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2404 | konopa | 1 | /* |
2 | * Copyright (c) 1987,1997, Prentice Hall |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use of the MINIX operating system in source and |
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6 | * binary forms, with or without modification, are permitted provided |
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7 | * that the following conditions are met: |
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8 | |||
9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | |||
12 | * - Redistributions in binary form must reproduce the above |
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13 | * copyright notice, this list of conditions and the following |
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14 | * disclaimer in the documentation and/or other materials provided |
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15 | * with the distribution. |
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16 | |||
17 | * - Neither the name of Prentice Hall nor the names of the software |
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18 | * authors or contributors may be used to endorse or promote |
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19 | * products derived from this software without specific prior |
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20 | * written permission. |
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21 | |||
22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS, AUTHORS, AND |
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23 | * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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24 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
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25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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26 | * IN NO EVENT SHALL PRENTICE HALL OR ANY AUTHORS OR CONTRIBUTORS BE |
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27 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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28 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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29 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
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30 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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31 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE |
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32 | * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
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33 | * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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34 | */ |
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2435 | jelen | 35 | |
36 | /** @addtogroup FileSystemImpl |
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37 | * @{ |
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38 | */ |
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2404 | konopa | 39 | |
2435 | jelen | 40 | /** |
41 | * @file utility.c |
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42 | * @brief Superblock support. |
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2382 | konopa | 43 | */ |
44 | |||
45 | #include <string.h> |
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46 | #include "fs.h" |
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47 | #include "block.h" |
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48 | #include "inode.h" |
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49 | #include "super.h" |
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50 | #include <stdio.h> |
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51 | |||
52 | |||
53 | super_block_t* super_block; |
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54 | |||
55 | static int v1(int magic, int *version, int *extend); |
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56 | static int v2(int magic ,int*version, int *extend); |
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57 | static int get_native(int magic, int *version, int *extend); |
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58 | |||
2435 | jelen | 59 | /** |
60 | * File system versions |
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61 | */ |
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2382 | konopa | 62 | int (*versions[TOTAL_VERSIONS])(int , int*, int*) = { |
63 | v1, /* 0 = V1 version */ |
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64 | v2 /* 1 = V2 version */ |
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65 | }; |
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66 | |||
2435 | jelen | 67 | /** |
68 | * Initializes the superblock structure for later use |
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69 | */ |
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2382 | konopa | 70 | int init_super_block() |
71 | { |
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72 | super_block = (super_block_t*)malloc(sizeof(super_block_t)); |
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73 | if (super_block != NULL) |
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74 | return TRUE; |
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75 | |||
76 | return FALSE; |
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77 | } |
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2435 | jelen | 78 | |
79 | /** |
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80 | * Return pointer at the superblock |
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81 | */ |
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2382 | konopa | 82 | super_block_t *get_super() |
83 | { |
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84 | return super_block; |
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85 | } |
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86 | |||
2435 | jelen | 87 | /** |
88 | * Read a superblock |
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89 | */ |
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2382 | konopa | 90 | int read_super(register super_block_t *sp) |
91 | { |
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92 | /* Read a superblock. */ |
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93 | |||
94 | register block_t *bp; |
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95 | int magic, version, extend, native; |
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96 | |||
97 | |||
98 | bp = get_block(SUPER_BLOCK); |
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99 | memcpy((void *)sp, (void *)(bp->b.b__data), (size_t)SUPER_SIZE); |
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100 | magic = sp->s_magic; /* determines file system type */ |
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101 | |||
102 | |||
103 | /* Get file system version and type. */ |
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104 | native = get_native(magic, &version, &extend); |
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105 | |||
106 | if (native == FS_EINVAL) { |
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107 | print_console("Unknown version of file system\n"); |
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108 | print_console("Magic is bad\n"); |
