1 | /*
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2 | * image.c --- writes out the critical parts of the filesystem as a
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3 | * flat file.
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4 | *
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5 | * Copyright (C) 2000 Theodore Ts'o.
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6 | *
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7 | * Note: this uses the POSIX IO interfaces, unlike most of the other
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8 | * functions in this library. So sue me.
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9 | *
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10 | * %Begin-Header%
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11 | * This file may be redistributed under the terms of the GNU Public
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12 | * License.
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13 | * %End-Header%
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14 | */
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15 |
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16 | #include <stdio.h>
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17 | #include <string.h>
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18 | #if HAVE_UNISTD_H
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19 | #include <unistd.h>
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20 | #endif
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21 | #if HAVE_ERRNO_H
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22 | #include <errno.h>
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23 | #endif
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24 | #include <fcntl.h>
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25 | #include <time.h>
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26 | #if HAVE_SYS_STAT_H
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27 | #include <sys/stat.h>
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28 | #endif
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29 | #if HAVE_SYS_TYPES_H
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30 | #include <sys/types.h>
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31 | #endif
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32 |
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33 | #include "ext2_fs.h"
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34 | #include "ext2fs.h"
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35 |
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36 | #ifndef HAVE_TYPE_SSIZE_T
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37 | typedef int ssize_t;
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38 | #endif
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39 |
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40 | /*
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41 | * This function returns 1 if the specified block is all zeros
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42 | */
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43 | static int check_zero_block(char *buf, int blocksize)
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44 | {
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45 | char *cp = buf;
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46 | int left = blocksize;
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47 |
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48 | while (left > 0) {
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49 | if (*cp++)
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50 | return 0;
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51 | left--;
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52 | }
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53 | return 1;
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54 | }
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55 |
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56 | /*
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57 | * Write the inode table out as a single block.
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58 | */
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59 | #define BUF_BLOCKS 32
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60 |
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61 | errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
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62 | {
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63 | unsigned int group, left, c, d;
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64 | char *buf, *cp;
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65 | blk_t blk;
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66 | ssize_t actual;
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67 | errcode_t retval;
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68 |
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69 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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70 |
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71 | for (group = 0; group < fs->group_desc_count; group++) {
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72 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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73 | if (!blk)
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74 | return EXT2_ET_MISSING_INODE_TABLE;
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75 | left = fs->inode_blocks_per_group;
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76 | while (left) {
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77 | c = BUF_BLOCKS;
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78 | if (c > left)
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79 | c = left;
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80 | retval = io_channel_read_blk(fs->io, blk, c, buf);
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81 | if (retval)
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82 | goto errout;
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83 | cp = buf;
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84 | while (c) {
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85 | if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
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86 | d = c;
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87 | goto skip_sparse;
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88 | }
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89 | /* Skip zero blocks */
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90 | if (check_zero_block(cp, fs->blocksize)) {
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91 | c--;
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92 | blk++;
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93 | left--;
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94 | cp += fs->blocksize;
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95 | lseek(fd, fs->blocksize, SEEK_CUR);
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96 | continue;
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97 | }
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98 | /* Find non-zero blocks */
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99 | for (d=1; d < c; d++) {
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100 | if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
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101 | break;
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102 | }
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103 | skip_sparse:
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104 | actual = write(fd, cp, fs->blocksize * d);
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105 | if (actual == -1) {
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106 | retval = errno;
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107 | goto errout;
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108 | }
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109 | if (actual != (ssize_t) (fs->blocksize * d)) {
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110 | retval = EXT2_ET_SHORT_WRITE;
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111 | goto errout;
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112 | }
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113 | blk += d;
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114 | left -= d;
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115 | cp += fs->blocksize * d;
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116 | c -= d;
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117 | }
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118 | }
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119 | }
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120 | retval = 0;
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121 |
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122 | errout:
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123 | free(buf);
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124 | return retval;
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125 | }
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126 |
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127 | /*
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128 | * Read in the inode table and stuff it into place
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129 | */
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130 | errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd,
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131 | int flags EXT2FS_ATTR((unused)))
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132 | {
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133 | unsigned int group, c, left;
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134 | char *buf;
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135 | blk_t blk;
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136 | ssize_t actual;
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137 | errcode_t retval;
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138 |
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139 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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140 |
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141 | for (group = 0; group < fs->group_desc_count; group++) {
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142 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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143 | if (!blk) {
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144 | retval = EXT2_ET_MISSING_INODE_TABLE;
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145 | goto errout;
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146 | }
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147 | left = fs->inode_blocks_per_group;
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148 | while (left) {
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149 | c = BUF_BLOCKS;
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150 | if (c > left)
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151 | c = left;
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152 | actual = read(fd, buf, fs->blocksize * c);
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153 | if (actual == -1) {
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154 | retval = errno;
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155 | goto errout;
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156 | }
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157 | if (actual != (ssize_t) (fs->blocksize * c)) {
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158 | retval = EXT2_ET_SHORT_READ;
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159 | goto errout;
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160 | }
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161 | retval = io_channel_write_blk(fs->io, blk, c, buf);
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162 | if (retval)
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163 | goto errout;
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164 |
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165 | blk += c;
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166 | left -= c;
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167 | }
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168 | }
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169 | retval = ext2fs_flush_icache(fs);
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170 |
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171 | errout:
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172 | free(buf);
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173 | return retval;
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174 | }
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175 |
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176 | /*
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177 | * Write out superblock and group descriptors
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178 | */
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179 | errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd,
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180 | int flags EXT2FS_ATTR((unused)))
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181 | {
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182 | char *buf, *cp;
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183 | ssize_t actual;
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184 | errcode_t retval;
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185 |
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186 | buf = xmalloc(fs->blocksize);
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187 |
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188 | /*
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189 | * Write out the superblock
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190 | */
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191 | memset(buf, 0, fs->blocksize);
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192 | memcpy(buf, fs->super, SUPERBLOCK_SIZE);
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193 | actual = write(fd, buf, fs->blocksize);
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194 | if (actual == -1) {
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195 | retval = errno;
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196 | goto errout;
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197 | }
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198 | if (actual != (ssize_t) fs->blocksize) {
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199 | retval = EXT2_ET_SHORT_WRITE;
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200 | goto errout;
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201 | }
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202 |
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203 | /*
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204 | * Now write out the block group descriptors
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205 | */
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206 | cp = (char *) fs->group_desc;
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207 | actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
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208 | if (actual == -1) {
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209 | retval = errno;
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210 | goto errout;
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211 | }
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212 | if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
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213 | retval = EXT2_ET_SHORT_WRITE;
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214 | goto errout;
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215 | }
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216 |
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217 | retval = 0;
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218 |
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219 | errout:
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220 | free(buf);
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221 | return retval;
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222 | }
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223 |
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224 | /*
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225 | * Read the superblock and group descriptors and overwrite them.
