boot.c revision 1.15 1 1.15 lukem /* $NetBSD: boot.c,v 1.15 2009/04/11 07:14:50 lukem Exp $ */
2 1.1 ws
3 1.1 ws /*
4 1.5 ws * Copyright (C) 1995, 1997 Wolfgang Solfrank
5 1.1 ws * Copyright (c) 1995 Martin Husemann
6 1.1 ws *
7 1.1 ws * Redistribution and use in source and binary forms, with or without
8 1.1 ws * modification, are permitted provided that the following conditions
9 1.1 ws * are met:
10 1.1 ws * 1. Redistributions of source code must retain the above copyright
11 1.1 ws * notice, this list of conditions and the following disclaimer.
12 1.1 ws * 2. Redistributions in binary form must reproduce the above copyright
13 1.1 ws * notice, this list of conditions and the following disclaimer in the
14 1.1 ws * documentation and/or other materials provided with the distribution.
15 1.1 ws *
16 1.1 ws * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
17 1.1 ws * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 1.1 ws * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 1.1 ws * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 1.1 ws * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 1.1 ws * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 1.1 ws * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 1.1 ws * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 1.1 ws * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 1.1 ws * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 1.1 ws */
27 1.1 ws
28 1.1 ws
29 1.4 lukem #include <sys/cdefs.h>
30 1.1 ws #ifndef lint
31 1.15 lukem __RCSID("$NetBSD: boot.c,v 1.15 2009/04/11 07:14:50 lukem Exp $");
32 1.1 ws #endif /* not lint */
33 1.1 ws
34 1.1 ws #include <stdlib.h>
35 1.1 ws #include <string.h>
36 1.1 ws #include <stdio.h>
37 1.1 ws #include <unistd.h>
38 1.1 ws
39 1.1 ws #include "ext.h"
40 1.3 christos #include "fsutil.h"
41 1.1 ws
42 1.1 ws int
43 1.10 xtraeme readboot(int dosfs, struct bootblock *boot)
44 1.1 ws {
45 1.1 ws u_char block[DOSBOOTBLOCKSIZE];
46 1.5 ws u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
47 1.5 ws u_char backup[DOSBOOTBLOCKSIZE];
48 1.5 ws int ret = FSOK;
49 1.13 gdt int i;
50 1.1 ws
51 1.15 lukem if ((size_t)read(dosfs, block, sizeof block) != sizeof block) {
52 1.11 christos perr("could not read boot block");
53 1.1 ws return FSFATAL;
54 1.1 ws }
55 1.1 ws
56 1.5 ws if (block[510] != 0x55 || block[511] != 0xaa) {
57 1.5 ws pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]);
58 1.5 ws return FSFATAL;
59 1.5 ws }
60 1.5 ws
61 1.5 ws memset(boot, 0, sizeof *boot);
62 1.5 ws boot->ValidFat = -1;
63 1.5 ws
64 1.1 ws /* decode bios parameter block */
65 1.1 ws boot->BytesPerSec = block[11] + (block[12] << 8);
66 1.1 ws boot->SecPerClust = block[13];
67 1.1 ws boot->ResSectors = block[14] + (block[15] << 8);
68 1.1 ws boot->FATs = block[16];
69 1.1 ws boot->RootDirEnts = block[17] + (block[18] << 8);
70 1.1 ws boot->Sectors = block[19] + (block[20] << 8);
71 1.1 ws boot->Media = block[21];
72 1.5 ws boot->FATsmall = block[22] + (block[23] << 8);
73 1.1 ws boot->SecPerTrack = block[24] + (block[25] << 8);
74 1.1 ws boot->Heads = block[26] + (block[27] << 8);
75 1.1 ws boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24);
76 1.1 ws boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24);
77 1.5 ws
78 1.5 ws boot->FATsecs = boot->FATsmall;
