+/* GNU tar Archive Format description.
+
+ Copyright 1988-1989, 1991-1997, 2000-2001, 2003-2007, 2012-2013
+ Free Software Foundation, Inc.
+
+ This file is part of GNU tar.
+
+ GNU tar is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ GNU tar is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+/* tar Header Block, from POSIX 1003.1-1990. */
+
+/* POSIX header. */
+
+struct posix_header
+{ /* byte offset */
+ char name[100]; /* 0 */
+ char mode[8]; /* 100 */
+ char uid[8]; /* 108 */
+ char gid[8]; /* 116 */
+ char size[12]; /* 124 */
+ char mtime[12]; /* 136 */
+ char chksum[8]; /* 148 */
+ char typeflag; /* 156 */
+ char linkname[100]; /* 157 */
+ char magic[6]; /* 257 */
+ char version[2]; /* 263 */
+ char uname[32]; /* 265 */
+ char gname[32]; /* 297 */
+ char devmajor[8]; /* 329 */
+ char devminor[8]; /* 337 */
+ char prefix[155]; /* 345 */
+ /* 500 */
+};
+
+#define TMAGIC "ustar" /* ustar and a null */
+#define TMAGLEN 6
+#define TVERSION "00" /* 00 and no null */
+#define TVERSLEN 2
+
+/* Values used in typeflag field. */
+#define REGTYPE '0' /* regular file */
+#define AREGTYPE '\0' /* regular file */
+#define LNKTYPE '1' /* link */
+#define SYMTYPE '2' /* reserved */
+#define CHRTYPE '3' /* character special */
+#define BLKTYPE '4' /* block special */
+#define DIRTYPE '5' /* directory */
+#define FIFOTYPE '6' /* FIFO special */
+#define CONTTYPE '7' /* reserved */
+
+#define XHDTYPE 'x' /* Extended header referring to the
+ next file in the archive */
+#define XGLTYPE 'g' /* Global extended header */
+
+/* Bits used in the mode field, values in octal. */
+#define TSUID 04000 /* set UID on execution */
+#define TSGID 02000 /* set GID on execution */
+#define TSVTX 01000 /* reserved */
+ /* file permissions */
+#define TUREAD 00400 /* read by owner */
+#define TUWRITE 00200 /* write by owner */
+#define TUEXEC 00100 /* execute/search by owner */
+#define TGREAD 00040 /* read by group */
+#define TGWRITE 00020 /* write by group */
+#define TGEXEC 00010 /* execute/search by group */
+#define TOREAD 00004 /* read by other */
+#define TOWRITE 00002 /* write by other */
+#define TOEXEC 00001 /* execute/search by other */
+
+/* tar Header Block, GNU extensions. */
+
+/* In GNU tar, SYMTYPE is for to symbolic links, and CONTTYPE is for
+ contiguous files, so maybe disobeying the "reserved" comment in POSIX
+ header description. I suspect these were meant to be used this way, and
+ should not have really been "reserved" in the published standards. */
+
+/* *BEWARE* *BEWARE* *BEWARE* that the following information is still
+ boiling, and may change. Even if the OLDGNU format description should be
+ accurate, the so-called GNU format is not yet fully decided. It is
+ surely meant to use only extensions allowed by POSIX, but the sketch
+ below repeats some ugliness from the OLDGNU format, which should rather
+ go away. Sparse files should be saved in such a way that they do *not*
+ require two passes at archive creation time. Huge files get some POSIX
+ fields to overflow, alternate solutions have to be sought for this. */
+
+/* Descriptor for a single file hole. */
+
+struct sparse
+{ /* byte offset */
+ char offset[12]; /* 0 */
+ char numbytes[12]; /* 12 */
+ /* 24 */
+};
+
+/* Sparse files are not supported in POSIX ustar format. For sparse files
+ with a POSIX header, a GNU extra header is provided which holds overall
+ sparse information and a few sparse descriptors. When an old GNU header
+ replaces both the POSIX header and the GNU extra header, it holds some
+ sparse descriptors too. Whether POSIX or not, if more sparse descriptors
+ are still needed, they are put into as many successive sparse headers as
