Original Unix Version 7 (V7) AT&T tar tool prior to standardization.
   ///
   /// The structure of the V7 Header consists of the following:
   ///
   /// Start | End | Field
   /// =========================================================================
   /// 0     | 100 | Path name, stored as null-terminated string.
   /// 100   | 108 | File mode, stored as an octal number in ASCII.
   /// 108   | 116 | User id of owner, as octal number in ASCII.
   /// 116   | 124 | Group id of owner, as octal number in ASCII.
   /// 124   | 136 | Size of file, as octal number in ASCII.
   /// 136   | 148 | Modification time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 148   | 156 | Header checksum, stored as an octal number in ASCII.
   /// 156   | 157 | Link flag, determines the kind of header.
   /// 157   | 257 | Link name, stored as a string.
   /// 257   | 512 | NUL pad.
   ///
   /// Unused bytes are set to NUL ('\x00')s
   ///
   /// Reference:
   /// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
   /// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
   /// http://cdrtools.sourceforge.net/private/man/star/star.4.html
   v7(1, 'V7'),

   /// USTAR (Unix Standard TAR) header format defined in POSIX.1-1988.
   ///
   /// The structure of the USTAR Header consists of the following:
   ///
   /// Start | End | Field
   /// =========================================================================
   /// 0     | 100 | Path name, stored as null-terminated string.
   /// 100   | 108 | File mode, stored as an octal number in ASCII.
   /// 108   | 116 | User id of owner, as octal number in ASCII.
   /// 116   | 124 | Group id of owner, as octal number in ASCII.
   /// 124   | 136 | Size of file, as octal number in ASCII.
   /// 136   | 148 | Modification time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 148   | 156 | Header checksum, stored as an octal number in ASCII.
   /// 156   | 157 | Type flag, determines the kind of header.
   ///               Note that the meaning of the size field depends on the type.
   /// 157   | 257 | Link name, stored as a string.
   /// 257   | 263 | Contains the magic value "ustar\x00" to indicate that this is
   ///               the USTAR format. Full compliance requires user name and
   ///               group name fields to be set.
   /// 263   | 265 | Version. "00" for POSIX standard archives.
   /// 265   | 297 | User name, as null-terminated ASCII string.
   /// 297   | 329 | Group name, as null-terminated ASCII string.
   /// 329   | 337 | Major number for character or block device entry.
   /// 337   | 345 | Minor number for character or block device entry.
   /// 345   | 500 | Prefix. If the pathname is too long to fit in the 100 bytes
   ///               provided at the start, it can be split at any / character
   ///               with the first portion going here.
   /// 500   | 512 | NUL pad.
   ///
   /// Unused bytes are set to NUL ('\x00')s
   ///
   /// User and group names should be used in preference to uid/gid values when
   /// they are set and the corresponding names exist on the system.
   ///
   /// While this format is compatible with most tar readers, the format has
   /// several limitations making it unsuitable for some usages. Most notably, it
   /// cannot support sparse files, files larger than 8GiB, filenames larger than
   /// 256 characters, and non-ASCII filenames.
   ///
   /// Reference:
   /// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
   /// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
   ///	http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
   ustar(2, 'USTAR'),

   /// PAX header format defined in POSIX.1-2001.
   ///
   /// PAX extends USTAR by writing a special file with either the `x` or `g`
   /// type flags to allow for attributes that are not conveniently stored in a
   /// POSIX ustar archive to be held.
   ///
   /// Some newer formats add their own extensions to PAX by defining their
   /// own keys and assigning certain semantic meaning to the associated values.
   /// For example, sparse file support in PAX is implemented using keys
   /// defined by the GNU manual (e.g., "GNU.sparse.map").
   ///
   /// Reference:
   /// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
   /// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
   /// http://cdrtools.sourceforge.net/private/man/star/star.4.html
   ///	http://pubs.opengroup.org/onlinepubs/009695399/utilities/pax.html
   pax(4, 'PAX'),

