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 vlong tapelen;
46 Fileinf iget(int ino);
47 long bmap(Ram *r, long bno);
48 void getblk(Ram *r, long bno, char *buf);
49
50 void
populate(char * name)51 populate(char *name)
52 {
53 Fileinf f;
54 Dir *d;
55
56 replete = 0;
57 tapefile = open(name, OREAD);
58 if (tapefile<0)
59 error("Can't open argument file");
60 if ((d=dirfstat(tapefile)) == nil)
61 error("dirfstat");
62 tapelen = d->length;
63 free(d);
64 f = iget(VROOT);
65 ram->perm = f.mode;
66 ram->mtime = f.mdate;
67 ram->addr = f.addr;
68 ram->data = f.data;
69 ram->ndata = f.size;
70 }
71
72 void
popdir(Ram * r)73 popdir(Ram *r)
74 {
75 int i, ino;
76 char *cp;
77 struct v10dir *dp;
78 Fileinf f;
79 char name[VNAMELEN+1];
80
81 cp = 0;
82 for (i=0; i<r->ndata; i+=sizeof(struct v10dir)) {
83 if (i%BLSIZE==0)
84 cp = doread(r, i, BLSIZE);
85 dp = (struct v10dir *)(cp+i%BLSIZE);
86 ino = g2byte(dp->ino);
87 if (strcmp(dp->name, ".")==0 || strcmp(dp->name, "..")==0)
88 continue;
89 if (ino==0)
90 continue;
91 f = iget(ino);
92 strncpy(name, dp->name, VNAMELEN);
93 name[VNAMELEN] = '\0';
94 f.name = name;
95 popfile(r, f);
96 }
97 r->replete = 1;
98 }
99
100 void
dotrunc(Ram * r)101 dotrunc(Ram *r)
102 {
103 USED(r);
104 }
105
106 void
docreate(Ram * r)107 docreate(Ram *r)
108 {
109 USED(r);
110 }
111
112 char *
doread(Ram * r,vlong off,long cnt)113 doread(Ram *r, vlong off, long cnt)
114 {
115 static char buf[Maxbuf+BLSIZE];
116 int bno, i;
117
118 bno = off/BLSIZE;
119 off -= bno*BLSIZE;
120 if (cnt>Maxbuf)
121 error("count too large");
122 if (off)
123 cnt += off;
124 i = 0;
125 while (cnt>0) {
126 getblk(r, bno, &buf[i*BLSIZE]);
127 cnt -= BLSIZE;
128 bno++;
129 i++;
130 }
131 return buf+off;
132 }
133
134 void
dowrite(Ram * r,char * buf,long off,long cnt)135 dowrite(Ram *r, char *buf, long off, long cnt)
136 {
137 USED(r); USED(buf); USED(off); USED(cnt);
138 }
139
140 int
dopermw(Ram * r)141 dopermw(Ram *r)
142 {
143 USED(r);
144 return 0;
145 }
146
147 /*
148 * fetch an i-node
149 * -- no sanity check for now
150 * -- magic inode-to-disk-block stuff here
151 */
152
153 Fileinf
iget(int ino)154 iget(int ino)
155 {
156 char buf[BLSIZE];
157 struct v10dinode *dp;
158 long flags, i;
159 Fileinf f;
160
161 seek(tapefile, BLSIZE*((ino-1)/LINOPB + VSUPERB + 1), 0);
162 if (read(tapefile, buf, BLSIZE) != BLSIZE)
163 error("Can't read inode");
164 dp = ((struct v10dinode *)buf) + ((ino-1)%LINOPB);
165 flags = g2byte(dp->flags);
166 f.size = g4byte(dp->size);
167 if ((flags&VFMT)==VIFCHR || (flags&VFMT)==VIFBLK)
168 f.size = 0;
169 f.data = emalloc(VNADDR*sizeof(long));
170 for (i = 0; i < VNADDR; i++)
171 ((long*)f.data)[i] = g3byte(dp->addr+3*i);
172 f.mode = flags & VMODE;
173 if ((flags&VFMT)==VIFDIR)
174 f.mode |= DMDIR;
175 f.uid = g2byte(dp->uid);
176 f.gid = g2byte(dp->gid);
177 f.mdate = g4byte(dp->mtime);
178 return f;
179 }
180
181 void
getblk(Ram * r,long bno,char * buf)182 getblk(Ram *r, long bno, char *buf)
183 {
184 long dbno;
185
186 if ((dbno = bmap(r, bno)) == 0) {
187 memset(buf, 0, BLSIZE);
188 return;
189 }
190 if ((vlong)(dbno+1)*BLSIZE > tapelen) {
191 fprint(2, "read past end of tape: %lld\n", (vlong)dbno*BLSIZE);
192 memset(buf, 0, BLSIZE);
193 return;
194 }
195 seek(tapefile, dbno*BLSIZE, 0);
196 if (readn(tapefile, buf, BLSIZE) != BLSIZE){
197 fprint(2, "readn at %lld: %r\n", (vlong)dbno*BLSIZE);
198 error("bad read");
199 }
200 }
201
202 /*
203 * logical to physical block
204 * only singly-indirect files for now
205 */
206
207 long
bmap(Ram * r,long bno)208 bmap(Ram *r, long bno)
209 {
210 unsigned char indbuf[LNINDIR][sizeof(long)];
211
212 if (bno < VNADDR-3)
213 return ((long*)r->data)[bno];
214 if (bno < VNADDR*LNINDIR) {
215 seek(tapefile, ((long *)r->data)[(bno-(VNADDR-3))/LNINDIR+(VNADDR-3)]*BLSIZE, 0);
216 if (read(tapefile, (char *)indbuf, BLSIZE) != BLSIZE)
217 return 0;
218 return ((indbuf[(bno-(VNADDR-3))%LNINDIR][2]<<16) + (indbuf[(bno-(VNADDR-3))%LNINDIR][1]<<8)
219 + indbuf[(bno-(VNADDR-3))%LNINDIR][0]);
220 }
221 return 0;
222 }
223