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
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
|
/*
* Copyright (C) 1995, 1997 Wolfgang Solfrank
* Copyright (c) 1995 Martin Husemann
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: boot.c,v 1.11 2006/06/05 16:51:18 christos Exp ");
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include "ext.h"
#include "fsutil.h"
int
readboot(int dosfs, struct bootblock *boot)
{
u_char block[DOSBOOTBLOCKSIZE];
u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
u_char backup[DOSBOOTBLOCKSIZE];
int ret = FSOK;
int i;
if ((size_t)read(dosfs, block, sizeof block) != sizeof block) {
perr("could not read boot block");
return FSFATAL;
}
if (block[510] != 0x55 || block[511] != 0xaa) {
pfatal("Invalid signature in boot block: %02x%02x",
block[511], block[510]);
return FSFATAL;
}
memset(boot, 0, sizeof *boot);
boot->ValidFat = -1;
/* decode bios parameter block */
boot->bpbBytesPerSec = block[11] + (block[12] << 8);
boot->bpbSecPerClust = block[13];
boot->bpbResSectors = block[14] + (block[15] << 8);
boot->bpbFATs = block[16];
boot->bpbRootDirEnts = block[17] + (block[18] << 8);
boot->bpbSectors = block[19] + (block[20] << 8);
boot->bpbMedia = block[21];
boot->bpbFATsmall = block[22] + (block[23] << 8);
boot->SecPerTrack = block[24] + (block[25] << 8);
boot->bpbHeads = block[26] + (block[27] << 8);
boot->bpbHiddenSecs = block[28] + (block[29] << 8) +
(block[30] << 16) + (block[31] << 24);
boot->bpbHugeSectors = block[32] + (block[33] << 8) +
(block[34] << 16) + (block[35] << 24);
boot->FATsecs = boot->bpbFATsmall;
if (!boot->bpbRootDirEnts)
boot->flags |= FAT32;
if (boot->flags & FAT32) {
boot->FATsecs = block[36] + (block[37] << 8)
+ (block[38] << 16) + (block[39] << 24);
if (block[40] & 0x80)
boot->ValidFat = block[40] & 0x0f;
/* check version number: */
if (block[42] || block[43]) {
/* Correct? XXX */
pfatal("Unknown file system version: %x.%x",
block[43], block[42]);
return FSFATAL;
}
boot->bpbRootClust = block[44] + (block[45] << 8)
+ (block[46] << 16) + (block[47] << 24);
boot->bpbFSInfo = block[48] + (block[49] << 8);
boot->bpbBackup = block[50] + (block[51] << 8);
if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec,
SEEK_SET) != boot->bpbFSInfo * boot->bpbBytesPerSec
|| read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) {
perr("could not read fsinfo block");
return FSFATAL;
}
if (memcmp(fsinfo, "RRaA", 4)
|| memcmp(fsinfo + 0x1e4, "rrAa", 4)
|| fsinfo[0x1fc]
|| fsinfo[0x1fd]
|| fsinfo[0x1fe] != 0x55
|| fsinfo[0x1ff] != 0xaa
|| fsinfo[0x3fc]
|| fsinfo[0x3fd]
|| fsinfo[0x3fe] != 0x55
|| fsinfo[0x3ff] != 0xaa) {
pwarn("Invalid signature in fsinfo block\n");
if (ask(0, "Fix")) {
memcpy(fsinfo, "RRaA", 4);
memcpy(fsinfo + 0x1e4, "rrAa", 4);
fsinfo[0x1fc] = fsinfo[0x1fd] = 0;
fsinfo[0x1fe] = 0x55;
fsinfo[0x1ff] = 0xaa;
fsinfo[0x3fc] = fsinfo[0x3fd] = 0;
fsinfo[0x3fe] = 0x55;
fsinfo[0x3ff] = 0xaa;
if (lseek(dosfs, boot->bpbFSInfo *
boot->bpbBytesPerSec, SEEK_SET)
!= boot->bpbFSInfo * boot->bpbBytesPerSec
|| write(dosfs, fsinfo, sizeof fsinfo)
!= sizeof fsinfo) {
perr("Unable to write bpbFSInfo");
return FSFATAL;
}
ret = FSBOOTMOD;
} else
boot->bpbFSInfo = 0;
}
if (boot->bpbFSInfo) {
boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8)
+ (fsinfo[0x1ea] << 16)
+ (fsinfo[0x1eb] << 24);
boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8)
+ (fsinfo[0x1ee] << 16)
+ (fsinfo[0x1ef] << 24);
}
if (lseek(dosfs, boot->bpbBackup * boot->bpbBytesPerSec,
SEEK_SET)
!= boot->bpbBackup * boot->bpbBytesPerSec
|| read(dosfs, backup, sizeof backup) != sizeof backup) {
perr("could not read backup bootblock");
return FSFATAL;
}
backup[65] = block[65]; /* XXX */
if (memcmp(block + 11, backup + 11, 79)) {
/*
* XXX We require a reference that explains
* that these bytes need to match, or should
* drop the check. gdt@NetBSD has observed
* filesystems that work fine under Windows XP
* and NetBSD that do not match, so the
* requirement is suspect. For now, just
* print out useful information and continue.