   /// GNU header format.
   ///
   /// The GNU header format is older than the USTAR and PAX standards and
   /// is not compatible with them. The GNU format supports
   /// arbitrary file sizes, filenames of arbitrary encoding and length,
   /// sparse files, and other features.
   ///
   /// Start | End | Field
   /// =========================================================================
   /// 0     | 100 | Path name, stored as null-terminated string.
   /// 100   | 108 | File mode, stored as an octal number in ASCII.
   /// 108   | 116 | User id of owner, as octal number in ASCII.
   /// 116   | 124 | Group id of owner, as octal number in ASCII.
   /// 124   | 136 | Size of file, as octal number in ASCII.
   /// 136   | 148 | Modification time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 148   | 156 | Header checksum, stored as an octal number in ASCII.
   /// 156   | 157 | Type flag, determines the kind of header.
   ///               Note that the meaning of the size field depends on the type.
   /// 157   | 257 | Link name, stored as a string.
   /// 257   | 263 | Contains the magic value "ustar " to indicate that this is
   ///               the GNU format.
   /// 263   | 265 | Version. " \x00" for POSIX standard archives.
   /// 265   | 297 | User name, as null-terminated ASCII string.
   /// 297   | 329 | Group name, as null-terminated ASCII string.
   /// 329   | 337 | Major number for character or block device entry.
   /// 337   | 345 | Minor number for character or block device entry.
   /// 345   | 357 | Last Access time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 357   | 369 | Last Changed time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 369   | 381 | Offset - not used.
   /// 381   | 385 | Longnames - deprecated
   /// 385   | 386 | Unused.
   /// 386   | 482 | Sparse data - 4 sets of (offset, numbytes) stored as
   ///               octal numbers in ASCII.
   /// 482   | 483 | isExtended - if this field is non-zero, this header is
   ///               followed by  additional sparse records, which are in the
   ///               same format as above.
   /// 483   | 495 | Binary representation of the file's complete size, inclusive
   ///               of the sparse data.
   /// 495   | 512 | NUL pad.
   ///
   /// It is recommended that PAX be chosen over GNU unless the target
   /// application can only parse GNU formatted archives.
   ///
   /// Reference:
   ///	https://www.gnu.org/software/tar/manual/html_node/Standard.html
   gnu(8, 'GNU'),

   /// Schily's TAR format, which is incompatible with USTAR.
   /// This does not cover STAR extensions to the PAX format; these fall under
   /// the PAX format.
   ///
   /// Start | End | Field
   /// =========================================================================
   /// 0     | 100 | Path name, stored as null-terminated string.
   /// 100   | 108 | File mode, stored as an octal number in ASCII.
   /// 108   | 116 | User id of owner, as octal number in ASCII.
   /// 116   | 124 | Group id of owner, as octal number in ASCII.
   /// 124   | 136 | Size of file, as octal number in ASCII.
   /// 136   | 148 | Modification time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 148   | 156 | Header checksum, stored as an octal number in ASCII.
   /// 156   | 157 | Type flag, determines the kind of header.
   ///               Note that the meaning of the size field depends on the type.
   /// 157   | 257 | Link name, stored as a string.
   /// 257   | 263 | Contains the magic value "ustar\x00" to indicate that this is
   ///               the GNU format.
   /// 263   | 265 | Version. "00" for STAR archives.
   /// 265   | 297 | User name, as null-terminated ASCII string.
   /// 297   | 329 | Group name, as null-terminated ASCII string.
   /// 329   | 337 | Major number for character or block device entry.
   /// 337   | 345 | Minor number for character or block device entry.
   /// 345   | 476 | Prefix. If the pathname is too long to fit in the 100 bytes
   ///               provided at the start, it can be split at any / character
   ///               with the first portion going here.
   /// 476   | 488 | Last Access time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 488   | 500 | Last Changed time of file, number of seconds from epoch,
   ///               stored as an octal number in ASCII.
   /// 500   | 508 | NUL pad.
   /// 508   | 512 | Trailer - "tar\x00".
   ///
   /// Reference:
   /// http://cdrtools.sourceforge.net/private/man/star/star.4.html
   star(16, 'STAR'),
   ;

   @override
   final int _value;

   final String _name;

   const TarFormat(this._value, this._name);

   @override
   bool get valid => true;

   @override
   MaybeTarFormat operator |(TarFormat other) {
     return other == this ? this : _MaybeTarFormat(_value | other._value);
   }

   @override
   bool has(MaybeTarFormat other) {
     return other == this;
   }

   @override
   MaybeTarFormat mayOnlyBe(MaybeTarFormat other) {
     return MaybeTarFormat._(_value & other._value);
   }

   @override
   String toString() => _name;
 }

 final class _MaybeTarFormat implements MaybeTarFormat {
   // Note: We never represent a single tar format in a _MaybeTarFormat, these
   // are represented in the TarFormat enum.
   @override
   final int _value;

   const _MaybeTarFormat(this._value);

