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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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35 | |||
36 | |||
2382 | konopa | 37 | /* Superblock support. */ |
38 | |||
39 | /* Methods: |
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40 | * init_super: initializes the superblock structure for later use |
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41 | * get_super: return pointer at the superblock |
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42 | * read_super: read a superblock |
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43 | */ |
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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 | |||
59 | int (*versions[TOTAL_VERSIONS])(int , int*, int*) = { |
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60 | v1, /* 0 = V1 version */ |
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61 | v2 /* 1 = V2 version */ |
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62 | }; |
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63 | |||
64 | int init_super_block() |
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65 | { |
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66 | |||
67 | super_block = (super_block_t*)malloc(sizeof(super_block_t)); |
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68 | if (super_block != NULL) |
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69 | return TRUE; |
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70 | |||
71 | return FALSE; |
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72 | } |
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73 | |||
74 | super_block_t *get_super() |
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75 | { |
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76 | return super_block; |
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77 | } |
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78 | |||
79 | int read_super(register super_block_t *sp) |
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80 | { |
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81 | |||
82 | /* Read a superblock. */ |
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83 | |||
84 | register block_t *bp; |
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85 | int magic, version, extend, native; |
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86 | |||
87 | |||
88 | bp = get_block(SUPER_BLOCK); |
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89 | memcpy((void *)sp, (void *)(bp->b.b__data), (size_t)SUPER_SIZE); |
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90 | magic = sp->s_magic; /* determines file system type */ |
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91 | |||
92 | |||
93 | /* Get file system version and type. */ |
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94 | native = get_native(magic, &version, &extend); |
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95 | |||
96 | if (native == FS_EINVAL) { |
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97 | print_console("Unknown version of file system\n"); |
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98 | print_console("Magic is bad\n"); |
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99 | return FS_EINVAL; |
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100 | } |
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101 | |||
102 | /* In V1, the device size was kept in a short, s_nzones, which limited |
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103 | * devices to 32K zones. For V2, it was decided to keep the size as a |
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104 | * long. However, just changing s_nzones to a long would not work, since |
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105 | * then the position of s_magic in the super block would not be the same |
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106 | * in V1 and V2 file systems, and there would be no way to tell whether |
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107 | * a newly mounted file system was V1 or V2. The solution was to introduce |
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108 | * a new variable, s_zones, and copy the size there. |
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109 | * |
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110 | * Calculate some other numbers that depend on the version here too, to |
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111 | * hide some of the differences. |
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112 | */ |
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113 | |||
114 | if (version == V1) { |
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115 | sp->s_zones = sp->s_nzones; /* only V1 needs this copy */ |
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116 | sp->s_inodes_per_block = V1_INODES_PER_BLOCK; |
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117 | sp->s_ndzones = V1_NR_DZONES; |
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118 | sp->s_nindirs = V1_INDIRECTS; |
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119 | } |
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120 | else { |
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121 | sp->s_inodes_per_block = V2_INODES_PER_BLOCK; |
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122 | sp->s_ndzones = V2_NR_DZONES; |
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123 | sp->s_nindirs = V2_INDIRECTS; |
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124 | } |
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125 | |||
126 | sp->s_isearch = 0; /* inode searches initially start at 0 */ |
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127 | sp->s_zsearch = 0; /* zone searches initially start at 0 */ |
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128 | sp->s_version = version; |
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129 | sp->s_native = native; |
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130 | sp->s_extend = extend; |
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131 | |||
132 | |||
133 | /* Make a few basic checks to see if super block looks reasonable. */ |
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134 | if (sp->s_imap_blocks < 1 || sp->s_zmap_blocks < 1 |
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135 | || sp->s_ninodes < 1 || sp->s_zones < 1 |
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136 | || (unsigned) sp->s_log_zone_size > 4) { |
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137 | return FS_EINVAL; |
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138 | } |
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139 | |||
140 | return OK; |
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141 | } |
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142 | |||
143 | int v1(int magic, int* version, int *extend) |
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144 | { |
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145 | |||
146 | if (magic == SUPER_MAGIC || magic == conv2(BYTE_SWAP,SUPER_MAGIC)) { |
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147 | |||
148 | *version = V1; *extend = FALSE; |
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149 | return TRUE; |
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150 | } |
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151 | if (magic == SUPER_MAGIC2 || magic == conv2(BYTE_SWAP,SUPER_MAGIC2)) { |
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152 | *version = V1; *extend = TRUE; |
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153 | return TRUE; |
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154 | } |
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155 | |||
156 | return FALSE; |
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157 | } |
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158 | |||
159 | int v2(int magic, int *version, int *extend) |
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160 | { |
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161 | |||
162 | if (magic == SUPER_V2 || magic == conv2(BYTE_SWAP,SUPER_V2)) { |
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163 | *version = V2; *extend = FALSE; |
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164 | return TRUE; |
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165 | } |
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166 | |||
167 | if (magic == SUPER_V2E || magic == conv2(BYTE_SWAP,SUPER_V2E)) { |
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168 | *version = V2; *extend = TRUE; |
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169 | return TRUE; |
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170 | } |
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171 | |||
172 | return FALSE; |
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173 | } |
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174 | |||
175 | int get_native(int magic, int *version, int *extend) |
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176 | { |
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177 | |||
178 | |||
179 | int i, result; |
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180 | |||
181 | /* Get file system version and type */ |
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182 | for (i = 0; i < TOTAL_VERSIONS; i++) { |
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183 | result = versions[i](magic, version, extend); |
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184 | if (result) { |
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185 | return result; |
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186 | } |
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187 | } |
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188 | |||
189 | return FS_EINVAL; |
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190 | } |