1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * 3 *
4 * Copyright (C) 2019-2021 Paragon Software Gm 4 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
5 * 5 *
6 */ 6 */
7 7
8 #include <linux/types.h> 8 #include <linux/types.h>
9 9
10 #include "ntfs_fs.h" 10 #include "ntfs_fs.h"
11 11
12 #define BITS_IN_SIZE_T (sizeof(size_t) * 8) 12 #define BITS_IN_SIZE_T (sizeof(size_t) * 8)
13 13
14 /* 14 /*
15 * fill_mask[i] - first i bits are '1' , i = 0 15 * fill_mask[i] - first i bits are '1' , i = 0,1,2,3,4,5,6,7,8
16 * fill_mask[i] = 0xFF >> (8-i) 16 * fill_mask[i] = 0xFF >> (8-i)
17 */ 17 */
18 static const u8 fill_mask[] = { 0x00, 0x01, 0x 18 static const u8 fill_mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0F,
19 0x1F, 0x3F, 0x 19 0x1F, 0x3F, 0x7F, 0xFF };
20 20
21 /* 21 /*
22 * zero_mask[i] - first i bits are '' , i = 0, 22 * zero_mask[i] - first i bits are '' , i = 0,1,2,3,4,5,6,7,8
23 * zero_mask[i] = 0xFF << i 23 * zero_mask[i] = 0xFF << i
24 */ 24 */
25 static const u8 zero_mask[] = { 0xFF, 0xFE, 0x 25 static const u8 zero_mask[] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0,
26 0xE0, 0xC0, 0x 26 0xE0, 0xC0, 0x80, 0x00 };
27 27
28 /* 28 /*
29 * are_bits_clear 29 * are_bits_clear
30 * 30 *
31 * Return: True if all bits [bit, bit+nbits) a 31 * Return: True if all bits [bit, bit+nbits) are zeros "".
32 */ 32 */
33 bool are_bits_clear(const void *lmap, size_t b 33 bool are_bits_clear(const void *lmap, size_t bit, size_t nbits)
34 { 34 {
35 size_t pos = bit & 7; 35 size_t pos = bit & 7;
36 const u8 *map = (u8 *)lmap + (bit >> 3 36 const u8 *map = (u8 *)lmap + (bit >> 3);
37 37
38 if (pos) { 38 if (pos) {
39 if (8 - pos >= nbits) 39 if (8 - pos >= nbits)
40 return !nbits || !(*ma 40 return !nbits || !(*map & fill_mask[pos + nbits] &
41 zer 41 zero_mask[pos]);
42 42
43 if (*map++ & zero_mask[pos]) 43 if (*map++ & zero_mask[pos])
44 return false; 44 return false;
45 nbits -= 8 - pos; 45 nbits -= 8 - pos;
46 } 46 }
47 47
48 pos = ((size_t)map) & (sizeof(size_t) 48 pos = ((size_t)map) & (sizeof(size_t) - 1);
49 if (pos) { 49 if (pos) {
50 pos = sizeof(size_t) - pos; 50 pos = sizeof(size_t) - pos;
51 if (nbits >= pos * 8) { 51 if (nbits >= pos * 8) {
52 for (nbits -= pos * 8; 52 for (nbits -= pos * 8; pos; pos--, map++) {
53 if (*map) 53 if (*map)
54 return 54 return false;
55 } 55 }
56 } 56 }
57 } 57 }
58 58
59 for (pos = nbits / BITS_IN_SIZE_T; pos 59 for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
60 if (*((size_t *)map)) 60 if (*((size_t *)map))
61 return false; 61 return false;
62 } 62 }
63 63
64 for (pos = (nbits % BITS_IN_SIZE_T) >> 64 for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
65 if (*map) 65 if (*map)
66 return false; 66 return false;
67 } 67 }
68 68
69 pos = nbits & 7; 69 pos = nbits & 7;
70 if (pos && (*map & fill_mask[pos])) 70 if (pos && (*map & fill_mask[pos]))
71 return false; 71 return false;
72 72
73 return true; 73 return true;
74 } 74 }
75 75
76 /* 76 /*
77 * are_bits_set 77 * are_bits_set
78 * 78 *
79 * Return: True if all bits [bit, bit+nbits) a 79 * Return: True if all bits [bit, bit+nbits) are ones "1".
80 */ 80 */
81 bool are_bits_set(const void *lmap, size_t bit 81 bool are_bits_set(const void *lmap, size_t bit, size_t nbits)
82 { 82 {
83 u8 mask; 83 u8 mask;
84 size_t pos = bit & 7; 84 size_t pos = bit & 7;
85 const u8 *map = (u8 *)lmap + (bit >> 3 85 const u8 *map = (u8 *)lmap + (bit >> 3);
86 86
87 if (pos) { 87 if (pos) {
88 if (8 - pos >= nbits) { 88 if (8 - pos >= nbits) {
89 mask = fill_mask[pos + 89 mask = fill_mask[pos + nbits] & zero_mask[pos];
90 return !nbits || (*map 90 return !nbits || (*map & mask) == mask;
91 } 91 }
92 92
93 mask = zero_mask[pos]; 93 mask = zero_mask[pos];
94 if ((*map++ & mask) != mask) 94 if ((*map++ & mask) != mask)
95 return false; 95 return false;
96 nbits -= 8 - pos; 96 nbits -= 8 - pos;
97 } 97 }
98 98
99 pos = ((size_t)map) & (sizeof(size_t) 99 pos = ((size_t)map) & (sizeof(size_t) - 1);
100 if (pos) { 100 if (pos) {
101 pos = sizeof(size_t) - pos; 101 pos = sizeof(size_t) - pos;
102 if (nbits >= pos * 8) { 102 if (nbits >= pos * 8) {
103 for (nbits -= pos * 8; 103 for (nbits -= pos * 8; pos; pos--, map++) {
104 if (*map != 0x 104 if (*map != 0xFF)
105 return 105 return false;
106 } 106 }
107 } 107 }
108 } 108 }
109 109
110 for (pos = nbits / BITS_IN_SIZE_T; pos 110 for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
111 if (*((size_t *)map) != MINUS_ 111 if (*((size_t *)map) != MINUS_ONE_T)
112 return false; 112 return false;
113 } 113 }
114 114
115 for (pos = (nbits % BITS_IN_SIZE_T) >> 115 for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
116 if (*map != 0xFF) 116 if (*map != 0xFF)
117 return false; 117 return false;
118 } 118 }
119 119
120 pos = nbits & 7; 120 pos = nbits & 7;
121 if (pos) { 121 if (pos) {
122 mask = fill_mask[pos]; 122 mask = fill_mask[pos];
123 if ((*map & mask) != mask) 123 if ((*map & mask) != mask)
124 return false; 124 return false;
125 } 125 }
126 126
127 return true; 127 return true;
128 } 128 }
129 129
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