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/*
* openfs.c --- open an ext2 filesystem
*
* Copyright (C) 1993, 1994, 1995 Theodore Ts'o.
*
* This file may be redistributed under the terms of the GNU Public
* License.
*/
#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <fcntl.h>
#include <time.h>
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/ext2_fs.h>
#include "ext2fs.h"
/*
* Note: if superblock is non-zero, block-size must also be non-zero.
* Superblock and block_size can be zero to use the default size.
*/
errcode_t ext2fs_open(const char *name, int flags, int superblock,
int block_size, io_manager manager, ext2_filsys *ret_fs)
{
ext2_filsys fs;
errcode_t retval;
int i, j, group_block, groups_per_block;
char *dest;
struct ext2_group_desc *gdp;
EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
fs = (ext2_filsys) malloc(sizeof(struct struct_ext2_filsys));
if (!fs)
return ENOMEM;
memset(fs, 0, sizeof(struct struct_ext2_filsys));
fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
fs->flags = flags;
retval = manager->open(name, (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
&fs->io);
if (retval)
goto cleanup;
fs->device_name = malloc(strlen(name)+1);
if (!fs->device_name) {
retval = ENOMEM;
goto cleanup;
}
strcpy(fs->device_name, name);
fs->super = malloc(SUPERBLOCK_SIZE);
if (!fs->super) {
retval = ENOMEM;
goto cleanup;
}
/*
* If the user specifies a specific block # for the
* superblock, then he/she must also specify the block size!
* Otherwise, read the master superblock located at offset
* SUPERBLOCK_OFFSET from the start of the partition.
*/
if (superblock) {
if (!block_size) {
retval = EINVAL;
goto cleanup;
}
io_channel_set_blksize(fs->io, block_size);
group_block = superblock + 1;
} else {
io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
superblock = 1;
group_block = 0;
}
retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
fs->super);
if (retval)
goto cleanup;
if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
(fs->flags & EXT2_SWAP_BYTES)) {
fs->flags |= EXT2_SWAP_BYTES;
ext2fs_swap_super(fs->super);
}
if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
retval = EXT2_ET_BAD_MAGIC;
goto cleanup;
}
#ifdef EXT2_DYNAMIC_REV
if (fs->super->s_rev_level > EXT2_DYNAMIC_REV) {
retval = EXT2_ET_REV_TOO_HIGH;
goto cleanup;
}
#else
#ifdef EXT2_CURRENT_REV
if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
retval = EXT2_ET_REV_TOO_HIGH;
goto cleanup;
}
#endif
#endif
fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
if (fs->blocksize == 0) {
retval = EXT2_ET_CORRUPT_SUPERBLOCK;
goto cleanup;
}
fs->fragsize = EXT2_FRAG_SIZE(fs->super);
fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
EXT2_INODE_SIZE(fs->super) +
EXT2_BLOCK_SIZE(fs->super) - 1) /
EXT2_BLOCK_SIZE(fs->super));
if (block_size) {
if (block_size != fs->blocksize) {
retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
goto cleanup;
}
}
/*
* Set the blocksize to the filesystem's blocksize.
*/
io_channel_set_blksize(fs->io, fs->blocksize);
/*
* Read group descriptors
*/
fs->group_desc_count = (fs->super->s_blocks_count -
fs->super->s_first_data_block +
EXT2_BLOCKS_PER_GROUP(fs->super) - 1)
/ EXT2_BLOCKS_PER_GROUP(fs->super);
fs->desc_blocks = (fs->group_desc_count +
EXT2_DESC_PER_BLOCK(fs->super) - 1)
/ EXT2_DESC_PER_BLOCK(fs->super);
fs->group_desc = malloc(fs->desc_blocks * fs->blocksize);
if (!fs->group_desc) {
retval = ENOMEM;
goto cleanup;
}
if (!group_block)
group_block = fs->super->s_first_data_block + 1;
dest = (char *) fs->group_desc;
for (i=0 ; i < fs->desc_blocks; i++) {
retval = io_channel_read_blk(fs->io, group_block, 1, dest);
if (retval)
goto cleanup;
group_block++;
if (fs->flags & EXT2_SWAP_BYTES) {
gdp = (struct ext2_group_desc *) dest;
groups_per_block = fs->blocksize /
sizeof(struct ext2_group_desc);
for (j=0; j < groups_per_block; j++)
ext2fs_swap_group_desc(gdp++);
}
dest += fs->blocksize;
}
*ret_fs = fs;
return 0;
cleanup:
ext2fs_free(fs);
return retval;
}
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