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 Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #if HAVE_ERRNO_H
  19 #include <errno.h>
  20 #endif
  21 #include <time.h>
  22
  23 #include "ext2_fs.h"
  24 #include "ext2fs.h"
  25
  26 /*
  27  * For checking structure magic numbers...
  28  */
  29
  30 #define EXT2_CHECK_MAGIC(struct, code) \
  31           if ((struct)->magic != (code)) return (code)
  32
  33 struct inode_private_data {
  34         int                             magic;
  35         char                            name[32];
  36         ext2_file_t                     file;
  37         ext2_filsys                     fs;
  38         ext2_ino_t                      ino;
  39         struct ext2_inode               inode;
  40         int                             flags;
  41         struct inode_private_data       *next;
  42 };
  43
  44 #define CHANNEL_HAS_INODE       0x8000
  45
  46 static struct inode_private_data *top_intern;
  47 static int ino_unique = 0;
  48
  49 static errcode_t inode_open(const char *name, int flags, io_channel *channel);
  50 static errcode_t inode_close(io_channel channel);
  51 static errcode_t inode_set_blksize(io_channel channel, int blksize);
  52 static errcode_t inode_read_blk(io_channel channel, unsigned long block,
  53                                int count, void *data);
  54 static errcode_t inode_write_blk(io_channel channel, unsigned long block,
  55                                 int count, const void *data);
  56 static errcode_t inode_flush(io_channel channel);
  57 static errcode_t inode_write_byte(io_channel channel, unsigned long offset,
  58                                 int size, const void *data);
  59 static errcode_t inode_read_blk64(io_channel channel,
  60                                 unsigned long long block, int count, void *data);
  61 static errcode_t inode_write_blk64(io_channel channel,
  62                                 unsigned long long block, int count, const void *data);
  63
  64 static struct struct_io_manager struct_inode_manager = {
  65         EXT2_ET_MAGIC_IO_MANAGER,
  66         "Inode I/O Manager",
  67         inode_open,
  68         inode_close,
  69         inode_set_blksize,
  70         inode_read_blk,
  71         inode_write_blk,
  72         inode_flush,
  73         inode_write_byte,
  74         NULL,
  75         NULL,
  76         inode_read_blk64,
  77         inode_write_blk64
  78 };
  79
  80 io_manager inode_io_manager = &struct_inode_manager;
  81
  82 errcode_t ext2fs_inode_io_intern2(ext2_filsys fs, ext2_ino_t ino,
  83                                   struct ext2_inode *inode,
  84                                   char **name)
  85 {
  86         struct inode_private_data       *data;
  87         errcode_t                       retval;
  88
  89         if ((retval = ext2fs_get_mem(sizeof(struct inode_private_data),
  90                                      &data)))
  91                 return retval;
  92         data->magic = EXT2_ET_MAGIC_INODE_IO_CHANNEL;
  93         sprintf(data->name, "%u:%d", ino, ino_unique++);
  94         data->file = 0;
  95         data->fs = fs;
  96         data->ino = ino;
  97         data->flags = 0;
  98         if (inode) {
  99                 memcpy(&data->inode, inode, sizeof(struct ext2_inode));
 100                 data->flags |= CHANNEL_HAS_INODE;
 101         }
 102         data->next = top_intern;
 103         top_intern = data;
 104         *name = data->name;
 105         return 0;
 106 }
 107
 108 errcode_t ext2fs_inode_io_intern(ext2_filsys fs, ext2_ino_t ino,
 109                                  char **name)
 110 {
 111         return ext2fs_inode_io_intern2(fs, ino, NULL, name);
 112 }
 113
 114
 115 static errcode_t inode_open(const char *name, int flags, io_channel *channel)
 116 {
 117         io_channel      io = NULL;
 118         struct inode_private_data *prev, *data = NULL;
 119         errcode_t       retval;
 120         int             open_flags;
 121
 122         if (name == 0)
 123                 return EXT2_ET_BAD_DEVICE_NAME;
 124
 125         for (data = top_intern, prev = NULL; data;
 126              prev = data, data = data->next)
 127                 if (strcmp(name, data->name) == 0)
 128                         break;
 129         if (!data)
 130                 return ENOENT;
 131         if (prev)
 132                 prev->next = data->next;
 133         else
 134                 top_intern = data->next;
 135
 136         retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
 137         if (retval)
 138                 goto cleanup;
 139         memset(io, 0, sizeof(struct struct_io_channel));
 140
 141         io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
 142         io->manager = inode_io_manager;
 143         retval = ext2fs_get_mem(strlen(name)+1, &io->name);
 144         if (retval)
 145                 goto cleanup;
 146
 147         strcpy(io->name, name);
 148         io->private_data = data;
 149         io->block_size = 1024;
 150         io->read_error = 0;
 151         io->write_error = 0;
 152         io->refcount = 1;
 153
 154         open_flags = (flags & IO_FLAG_RW) ? EXT2_FILE_WRITE : 0;
 155         retval = ext2fs_file_open2(data->fs, data->ino,
 156                                    (data->flags & CHANNEL_HAS_INODE) ?
 157                                    &data->inode : 0, open_flags,
 158                                    &data->file);
 159         if (retval)
 160                 goto cleanup;
 161
 162         *channel = io;
 163         return 0;
 164
 165 cleanup:
 166         if (data) {
 167                 ext2fs_free_mem(&data);
 168         }
 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_lseek(data->file,
 219                                         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_lseek(data->file,
 245                                         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