/* vi: set sw=4 ts=4: */ /* * mkfs_ext2: utility to create EXT2 filesystem * inspired by genext2fs * * Busybox'ed (2009) by Vladimir Dronnikov * * Licensed under GPLv2, see file LICENSE in this tarball for details. */ #include "libbb.h" #include #include #include "volume_id/volume_id_internal.h" #define ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT 0 #define ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX 1 // from e2fsprogs #define s_reserved_gdt_blocks s_padding1 #define s_mkfs_time s_reserved[0] #define s_flags s_reserved[22] #define EXT2_HASH_HALF_MD4 1 #define EXT2_FLAGS_SIGNED_HASH 0x0001 // whiteout: for writable overlays //#define LINUX_S_IFWHT 0160000 //#define EXT2_FEATURE_INCOMPAT_WHITEOUT 0x0020 // storage helper void BUG_unsupported_field_size(void); #define STORE_LE(field, value) \ do { \ if (sizeof(field) == 4) \ field = cpu_to_le32(value); \ else if (sizeof(field) == 2) \ field = cpu_to_le16(value); \ else if (sizeof(field) == 1) \ field = (value); \ else \ BUG_unsupported_field_size(); \ } while (0) // All fields are little-endian struct ext2_dir { uint32_t inode1; uint16_t rec_len1; uint8_t name_len1; uint8_t file_type1; char name1[4]; uint32_t inode2; uint16_t rec_len2; uint8_t name_len2; uint8_t file_type2; char name2[4]; uint32_t inode3; uint16_t rec_len3; uint8_t name_len3; uint8_t file_type3; char name3[12]; }; static unsigned int_log2(unsigned arg) { unsigned r = 0; while ((arg >>= 1) != 0) r++; return r; } // taken from mkfs_minix.c. libbb candidate? static unsigned div_roundup(uint32_t size, uint32_t n) { // Overflow-resistant uint32_t res = size / n; if (res * n != size) res++; return res; } static void allocate(uint8_t *bitmap, uint32_t blocksize, uint32_t start, uint32_t end) { uint32_t i; memset(bitmap, 0, blocksize); i = start / 8; memset(bitmap, 0xFF, i); bitmap[i] = 0xFF >> (8-(start&7)); //bb_info_msg("ALLOC: [%u][%u][%u]: [%u]:=[%x]", blocksize, start, end, blocksize - end/8 - 1, (uint8_t)(0xFF << (8-(end&7)))); i = end / 8; bitmap[blocksize - i - 1] = 0xFF << (8 - (end & 7)); memset(bitmap + blocksize - i, 0xFF, i); // N.B. no overflow here! } static uint32_t has_super(uint32_t x) { // 0, 1 and powers of 3, 5, 7 up to 2^32 limit static const uint32_t supers[] = { 0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729, 2187, 2401, 3125, 6561, 15625, 16807, 19683, 59049, 78125, 117649, 177147, 390625, 531441, 823543, 1594323, 1953125, 4782969, 5764801, 9765625, 14348907, 40353607, 43046721, 48828125, 129140163, 244140625, 282475249, 387420489, 1162261467, 1220703125, 1977326743, 3486784401/* >2^31 */, }; const uint32_t *sp = supers + ARRAY_SIZE(supers); while (1) { sp--; if (x == *sp) return 1; if (x > *sp) return 0; } } /* Standard mke2fs 1.41.9: * Usage: mke2fs [-c|-l filename] [-b block-size] [-f fragment-size] * [-i bytes-per-inode] [-I inode-size] [-J journal-options] * [-G meta group size] [-N number-of-inodes] * [-m reserved-blocks-percentage] [-o creator-os] * [-g blocks-per-group] [-L volume-label] [-M last-mounted-directory] * [-O feature[,...]] [-r fs-revision] [-E extended-option[,...]] * [-T fs-type] [-U UUID] [-jnqvFSV] device [blocks-count] */ // N.B. not commented below options are taken and silently ignored enum { OPT_c = 1 << 0, OPT_l = 1 << 1, OPT_b = 1 << 2, // block size, in bytes OPT_f = 1 << 3, OPT_i = 1 << 4, // bytes per inode OPT_I = 1 << 5, OPT_J = 1 << 6, OPT_G = 1 << 7, OPT_N = 1 << 8, OPT_m = 1 << 9, // percentage of blocks reserved for superuser OPT_o = 1 << 10, OPT_g = 1 << 11, OPT_L = 1 << 12, // label OPT_M = 1 << 13, OPT_O = 1 << 14, OPT_r = 1 << 15, OPT_E = 1 << 16, OPT_T = 1 << 17, OPT_U = 1 << 18, OPT_j = 1 << 19, OPT_n = 1 << 20, // dry run: do not write anything OPT_q = 1 << 21, OPT_v = 1 << 22, OPT_F = 1 << 23, OPT_S = 