typedef struct Super Super;typedef struct Group Group;typedef struct Inode Inode;typedef struct Dirent Dirent;typedef struct Ext2 Ext2; enum{	BYTESPERSEC	= 512, 	SBOFF = 1024,	SBSIZE = 1024, 	SUPERMAGIC = 0xEF53,	MINBLOCKSIZE = 1024,	MAXBLOCKSIZE = 4096,	ROOTINODE = 2,	FIRSTINODE = 11,	VALIDFS = 0x0001,	ERRORFS = 0x0002, 	NDIRBLOCKS = 12,	INDBLOCK = NDIRBLOCKS,	DINDBLOCK = INDBLOCK+1,	TINDBLOCK = DINDBLOCK+1,	NBLOCKS = TINDBLOCK+1, 	NAMELEN = 255, 	/* permissions in Inode.mode */	IEXEC = 00100,	IWRITE = 0200,	IREAD = 0400,	ISVTX = 01000,	ISGID = 02000,	ISUID = 04000, 	/* type in Inode.mode */	IFMT = 0170000,	IFIFO = 0010000,	IFCHR = 0020000,	IFDIR = 0040000,	IFBLK = 0060000,	IFREG = 0100000,	IFLNK = 0120000,	IFSOCK = 0140000,	IFWHT = 0160000}; #define DIRLEN(namlen)	(((namlen)+8+3)&~3)  /* * Super block */struct Super{	u32int	ninode;		/* Inodes count */	u32int	nblock;		/* Blocks count */	u32int	rblockcount;	/* Reserved blocks count */	u32int	freeblockcount;	/* Free blocks count */	u32int	freeinodecount;	/* Free inodes count */	u32int	firstdatablock;	/* First Data Block */	u32int	logblocksize;	/* Block size */	u32int	logfragsize;	/* Fragment size */	u32int	blockspergroup;	/* # Blocks per group */	u32int	fragpergroup;	/* # Fragments per group */	u32int	inospergroup;	/* # Inodes per group */	u32int	mtime;		/* Mount time */	u32int	wtime;		/* Write time */	u16int	mntcount;		/* Mount count */	u16int	maxmntcount;	/* Maximal mount count */	u16int	magic;		/* Magic signature */	u16int	state;		/* File system state */	u16int	errors;		/* Behaviour when detecting errors */	u16int	pad;	u32int	lastcheck;		/* time of last check */	u32int	checkinterval;	/* max. time between checks */	u32int	creatoros;		/* OS */	u32int	revlevel;		/* Revision level */	u16int	defresuid;		/* Default uid for reserved blocks */	u16int	defresgid;		/* Default gid for reserved blocks */		/* the following are only available with revlevel = 1 */	u32int	firstino;		/* First non-reserved inode */	u16int	inosize;		/* size of inode structure */	u16int	blockgroupnr;	/* block group # of this super block */	u32int	reserved[233];	/* Padding to the end of the block */}; /* * Block group */struct Group{	u32int	bitblock;		/* Blocks bitmap block */	u32int	inodebitblock;		/* Inodes bitmap block */	u32int	inodeaddr;		/* Inodes table block */	u16int	freeblockscount;	/* Free blocks count */	u16int	freeinodescount;	/* Free inodes count */	u16int	useddirscount;	/* Directories count */};enum{	GroupSize = 32}; /* * Inode */struct Inode{	u16int	mode;		/* File mode */	u16int	uid;		/* Owner Uid */	u32int	size;		/* Size in bytes */	u32int	atime;		/* Access time */	u32int	ctime;		/* Creation time */	u32int	mtime;		/* Modification time */	u32int	dtime;		/* Deletion Time */	u16int	gid;		/* Group Id */	u16int	nlink;	/* Links count */	u32int	nblock;	/* Blocks count */	u32int	flags;		/* File flags */	u32int	block[NBLOCKS];/* Pointers to blocks */	u32int	version;	/* File version (for NFS) */	u32int	fileacl;	/* File ACL */	u32int	diracl;	/* Directory ACL or high size bits */	u32int	faddr;		/* Fragment address */}; /* * Directory entry */struct Dirent{	u32int	ino;			/* Inode number */	u16int	reclen;		/* Directory entry length */	u8int	namlen;		/* Name length */	char	*name;	/* File name */};enum{	MinDirentSize = 4+2+1+1}; /* * In-core fs info. */struct Ext2{	uint	blocksize;	uint	nblock;	uint	ngroup;	uint	inospergroup;	uint	blockspergroup;	uint	inosperblock;	uint	inosize;	uint	groupaddr;	uint	descperblock;	uint	firstblock;	Disk *disk;	Fsys *fsys;};