tv10fs.c - plan9port - [fork] Plan 9 from user space
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tv10fs.c (3799B)
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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 }