lib/ext2fs/inode_io.c

   1 /*
   2  * inode_io.c --- This is allows an inode in an ext2 filesystem image
   3  *      to be accessed via the I/O manager interface.
   4  *
   5  * Copyright (C) 2002 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Library
   9  * General Public License, version 2.
  10  * %End-Header%
  11  */
  12
  13 #include "config.h"
  14 #include <stdio.h>
  15 #include <string.h>
  16 #if HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 #if HAVE_ERRNO_H
  20 #include <errno.h>
  21 #endif
  22 #include <time.h>
  23
  24 #include "ext2_fs.h"
  25 #include "ext2fs.h"
  26
  27 /*
  28  * For checking structure magic numbers...
  29  */
  30
  31 #define EXT2_CHECK_MAGIC(struct, code) \
  32           if ((struct)->magic != (code)) return (code)
  33
  34 struct inode_private_data {
  35         int                             magic;
  36         char                            name[32];
  37         ext2_file_t                     file;
  38         ext2_filsys                     fs;
  39         ext2_ino_t                      ino;
  40         struct ext2_inode               inode;
  41         int                             flags;
  42         struct inode_private_data       *next;
  43 };
  44
  45 #define CHANNEL_HAS_INODE       0x8000
  46
  47 static struct inode_private_data *top_intern;
  48 static int ino_unique = 0;
  49
  50 static errcode_t inode_open(const char *name, int flags, io_channel *channel);
  51 static errcode_t inode_close(io_channel channel);
  52 static errcode_t inode_set_blksize(io_channel channel, int blksize);
  53 static errcode_t inode_read_blk(io_channel channel, unsigned long block,
  54                                int count, void *data);
  55 static errcode_t inode_write_blk(io_channel channel, unsigned long block,
  56                                 int count, const void *data);
  57 static errcode_t inode_flush(io_channel channel);
  58 static errcode_t inode_write_byte(io_channel channel, unsigned long offset,
  59                                 int size, const void *data);
  60 static errcode_t inode_read_blk64(io_channel channel,
  61                                 unsigned long long block, int count, void *data);
  62 static errcode_t inode_write_blk64(io_channel channel,
  63                                 unsigned long long block, int count, const void *data);
  64
  65 static struct struct_io_manager struct_inode_manager = {
  66         .magic          = EXT2_ET_MAGIC_IO_MANAGER,
  67         .name           = "Inode I/O Manager",
  68         .open           = inode_open,
  69         .close          = inode_close,
  70         .set_blksize    = inode_set_blksize,
  71         .read_blk       = inode_read_blk,
  72         .write_blk      = inode_write_blk,
  73         .flush          = inode_flush,
  74         .write_byte     = inode_write_byte,
  75         .read_blk64     = inode_read_blk64,
  76         .write_blk64    = inode_write_blk64
  77 };
  78
  79 io_manager inode_io_manager = &struct_inode_manager;
  80
  81 errcode_t ext2fs_inode_io_intern2(ext2_filsys fs, ext2_ino_t ino,
  82                                   struct ext2_inode *inode,
  83                                   char **name)
  84 {
  85         struct inode_private_data       *data;
  86         errcode_t                       retval;
  87
  88         if ((retval = ext2fs_get_mem(sizeof(struct inode_private_data),
  89                                      &data)))
  90                 return retval;
  91         data->magic = EXT2_ET_MAGIC_INODE_IO_CHANNEL;
  92         sprintf(data->name, "%u:%d", ino, ino_unique++);
  93         data->file = 0;
  94         data->fs = fs;
  95         data->ino = ino;
  96         data->flags = 0;
  97         if (inode) {
  98                 memcpy(&data->inode, inode, sizeof(struct ext2_inode));
  99                 data->flags |= CHANNEL_HAS_INODE;
 100         }
 101         data->next = top_intern;
 102         top_intern = data;
 103         *name = data->name;
 104         return 0;
 105 }
 106
 107 errcode_t ext2fs_inode_io_intern(ext2_filsys fs, ext2_ino_t ino,
 108                                  char **name)
 109 {
 110         return ext2fs_inode_io_intern2(fs, ino, NULL, name);
 111 }
 112
 113
 114 static errcode_t inode_open(const char *name, int flags, io_channel *channel)
 115 {
 116         io_channel      io = NULL;
 117         struct inode_private_data *prev, *data = NULL;
 118         errcode_t       retval;
 119         int             open_flags;
 120
 121         if (name == 0)
 122                 return EXT2_ET_BAD_DEVICE_NAME;
 123
 124         for (data = top_intern, prev = NULL; data;
 125              prev = data, data = data->next)
 126                 if (strcmp(name, data->name) == 0)
 127                         break;
 128         if (!data)
 129                 return ENOENT;
 130         if (prev)
 131                 prev->next = data->next;
 132         else
 133                 top_intern = data->next;
 134
 135         retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
 136         if (retval)
 137                 goto cleanup;
 138         memset(io, 0, sizeof(struct struct_io_channel));
 139
 140         io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
 141         io->manager = inode_io_manager;
 142         retval = ext2fs_get_mem(strlen(name)+1, &io->name);
 143         if (retval)
 144                 goto cleanup;
 145
 146         strcpy(io->name, name);
 147         io->private_data = data;
 148         io->block_size = 1024;
 149         io->read_error = 0;
 150         io->write_error = 0;
 151         io->refcount = 1;
 152
 153         open_flags = (flags & IO_FLAG_RW) ? EXT2_FILE_WRITE : 0;
 154         retval = ext2fs_file_open2(data->fs, data->ino,
 155                                    (data->flags & CHANNEL_HAS_INODE) ?
