1 | /*
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2 | * inode_io.c --- This is allows an inode in an ext2 filesystem image
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3 | * to be accessed via the I/O manager interface.
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4 | *
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5 | * Copyright (C) 2002 Theodore Ts'o.
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6 | *
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7 | * %Begin-Header%
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8 | * This file may be redistributed under the terms of the GNU Public
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9 | * License.
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10 | * %End-Header%
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11 | */
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12 |
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13 | #include <stdio.h>
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14 | #include <string.h>
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15 | #if HAVE_UNISTD_H
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16 | #include <unistd.h>
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17 | #endif
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18 | #if HAVE_ERRNO_H
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19 | #include <errno.h>
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20 | #endif
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21 | #include <time.h>
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22 |
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23 | #include "ext2_fs.h"
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24 | #include "ext2fs.h"
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25 |
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26 | /*
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27 | * For checking structure magic numbers...
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28 | */
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29 |
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30 | #define EXT2_CHECK_MAGIC(struct, code) \
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31 | if ((struct)->magic != (code)) return (code)
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32 |
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33 | struct inode_private_data {
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34 | int magic;
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35 | char name[32];
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36 | ext2_file_t file;
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37 | ext2_filsys fs;
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38 | ext2_ino_t ino;
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39 | struct ext2_inode inode;
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40 | int flags;
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41 | struct inode_private_data *next;
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42 | };
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43 |
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44 | #define CHANNEL_HAS_INODE 0x8000
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45 |
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46 | static struct inode_private_data *top_intern;
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47 | static int ino_unique = 0;
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48 |
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49 | static errcode_t inode_open(const char *name, int flags, io_channel *channel);
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50 | static errcode_t inode_close(io_channel channel);
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51 | static errcode_t inode_set_blksize(io_channel channel, int blksize);
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52 | static errcode_t inode_read_blk(io_channel channel, unsigned long block,
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53 | int count, void *data);
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54 | static errcode_t inode_write_blk(io_channel channel, unsigned long block,
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55 | int count, const void *data);
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56 | static errcode_t inode_flush(io_channel channel);
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57 | static errcode_t inode_write_byte(io_channel channel, unsigned long offset,
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58 | int size, const void *data);
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59 |
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60 | static struct struct_io_manager struct_inode_manager = {
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61 | EXT2_ET_MAGIC_IO_MANAGER,
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62 | "Inode I/O Manager",
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63 | inode_open,
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64 | inode_close,
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65 | inode_set_blksize,
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66 | inode_read_blk,
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67 | inode_write_blk,
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68 | inode_flush,
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69 | inode_write_byte
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70 | };
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71 |
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72 | io_manager inode_io_manager = &struct_inode_manager;
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73 |
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74 | errcode_t ext2fs_inode_io_intern2(ext2_filsys fs, ext2_ino_t ino,
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75 | struct ext2_inode *inode,
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76 | char **name)
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77 | {
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78 | struct inode_private_data *data;
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79 | errcode_t retval;
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80 |
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81 | if ((retval = ext2fs_get_mem(sizeof(struct inode_private_data),
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82 | &data)))
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83 | return retval;
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84 | data->magic = EXT2_ET_MAGIC_INODE_IO_CHANNEL;
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85 | sprintf(data->name, "%u:%d", ino, ino_unique++);
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86 | data->file = 0;
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87 | data->fs = fs;
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88 | data->ino = ino;
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89 | data->flags = 0;
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90 | if (inode) {
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91 | memcpy(&data->inode, inode, sizeof(struct ext2_inode));
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92 | data->flags |= CHANNEL_HAS_INODE;
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93 | }
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94 | data->next = top_intern;
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95 | top_intern = data;
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96 | *name = data->name;
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97 | return 0;
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98 | }
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99 |
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100 | errcode_t ext2fs_inode_io_intern(ext2_filsys fs, ext2_ino_t ino,
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101 | char **name)
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102 | {
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103 | return ext2fs_inode_io_intern2(fs, ino, NULL, name);
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104 | }
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105 |
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106 |
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107 | static errcode_t inode_open(const char *name, int flags, io_channel *channel)
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108 | {
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109 | io_channel io = NULL;
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110 | struct inode_private_data *prev, *data = NULL;
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111 | errcode_t retval;
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112 | int open_flags;
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113 |
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114 | if (name == 0)
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115 | return EXT2_ET_BAD_DEVICE_NAME;
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116 |
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117 | for (data = top_intern, prev = NULL; data;
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118 | prev = data, data = data->next)
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119 | if (strcmp(name, data->name) == 0)
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120 | break;
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121 | if (!data)
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122 | return ENOENT;
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123 | if (prev)
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124 | prev->next = data->next;
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125 | else
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126 | top_intern = data->next;
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127 |
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128 | retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
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129 | if (retval)
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130 | goto cleanup;
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131 | memset(io, 0, sizeof(struct struct_io_channel));
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132 |
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133 | io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
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134 | io->manager = inode_io_manager;
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135 | retval = ext2fs_get_mem(strlen(name)+1, &io->name);
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136 | if (retval)
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137 | goto cleanup;
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138 |
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139 | strcpy(io->name, name);
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140 | io->private_data = data;
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141 | io->block_size = 1024;
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142 | io->read_error = 0;
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143 | io->write_error = 0;
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144 | io->refcount = 1;
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145 |
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146 | open_flags = (flags & IO_FLAG_RW) ? EXT2_FILE_WRITE : 0;
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147 | retval = ext2fs_file_open2(data->fs, data->ino,
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148 | (data->flags & CHANNEL_HAS_INODE) ?
