1 /*
2  * 10th edition 4K file system
3  */
4 #include <u.h>
5 #include <libc.h>
6 #include <auth.h>
7 #include <fcall.h>
8 #include "tapefs.h"
9 
10 /*
11  * v10 disk inode
12  */
13 #define	VNADDR	13
14 #define	VFMT	0160000
15 #define	VIFREG	0100000
16 #define	VIFDIR	0040000
17 #define	VIFCHR	0120000
18 #define	VIFBLK	0160000
19 #define	VMODE	0777
20 #define	VSUPERB	1
21 #define	VROOT		2	/* root inode */
22 #define	VNAMELEN	14
23 #define	BLSIZE	4096
24 #define	LINOPB	(BLSIZE/sizeof(struct v10dinode))
25 #define	LNINDIR	(BLSIZE/sizeof(unsigned long))
26 
27 struct v10dinode {
28 	unsigned char flags[2];
29 	unsigned char nlinks[2];
30 	unsigned char uid[2];
31 	unsigned char gid[2];
32 	unsigned char size[4];
33 	unsigned char addr[40];
34 	unsigned char atime[4];
35 	unsigned char mtime[4];
36 	unsigned char ctime[4];
37 };
38 
39 struct	v10dir {
40 	uchar	ino[2];
41 	char	name[VNAMELEN];
42 };
43 
44 int	tapefile;
45 Fileinf	iget(int ino);
46 long	bmap(Ram *r, long bno);
47 void	getblk(Ram *r, long bno, char *buf);
48 
49 void
50 populate(char *name)
51 {
52 	Fileinf f;
53 
54 	replete = 0;
55 	tapefile = open(name, OREAD);
56 	if (tapefile<0)
57 		error("Can't open argument file");
58 	f = iget(VROOT);
59 	ram->perm = f.mode;
60 	ram->mtime = f.mdate;
61 	ram->addr = f.addr;
62 	ram->data = f.data;
63 	ram->ndata = f.size;
64 }
65 
66 void
67 popdir(Ram *r)
68 {
69 	int i, ino;
70 	char *cp;
71 	struct v10dir *dp;
72 	Fileinf f;
73 	char name[VNAMELEN+1];
74 
75 	cp = 0;
76 	for (i=0; i<r->ndata; i+=sizeof(struct v10dir)) {
77 		if (i%BLSIZE==0)
78 			cp = doread(r, i, BLSIZE);
79 		dp = (struct v10dir *)(cp+i%BLSIZE);
80 		ino = g2byte(dp->ino);
81 		if (strcmp(dp->name, ".")==0 || strcmp(dp->name, "..")==0)
82 			continue;
83 		if (ino==0)
84 			continue;
85 		f = iget(ino);
86 		strncpy(name, dp->name, VNAMELEN);
87 		name[VNAMELEN] = '\0';
88 		f.name = name;
89 		popfile(r, f);
90 	}
91 	r->replete = 1;
92 }
93 
94 void
95 dotrunc(Ram *r)
96 {
97 	USED(r);
98 }
99 
100 void
101 docreate(Ram *r)
102 {
103 	USED(r);
104 }
105 
106 char *
107 doread(Ram *r, vlong off, long cnt)
108 {
109 	static char buf[Maxbuf+BLSIZE];
110 	int bno, i;
111 
112 	bno = off/BLSIZE;
113 	off -= bno*BLSIZE;
114 	if (cnt>Maxbuf)
115 		error("count too large");
116 	if (off)
117 		cnt += off;
118 	i = 0;
119 	while (cnt>0) {
120 		getblk(r, bno, &buf[i*BLSIZE]);
121 		cnt -= BLSIZE;
122 		bno++;
123 		i++;
124 	}
125 	return buf+off;
126 }
127 
128 void
129 dowrite(Ram *r, char *buf, long off, long cnt)
130 {
131 	USED(r); USED(buf); USED(off); USED(cnt);
132 }
133 
134 int
135 dopermw(Ram *r)
136 {
137 	USED(r);
138 	return 0;
139 }
140 
141 /*
142  * fetch an i-node
143  * -- no sanity check for now
144  * -- magic inode-to-disk-block stuff here
145  */
146 
147 Fileinf
148 iget(int ino)
149 {
150 	char buf[BLSIZE];
151 	struct v10dinode *dp;
152 	long flags, i;
153 	Fileinf f;
154 
155 	memset(&f, 0, sizeof f);
156 	seek(tapefile, BLSIZE*((ino-1)/LINOPB + VSUPERB + 1), 0);
157 	if (read(tapefile, buf, BLSIZE) != BLSIZE)
158 		error("Can't read inode");
159 	dp = ((struct v10dinode *)buf) + ((ino-1)%LINOPB);
160 	flags = g2byte(dp->flags);
161 	f.size = g4byte(dp->size);
162 	if ((flags&VFMT)==VIFCHR || (flags&VFMT)==VIFBLK)
163 		f.size = 0;
164 	f.data = emalloc(VNADDR*sizeof(long));
165 	for (i = 0; i < VNADDR; i++)
166 		((long*)f.data)[i] = g3byte(dp->addr+3*i);
167 	f.mode = flags & VMODE;
168 	if ((flags&VFMT)==VIFDIR)
169 		f.mode |= DMDIR;
170 	f.uid = g2byte(dp->uid);
171 	f.gid = g2byte(dp->gid);
172 	f.mdate = g4byte(dp->mtime);
173 	return f;
174 }
175 
176 void
177 getblk(Ram *r, long bno, char *buf)
178 {
179 	long dbno;
180 
181 	if ((dbno = bmap(r, bno)) == 0) {
182 		memset(buf, 0, BLSIZE);
183 		return;
184 	}
185 	seek(tapefile, dbno*BLSIZE, 0);
186 	if (read(tapefile, buf, BLSIZE) != BLSIZE)
187 		error("bad read");
188 }
189 
190 /*
191  * logical to physical block
192  * only singly-indirect files for now
193  */
194 
195 long
196 bmap(Ram *r, long bno)
197 {
198 	unsigned char indbuf[LNINDIR][sizeof(long)];
199 
200 	if (bno < VNADDR-3)
201 		return ((long*)r->data)[bno];
202 	if (bno < VNADDR*LNINDIR) {
203 		seek(tapefile, ((long *)r->data)[(bno-(VNADDR-3))/LNINDIR+(VNADDR-3)]*BLSIZE, 0);
204 		if (read(tapefile, (char *)indbuf, BLSIZE) != BLSIZE)
205 			return 0;
206 		return ((indbuf[(bno-(VNADDR-3))%LNINDIR][2]<<16) + (indbuf[(bno-(VNADDR-3))%LNINDIR][1]<<8)
207 			+ indbuf[(bno-(VNADDR-3))%LNINDIR][0]);
208 	}
209 	return 0;
210 }