1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * image.c --- writes out the critical parts of the filesystem as a
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4 | * flat file.
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5 | *
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6 | * Copyright (C) 2000 Theodore Ts'o.
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7 | *
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8 | * Note: this uses the POSIX IO interfaces, unlike most of the other
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9 | * functions in this library. So sue me.
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10 | *
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11 | * %Begin-Header%
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12 | * This file may be redistributed under the terms of the GNU Public
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13 | * License.
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14 | * %End-Header%
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15 | */
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16 |
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17 | #include <stdio.h>
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18 | #include <string.h>
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19 | #if HAVE_UNISTD_H
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20 | #include <unistd.h>
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21 | #endif
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22 | #if HAVE_ERRNO_H
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23 | #include <errno.h>
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24 | #endif
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25 | #include <fcntl.h>
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26 | #include <time.h>
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27 | #if HAVE_SYS_STAT_H
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28 | #include <sys/stat.h>
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29 | #endif
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30 | #if HAVE_SYS_TYPES_H
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31 | #include <sys/types.h>
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32 | #endif
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33 |
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34 | #include "ext2_fs.h"
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35 | #include "ext2fs.h"
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36 |
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37 | #ifndef HAVE_TYPE_SSIZE_T
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38 | typedef int ssize_t;
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39 | #endif
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40 |
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41 | /*
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42 | * This function returns 1 if the specified block is all zeros
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43 | */
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44 | static int check_zero_block(char *buf, int blocksize)
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45 | {
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46 | char *cp = buf;
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47 | int left = blocksize;
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48 |
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49 | while (left > 0) {
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50 | if (*cp++)
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51 | return 0;
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52 | left--;
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53 | }
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54 | return 1;
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55 | }
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56 |
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57 | /*
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58 | * Write the inode table out as a single block.
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59 | */
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60 | #define BUF_BLOCKS 32
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61 |
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62 | errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
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63 | {
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64 | unsigned int group, left, c, d;
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65 | char *buf, *cp;
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66 | blk_t blk;
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67 | ssize_t actual;
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68 | errcode_t retval;
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69 |
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70 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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71 |
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72 | for (group = 0; group < fs->group_desc_count; group++) {
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73 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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74 | if (!blk)
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75 | return EXT2_ET_MISSING_INODE_TABLE;
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76 | left = fs->inode_blocks_per_group;
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77 | while (left) {
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78 | c = BUF_BLOCKS;
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79 | if (c > left)
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80 | c = left;
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81 | retval = io_channel_read_blk(fs->io, blk, c, buf);
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82 | if (retval)
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83 | goto errout;
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84 | cp = buf;
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85 | while (c) {
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86 | if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
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87 | d = c;
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88 | goto skip_sparse;
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89 | }
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90 | /* Skip zero blocks */
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91 | if (check_zero_block(cp, fs->blocksize)) {
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92 | c--;
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93 | blk++;
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94 | left--;
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95 | cp += fs->blocksize;
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96 | lseek(fd, fs->blocksize, SEEK_CUR);
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97 | continue;
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98 | }
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99 | /* Find non-zero blocks */
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100 | for (d=1; d < c; d++) {
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101 | if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
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102 | break;
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103 | }
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104 | skip_sparse:
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105 | actual = write(fd, cp, fs->blocksize * d);
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106 | if (actual == -1) {
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107 | retval = errno;
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108 | goto errout;
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109 | }
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110 | if (actual != (ssize_t) (fs->blocksize * d)) {
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111 | retval = EXT2_ET_SHORT_WRITE;
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112 | goto errout;
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113 | }
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114 | blk += d;
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115 | left -= d;
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116 | cp += fs->blocksize * d;
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117 | c -= d;
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118 | }
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119 | }
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120 | }
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121 | retval = 0;