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149 | &data->inode : 0, open_flags,
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150 | &data->file);
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151 | if (retval)
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152 | goto cleanup;
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153 |
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154 | *channel = io;
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155 | return 0;
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156 |
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157 | cleanup:
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158 | if (data) {
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159 | ext2fs_free_mem(&data);
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160 | }
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161 | if (io)
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162 | ext2fs_free_mem(&io);
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163 | return retval;
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164 | }
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165 |
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166 | static errcode_t inode_close(io_channel channel)
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167 | {
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168 | struct inode_private_data *data;
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169 | errcode_t retval = 0;
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170 |
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171 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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172 | data = (struct inode_private_data *) channel->private_data;
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173 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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174 |
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175 | if (--channel->refcount > 0)
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176 | return 0;
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177 |
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178 | retval = ext2fs_file_close(data->file);
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179 |
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180 | ext2fs_free_mem(&channel->private_data);
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181 | if (channel->name)
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182 | ext2fs_free_mem(&channel->name);
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183 | ext2fs_free_mem(&channel);
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184 | return retval;
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185 | }
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186 |
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187 | static errcode_t inode_set_blksize(io_channel channel, int blksize)
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188 | {
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189 | struct inode_private_data *data;
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190 |
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191 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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192 | data = (struct inode_private_data *) channel->private_data;
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193 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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194 |
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195 | channel->block_size = blksize;
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196 | return 0;
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197 | }
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198 |
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199 |
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200 | static errcode_t inode_read_blk(io_channel channel, unsigned long block,
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201 | int count, void *buf)
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202 | {
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203 | struct inode_private_data *data;
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204 | errcode_t retval;
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205 |
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206 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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207 | data = (struct inode_private_data *) channel->private_data;
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208 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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209 |
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210 | if ((retval = ext2fs_file_lseek(data->file,
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211 | block * channel->block_size,
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212 | EXT2_SEEK_SET, 0)))
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213 | return retval;
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214 |
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215 | count = (count < 0) ? -count : (count * channel->block_size);
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216 |
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217 | return ext2fs_file_read(data->file, buf, count, 0);
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218 | }
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219 |
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220 | static errcode_t inode_write_blk(io_channel channel, unsigned long block,
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221 | int count, const void *buf)
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222 | {
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223 | struct inode_private_data *data;
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224 | errcode_t retval;
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225 |
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226 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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227 | data = (struct inode_private_data *) channel->private_data;
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228 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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229 |
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230 | if ((retval = ext2fs_file_lseek(data->file,
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231 | block * channel->block_size,
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232 | EXT2_SEEK_SET, 0)))
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233 | return retval;
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234 |
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235 | count = (count < 0) ? -count : (count * channel->block_size);
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236 |
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237 | return ext2fs_file_write(data->file, buf, count, 0);
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238 | }
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239 |
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240 | static errcode_t inode_write_byte(io_channel channel, unsigned long offset,
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241 | int size, const void *buf)
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242 | {
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243 | struct inode_private_data *data;
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244 | errcode_t retval = 0;
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245 |
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246 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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247 | data = (struct inode_private_data *) channel->private_data;
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248 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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249 |
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250 | if ((retval = ext2fs_file_lseek(data->file, offset,
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251 | EXT2_SEEK_SET, 0)))
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252 | return retval;
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253 |
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254 | return ext2fs_file_write(data->file, buf, size, 0);
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255 | }
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256 |
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257 | /*
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258 | * Flush data buffers to disk.
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259 | */
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260 | static errcode_t inode_flush(io_channel channel)
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261 | {
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262 | struct inode_private_data *data;
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263 |
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264 | EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
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265 | data = (struct inode_private_data *) channel->private_data;
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266 | EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
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267 |
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268 | return ext2fs_file_flush(data->file);
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269 | }
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270 |
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