79 1.5 ws
80 1.5 ws if (!boot->RootDirEnts)
81 1.5 ws boot->flags |= FAT32;
82 1.5 ws if (boot->flags & FAT32) {
83 1.5 ws boot->FATsecs = block[36] + (block[37] << 8)
84 1.5 ws + (block[38] << 16) + (block[39] << 24);
85 1.5 ws if (block[40] & 0x80)
86 1.5 ws boot->ValidFat = block[40] & 0x0f;
87 1.5 ws
88 1.5 ws /* check version number: */
89 1.5 ws if (block[42] || block[43]) {
90 1.5 ws /* Correct? XXX */
91 1.5 ws pfatal("Unknown filesystem version: %x.%x",
92 1.5 ws block[43], block[42]);
93 1.5 ws return FSFATAL;
94 1.5 ws }
95 1.5 ws boot->RootCl = block[44] + (block[45] << 8)
96 1.5 ws + (block[46] << 16) + (block[47] << 24);
97 1.5 ws boot->FSInfo = block[48] + (block[49] << 8);
98 1.5 ws boot->Backup = block[50] + (block[51] << 8);
99 1.5 ws
100 1.5 ws if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET)
101 1.5 ws != boot->FSInfo * boot->BytesPerSec
102 1.5 ws || read(dosfs, fsinfo, sizeof fsinfo)
103 1.5 ws != sizeof fsinfo) {
104 1.11 christos perr("could not read fsinfo block");
105 1.5 ws return FSFATAL;
106 1.5 ws }
107 1.5 ws if (memcmp(fsinfo, "RRaA", 4)
108 1.5 ws || memcmp(fsinfo + 0x1e4, "rrAa", 4)
109 1.5 ws || fsinfo[0x1fc]
110 1.5 ws || fsinfo[0x1fd]
111 1.5 ws || fsinfo[0x1fe] != 0x55
112 1.5 ws || fsinfo[0x1ff] != 0xaa
113 1.5 ws || fsinfo[0x3fc]
114 1.5 ws || fsinfo[0x3fd]
115 1.5 ws || fsinfo[0x3fe] != 0x55
116 1.5 ws || fsinfo[0x3ff] != 0xaa) {
117 1.5 ws pwarn("Invalid signature in fsinfo block");
118 1.5 ws if (ask(0, "fix")) {
119 1.5 ws memcpy(fsinfo, "RRaA", 4);
120 1.5 ws memcpy(fsinfo + 0x1e4, "rrAa", 4);
121 1.5 ws fsinfo[0x1fc] = fsinfo[0x1fd] = 0;
122 1.5 ws fsinfo[0x1fe] = 0x55;
123 1.5 ws fsinfo[0x1ff] = 0xaa;
124 1.5 ws fsinfo[0x3fc] = fsinfo[0x3fd] = 0;
125 1.5 ws fsinfo[0x3fe] = 0x55;
126 1.5 ws fsinfo[0x3ff] = 0xaa;
127 1.5 ws if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET)
128 1.5 ws != boot->FSInfo * boot->BytesPerSec
129 1.5 ws || write(dosfs, fsinfo, sizeof fsinfo)
130 1.5 ws != sizeof fsinfo) {
131 1.11 christos perr("Unable to write FSInfo");
132 1.5 ws return FSFATAL;
133 1.5 ws }
134 1.5 ws ret = FSBOOTMOD;
135 1.5 ws } else
136 1.5 ws boot->FSInfo = 0;
137 1.5 ws }
138 1.5 ws if (boot->FSInfo) {
139 1.5 ws boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8)
140 1.5 ws + (fsinfo[0x1ea] << 16)
141 1.5 ws + (fsinfo[0x1eb] << 24);
142 1.5 ws boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8)
143 1.5 ws + (fsinfo[0x1ee] << 16)
144 1.5 ws + (fsinfo[0x1ef] << 24);
145 1.5 ws }
146 1.5 ws
147 1.5 ws if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET)
148 1.5 ws != boot->Backup * boot->BytesPerSec
149 1.5 ws || read(dosfs, backup, sizeof backup) != sizeof backup) {
150 1.11 christos perr("could not read backup bootblock");
151 1.5 ws return FSFATAL;
152 1.5 ws }
153 1.9 ws backup[65] = block[65]; /* XXX */
154 1.9 ws if (memcmp(block + 11, backup + 11, 79)) {
155 1.13 gdt /*
156 1.13 gdt * XXX We require a reference that explains
157 1.13 gdt * that these bytes need to match, or should
158 1.13 gdt * drop the check. gdt@ has observed
159 1.13 gdt * filesystems that work fine under Windows XP
160 1.13 gdt * and NetBSD that do not match, so the
161 1.13 gdt * requirement is suspect. For now, just
162 1.13 gdt * print out useful information and continue.