   @override
   int get hashCode => _value;

   @override
   bool operator ==(Object other) {
     if (other is! TarFormat) return false;

     return _value == other._value;
   }

   @override
   String toString() {
     if (!valid) return 'Invalid';

     return TarFormat.values.where(has).map((e) => e._name).join(' or ');
   }

   @override
   bool has(MaybeTarFormat other) => _value & other._value != 0;

   @override
   bool get valid => _value != 0;

   @override
   MaybeTarFormat mayOnlyBe(MaybeTarFormat other) {
     return MaybeTarFormat._(_value & other._value);
   }

   @override
   MaybeTarFormat operator |(TarFormat other) {
     return MaybeTarFormat._(_value | other._value);
   }
 }
	/// Holds the possible TAR formats that a file could take.
	///
	/// This library supports the V7, USTAR, PAX, GNU, and STAR formats. The
	/// [MaybeTarFormat] class generally describes any combination of those formats
	/// and represents that we don't know the exact format yet. As soon as we do
	/// know, the [TarFormat] enum represents the exact format of a header.
	sealed class MaybeTarFormat {
	/// The TAR formats are encoded in powers of two in [_value], such that we
	/// can refine our guess via bit operations as we discover more information
	/// about the TAR file.
	/// A value of 0 means that the format is invalid.
	int get _value;

	factory MaybeTarFormat._(int value) {
	return switch (value) {
	1 => TarFormat.v7,
	2 => TarFormat.ustar,
	4 => TarFormat.pax,
	8 => TarFormat.gnu,
	16 => TarFormat.star,
	final other => _MaybeTarFormat(other),
	};
	}

	/// Returns a new [MaybeTarFormat] that signifies that it can be either
	/// `this` or [other]'s format.
	///
	/// Example:
	/// ```dart
	/// TarFormat format = TarFormat.ustar \| TarFormat.pax;
	/// ```
	///
	/// The above code would signify that we have limited `format` to either
	/// the USTAR or PAX format, but need further information to refine the guess.
	MaybeTarFormat operator \|(TarFormat other);

	/// Returns if [other] is a possible resolution of `this`.
	///
	/// For example, a [TarFormat] with a value of 6 means that we do not have
	/// enough information to determine if it is [TarFormat.ustar] or
	/// [TarFormat.pax], so either of them could be possible resolutions of
	/// `this`.
	bool has(MaybeTarFormat other);

	/// Returns a new [TarFormat] that signifies that it can only be [other]'s
	/// format.
	///
	/// Example:
	/// ```dart
	/// TarFormat format = TarFormat.PAX \| TarFormat.USTAR;
	/// ...
	/// format = format.mayOnlyBe(TarFormat.USTAR);
	/// ```
	///
	/// In the above example, we found that `format` could either be PAX or USTAR,
	/// but later learnt that it can only be the USTAR format.
	///
	/// If `has(other) == false`, [mayOnlyBe] will result in an unknown
	/// [TarFormat].
	MaybeTarFormat mayOnlyBe(MaybeTarFormat other);

	/// Returns if this format might be valid.
	///
	/// This returns true as well even if we have yet to fully determine what the
	/// format is.
	bool get valid;
	}

	/// A fully resolved tar format.
	///
	/// When we know that a tar entry must use a specific format, this is represented
	/// with a value from this [TarFormat] enum.
	enum TarFormat implements MaybeTarFormat {
	/// Original Unix Version 7 (V7) AT&T tar tool prior to standardization.
	///
	/// The structure of the V7 Header consists of the following:
	///
	/// Start \| End \| Field
	/// =========================================================================
	/// 0 \| 100 \| Path name, stored as null-terminated string.
	/// 100 \| 108 \| File mode, stored as an octal number in ASCII.
	/// 108 \| 116 \| User id of owner, as octal number in ASCII.
	/// 116 \| 124 \| Group id of owner, as octal number in ASCII.
	/// 124 \| 136 \| Size of file, as octal number in ASCII.
	/// 136 \| 148 \| Modification time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 148 \| 156 \| Header checksum, stored as an octal number in ASCII.
	/// 156 \| 157 \| Link flag, determines the kind of header.
	/// 157 \| 257 \| Link name, stored as a string.
	/// 257 \| 512 \| NUL pad.
	///
	/// Unused bytes are set to NUL ('\x00')s
	///
	/// Reference:
	/// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
	/// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
	/// http://cdrtools.sourceforge.net/private/man/star/star.4.html
	v7(1, 'V7'),

