1 /*
2  * An FFS file system is a sequence of cylinder groups.
3  *
4  * Each cylinder group is laid out as follows:
5  *
6  *	fs superblock (Fsblk)
7  *	cylinder group block (Cgblk)
8  *	inodes
9  *	data
10  *
11  * The location of the fs superblock in the first cylinder
12  * group is known.  The rest of the info about cylinder group
13  * layout can be derived from the super block.
14  */
15 
16 #define daddr_t u32int
17 #define time_t u32int
18 
19 typedef struct Cgblk Cgblk;
20 typedef struct Cylgrp Cylgrp;
21 typedef struct Cylsum Cylsum;
22 typedef struct Ffs Ffs;
23 typedef struct Fsblk Fsblk;
24 typedef struct Inode Inode;
25 typedef struct Dirent Dirent;
26 
27 enum
28 {
29 	BYTESPERSEC = 512,
30 
31 	/* constants for Fsblk */
32 	FSMAXMNTLEN = 512,
33 	FSNOCSPTRS = 128 / sizeof(void*) - 3,
34 	FSMAXSNAP = 20,
35 	FSMAGIC = 0x011954,
36 	FSCHECKSUM = 0x7c269d38,
37 	
38 	/* Fsblk.inodefmt */
39 	FS42INODEFMT = -1,
40 	FS44INODEFMT = 2,
41 
42 	/* offset and size of first boot block */
43 	BBOFF = 0,
44 	BBSIZE = 8192,
45 
46 	/* offset and size of first super block */
47 	SBOFF = BBOFF+BBSIZE,
48 	SBSIZE = 8192,
49 
50 	/* minimum block size */
51 	MINBSIZE = 4096,
52 
53 	/* maximum fragments per block */
54 	MAXFRAG = 8,
55 
56 	/* constants for Cgblk */
57 	CGMAGIC = 0x090255,
58 
59 	/* inode-related */
60 	ROOTINODE = 2,
61 	WHITEOUT = 1,
62 
63 	NDADDR = 12,
64 	NIADDR = 3,
65 
66 	/* permissions in Inode.mode */
67 	IEXEC = 00100,
68 	IWRITE = 0200,
69 	IREAD = 0400,
70 	ISVTX = 01000,
71 	ISGID = 02000,
72 	ISUID = 04000,
73 
74 	/* type in Inode.mode */
75 	IFMT = 0170000,
76 	IFIFO = 0010000,
77 	IFCHR = 0020000,
78 	IFDIR = 0040000,
79 	IFBLK = 0060000,
80 	IFREG = 0100000,
81 	IFLNK = 0120000,
82 	IFSOCK = 0140000,
83 	IFWHT = 0160000,
84 
85 	/* type in Dirent.type */
86 	DTUNKNOWN = 0,
87 	DTFIFO = 1,
88 	DTCHR = 2,
89 	DTDIR = 4,
90 	DTBLK = 6,
91 	DTREG = 8,
92 	DTLNK = 10,
93 	DTSOCK = 12,
94 	DTWHT = 14,
95 };
96 
97 struct Cylsum
98 {
99 	u32int	ndir;
100 	u32int	nbfree;
101 	u32int	nifree;
102 	u32int	nffree;
103 };
104 
105 struct Fsblk
106 {
107 	u32int	unused0;
108 	u32int	unused1;
109 	daddr_t	sfragno;		/* fragment address of super block in file system */
110 	daddr_t	cfragno;		/* fragment address if cylinder block in file system */
111 	daddr_t	ifragno;		/* fragment offset of inode blocks in file system */
112 	daddr_t	dfragno;		/* fragment offset of data blocks in cg */
113 	u32int	cgoffset;		/* block (maybe fragment?) offset of Cgblk in cylinder */
114 	u32int	cgmask;
115 	time_t	time;
116 	u32int	nfrag;		/* number of blocks in fs * fragsperblock */
117 	u32int	ndfrag;
118 	u32int	ncg;			/* number of cylinder groups in fs */
119 	u32int	blocksize;		/* block size in fs */
120 	u32int	fragsize;		/* frag size in fs */
121 	u32int	fragsperblock;	/* fragments per block: blocksize / fragsize */
122 	u32int	minfree;		/* ignored by us */
123 	u32int	rotdelay;		/* ... */
124 	u32int	rps;
125 	u32int	bmask;
126 	u32int	fmask;
127 	u32int	bshift;
128 	u32int	fshift;
129 	u32int	maxcontig;
130 	u32int	maxbpg;
131 	u32int	fragshift;
132 	u32int	fsbtodbshift;
133 	u32int	sbsize;		/* size of super block */
134 	u32int	unused2;		/* more stuff we don't use ... */
135 	u32int	unused3;
136 	u32int	nindir;
137 	u32int	inosperblock;	/* inodes per block */
138 	u32int	nspf;
139 	u32int	optim;
140 	u32int	npsect;
141 	u32int	interleave;
142 	u32int	trackskew;