163 1.13 gdt */
164 1.13 gdt pfatal("backup (block %d) mismatch with primary bootblock:\n",
165 1.13 gdt boot->Backup);
166 1.13 gdt for (i = 11; i < 11 + 90; i++) {
167 1.13 gdt if (block[i] != backup[i])
168 1.13 gdt pfatal("\ti=%d\tprimary 0x%02x\tbackup 0x%02x\n",
169 1.13 gdt i, block[i], backup[i]);
170 1.13 gdt }
171 1.5 ws }
172 1.5 ws /* Check backup FSInfo? XXX */
173 1.5 ws }
174 1.5 ws
175 1.1 ws boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
176 1.1 ws / boot->BytesPerSec
177 1.1 ws + boot->ResSectors
178 1.1 ws + boot->FATs * boot->FATsecs
179 1.1 ws - CLUST_FIRST * boot->SecPerClust;
180 1.1 ws
181 1.1 ws if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) {
182 1.5 ws pfatal("Invalid sector size: %u", boot->BytesPerSec);
183 1.1 ws return FSFATAL;
184 1.1 ws }
185 1.1 ws if (boot->SecPerClust == 0) {
186 1.5 ws pfatal("Invalid cluster size: %u", boot->SecPerClust);
187 1.1 ws return FSFATAL;
188 1.1 ws }
189 1.1 ws if (boot->Sectors) {
190 1.1 ws boot->HugeSectors = 0;
191 1.1 ws boot->NumSectors = boot->Sectors;
192 1.1 ws } else
193 1.1 ws boot->NumSectors = boot->HugeSectors;
194 1.1 ws boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust;
195 1.1 ws
196 1.5 ws if (boot->flags&FAT32)
197 1.5 ws boot->ClustMask = CLUST32_MASK;
198 1.5 ws else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK))
199 1.5 ws boot->ClustMask = CLUST12_MASK;
200 1.5 ws else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK))
201 1.5 ws boot->ClustMask = CLUST16_MASK;
202 1.5 ws else {
203 1.5 ws pfatal("Filesystem too big (%u clusters) for non-FAT32 partition",
204 1.5 ws boot->NumClusters);
205 1.5 ws return FSFATAL;
206 1.5 ws }
207 1.5 ws
208 1.5 ws switch (boot->ClustMask) {
209 1.5 ws case CLUST32_MASK:
210 1.5 ws boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4;
211 1.5 ws break;
212 1.5 ws case CLUST16_MASK:
213 1.1 ws boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2;
214 1.5 ws break;
215 1.5 ws default:
216 1.1 ws boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3;
217 1.5 ws break;
218 1.5 ws }
219 1.5 ws
220 1.1 ws if (boot->NumFatEntries < boot->NumClusters) {
221 1.5 ws pfatal("FAT size too small, %u entries won't fit into %u sectors\n",
222 1.1 ws boot->NumClusters, boot->FATsecs);
223 1.1 ws return FSFATAL;
224 1.1 ws }
225 1.1 ws boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust;
226 1.1 ws
227 1.1 ws boot->NumFiles = 1;
228 1.1 ws boot->NumFree = 0;
229 1.5 ws
230 1.5 ws return ret;
231 1.5 ws }
232 1.5 ws
233 1.5 ws int
234 1.10 xtraeme writefsinfo(int dosfs, struct bootblock *boot)
235 1.5 ws {
236 1.5 ws u_char fsinfo[2 * DOSBOOTBLOCKSIZE];
237 1.5 ws
238 1.5 ws if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET)
239 1.5 ws != boot->FSInfo * boot->BytesPerSec
240 1.5 ws || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) {
241 1.11 christos perr("could not read fsinfo block");
242 1.5 ws return FSFATAL;
243 1.5 ws }
244 1.5 ws fsinfo[0x1e8] = (u_char)boot->FSFree;
245 1.5 ws fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8);
246 1.5 ws fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16);
247 1.5 ws fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24);
248 1.5 ws fsinfo[0x1ec] = (u_char)boot->FSNext;
249 1.5 ws fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8);
250 1.5 ws fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16);
251 1.5 ws fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24);
252 1.5 ws if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET)
253 1.5 ws != boot->FSInfo * boot->BytesPerSec
254 1.5 ws || write(dosfs, fsinfo, sizeof fsinfo)
255 1.5 ws != sizeof fsinfo) {
256 1.11 christos perr("Unable to write FSInfo");
257 1.5 ws return FSFATAL;
258 1.5 ws }
259 1.6 ws /*
260 1.6 ws * Technically, we should return FSBOOTMOD here.
261 1.6 ws *
262 1.6 ws * However, since Win95 OSR2 (the first M$ OS that has
263 1.6 ws * support for FAT32) doesn't maintain the FSINFO block
264 1.6 ws * correctly, it has to be fixed pretty often.
265 1.6 ws *
266 1.6 ws * Therefor, we handle the FSINFO block only informally,
267 1.7 wiz * fixing it if necessary, but otherwise ignoring the
268 1.6 ws * fact that it was incorrect.
269 1.6 ws */
270 1.6 ws return 0;
271 1.1 ws }
272