	/// USTAR (Unix Standard TAR) header format defined in POSIX.1-1988.
	///
	/// The structure of the USTAR Header consists of the following:
	///
	/// Start \| End \| Field
	/// =========================================================================
	/// 0 \| 100 \| Path name, stored as null-terminated string.
	/// 100 \| 108 \| File mode, stored as an octal number in ASCII.
	/// 108 \| 116 \| User id of owner, as octal number in ASCII.
	/// 116 \| 124 \| Group id of owner, as octal number in ASCII.
	/// 124 \| 136 \| Size of file, as octal number in ASCII.
	/// 136 \| 148 \| Modification time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 148 \| 156 \| Header checksum, stored as an octal number in ASCII.
	/// 156 \| 157 \| Type flag, determines the kind of header.
	/// Note that the meaning of the size field depends on the type.
	/// 157 \| 257 \| Link name, stored as a string.
	/// 257 \| 263 \| Contains the magic value "ustar\x00" to indicate that this is
	/// the USTAR format. Full compliance requires user name and
	/// group name fields to be set.
	/// 263 \| 265 \| Version. "00" for POSIX standard archives.
	/// 265 \| 297 \| User name, as null-terminated ASCII string.
	/// 297 \| 329 \| Group name, as null-terminated ASCII string.
	/// 329 \| 337 \| Major number for character or block device entry.
	/// 337 \| 345 \| Minor number for character or block device entry.
	/// 345 \| 500 \| Prefix. If the pathname is too long to fit in the 100 bytes
	/// provided at the start, it can be split at any / character
	/// with the first portion going here.
	/// 500 \| 512 \| NUL pad.
	///
	/// Unused bytes are set to NUL ('\x00')s
	///
	/// User and group names should be used in preference to uid/gid values when
	/// they are set and the corresponding names exist on the system.
	///
	/// While this format is compatible with most tar readers, the format has
	/// several limitations making it unsuitable for some usages. Most notably, it
	/// cannot support sparse files, files larger than 8GiB, filenames larger than
	/// 256 characters, and non-ASCII filenames.
	///
	/// Reference:
	/// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
	/// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
	/// http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
	ustar(2, 'USTAR'),

	/// PAX header format defined in POSIX.1-2001.
	///
	/// PAX extends USTAR by writing a special file with either the `x` or `g`
	/// type flags to allow for attributes that are not conveniently stored in a
	/// POSIX ustar archive to be held.
	///
	/// Some newer formats add their own extensions to PAX by defining their
	/// own keys and assigning certain semantic meaning to the associated values.
	/// For example, sparse file support in PAX is implemented using keys
	/// defined by the GNU manual (e.g., "GNU.sparse.map").
	///
	/// Reference:
	/// https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5&format=html
	/// https://www.gnu.org/software/tar/manual/html_chapter/tar_15.html#SEC188
	/// http://cdrtools.sourceforge.net/private/man/star/star.4.html
	/// http://pubs.opengroup.org/onlinepubs/009695399/utilities/pax.html
	pax(4, 'PAX'),

	/// GNU header format.
	///
	/// The GNU header format is older than the USTAR and PAX standards and
	/// is not compatible with them. The GNU format supports
	/// arbitrary file sizes, filenames of arbitrary encoding and length,
	/// sparse files, and other features.
	///
	/// Start \| End \| Field
	/// =========================================================================
	/// 0 \| 100 \| Path name, stored as null-terminated string.
	/// 100 \| 108 \| File mode, stored as an octal number in ASCII.
	/// 108 \| 116 \| User id of owner, as octal number in ASCII.
	/// 116 \| 124 \| Group id of owner, as octal number in ASCII.
	/// 124 \| 136 \| Size of file, as octal number in ASCII.
	/// 136 \| 148 \| Modification time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 148 \| 156 \| Header checksum, stored as an octal number in ASCII.
	/// 156 \| 157 \| Type flag, determines the kind of header.
	/// Note that the meaning of the size field depends on the type.
	/// 157 \| 257 \| Link name, stored as a string.
	/// 257 \| 263 \| Contains the magic value "ustar " to indicate that this is
	/// the GNU format.
	/// 263 \| 265 \| Version. " \x00" for POSIX standard archives.
	/// 265 \| 297 \| User name, as null-terminated ASCII string.
	/// 297 \| 329 \| Group name, as null-terminated ASCII string.
	/// 329 \| 337 \| Major number for character or block device entry.
	/// 337 \| 345 \| Minor number for character or block device entry.
	/// 345 \| 357 \| Last Access time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 357 \| 369 \| Last Changed time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 369 \| 381 \| Offset - not used.
	/// 381 \| 385 \| Longnames - deprecated
	/// 385 \| 386 \| Unused.
	/// 386 \| 482 \| Sparse data - 4 sets of (offset, numbytes) stored as
	/// octal numbers in ASCII.
	/// 482 \| 483 \| isExtended - if this field is non-zero, this header is
	/// followed by additional sparse records, which are in the
	/// same format as above.
	/// 483 \| 495 \| Binary representation of the file's complete size, inclusive
	/// of the sparse data.
	/// 495 \| 512 \| NUL pad.
	///
	/// It is recommended that PAX be chosen over GNU unless the target
	/// application can only parse GNU formatted archives.
	///
	/// Reference:
	/// https://www.gnu.org/software/tar/manual/html_node/Standard.html
	gnu(8, 'GNU'),

