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1 /* |
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2 * Block driver for the various disk image formats used by Bochs |
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3 * Currently only for "growing" type in read-only mode |
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4 * |
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5 * Copyright (c) 2005 Alex Beregszaszi |
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6 * |
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7 * Permission is hereby granted, free of charge, to any person obtaining a copy |
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8 * of this software and associated documentation files (the "Software"), to deal |
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9 * in the Software without restriction, including without limitation the rights |
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10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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11 * copies of the Software, and to permit persons to whom the Software is |
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12 * furnished to do so, subject to the following conditions: |
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13 * |
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14 * The above copyright notice and this permission notice shall be included in |
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15 * all copies or substantial portions of the Software. |
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16 * |
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17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
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23 * THE SOFTWARE. |
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24 */ |
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25 #include "qemu-common.h" |
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26 #include "block_int.h" |
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27 |
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28 /**************************************************************/ |
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29 |
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30 #define HEADER_MAGIC "Bochs Virtual HD Image" |
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31 #define HEADER_VERSION 0x00020000 |
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32 #define HEADER_V1 0x00010000 |
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33 #define HEADER_SIZE 512 |
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34 |
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35 #define REDOLOG_TYPE "Redolog" |
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36 #define GROWING_TYPE "Growing" |
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37 |
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38 // not allocated: 0xffffffff |
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39 |
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40 // always little-endian |
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41 struct bochs_header_v1 { |
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42 char magic[32]; // "Bochs Virtual HD Image" |
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43 char type[16]; // "Redolog" |
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44 char subtype[16]; // "Undoable" / "Volatile" / "Growing" |
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45 uint32_t version; |
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46 uint32_t header; // size of header |
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47 |
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48 union { |
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49 struct { |
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50 uint32_t catalog; // num of entries |
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51 uint32_t bitmap; // bitmap size |
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52 uint32_t extent; // extent size |
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53 uint64_t disk; // disk size |
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54 char padding[HEADER_SIZE - 64 - 8 - 20]; |
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55 } redolog; |
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56 char padding[HEADER_SIZE - 64 - 8]; |
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57 } extra; |
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58 }; |
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59 |
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60 // always little-endian |
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61 struct bochs_header { |
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62 char magic[32]; // "Bochs Virtual HD Image" |
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63 char type[16]; // "Redolog" |
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64 char subtype[16]; // "Undoable" / "Volatile" / "Growing" |
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65 uint32_t version; |
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66 uint32_t header; // size of header |
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67 |
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68 union { |
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69 struct { |
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70 uint32_t catalog; // num of entries |
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71 uint32_t bitmap; // bitmap size |
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72 uint32_t extent; // extent size |
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73 uint32_t reserved; // for ??? |
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74 uint64_t disk; // disk size |
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75 char padding[HEADER_SIZE - 64 - 8 - 24]; |
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76 } redolog; |
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77 char padding[HEADER_SIZE - 64 - 8]; |
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78 } extra; |
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79 }; |
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80 |
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81 typedef struct BDRVBochsState { |
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82 int fd; |
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83 |
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84 uint32_t *catalog_bitmap; |
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85 int catalog_size; |
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86 |
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87 int data_offset; |
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88 |
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89 int bitmap_blocks; |
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90 int extent_blocks; |
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91 int extent_size; |
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92 } BDRVBochsState; |
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93 |
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94 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) |
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95 { |
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96 const struct bochs_header *bochs = (const void *)buf; |
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97 |
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98 if (buf_size < HEADER_SIZE) |
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99 return 0; |
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100 |
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101 if (!strcmp(bochs->magic, HEADER_MAGIC) && |
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102 !strcmp(bochs->type, REDOLOG_TYPE) && |
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103 !strcmp(bochs->subtype, GROWING_TYPE) && |
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104 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || |
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105 (le32_to_cpu(bochs->version) == HEADER_V1))) |
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106 return 100; |
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107 |
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108 return 0; |
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109 } |
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110 |
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111 static int bochs_open(BlockDriverState *bs, const char *filename, int flags) |
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112 { |
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113 BDRVBochsState *s = bs->opaque; |
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114 int fd, i; |
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115 struct bochs_header bochs; |
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116 struct bochs_header_v1 header_v1; |
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117 |
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118 fd = open(filename, O_RDWR | O_BINARY); |
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119 if (fd < 0) { |
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120 fd = open(filename, O_RDONLY | O_BINARY); |
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121 if (fd < 0) |
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122 return -1; |
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123 } |
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124 |
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125 bs->read_only = 1; // no write support yet |
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126 |
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127 s->fd = fd; |
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128 |
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129 if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) { |