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226 | */
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227 | errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd,
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228 | int flags EXT2FS_ATTR((unused)))
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229 | {
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230 | char *buf;
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231 | ssize_t actual, size;
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232 | errcode_t retval;
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233 |
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234 | size = fs->blocksize * (fs->group_desc_count + 1);
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235 | buf = xmalloc(size);
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236 |
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237 | /*
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238 | * Read it all in.
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239 | */
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240 | actual = read(fd, buf, size);
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241 | if (actual == -1) {
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242 | retval = errno;
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243 | goto errout;
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244 | }
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245 | if (actual != size) {
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246 | retval = EXT2_ET_SHORT_READ;
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247 | goto errout;
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248 | }
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249 |
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250 | /*
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251 | * Now copy in the superblock and group descriptors
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252 | */
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253 | memcpy(fs->super, buf, SUPERBLOCK_SIZE);
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254 |
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255 | memcpy(fs->group_desc, buf + fs->blocksize,
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256 | fs->blocksize * fs->group_desc_count);
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257 |
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258 | retval = 0;
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259 |
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260 | errout:
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261 | free(buf);
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262 | return retval;
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263 | }
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264 |
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265 | /*
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266 | * Write the block/inode bitmaps.
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267 | */
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268 | errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
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269 | {
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270 | char *ptr;
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271 | int c, size;
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272 | char zero_buf[1024];
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273 | ssize_t actual;
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274 | errcode_t retval;
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275 |
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276 | if (flags & IMAGER_FLAG_INODEMAP) {
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277 | if (!fs->inode_map) {
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278 | retval = ext2fs_read_inode_bitmap(fs);
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279 | if (retval)
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280 | return retval;
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281 | }
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282 | ptr = fs->inode_map->bitmap;
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283 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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284 | } else {
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285 | if (!fs->block_map) {
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286 | retval = ext2fs_read_block_bitmap(fs);
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287 | if (retval)
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288 | return retval;
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289 | }
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290 | ptr = fs->block_map->bitmap;
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291 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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292 | }
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293 | size = size * fs->group_desc_count;
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294 |
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295 | actual = write(fd, ptr, size);
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296 | if (actual == -1) {
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297 | retval = errno;
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298 | goto errout;
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299 | }
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300 | if (actual != size) {
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301 | retval = EXT2_ET_SHORT_WRITE;
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302 | goto errout;
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303 | }
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304 | size = size % fs->blocksize;
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305 | memset(zero_buf, 0, sizeof(zero_buf));
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306 | if (size) {
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307 | size = fs->blocksize - size;
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308 | while (size) {
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309 | c = size;
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310 | if (c > (int) sizeof(zero_buf))
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311 | c = sizeof(zero_buf);
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312 | actual = write(fd, zero_buf, c);
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313 | if (actual == -1) {
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314 | retval = errno;
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315 | goto errout;
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316 | }
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317 | if (actual != c) {
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318 | retval = EXT2_ET_SHORT_WRITE;
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319 | goto errout;
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320 | }
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321 | size -= c;
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322 | }
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323 | }
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324 | retval = 0;
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325 | errout:
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326 | return (retval);
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327 | }
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328 |
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329 |
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330 | /*
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331 | * Read the block/inode bitmaps.
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332 | */
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333 | errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
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334 | {
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335 | char *ptr, *buf = 0;
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336 | int size;
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337 | ssize_t actual;
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338 | errcode_t retval;
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339 |
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340 | if (flags & IMAGER_FLAG_INODEMAP) {
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341 | if (!fs->inode_map) {
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342 | retval = ext2fs_read_inode_bitmap(fs);
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343 | if (retval)
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344 | return retval;
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345 | }
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346 | ptr = fs->inode_map->bitmap;
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347 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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348 | } else {
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349 | if (!fs->block_map) {
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350 | retval = ext2fs_read_block_bitmap(fs);
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351 | if (retval)
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352 | return retval;
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353 | }
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354 | ptr = fs->block_map->bitmap;
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355 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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356 | }
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357 | size = size * fs->group_desc_count;
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358 |
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359 | buf = xmalloc(size);
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360 |
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361 | actual = read(fd, buf, size);
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362 | if (actual == -1) {
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363 | retval = errno;
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364 | goto errout;
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365 | }
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366 | if (actual != size) {
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367 | retval = EXT2_ET_SHORT_WRITE;
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368 | goto errout;
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369 | }
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370 | memcpy(ptr, buf, size);
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371 |
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372 | retval = 0;
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373 | errout:
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374 | free(buf);
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375 | return (retval);
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376 | }
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