	/// Schily's TAR format, which is incompatible with USTAR.
	/// This does not cover STAR extensions to the PAX format; these fall under
	/// the PAX format.
	///
	/// Start \| End \| Field
	/// =========================================================================
	/// 0 \| 100 \| Path name, stored as null-terminated string.
	/// 100 \| 108 \| File mode, stored as an octal number in ASCII.
	/// 108 \| 116 \| User id of owner, as octal number in ASCII.
	/// 116 \| 124 \| Group id of owner, as octal number in ASCII.
	/// 124 \| 136 \| Size of file, as octal number in ASCII.
	/// 136 \| 148 \| Modification time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 148 \| 156 \| Header checksum, stored as an octal number in ASCII.
	/// 156 \| 157 \| Type flag, determines the kind of header.
	/// Note that the meaning of the size field depends on the type.
	/// 157 \| 257 \| Link name, stored as a string.
	/// 257 \| 263 \| Contains the magic value "ustar\x00" to indicate that this is
	/// the GNU format.
	/// 263 \| 265 \| Version. "00" for STAR archives.
	/// 265 \| 297 \| User name, as null-terminated ASCII string.
	/// 297 \| 329 \| Group name, as null-terminated ASCII string.
	/// 329 \| 337 \| Major number for character or block device entry.
	/// 337 \| 345 \| Minor number for character or block device entry.
	/// 345 \| 476 \| Prefix. If the pathname is too long to fit in the 100 bytes
	/// provided at the start, it can be split at any / character
	/// with the first portion going here.
	/// 476 \| 488 \| Last Access time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 488 \| 500 \| Last Changed time of file, number of seconds from epoch,
	/// stored as an octal number in ASCII.
	/// 500 \| 508 \| NUL pad.
	/// 508 \| 512 \| Trailer - "tar\x00".
	///
	/// Reference:
	/// http://cdrtools.sourceforge.net/private/man/star/star.4.html
	star(16, 'STAR'),
	;

	@override
	final int _value;

	final String _name;

	const TarFormat(this._value, this._name);

	@override
	bool get valid => true;

	@override
	MaybeTarFormat operator \|(TarFormat other) {
	return other == this ? this : _MaybeTarFormat(_value \| other._value);
	}

	@override
	bool has(MaybeTarFormat other) {
	return other == this;
	}

	@override
	MaybeTarFormat mayOnlyBe(MaybeTarFormat other) {
	return MaybeTarFormat._(_value & other._value);
	}

	@override
	String toString() => _name;
	}

	final class _MaybeTarFormat implements MaybeTarFormat {
	// Note: We never represent a single tar format in a _MaybeTarFormat, these
	// are represented in the TarFormat enum.
	@override
	final int _value;

	const _MaybeTarFormat(this._value);

	@override
	int get hashCode => _value;

	@override
	bool operator ==(Object other) {
	if (other is! TarFormat) return false;

	return _value == other._value;
	}

	@override
	String toString() {
	if (!valid) return 'Invalid';

	return TarFormat.values.where(has).map((e) => e._name).join(' or ');
	}

	@override
	bool has(MaybeTarFormat other) => _value & other._value != 0;

	@override
	bool get valid => _value != 0;

	@override
	MaybeTarFormat mayOnlyBe(MaybeTarFormat other) {
	return MaybeTarFormat._(_value & other._value);
	}

	@override
	MaybeTarFormat operator \|(TarFormat other) {
	return MaybeTarFormat._(_value \| other._value);
	}
	}