Listing 7

#
# ----- S51K FILESYSTEM STRUCTURE TRANSLATION -------------------------------
# Copyright 1992, Chris Hare
#
# AT&T S51K Superblock
#
#       NOTES:
#               ushort          unsigned short
#               daddr_t         long
#               time_t          long
#       ushort  s_isize;        /* size in blocks of i-list */
#       daddr_t s_fsize;        /* size in blocks of entire volume */
#       short   s_nfree;        /* number of addresses in s_free */
#       daddr_t s_free[NICFREE];/* free block list */
#       short   s_ninode;       /* number of i-nodes in s_inode */
#       ushort  s_inode[NICINOD];/* free i-node list */
#       char    s_flock;        /* lock during free list manipulation */
#       char    s_ilock;        /* lock during i-list manipulation */
#       char    s_fmod;         /* super block modified flag */
#       char    s_ronly;        /* mounted read-only flag */
#       time_t  s_time;         /* last super block update */
#       short   s_dinfo[4];     /* device information */
#       daddr_t s_tfree;        /* total free blocks*/
#       ushort  s_tinode;       /* total free inodes */
#       char    s_fname[6];     /* file system name */
#       char    s_fpack[6];     /* file system pack name */
#       long    s_fill[14];     /* adjust to make sizeof filsys be 512 */
#       long    s_state;        /* file system state */
#       long    s_magic;        /* magic number to indicate new file system */
#       long    s_type;         /* type of new file system */
#
$NICFREE = 50;
$NICINOD = 100;
#
# There are four bytes in a long ...
#
$A_NICFREE = $NICFREE * 4;
#
# and two bytes in a short ...
#
$A_NICINOD = $NICINOD * 2;
#
# This is the actual translation of the S51K filesystem structure
# (there was a lot of pain in the translation ...)
#
$S51K = "S l s A$A_NICFREE s A$A_NICINOD c c c c l A8 l S a6 a6 A56 l l l";
#
# and these structures will unpack the Free Block List, and the Free Inode
# List
# ( some pain in these too ...)
#
$S51K_s_free = "l$NICFREE";
$S51K_s_inode = "S$NICINOD";

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