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122 |
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123 | errout:
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124 | free(buf);
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125 | return retval;
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126 | }
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127 |
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128 | /*
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129 | * Read in the inode table and stuff it into place
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130 | */
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131 | errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd,
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132 | int flags EXT2FS_ATTR((unused)))
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133 | {
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134 | unsigned int group, c, left;
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135 | char *buf;
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136 | blk_t blk;
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137 | ssize_t actual;
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138 | errcode_t retval;
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139 |
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140 | buf = xmalloc(fs->blocksize * BUF_BLOCKS);
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141 |
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142 | for (group = 0; group < fs->group_desc_count; group++) {
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143 | blk = fs->group_desc[(unsigned)group].bg_inode_table;
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144 | if (!blk) {
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145 | retval = EXT2_ET_MISSING_INODE_TABLE;
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146 | goto errout;
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147 | }
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148 | left = fs->inode_blocks_per_group;
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149 | while (left) {
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150 | c = BUF_BLOCKS;
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151 | if (c > left)
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152 | c = left;
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153 | actual = read(fd, buf, fs->blocksize * c);
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154 | if (actual == -1) {
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155 | retval = errno;
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156 | goto errout;
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157 | }
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158 | if (actual != (ssize_t) (fs->blocksize * c)) {
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159 | retval = EXT2_ET_SHORT_READ;
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160 | goto errout;
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161 | }
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162 | retval = io_channel_write_blk(fs->io, blk, c, buf);
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163 | if (retval)
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164 | goto errout;
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165 |
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166 | blk += c;
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167 | left -= c;
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168 | }
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169 | }
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170 | retval = ext2fs_flush_icache(fs);
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171 |
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172 | errout:
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173 | free(buf);
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174 | return retval;
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175 | }
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176 |
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177 | /*
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178 | * Write out superblock and group descriptors
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179 | */
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180 | errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd,
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181 | int flags EXT2FS_ATTR((unused)))
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182 | {
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183 | char *buf, *cp;
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184 | ssize_t actual;
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185 | errcode_t retval;
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186 |
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187 | buf = xmalloc(fs->blocksize);
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188 |
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189 | /*
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190 | * Write out the superblock
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191 | */
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192 | memset(buf, 0, fs->blocksize);
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193 | memcpy(buf, fs->super, SUPERBLOCK_SIZE);
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194 | actual = write(fd, buf, fs->blocksize);
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195 | if (actual == -1) {
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196 | retval = errno;
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197 | goto errout;
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198 | }
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199 | if (actual != (ssize_t) fs->blocksize) {
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200 | retval = EXT2_ET_SHORT_WRITE;
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201 | goto errout;
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202 | }
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203 |
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204 | /*
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205 | * Now write out the block group descriptors
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206 | */
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207 | cp = (char *) fs->group_desc;
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208 | actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
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209 | if (actual == -1) {
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210 | retval = errno;
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211 | goto errout;
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212 | }
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213 | if (actual != (ssize_t) (fs->blocksize * fs->desc_blocks)) {
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214 | retval = EXT2_ET_SHORT_WRITE;
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215 | goto errout;
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216 | }
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217 |
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218 | retval = 0;
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219 |
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220 | errout:
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221 | free(buf);
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222 | return retval;
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223 | }
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224 |
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225 | /*
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226 | * Read the superblock and group descriptors and overwrite them.
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227 | */
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228 | errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd,
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229 | int flags EXT2FS_ATTR((unused)))
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230 | {
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231 | char *buf;
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232 | ssize_t actual, size;
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233 | errcode_t retval;
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234 |
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235 | size = fs->blocksize * (fs->group_desc_count + 1);
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236 | buf = xmalloc(size);
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237 |
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238 | /*
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239 | * Read it all in.