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130 goto fail; |
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131 } |
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132 |
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133 if (strcmp(bochs.magic, HEADER_MAGIC) || |
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134 strcmp(bochs.type, REDOLOG_TYPE) || |
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135 strcmp(bochs.subtype, GROWING_TYPE) || |
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136 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && |
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137 (le32_to_cpu(bochs.version) != HEADER_V1))) { |
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138 goto fail; |
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139 } |
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140 |
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141 if (le32_to_cpu(bochs.version) == HEADER_V1) { |
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142 memcpy(&header_v1, &bochs, sizeof(bochs)); |
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143 bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512; |
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144 } else { |
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145 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; |
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146 } |
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147 |
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148 lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET); |
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149 |
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150 s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog); |
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151 s->catalog_bitmap = qemu_malloc(s->catalog_size * 4); |
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152 if (!s->catalog_bitmap) |
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153 goto fail; |
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154 if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) != |
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155 s->catalog_size * 4) |
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156 goto fail; |
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157 for (i = 0; i < s->catalog_size; i++) |
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158 le32_to_cpus(&s->catalog_bitmap[i]); |
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159 |
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160 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); |
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161 |
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162 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512; |
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163 s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512; |
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164 |
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165 s->extent_size = le32_to_cpu(bochs.extra.redolog.extent); |
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166 |
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167 return 0; |
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168 fail: |
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169 close(fd); |
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170 return -1; |
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171 } |
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172 |
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173 static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num) |
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174 { |
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175 BDRVBochsState *s = bs->opaque; |
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176 int64_t offset = sector_num * 512; |
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177 int64_t extent_index, extent_offset, bitmap_offset, block_offset; |
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178 char bitmap_entry; |
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179 |
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180 // seek to sector |
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181 extent_index = offset / s->extent_size; |
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182 extent_offset = (offset % s->extent_size) / 512; |
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183 |
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184 if (s->catalog_bitmap[extent_index] == 0xffffffff) |
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185 { |
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186 // fprintf(stderr, "page not allocated [%x - %x:%x]\n", |
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187 // sector_num, extent_index, extent_offset); |
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188 return -1; // not allocated |
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189 } |
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190 |
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191 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] * |
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192 (s->extent_blocks + s->bitmap_blocks)); |
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193 block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); |
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194 |
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195 // fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n", |
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196 // sector_num, extent_index, extent_offset, |
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197 // le32_to_cpu(s->catalog_bitmap[extent_index]), |
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198 // bitmap_offset, block_offset); |
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199 |
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200 // read in bitmap for current extent |
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201 lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET); |
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202 |
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203 read(s->fd, &bitmap_entry, 1); |
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204 |
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205 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) |
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206 { |
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207 // fprintf(stderr, "sector (%x) in bitmap not allocated\n", |
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208 // sector_num); |
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209 return -1; // not allocated |
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210 } |
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211 |
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212 lseek(s->fd, block_offset, SEEK_SET); |
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213 |
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214 return 0; |
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215 } |
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216 |
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217 static int bochs_read(BlockDriverState *bs, int64_t sector_num, |
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218 uint8_t *buf, int nb_sectors) |
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219 { |
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220 BDRVBochsState *s = bs->opaque; |
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221 int ret; |
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222 |
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223 while (nb_sectors > 0) { |
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224 if (!seek_to_sector(bs, sector_num)) |
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225 { |
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226 ret = read(s->fd, buf, 512); |
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227 if (ret != 512) |
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228 return -1; |
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229 } |
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230 else |
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231 memset(buf, 0, 512); |
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232 nb_sectors--; |
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233 sector_num++; |
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234 buf += 512; |
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235 } |
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236 return 0; |
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237 } |
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238 |
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239 static void bochs_close(BlockDriverState *bs) |
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240 { |
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241 BDRVBochsState *s = bs->opaque; |
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242 qemu_free(s->catalog_bitmap); |
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243 close(s->fd); |
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244 } |
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245 |
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246 BlockDriver bdrv_bochs = { |
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247 "bochs", |
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248 sizeof(BDRVBochsState), |
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249 bochs_probe, |
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250 bochs_open, |
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251 bochs_read, |
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252 NULL, |
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253 bochs_close, |
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254 }; |