*/
pfatal("backup (block %d) mismatch with primary bootblock:\n",
boot->bpbBackup);
for (i = 11; i < 11 + 90; i++) {
if (block[i] != backup[i])
pfatal("\ti=%d\tprimary 0x%02x\tbackup 0x%02x\n",
i, block[i], backup[i]);
}
}
/* Check backup bpbFSInfo? XXX */
}
boot->ClusterOffset = (boot->bpbRootDirEnts * 32 +
boot->bpbBytesPerSec - 1) / boot->bpbBytesPerSec +
boot->bpbResSectors + boot->bpbFATs * boot->FATsecs -
CLUST_FIRST * boot->bpbSecPerClust;
if (boot->bpbBytesPerSec % DOSBOOTBLOCKSIZE != 0) {
pfatal("Invalid sector size: %u", boot->bpbBytesPerSec);
return FSFATAL;
}
if (boot->bpbSecPerClust == 0) {
pfatal("Invalid cluster size: %u", boot->bpbSecPerClust);
return FSFATAL;
}
if (boot->bpbSectors) {
boot->bpbHugeSectors = 0;
boot->NumSectors = boot->bpbSectors;
} else
boot->NumSectors = boot->bpbHugeSectors;
boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) /
boot->bpbSecPerClust;
if (boot->flags&FAT32)
boot->ClustMask = CLUST32_MASK;
else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK))
boot->ClustMask = CLUST12_MASK;
else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK))
boot->ClustMask = CLUST16_MASK;
else {
pfatal("Filesystem too big (%u clusters) for non-FAT32 partition",
boot->NumClusters);
return FSFATAL;
}
switch (boot->ClustMask) {
case CLUST32_MASK:
boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 4;
break;
case CLUST16_MASK:
boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 2;
break;
default:
boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec * 2) / 3;
break;
}
if (boot->NumFatEntries < boot->NumClusters) {
pfatal("FAT size too small, %u entries won't fit into %u sectors\n",
boot->NumClusters, boot->FATsecs);
return FSFATAL;
}
boot->ClusterSize = boot->bpbBytesPerSec * boot->bpbSecPerClust;
boot->NumFiles = 1;
boot->NumFree = 0;
return ret;
}
int
writefsinfo(int dosfs, struct bootblock *boot)
{
u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET)
!= boot->bpbFSInfo * boot->bpbBytesPerSec
|| read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) {
perr("could not read fsinfo block");
return FSFATAL;
}
fsinfo[0x1e8] = (u_char)boot->FSFree;
fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8);
fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16);
fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24);
fsinfo[0x1ec] = (u_char)boot->FSNext;
fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8);
fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16);
fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24);
if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET)
!= boot->bpbFSInfo * boot->bpbBytesPerSec
|| write(dosfs, fsinfo, sizeof fsinfo)
!= sizeof fsinfo) {
perr("Unable to write bpbFSInfo");
return FSFATAL;
}
/*
* Technically, we should return FSBOOTMOD here.
*
* However, since Win95 OSR2 (the first M$ OS that has
* support for FAT32) doesn't maintain the FSINFO block
* correctly, it has to be fixed pretty often.
*
* Therefor, we handle the FSINFO block only informally,
* fixing it if necessary, but otherwise ignoring the
* fact that it was incorrect.
*/
return 0;
}
|