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109 | return FS_EINVAL; |
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110 | } |
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111 | |||
112 | /* In V1, the device size was kept in a short, s_nzones, which limited |
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113 | * devices to 32K zones. For V2, it was decided to keep the size as a |
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114 | * long. However, just changing s_nzones to a long would not work, since |
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115 | * then the position of s_magic in the super block would not be the same |
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116 | * in V1 and V2 file systems, and there would be no way to tell whether |
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117 | * a newly mounted file system was V1 or V2. The solution was to introduce |
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118 | * a new variable, s_zones, and copy the size there. |
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119 | * |
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120 | * Calculate some other numbers that depend on the version here too, to |
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121 | * hide some of the differences. |
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122 | */ |
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123 | |||
124 | if (version == V1) { |
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125 | sp->s_zones = sp->s_nzones; /* only V1 needs this copy */ |
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126 | sp->s_inodes_per_block = V1_INODES_PER_BLOCK; |
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127 | sp->s_ndzones = V1_NR_DZONES; |
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128 | sp->s_nindirs = V1_INDIRECTS; |
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129 | } |
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130 | else { |
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131 | sp->s_inodes_per_block = V2_INODES_PER_BLOCK; |
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132 | sp->s_ndzones = V2_NR_DZONES; |
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133 | sp->s_nindirs = V2_INDIRECTS; |
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134 | } |
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135 | |||
136 | sp->s_isearch = 0; /* inode searches initially start at 0 */ |
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137 | sp->s_zsearch = 0; /* zone searches initially start at 0 */ |
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138 | sp->s_version = version; |
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139 | sp->s_native = native; |
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140 | sp->s_extend = extend; |
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141 | |||
142 | |||
143 | /* Make a few basic checks to see if super block looks reasonable. */ |
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144 | if (sp->s_imap_blocks < 1 || sp->s_zmap_blocks < 1 |
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145 | || sp->s_ninodes < 1 || sp->s_zones < 1 |
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146 | || (unsigned) sp->s_log_zone_size > 4) { |
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147 | return FS_EINVAL; |
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148 | } |
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149 | |||
150 | return OK; |
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151 | } |
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152 | |||
2435 | jelen | 153 | /** |
154 | * Test the superblock against MINIX FS v1 |
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155 | */ |
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2382 | konopa | 156 | int v1(int magic, int* version, int *extend) |
157 | { |
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158 | |||
159 | if (magic == SUPER_MAGIC || magic == conv2(BYTE_SWAP,SUPER_MAGIC)) { |
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160 | |||
161 | *version = V1; *extend = FALSE; |
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162 | return TRUE; |
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163 | } |
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164 | if (magic == SUPER_MAGIC2 || magic == conv2(BYTE_SWAP,SUPER_MAGIC2)) { |
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165 | *version = V1; *extend = TRUE; |
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166 | return TRUE; |
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167 | } |
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168 | |||
169 | return FALSE; |
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170 | } |
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171 | |||
2435 | jelen | 172 | /** |
173 | * Test the superblock against MINIX FS v2 |
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174 | */ |
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2382 | konopa | 175 | int v2(int magic, int *version, int *extend) |
176 | { |
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177 | |||
178 | if (magic == SUPER_V2 || magic == conv2(BYTE_SWAP,SUPER_V2)) { |
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179 | *version = V2; *extend = FALSE; |
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180 | return TRUE; |
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181 | } |
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182 | |||
183 | if (magic == SUPER_V2E || magic == conv2(BYTE_SWAP,SUPER_V2E)) { |
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184 | *version = V2; *extend = TRUE; |
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185 | return TRUE; |
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186 | } |
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187 | |||
188 | return FALSE; |
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189 | } |
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190 | |||
2435 | jelen | 191 | /** |
192 | * Check the file system version and type |
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193 | */ |
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2382 | konopa | 194 | int get_native(int magic, int *version, int *extend) |
2435 | jelen | 195 | { |
2382 | konopa | 196 | int i, result; |
197 | |||
198 | /* Get file system version and type */ |
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199 | for (i = 0; i < TOTAL_VERSIONS; i++) { |
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200 | result = versions[i](magic, version, extend); |
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201 | if (result) { |
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202 | return result; |
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203 | } |
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204 | } |
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205 | |||
206 | return FS_EINVAL; |
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207 | } |
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2435 | jelen | 208 | |
209 | /** |
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210 | * } |
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211 | */ |
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212 |