143 	u32int	id[2];
144 	daddr_t	csaddr;		/* blk addr of cyl grp summary area */
145 	u32int	cssize;		/* size of cyl grp summary area */
146 	u32int	cgsize;		/* cylinder group size */
147 	u32int	trackspercyl;	/* tracks per cylinder */
148 	u32int	secspertrack;	/* sectors per track */
149 	u32int	secspercyl;	/* sectors per cylinder */
150 	u32int	ncyl;			/* cylinders in fs */
151 	u32int	cylspergroup;	/* cylinders per group */
152 	u32int	inospergroup;	/* inodes per group */
153 	u32int	fragspergroup;	/* data blocks per group * fragperblock */
154 	Cylsum	cstotal;		/* more unused... */
155 	u8int	fmod;
156 	u8int	clean;
157 	u8int	ronly;
158 	u8int	flags;
159 	char		fsmnt[FSMAXMNTLEN];
160 	u32int	cgrotor;
161 	void*	ocsp[FSNOCSPTRS];
162 	u8int*	contigdirs;
163 	Cylsum*	csp;
164 	u32int*	maxcluster;
165 	u32int	cpc;
166 	u16int	opostbl[16][8];
167 	u32int	snapinum[FSMAXSNAP];
168 	u32int	avgfilesize;
169 	u32int	avgfpdir;
170 	u32int	sparecon[26];
171 	u32int	pendingblocks;
172 	u32int	pendinginodes;
173 	u32int	contigsumsize;
174 	u32int	maxsymlinklen;
175 	u32int	inodefmt;		/* format of on-disk inodes */
176 	u64int	maxfilesize;	/* maximum representable file size */
177 	u64int	qbmask;
178 	u64int	qfmask;
179 	u32int	state;
180 	u32int	postblformat;
181 	u32int	nrpos;
182 	u32int	postbloff;
183 	u32int	rotbloff;
184 	u32int	magic;		/* FS_MAGIC */
185 };
186 
187 /*
188  * Cylinder group block for a file system.
189  */
190 struct Cgblk
191 {
192 	u32int	unused0;
193 	u32int	magic;		/* CGMAGIC */
194 	u32int	time;			/* time last written */
195 	u32int	num;		/* we are cg #cgnum */
196 	u16int	ncyl;			/* number of cylinders in gp */
197 	u16int	nino;		/* number of inodes */
198 	u32int	nfrag;		/* number of fragments  */
199 	Cylsum	csum;
200 	u32int	rotor;
201 	u32int	frotor;
202 	u32int	irotor;
203 	u32int	frsum[MAXFRAG];	/* counts of available frags */
204 	u32int	btotoff;
205 	u32int	boff;
206 	u32int	imapoff;		/* offset to used inode map */
207 	u32int	fmapoff;		/* offset to free fragment map */
208 	u32int	nextfrag;		/* next free fragment */
209 	u32int	csumoff;
210 	u32int	clusteroff;
211 	u32int	ncluster;
212 	u32int	sparecon[13];
213 };
214 
215 struct Cylgrp
216 {
217 	/* these are block numbers not fragment numbers */
218 	u32int	bno;			/* disk block address of start of cg */
219 	u32int	ibno;			/* disk block address of first inode */
220 	u32int	dbno;		/* disk block address of first data */
221 	u32int	cgblkno;
222 };
223 
224 /*
225  * this is the on-disk structure
226  */
227 struct Inode
228 {
229 	u16int	mode;
230 	u16int	nlink;
231 	u32int	unused;
232 	u64int	size;
233 	u32int	atime;
234 	u32int	atimensec;
235 	u32int	mtime;
236 	u32int	mtimensec;
237 	u32int	ctime;
238 	u32int	ctimensec;
239 	/* rdev is db[0] */
240 	u32int	db[NDADDR];
241 	u32int	ib[NIADDR];
242 	u32int	flags;
243 	u32int	nblock;
244 	u32int	gen;
245 	u32int	uid;
246 	u32int	gid;
247 	u32int	spare[2];
248 };
249 
250 struct Dirent
251 {
252 	u32int	ino;
253 	u16int	reclen;
254 	u8int	type;
255 	u8int	namlen;
256 	char		name[1];
257 };
258 
259 /*
260  * main file system structure
261  */
262 struct Ffs
263 {
264 	int		blocksize;
265 	int		nblock;
266 	int		fragsize;
267 	int		fragsperblock;
268 	int		inosperblock;
269 	int		blockspergroup;
270 	int		fragspergroup;
271 	int		inospergroup;
272 
273 	u32int	nfrag;
274 	u32int	ndfrag;
275 
276 	int		ncg;
277 	Cylgrp	*cg;
278 
279 	Disk		*disk;
280 };
281