1 | /*
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2 | * rw_bitmaps.c --- routines to read and write the inode and block bitmaps.
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3 | *
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4 | * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
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5 | *
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6 | * %Begin-Header%
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7 | * This file may be redistributed under the terms of the GNU Public
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8 | * License.
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9 | * %End-Header%
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10 | */
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11 |
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12 | #include <stdio.h>
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13 | #include <string.h>
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14 | #if HAVE_UNISTD_H
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15 | #include <unistd.h>
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16 | #endif
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17 | #include <fcntl.h>
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18 | #include <time.h>
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19 | #ifdef HAVE_SYS_STAT_H
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20 | #include <sys/stat.h>
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21 | #endif
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22 | #ifdef HAVE_SYS_TYPES_H
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23 | #include <sys/types.h>
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24 | #endif
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25 |
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26 | #include "ext2_fs.h"
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27 | #include "ext2fs.h"
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28 | #include "e2image.h"
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29 |
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30 | #if defined(__powerpc__) && BB_BIG_ENDIAN
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31 | /*
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32 | * On the PowerPC, the big-endian variant of the ext2 filesystem
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33 | * has its bitmaps stored as 32-bit words with bit 0 as the LSB
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34 | * of each word. Thus a bitmap with only bit 0 set would be, as
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35 | * a string of bytes, 00 00 00 01 00 ...
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36 | * To cope with this, we byte-reverse each word of a bitmap if
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37 | * we have a big-endian filesystem, that is, if we are *not*
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38 | * byte-swapping other word-sized numbers.
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39 | */
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40 | #define EXT2_BIG_ENDIAN_BITMAPS
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41 | #endif
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42 |
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43 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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44 | static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
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45 | {
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46 | __u32 *p = (__u32 *) bitmap;
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47 | int n;
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48 |
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49 | for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
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50 | *p = ext2fs_swab32(*p);
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51 | }
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52 | #endif
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53 |
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54 | errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
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55 | {
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56 | dgrp_t i;
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57 | size_t nbytes;
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58 | errcode_t retval;
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59 | char * inode_bitmap = fs->inode_map->bitmap;
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60 | char * bitmap_block = NULL;
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61 | blk_t blk;
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62 |
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63 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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64 |
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65 | if (!(fs->flags & EXT2_FLAG_RW))
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66 | return EXT2_ET_RO_FILSYS;
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67 | if (!inode_bitmap)
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68 | return 0;
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69 | nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
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70 |
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71 | retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
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72 | if (retval)
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73 | return retval;
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74 | memset(bitmap_block, 0xff, fs->blocksize);
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75 | for (i = 0; i < fs->group_desc_count; i++) {
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76 | memcpy(bitmap_block, inode_bitmap, nbytes);
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77 | blk = fs->group_desc[i].bg_inode_bitmap;
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78 | if (blk) {
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79 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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80 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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81 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
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82 | ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
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83 | #endif
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84 | retval = io_channel_write_blk(fs->io, blk, 1,
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85 | bitmap_block);
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86 | if (retval)
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87 | return EXT2_ET_INODE_BITMAP_WRITE;
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88 | }
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89 | inode_bitmap += nbytes;
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90 | }
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91 | fs->flags &= ~EXT2_FLAG_IB_DIRTY;
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92 | ext2fs_free_mem(&bitmap_block);
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93 | return 0;
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94 | }
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95 |
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96 | errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
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97 | {
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98 | dgrp_t i;
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99 | unsigned int j;
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100 | int nbytes;
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101 | unsigned int nbits;
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102 | errcode_t retval;
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103 | char * block_bitmap = fs->block_map->bitmap;
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104 | char * bitmap_block = NULL;
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105 | blk_t blk;
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106 |
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107 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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108 |
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109 | if (!(fs->flags & EXT2_FLAG_RW))
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110 | return EXT2_ET_RO_FILSYS;
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111 | if (!block_bitmap)
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112 | return 0;
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113 | nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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114 | retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
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115 | if (retval)
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116 | return retval;
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117 | memset(bitmap_block, 0xff, fs->blocksize);
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118 | for (i = 0; i < fs->group_desc_count; i++) {
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119 | memcpy(bitmap_block, block_bitmap, nbytes);
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120 | if (i == fs->group_desc_count - 1) {
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121 | /* Force bitmap padding for the last group */
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122 | nbits = ((fs->super->s_blocks_count
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123 | - fs->super->s_first_data_block)
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124 | % EXT2_BLOCKS_PER_GROUP(fs->super));
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125 | if (nbits)
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126 | for (j = nbits; j < fs->blocksize * 8; j++)
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127 | ext2fs_set_bit(j, bitmap_block);
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128 | }
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129 | blk = fs->group_desc[i].bg_block_bitmap;
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130 | if (blk) {
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131 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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132 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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133 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
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134 | ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
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135 | #endif
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136 | retval = io_channel_write_blk(fs->io, blk, 1,
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137 | bitmap_block);
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138 | if (retval)
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139 | return EXT2_ET_BLOCK_BITMAP_WRITE;
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140 | }
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141 | block_bitmap += nbytes;
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142 | }
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143 | fs->flags &= ~EXT2_FLAG_BB_DIRTY;
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144 | ext2fs_free_mem(&bitmap_block);
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145 | return 0;
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146 | }
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147 |
