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1.1 root 1: /*
2: * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * Portions Copyright (c) 1999 Apple Computer, Inc. All Rights
7: * Reserved. This file contains Original Code and/or Modifications of
8: * Original Code as defined in and that are subject to the Apple Public
9: * Source License Version 1.1 (the "License"). You may not use this file
10: * except in compliance with the License. Please obtain a copy of the
11: * License at http://www.apple.com/publicsource and read it before using
12: * this file.
13: *
14: * The Original Code and all software distributed under the License are
15: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
16: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
17: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
18: * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the
19: * License for the specific language governing rights and limitations
20: * under the License.
21: *
22: * @APPLE_LICENSE_HEADER_END@
23: */
24: /* Copyright (c) 1992 NeXT Computer, Inc. All rights reserved.
25: *
26: * label_subr.c - machine-independent disk label routines
27: *
28: * HISTORY
29: * 01-Apr-92 Doug Mitchell at NeXT
30: * Created.
31: */
32: #import <bsd/sys/param.h>
33: #import <bsd/dev/disk_label.h>
34: #import <driverkit/disk_label.h>
35: #import <driverkit/diskstruct.h>
36: #import <architecture/byte_order.h>
37:
38:
39: /*
40: * Inlines used to manipulate m68k-style disk label fields.
41: */
42: static inline unsigned int
43: get_word(const void *src)
44: {
45: return ( NXSwapBigIntToHost(*((unsigned int *)src)));
46: }
47:
48: static inline void
49: put_word(unsigned s, void *dest)
50: {
51: *((unsigned int *)dest) = NXSwapHostIntToBig(s);
52: }
53:
54:
55: static inline unsigned short
56: get_short(const void *src)
57: {
58: return ( NXSwapBigShortToHost(*((unsigned short *)src)));
59: }
60:
61: static inline void
62: put_short(unsigned short s, void *dest)
63: {
64: *((unsigned short *)dest) = NXSwapHostShortToBig(s);
65: }
66:
67: /*
68: * Machine-independent version of kernel's checksum_16().
69: * *wp is a raw m68k-style label.
70: */
71: unsigned short
72: checksum16(unsigned short *wp, int num_shorts)
73: {
74: int sum1 = 0;
75: int sum2;
76:
77: while (num_shorts--){
78: sum1 += NXSwapBigShortToHost(*wp);
79: wp++;
80: }
81: sum2 = ((sum1 & 0xffff0000) >> 16) + (sum1 & 0xffff);
82: if(sum2 > 65535) {
83: sum2 -= 65535;
84: }
85: return sum2;
86: }
87:
88: /*
89: * Validate an m68k-style label. Returns NULL if good, else returns pointer
90: * to an error string describing what is wrong with the label.
91: */
92: char *
93: check_label(char *raw_label, // as it came off disk
94: int block_num)
95: {
96: unsigned short sum;
97: unsigned short cksum;
98: unsigned short size;
99: void *dl_cksump;
100: int version;
101: int label_blkno;
102:
103: version = get_word(raw_label + DISK_LABEL_DL_VERSION);
104: if(version == DL_V1 || version == DL_V2) {
105: size = SIZEOF_DISK_LABEL_T;
106: dl_cksump = raw_label + DISK_LABEL_DL_CHECKSUM;
107: }
108: else if(version == DL_V3) {
109: size = SIZEOF_DISK_LABEL_T - SIZEOF_DL_UN_T;
110: dl_cksump = raw_label + DISK_LABEL_DL_UN;
111: }
112: else {
113: return "Bad disk label magic number";
114: }
115: label_blkno = get_word(raw_label + DISK_LABEL_DL_LABEL_BLKNO);
116: if(label_blkno != block_num) {
117: return "Label in wrong location";
118: }
119:
120: /*
121: * Block number in label has to be 0 for checksum calculation.
122: */
123: put_word(0, raw_label + DISK_LABEL_DL_LABEL_BLKNO);
124: cksum = get_short(dl_cksump);
125: put_short(0, dl_cksump);
126: sum = checksum16((unsigned short *)raw_label, size >> 1);
127: if (sum != cksum) {
128: return "Label checksum error";
129: }
130:
131: /*
132: * Success. Restore block number.
133: */
134: put_word(block_num, raw_label + DISK_LABEL_DL_LABEL_BLKNO);
135: put_short(cksum, dl_cksump);
136: return NULL;
137: }
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