[TUHS] Re: ancient unix filesystems

On Mon, 6 May 2002 tuhs-request(a)minnie.tuhs.org wrote: The source code is sitting on http://www.esc.auckland.ac.nz/People/Staff/Norris/src/u5e-0.2.tar.gz and the INTRO file contains a description of the filesystem. I don't think it works with current Linux kernels (I havn't touched it for a long while), so it might be easiest to start afresh using the minix filesystem module as a start. Briefly, the filesystem is like -- * Block size: 512 * General layout: Block 0 boot block Block 1 super block Blocks 2 -> isize-1 inodes Blocks isize -> fsize-1 data blocks * Byte ordering of "short" (16 bit entities) is little endian 0 1 * Byte ordering of "long" (32 bit entities) is PDP-11 2 3 0 1 * Inode on disk: "short" 0 means non-existent 1 root dir * Maximum number of hard links to a file: 256 * Super-block location: bytes 512-1023 * Super-block layout: unsigned short s_isize; /* size in blocks of I list */ unsigned short s_fsize; /* size in blocks of entire volume */ unsigned short s_nfree; /* number of in core free blocks (0-100) */ unsigned short s_free[100]; /* in core free blocks */ unsigned short s_ninode; /* number of in core I nodes (0-100) */ unsigned short s_inode[100];/* in core free I nodes */ 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 */ unsigned long s_time; /* current date of last update */ * Inode layout: unsigned short i_mode; /* access permissions */ unsigned char i_nlink; /* number of links to file */ unsigned char i_uid; /* owner */ unsigned char i_gid; /* group */ unsigned char i_size0; /* size of file */ unsigned short i_size1; unsigned short i_addr[8];/* address of blocks */ unsigned long i_atime; /* time of last access */ unsigned long i_mtime; /* time of last modification */ * Regular file data blocks are organized as if (010000 bit set) the file is large: i_addr[] contains indirect blocks else the file is small: * Inode size 32, 16 inodes per block * Directory entry on disk unsigned short inode; char name[14]; * Dir entry size 16, 32 dir entries per block * There are no symbolic links -- Stuart Norris s.norris(a)auckland.ac.nz Bioengineering Institute, University of Auckland hm: +(64 9) 307 0006 http://www.esc.auckland.ac.nz/People/Staff/Norris wk: +(64 9) 373 7599 x3055