 156                                    &data->inode : 0, open_flags,
 157                                    &data->file);
 158         if (retval)
 159                 goto cleanup;
 160
 161         *channel = io;
 162         return 0;
 163
 164 cleanup:
 165         if (io && io->name)
 166                 ext2fs_free_mem(&io->name);
 167         if (data)
 168                 ext2fs_free_mem(&data);
 169         if (io)
 170                 ext2fs_free_mem(&io);
 171         return retval;
 172 }
 173
 174 static errcode_t inode_close(io_channel channel)
 175 {
 176         struct inode_private_data *data;
 177         errcode_t       retval = 0;
 178
 179         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 180         data = (struct inode_private_data *) channel->private_data;
 181         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 182
 183         if (--channel->refcount > 0)
 184                 return 0;
 185
 186         retval = ext2fs_file_close(data->file);
 187
 188         ext2fs_free_mem(&channel->private_data);
 189         if (channel->name)
 190                 ext2fs_free_mem(&channel->name);
 191         ext2fs_free_mem(&channel);
 192         return retval;
 193 }
 194
 195 static errcode_t inode_set_blksize(io_channel channel, int blksize)
 196 {
 197         struct inode_private_data *data;
 198
 199         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 200         data = (struct inode_private_data *) channel->private_data;
 201         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 202
 203         channel->block_size = blksize;
 204         return 0;
 205 }
 206
 207
 208 static errcode_t inode_read_blk64(io_channel channel,
 209                                 unsigned long long block, int count, void *buf)
 210 {
 211         struct inode_private_data *data;
 212         errcode_t       retval;
 213
 214         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 215         data = (struct inode_private_data *) channel->private_data;
 216         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 217
 218         if ((retval = ext2fs_file_llseek(data->file,
 219                                 (ext2_off64_t)(block * channel->block_size),
 220                                 EXT2_SEEK_SET, 0)))
 221                 return retval;
 222
 223         count = (count < 0) ? -count : (count * channel->block_size);
 224
 225         return ext2fs_file_read(data->file, buf, count, 0);
 226 }
 227
 228 static errcode_t inode_read_blk(io_channel channel, unsigned long block,
 229                                int count, void *buf)
 230 {
 231         return inode_read_blk64(channel, block, count, buf);
 232 }
 233
 234 static errcode_t inode_write_blk64(io_channel channel,
 235                                 unsigned long long block, int count, const void *buf)
 236 {
 237         struct inode_private_data *data;
 238         errcode_t       retval;
 239
 240         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 241         data = (struct inode_private_data *) channel->private_data;
 242         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 243
 244         if ((retval = ext2fs_file_llseek(data->file,
 245                                 (ext2_off64_t) (block * channel->block_size),
 246                                 EXT2_SEEK_SET, 0)))
 247                 return retval;
 248
 249         count = (count < 0) ? -count : (count * channel->block_size);
 250
 251         return ext2fs_file_write(data->file, buf, count, 0);
 252 }
 253
 254 static errcode_t inode_write_blk(io_channel channel, unsigned long block,
 255                                 int count, const void *buf)
 256 {
 257         return inode_write_blk64(channel, block, count, buf);
 258 }
 259
 260 static errcode_t inode_write_byte(io_channel channel, unsigned long offset,
 261                                  int size, const void *buf)
 262 {
 263         struct inode_private_data *data;
 264         errcode_t       retval = 0;
 265
 266         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 267         data = (struct inode_private_data *) channel->private_data;
 268         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 269
 270         if ((retval = ext2fs_file_lseek(data->file, offset,
 271                                         EXT2_SEEK_SET, 0)))
 272                 return retval;
 273
 274         return ext2fs_file_write(data->file, buf, size, 0);
 275 }
 276
 277 /*
 278  * Flush data buffers to disk.
 279  */
 280 static errcode_t inode_flush(io_channel channel)
 281 {
 282         struct inode_private_data *data;
 283
 284         EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
 285         data = (struct inode_private_data *) channel->private_data;
 286         EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_INODE_IO_CHANNEL);
 287
 288         return ext2fs_file_flush(data->file);
 289 }
 290