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148 | static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
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149 | {
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150 | dgrp_t i;
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151 | char *block_bitmap = 0, *inode_bitmap = 0;
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152 | char *buf;
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153 | errcode_t retval;
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154 | int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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155 | int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
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156 | blk_t blk;
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157 |
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158 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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159 |
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160 | fs->write_bitmaps = ext2fs_write_bitmaps;
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161 |
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162 | retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
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163 | if (retval)
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164 | return retval;
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165 | if (do_block) {
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166 | ext2fs_free_block_bitmap(fs->block_map);
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167 | sprintf(buf, "block bitmap for %s", fs->device_name);
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168 | retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
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169 | if (retval)
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170 | goto cleanup;
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171 | block_bitmap = fs->block_map->bitmap;
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172 | }
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173 | if (do_inode) {
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174 | ext2fs_free_inode_bitmap(fs->inode_map);
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175 | sprintf(buf, "inode bitmap for %s", fs->device_name);
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176 | retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
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177 | if (retval)
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178 | goto cleanup;
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179 | inode_bitmap = fs->inode_map->bitmap;
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180 | }
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181 | ext2fs_free_mem(&buf);
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182 |
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183 | if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
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184 | if (inode_bitmap) {
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185 | blk = (fs->image_header->offset_inodemap /
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186 | fs->blocksize);
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187 | retval = io_channel_read_blk(fs->image_io, blk,
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188 | -(inode_nbytes * fs->group_desc_count),
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189 | inode_bitmap);
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190 | if (retval)
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191 | goto cleanup;
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192 | }
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193 | if (block_bitmap) {
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194 | blk = (fs->image_header->offset_blockmap /
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195 | fs->blocksize);
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196 | retval = io_channel_read_blk(fs->image_io, blk,
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197 | -(block_nbytes * fs->group_desc_count),
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198 | block_bitmap);
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199 | if (retval)
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200 | goto cleanup;
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201 | }
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202 | return 0;
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203 | }
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204 |
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205 | for (i = 0; i < fs->group_desc_count; i++) {
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206 | if (block_bitmap) {
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207 | blk = fs->group_desc[i].bg_block_bitmap;
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208 | if (blk) {
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209 | retval = io_channel_read_blk(fs->io, blk,
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210 | -block_nbytes, block_bitmap);
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211 | if (retval) {
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212 | retval = EXT2_ET_BLOCK_BITMAP_READ;
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213 | goto cleanup;
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214 | }
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215 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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216 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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217 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
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218 | ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
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219 | #endif
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220 | } else
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221 | memset(block_bitmap, 0, block_nbytes);
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222 | block_bitmap += block_nbytes;
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223 | }
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224 | if (inode_bitmap) {
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225 | blk = fs->group_desc[i].bg_inode_bitmap;
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226 | if (blk) {
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227 | retval = io_channel_read_blk(fs->io, blk,
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228 | -inode_nbytes, inode_bitmap);
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229 | if (retval) {
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230 | retval = EXT2_ET_INODE_BITMAP_READ;
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231 | goto cleanup;
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232 | }
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233 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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234 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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235 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
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236 | ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
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237 | #endif
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238 | } else
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239 | memset(inode_bitmap, 0, inode_nbytes);
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240 | inode_bitmap += inode_nbytes;
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241 | }
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242 | }
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243 | return 0;
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244 |
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245 | cleanup:
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246 | if (do_block) {
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247 | ext2fs_free_mem(&fs->block_map);
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248 | }
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249 | if (do_inode) {
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250 | ext2fs_free_mem(&fs->inode_map);
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251 | }
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252 | ext2fs_free_mem(&buf);
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253 | return retval;
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254 | }
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255 |
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256 | errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
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257 | {
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258 | return read_bitmaps(fs, 1, 0);
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259 | }
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260 |
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261 | errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
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262 | {
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263 | return read_bitmaps(fs, 0, 1);
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264 | }
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265 |
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266 | errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
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267 | {
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268 |
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269 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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270 |
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271 | if (fs->inode_map && fs->block_map)
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272 | return 0;
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273 |
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274 | return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
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275 | }
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276 |
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277 | errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
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278 | {
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279 | errcode_t retval;
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280 |
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281 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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282 |
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283 | if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
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284 | retval = ext2fs_write_block_bitmap(fs);
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285 | if (retval)
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286 | return retval;
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287 | }
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288 | if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
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289 | retval = ext2fs_write_inode_bitmap(fs);
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290 | if (retval)
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291 | return retval;
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292 | }
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293 | return 0;
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294 | }
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295 |
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