1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/*
* File system for tar archives (read-only)
*/
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include "tapefs.h"
/* fundamental constants */
enum {
Tblock = 512,
Namsiz = 100,
Maxpfx = 155, /* from POSIX */
Maxname = Namsiz + 1 + Maxpfx,
Binsize = 0x80, /* flag in size[0], from gnu: positive binary size */
Binnegsz = 0xff, /* flag in size[0]: negative binary size */
};
/* POSIX link flags */
enum {
LF_PLAIN1 = '\0',
LF_PLAIN2 = '0',
LF_LINK = '1',
LF_SYMLINK1 = '2',
LF_SYMLINK2 = 's', /* 4BSD used this */
LF_CHR = '3',
LF_BLK = '4',
LF_DIR = '5',
LF_FIFO = '6',
LF_CONTIG = '7',
/* 'A' - 'Z' are reserved for custom implementations */
};
typedef union {
char dummy[Tblock];
char tbuf[Maxbuf];
struct Header {
char name[Namsiz];
char mode[8];
char uid[8];
char gid[8];
char size[12];
char mtime[12];
char chksum[8];
char linkflag;
char linkname[Namsiz];
/* rest are defined by POSIX's ustar format; see p1003.2b */
char magic[6]; /* "ustar" */
char version[2];
char uname[32];
char gname[32];
char devmajor[8];
char devminor[8];
char prefix[Maxpfx]; /* if non-null, path= prefix "/" name */
};
} Hdr;
Hdr dblock;
int tapefile;
int checksum(void);
static int
isustar(Hdr *hp)
{
return strcmp(hp->magic, "ustar") == 0;
}
/*
* s is at most n bytes long, but need not be NUL-terminated.
* if shorter than n bytes, all bytes after the first NUL must also
* be NUL.
*/
static int
strnlen(char *s, int n)
{
return s[n - 1] != '\0'? n: strlen(s);
}
/* set fullname from header */
static char *
tarname(Hdr *hp)
{
int pfxlen, namlen;
static char fullname[Maxname+1];
namlen = strnlen(hp->name, sizeof hp->name);
if (hp->prefix[0] == '\0' || !isustar(hp)) { /* old-style name? */
memmove(fullname, hp->name, namlen);
fullname[namlen] = '\0';
return fullname;
}
/* posix name: name is in two pieces */
pfxlen = strnlen(hp->prefix, sizeof hp->prefix);
memmove(fullname, hp->prefix, pfxlen);
fullname[pfxlen] = '/';
memmove(fullname + pfxlen + 1, hp->name, namlen);
fullname[pfxlen + 1 + namlen] = '\0';
return fullname;
}
void
populate(char *name)
{
long chksum, linkflg;
vlong blkno;
char *fname;
Fileinf f;
Hdr *hp;
tapefile = open(name, OREAD);
if (tapefile < 0)
error("Can't open argument file");
replete = 1;
hp = &dblock;
for (blkno = 0; ; blkno++) {
seek(tapefile, Tblock*blkno, 0);
if (readn(tapefile, hp->dummy, sizeof hp->dummy) < sizeof hp->dummy)
break;
fname = tarname(hp);
if (fname[0] == '\0')
break;
/* crack header */
f.addr = blkno + 1;
f.mode = strtoul(hp->mode, 0, 8);
f.uid = strtoul(hp->uid, 0, 8);
f.gid = strtoul(hp->gid, 0, 8);
if((uchar)hp->size[0] == 0x80)
f.size = b8byte(hp->size+3);
else
f.size = strtoull(hp->size, 0, 8);
f.mdate = strtoul(hp->mtime, 0, 8);
chksum = strtoul(hp->chksum, 0, 8);
/* the mode test is ugly but sometimes necessary */
if (hp->linkflag == LF_DIR || (f.mode&0170000) == 040000 ||
strrchr(fname, '\0')[-1] == '/'){
f.mode |= DMDIR;
f.size = 0;
}
f.mode &= DMDIR | 0777;
/* make file name safe, canonical and free of . and .. */
while (fname[0] == '/') /* don't allow absolute paths */
++fname;
cleanname(fname);
while (strncmp(fname, "../", 3) == 0)
fname += 3;
/* reject links */
linkflg = hp->linkflag == LF_SYMLINK1 ||
hp->linkflag == LF_SYMLINK2 || hp->linkflag == LF_LINK;
if (chksum != checksum()){
fprint(2, "%s: bad checksum on %.28s at offset %lld\n",
argv0, fname, Tblock*blkno);
exits("checksum");
}
if (linkflg) {
/*fprint(2, "link %s->%s skipped\n", fname, hp->linkname);*/
f.size = 0;
} else {
/* accept this file */
f.name = fname;
if (f.name[0] == '\0')
fprint(2, "%s: null name skipped\n", argv0);
else
poppath(f, 1);
blkno += (f.size + Tblock - 1)/Tblock;
}
}
}
void
dotrunc(Ram *r)
{
USED(r);
}
void
docreate(Ram *r)
{
USED(r);
}
char *
doread(Ram *r, vlong off, long cnt)
{
int n;
seek(tapefile, Tblock*r->addr + off, 0);
if (cnt > sizeof dblock.tbuf)
error("read too big");
n = readn(tapefile, dblock.tbuf, cnt);
if (n != cnt)
memset(dblock.tbuf + n, 0, cnt - n);
return dblock.tbuf;
}
void
popdir(Ram *r)
{
USED(r);
}
void
dowrite(Ram *r, char *buf, long off, long cnt)
{
USED(r); USED(buf); USED(off); USED(cnt);
}
int
dopermw(Ram *r)
{
USED(r);
return 0;
}
int
checksum(void)
{
int i, n;
uchar *cp;
memset(dblock.chksum, ' ', sizeof dblock.chksum);
cp = (uchar *)dblock.dummy;
i = 0;
for (n = Tblock; n-- > 0; )
i += *cp++;
return i;
}
|