+ necessary. The following constants tell how many sparse descriptors fit
+ in each kind of header able to hold them. */
+
+#define SPARSES_IN_EXTRA_HEADER 16
+#define SPARSES_IN_OLDGNU_HEADER 4
+#define SPARSES_IN_SPARSE_HEADER 21
+
+/* Extension header for sparse files, used immediately after the GNU extra
+ header, and used only if all sparse information cannot fit into that
+ extra header. There might even be many such extension headers, one after
+ the other, until all sparse information has been recorded. */
+
+struct sparse_header
+{ /* byte offset */
+ struct sparse sp[SPARSES_IN_SPARSE_HEADER];
+ /* 0 */
+ char isextended; /* 504 */
+ /* 505 */
+};
+
+/* The old GNU format header conflicts with POSIX format in such a way that
+ POSIX archives may fool old GNU tar's, and POSIX tar's might well be
+ fooled by old GNU tar archives. An old GNU format header uses the space
+ used by the prefix field in a POSIX header, and cumulates information
+ normally found in a GNU extra header. With an old GNU tar header, we
+ never see any POSIX header nor GNU extra header. Supplementary sparse
+ headers are allowed, however. */
+
+struct oldgnu_header
+{ /* byte offset */
+ char unused_pad1[345]; /* 0 */
+ char atime[12]; /* 345 Incr. archive: atime of the file */
+ char ctime[12]; /* 357 Incr. archive: ctime of the file */
+ char offset[12]; /* 369 Multivolume archive: the offset of
+ the start of this volume */
+ char longnames[4]; /* 381 Not used */
+ char unused_pad2; /* 385 */
+ struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
+ /* 386 */
+ char isextended; /* 482 Sparse file: Extension sparse header
+ follows */
+ char realsize[12]; /* 483 Sparse file: Real size*/
+ /* 495 */
+};
+
+/* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
+ Found in an archive, it indicates an old GNU header format, which will be
+ hopefully become obsolescent. With OLDGNU_MAGIC, uname and gname are
+ valid, though the header is not truly POSIX conforming. */
+#define OLDGNU_MAGIC "ustar " /* 7 chars and a null */
+
+/* The standards committee allows only capital A through capital Z for
+ user-defined expansion. Other letters in use include:
+
+ 'A' Solaris Access Control List
+ 'E' Solaris Extended Attribute File
+ 'I' Inode only, as in 'star'
+ 'N' Obsolete GNU tar, for file names that do not fit into the main header.
+ 'X' POSIX 1003.1-2001 eXtended (VU version) */
+
+/* This is a dir entry that contains the names of files that were in the
+ dir at the time the dump was made. */
+#define GNUTYPE_DUMPDIR 'D'
+
+/* Identifies the *next* file on the tape as having a long linkname. */
+#define GNUTYPE_LONGLINK 'K'
+
+/* Identifies the *next* file on the tape as having a long name. */
+#define GNUTYPE_LONGNAME 'L'
+
+/* This is the continuation of a file that began on another volume. */
+#define GNUTYPE_MULTIVOL 'M'
+
+/* This is for sparse files. */
+#define GNUTYPE_SPARSE 'S'
+
+/* This file is a tape/volume header. Ignore it on extraction. */
+#define GNUTYPE_VOLHDR 'V'
+
+/* Solaris extended header */
+#define SOLARIS_XHDTYPE 'X'
+
+/* J@"org Schilling star header */
+
+struct star_header
+{ /* byte offset */
+ char name[100]; /* 0 */
+ char mode[8]; /* 100 */
+ char uid[8]; /* 108 */
+ char gid[8]; /* 116 */
+ char size[12]; /* 124 */
+ char mtime[12]; /* 136 */
+ char chksum[8]; /* 148 */
+ char typeflag; /* 156 */
+ char linkname[100]; /* 157 */
+ char magic[6]; /* 257 */
+ char version[2]; /* 263 */
+ char uname[32]; /* 265 */
+ char gname[32]; /* 297 */
+ char devmajor[8]; /* 329 */
+ char devminor[8]; /* 337 */
+ char prefix[131]; /* 345 */
+ char atime[12]; /* 476 */
+ char ctime[12]; /* 488 */
+ /* 500 */