(tar.info.gz) Old GNU Format

Info Catalog

(tar.info.gz) Sparse Formats

(tar.info.gz) PAX 0

 
 Old GNU Format
 --------------
 
 The format introduced in November 1990 (v.  1.09) was designed on top of
 standard 'ustar' headers in such an unfortunate way that some of its
 fields overwrote fields required by POSIX.
 
    An old GNU sparse header is designated by type 'S' ('GNUTYPE_SPARSE')
 and has the following layout:
 
 Offset  Size    Name           Data type      Contents
 ----------------------------------------------------------------------------
 0       345                    N/A            Not used.
 345     12      atime          Number         'atime' of the file.
 357     12      ctime          Number         'ctime' of the file .
 369     12      offset         Number         For multivolume archives:
                                               the offset of the start of
                                               this volume.
 381     4                      N/A            Not used.
 385     1                      N/A            Not used.
 386     96      sp             'sparse_header'(4 entries) File map.
 482     1       isextended     Bool           '1' if an extension sparse
                                               header follows, '0'
                                               otherwise.
 483     12      realsize       Number         Real size of the file.
 
    Each of 'sparse_header' object at offset 386 describes a single data
 chunk.  It has the following structure:
 
 Offset  Size    Data type      Contents
 ---------------------------------------------------------------------------
 0       12      Number         Offset of the beginning of the chunk.
 12      12      Number         Size of the chunk.
 
    If the member contains more than four chunks, the 'isextended' field
 of the header has the value '1' and the main header is followed by one
 or more "extension headers".  Each such header has the following
 structure:
 
 Offset  Size    Name           Data type      Contents
 ----------------------------------------------------------------------------
 0       21      sp             'sparse_header'(21 entries) File map.
 504     1       isextended     Bool           '1' if an extension sparse
                                               header follows, or '0'
                                               otherwise.
 
    A header with 'isextended=0' ends the map.
 

Info Catalog

(tar.info.gz) Sparse Formats

(tar.info.gz) PAX 0