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240 | */
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241 | actual = read(fd, buf, size);
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242 | if (actual == -1) {
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243 | retval = errno;
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244 | goto errout;
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245 | }
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246 | if (actual != size) {
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247 | retval = EXT2_ET_SHORT_READ;
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248 | goto errout;
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249 | }
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250 |
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251 | /*
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252 | * Now copy in the superblock and group descriptors
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253 | */
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254 | memcpy(fs->super, buf, SUPERBLOCK_SIZE);
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255 |
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256 | memcpy(fs->group_desc, buf + fs->blocksize,
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257 | fs->blocksize * fs->group_desc_count);
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258 |
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259 | retval = 0;
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260 |
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261 | errout:
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262 | free(buf);
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263 | return retval;
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264 | }
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265 |
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266 | /*
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267 | * Write the block/inode bitmaps.
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268 | */
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269 | errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
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270 | {
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271 | char *ptr;
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272 | int c, size;
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273 | char zero_buf[1024];
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274 | ssize_t actual;
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275 | errcode_t retval;
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276 |
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277 | if (flags & IMAGER_FLAG_INODEMAP) {
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278 | if (!fs->inode_map) {
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279 | retval = ext2fs_read_inode_bitmap(fs);
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280 | if (retval)
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281 | return retval;
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282 | }
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283 | ptr = fs->inode_map->bitmap;
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284 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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285 | } else {
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286 | if (!fs->block_map) {
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287 | retval = ext2fs_read_block_bitmap(fs);
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288 | if (retval)
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289 | return retval;
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290 | }
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291 | ptr = fs->block_map->bitmap;
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292 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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293 | }
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294 | size = size * fs->group_desc_count;
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295 |
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296 | actual = write(fd, ptr, size);
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297 | if (actual == -1) {
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298 | retval = errno;
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299 | goto errout;
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300 | }
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301 | if (actual != size) {
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302 | retval = EXT2_ET_SHORT_WRITE;
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303 | goto errout;
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304 | }
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305 | size = size % fs->blocksize;
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306 | memset(zero_buf, 0, sizeof(zero_buf));
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307 | if (size) {
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308 | size = fs->blocksize - size;
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309 | while (size) {
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310 | c = size;
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311 | if (c > (int) sizeof(zero_buf))
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312 | c = sizeof(zero_buf);
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313 | actual = write(fd, zero_buf, c);
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314 | if (actual == -1) {
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315 | retval = errno;
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316 | goto errout;
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317 | }
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318 | if (actual != c) {
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319 | retval = EXT2_ET_SHORT_WRITE;
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320 | goto errout;
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321 | }
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322 | size -= c;
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323 | }
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324 | }
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325 | retval = 0;
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326 | errout:
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327 | return retval;
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328 | }
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329 |
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330 |
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331 | /*
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332 | * Read the block/inode bitmaps.
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333 | */
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334 | errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
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335 | {
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336 | char *ptr, *buf = 0;
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337 | int size;
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338 | ssize_t actual;
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339 | errcode_t retval;
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340 |
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341 | if (flags & IMAGER_FLAG_INODEMAP) {
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342 | if (!fs->inode_map) {
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343 | retval = ext2fs_read_inode_bitmap(fs);
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344 | if (retval)
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345 | return retval;
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346 | }
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347 | ptr = fs->inode_map->bitmap;
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348 | size = (EXT2_INODES_PER_GROUP(fs->super) / 8);
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349 | } else {
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350 | if (!fs->block_map) {
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351 | retval = ext2fs_read_block_bitmap(fs);
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352 | if (retval)
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353 | return retval;
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354 | }
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355 | ptr = fs->block_map->bitmap;
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356 | size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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357 | }
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358 | size = size * fs->group_desc_count;
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359 |
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360 | buf = xmalloc(size);
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361 |
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362 | actual = read(fd, buf, size);
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363 | if (actual == -1) {
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364 | retval = errno;
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365 | goto errout;
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366 | }
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367 | if (actual != size) {
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368 | retval = EXT2_ET_SHORT_WRITE;
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369 | goto errout;
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370 | }
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371 | memcpy(ptr, buf, size);
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372 |
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373 | retval = 0;
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374 | errout:
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375 | free(buf);
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376 | return retval;
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377 | }
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