mirror of https://github.com/vitalif/e2fsprogs
243 lines
6.3 KiB
C
243 lines
6.3 KiB
C
/*
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* openfs.c --- open an ext2 filesystem
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*
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* Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#include <stdio.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <fcntl.h>
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#include <time.h>
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#if HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#if HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#include "ext2_fs.h"
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#include "ext2fs.h"
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#include "e2image.h"
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/*
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* Note: if superblock is non-zero, block-size must also be non-zero.
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* Superblock and block_size can be zero to use the default size.
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*
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* Valid flags for ext2fs_open()
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*
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* EXT2_FLAG_RW - Open the filesystem for read/write.
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* EXT2_FLAG_FORCE - Open the filesystem even if some of the
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* features aren't supported.
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* EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
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*/
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errcode_t ext2fs_open(const char *name, int flags, int superblock,
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int block_size, io_manager manager, ext2_filsys *ret_fs)
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{
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ext2_filsys fs;
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errcode_t retval;
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int i, j, groups_per_block, blocks_per_group;
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blk_t group_block;
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char *dest;
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struct ext2_group_desc *gdp;
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EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
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retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys),
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(void **) &fs);
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if (retval)
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return retval;
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memset(fs, 0, sizeof(struct struct_ext2_filsys));
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fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
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fs->flags = flags;
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fs->umask = 022;
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retval = manager->open(name, (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
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&fs->io);
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if (retval)
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goto cleanup;
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fs->io->app_data = fs;
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retval = ext2fs_get_mem(strlen(name)+1, (void **) &fs->device_name);
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if (retval)
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goto cleanup;
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strcpy(fs->device_name, name);
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retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &fs->super);
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if (retval)
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goto cleanup;
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if (flags & EXT2_FLAG_IMAGE_FILE) {
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retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
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(void **) &fs->image_header);
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if (retval)
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goto cleanup;
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retval = io_channel_read_blk(fs->io, 0,
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-sizeof(struct ext2_image_hdr),
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fs->image_header);
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if (retval)
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goto cleanup;
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if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
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return EXT2_ET_MAGIC_E2IMAGE;
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superblock = 1;
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block_size = fs->image_header->fs_blocksize;
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}
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/*
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* If the user specifies a specific block # for the
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* superblock, then he/she must also specify the block size!
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* Otherwise, read the master superblock located at offset
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* SUPERBLOCK_OFFSET from the start of the partition.
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*
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* Note: we only save a backup copy of the superblock if we
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* are reading the superblock from the primary superblock location.
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*/
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if (superblock) {
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if (!block_size) {
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retval = EXT2_ET_INVALID_ARGUMENT;
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goto cleanup;
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}
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io_channel_set_blksize(fs->io, block_size);
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group_block = superblock + 1;
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fs->orig_super = 0;
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} else {
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io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
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superblock = 1;
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group_block = 0;
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retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
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(void **) &fs->orig_super);
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if (retval)
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goto cleanup;
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}
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retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
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fs->super);
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if (retval)
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goto cleanup;
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if (fs->orig_super)
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memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
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#ifdef EXT2FS_ENABLE_SWAPFS
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if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
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(fs->flags & EXT2_FLAG_SWAP_BYTES)) {
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fs->flags |= EXT2_FLAG_SWAP_BYTES;
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ext2fs_swap_super(fs->super);
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}
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#endif
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if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
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retval = EXT2_ET_BAD_MAGIC;
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goto cleanup;
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}
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if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
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retval = EXT2_ET_REV_TOO_HIGH;
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goto cleanup;
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}
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/*
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* Check for feature set incompatibility
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*/
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if (!(flags & EXT2_FLAG_FORCE)) {
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if (fs->super->s_feature_incompat &
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~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
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retval = EXT2_ET_UNSUPP_FEATURE;
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goto cleanup;
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}
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if ((flags & EXT2_FLAG_RW) &&
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(fs->super->s_feature_ro_compat &
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~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
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retval = EXT2_ET_RO_UNSUPP_FEATURE;
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goto cleanup;
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}
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if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
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(fs->super->s_feature_incompat &
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EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
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retval = EXT2_ET_UNSUPP_FEATURE;
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goto cleanup;
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}
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}
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fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
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if (fs->blocksize == 0) {
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retval = EXT2_ET_CORRUPT_SUPERBLOCK;
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goto cleanup;
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}
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fs->fragsize = EXT2_FRAG_SIZE(fs->super);
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fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
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EXT2_INODE_SIZE(fs->super) +
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EXT2_BLOCK_SIZE(fs->super) - 1) /
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EXT2_BLOCK_SIZE(fs->super));
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if (block_size) {
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if (block_size != fs->blocksize) {
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retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
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goto cleanup;
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}
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}
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/*
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* Set the blocksize to the filesystem's blocksize.
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*/
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io_channel_set_blksize(fs->io, fs->blocksize);
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/*
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* If this is an external journal device, don't try to read
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* the group descriptors, because they're not there.
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*/
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if (fs->super->s_feature_incompat &
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EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
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fs->group_desc_count = 0;
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*ret_fs = fs;
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return 0;
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}
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/*
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* Read group descriptors
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*/
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blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
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if (blocks_per_group == 0 ||
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blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
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fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
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retval = EXT2_ET_CORRUPT_SUPERBLOCK;
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goto cleanup;
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}
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fs->group_desc_count = (fs->super->s_blocks_count -
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fs->super->s_first_data_block +
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blocks_per_group - 1) / blocks_per_group;
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fs->desc_blocks = (fs->group_desc_count +
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EXT2_DESC_PER_BLOCK(fs->super) - 1)
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/ EXT2_DESC_PER_BLOCK(fs->super);
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retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
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(void **) &fs->group_desc);
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if (retval)
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goto cleanup;
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if (!group_block)
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group_block = fs->super->s_first_data_block + 1;
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dest = (char *) fs->group_desc;
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for (i=0 ; i < fs->desc_blocks; i++) {
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retval = io_channel_read_blk(fs->io, group_block, 1, dest);
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if (retval)
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goto cleanup;
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group_block++;
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#ifdef EXT2FS_ENABLE_SWAPFS
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if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
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gdp = (struct ext2_group_desc *) dest;
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groups_per_block = fs->blocksize /
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sizeof(struct ext2_group_desc);
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for (j=0; j < groups_per_block; j++)
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ext2fs_swap_group_desc(gdp++);
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}
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#endif
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dest += fs->blocksize;
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}
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*ret_fs = fs;
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return 0;
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cleanup:
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ext2fs_free(fs);
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return retval;
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}
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