/* * openfs.c --- open an ext2 filesystem * * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o. * * %Begin-Header% * This file may be redistributed under the terms of the GNU Public * License. * %End-Header% */ #include #include #if HAVE_UNISTD_H #include #endif #include #include #if HAVE_SYS_STAT_H #include #endif #if HAVE_SYS_TYPES_H #include #endif #include "ext2_fs.h" #include "ext2fs.h" #include "e2image.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. * * Valid flags for ext2fs_open() * * EXT2_FLAG_RW - Open the filesystem for read/write. * EXT2_FLAG_FORCE - Open the filesystem even if some of the * features aren't supported. * EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device */ 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, groups_per_block; blk_t group_block; char *dest; struct ext2_group_desc *gdp; EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER); retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), (void **) &fs); if (retval) return retval; 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->io->app_data = fs; retval = ext2fs_get_mem(strlen(name)+1, (void **) &fs->device_name); if (retval) goto cleanup; strcpy(fs->device_name, name); retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &fs->super); if (retval) goto cleanup; if (flags & EXT2_FLAG_IMAGE_FILE) { retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr), (void **) &fs->image_header); if (retval) goto cleanup; retval = io_channel_read_blk(fs->io, 0, -sizeof(struct ext2_image_hdr), fs->image_header); if (retval) goto cleanup; if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE) return EXT2_ET_MAGIC_E2IMAGE; superblock = 1; block_size = fs->image_header->fs_blocksize; } /* * 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. * * Note: we only save a backup copy of the superblock if we * are reading the superblock from the primary superblock location. */ if (superblock) { if (!block_size) { retval = EXT2_ET_INVALID_ARGUMENT; goto cleanup; } io_channel_set_blksize(fs->io, block_size); group_block = superblock + 1; fs->orig_super = 0; } else { io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET); superblock = 1; group_block = 0; retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &fs->orig_super); if (retval) goto cleanup; } retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE, fs->super); if (retval) goto cleanup; if (fs->orig_super) memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE); #ifdef EXT2FS_ENABLE_SWAPFS if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) || (fs->flags & EXT2_FLAG_SWAP_BYTES)) { fs->flags |= EXT2_FLAG_SWAP_BYTES; ext2fs_swap_super(fs->super); } #endif if (fs->super->s_magic != EXT2_SUPER_MAGIC) { printf("%x, %x\n",fs->super->s_magic, EXT2_SUPER_MAGIC); retval = EXT2_ET_BAD_MAGIC; goto cleanup; } if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) { retval = EXT2_ET_REV_TOO_HIGH; goto cleanup; } /* * Check for feature set incompatibility */ if (!(flags & EXT2_FLAG_FORCE)) { if (fs->super->s_feature_incompat & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) { retval = EXT2_ET_UNSUPP_FEATURE; goto cleanup; } if ((flags & EXT2_FLAG_RW) && (fs->super->s_feature_ro_compat & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) { retval = EXT2_ET_RO_UNSUPP_FEATURE; goto cleanup; } if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) && (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) { retval = EXT2_ET_UNSUPP_FEATURE; goto cleanup; } } 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); /* * If this is an external journal device, don't try to read * the group descriptors, because they're not there. */ if (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) { fs->group_desc_count = 0; *ret_fs = fs; return 0; } /* * Read group descriptors */ if ((EXT2_BLOCKS_PER_GROUP(fs->super)) == 0) { retval = EXT2_ET_CORRUPT_SUPERBLOCK; goto cleanup; } 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); retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize, (void **) &fs->group_desc); if (retval) 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++; #ifdef EXT2FS_ENABLE_SWAPFS if (fs->flags & EXT2_FLAG_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++); } #endif dest += fs->blocksize; } *ret_fs = fs; return 0; cleanup: ext2fs_free(fs); return retval; }