This data has been derived from the LSB 3.0 specs.

http://refspecs.freestandards.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/pkgformat.html#AEN27828

File format:

Field name     Size    Description
----------     ----    -----------
CPIO Header    110     As described below
Filename       Var.    Null-terminated ASCII string
Padding        Var.    0-3 bytes as to quad-align stream
Data           Var.    Contents of the file
Padding        Var.    0-3 bytes as to quad-align stream

CPIO Header:

Field name   Size   Type       Description
----------   ----   ----       -----------
c_magic      6      chars      Magic number: "070701"
c_ino        8      chars      Source inode number (link match)
c_mode       8      chars      ASCII repr of hex filemode
c_uid        8      chars      UID of the owner of this file
c_gid        8      chars      GID of the owner of this file
c_nlink      8      chars      # of links to this file (match files w/>1)
c_mtime      8      chars      Modification time of the file
c_filesize   8      chars      Size of the file
c_devmajor   8      chars      Major device number of source (link match)
c_devminor   8      chars      Minor device number of source (link match)
c_rdevmajor  8      chars      Raw major device number of source
c_rdevminor  8      chars      Raw minor device number of source
c_namesize   8      chars      Length of the filename
c_checksum   8      chars      CRC of the file data

The final record has "TRAILER!!!" as the filename.