1 << 24, //OPT_V = 1 << 25, // -V version. bbox applets don't support that }; #define fd 3 /* predefined output descriptor */ static void PUT(uint64_t off, void *buf, uint32_t size) { // bb_info_msg("PUT[%llu]:[%u]", off, size); xlseek(fd, off, SEEK_SET); xwrite(fd, buf, size); } int mkfs_ext2_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv) { unsigned i, pos, n; unsigned bs, bpi; unsigned blocksize, blocksize_log2; unsigned nreserved = 5; unsigned long long kilobytes; uint32_t nblocks; uint32_t ngroups; uint32_t bytes_per_inode; uint32_t first_data_block; uint32_t ninodes_per_group; uint32_t gdtsz, itsz; time_t timestamp; unsigned opts; const char *label; struct stat st; struct ext2_super_block *sb; // superblock struct ext2_group_desc *gd; // group descriptors struct ext2_inode *inode; struct ext2_dir *dir; uint8_t *buf; opt_complementary = "-1:b+:m+:i+"; opts = getopt32(argv, "cl:b:f:i:I:J:G:N:m:o:g:L:M:O:r:E:T:U:jnqvFS", NULL, &bs, NULL, &bpi, NULL, NULL, NULL, NULL, &nreserved, NULL, NULL, &label, NULL, NULL, NULL, NULL, NULL, NULL); argv += optind; // argv[0] -- device // reserved blocks percentage if (nreserved > 50) bb_error_msg_and_die("-%c is bad", 'm'); // check the device is a block device xmove_fd(xopen(argv[0], O_WRONLY), fd); fstat(fd, &st); if (!S_ISBLK(st.st_mode) && !(opts & OPT_F)) bb_error_msg_and_die("not a block device"); // check if it is mounted // N.B. what if we format a file? find_mount_point will return false negative since // it is loop block device which mounted! if (find_mount_point(argv[0], 0)) bb_error_msg_and_die("can't format mounted filesystem"); // open the device, get size in kbytes if (argv[1]) { kilobytes = xatoull(argv[1]); } else { kilobytes = (uoff_t)xlseek(fd, 0, SEEK_END) / 1024; } bytes_per_inode = 16384; if (kilobytes < 512*1024) bytes_per_inode = 4096; if (kilobytes < 3*1024) bytes_per_inode = 8192; if (opts & OPT_i) bytes_per_inode = bpi; // block size is a multiple of 1024 blocksize = 1024; if (kilobytes >= 512*1024) // mke2fs 1.41.9 compat blocksize = 4096; if (EXT2_MAX_BLOCK_SIZE > 4096) { // kilobytes >> 22 == size in 4gigabyte chunks. // if it is >= 16k gigs, blocksize must be increased. // Try "mke2fs -F image_std $((16 * 1024*1024*1024))" while ((kilobytes >> 22) >= blocksize) blocksize *= 2; } if (opts & OPT_b) blocksize = bs; if (blocksize < EXT2_MIN_BLOCK_SIZE || blocksize > EXT2_MAX_BLOCK_SIZE || (blocksize & (blocksize - 1)) // not power of 2 ) { bb_error_msg_and_die("blocksize %u is bad", blocksize); } blocksize_log2 = int_log2(blocksize); kilobytes >>= (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE); // nblocks: the total number of blocks in the filesystem nblocks = kilobytes; if (nblocks != kilobytes) bb_error_msg_and_die("block count doesn't fit in 32 bits"); if (nblocks < 8) bb_error_msg_and_die("need >= 8 blocks"); #define kilobytes kilobytes_unused_after_this // number of bits in one block, i.e. 8*blocksize #define blocks_per_group (8 * blocksize) /* e2fsprogs-1.41.9 overhead = 2 + fs->inode_blocks_per_group; if (has_super(fs->group_desc_count - 1)) overhead += 1 + fs->desc_blocks + super->s_reserved_gdt_blocks; rem = (nblocks - first_data_block) % blocks_per_group); if ((fs->group_desc_count == 1) && rem && (rem < overhead)) { retval = EXT2_ET_TOOSMALL; goto cleanup; } if (rem && (rem < overhead+50)) { nblocks -= rem; goto retry; } */ // N.B. a block group can have no more than blocks_per_group blocks first_data_block = (EXT2_MIN_BLOCK_SIZE == blocksize); ngroups = div_roundup(nblocks - first_data_block, blocks_per_group); if (0 == ngroups) bb_error_msg_and_die("ngroups"); { // ninodes is the total number of inodes (files) in the file system uint32_t ninodes = nblocks / (bytes_per_inode >> blocksize_log2); if (ninodes < EXT2_GOOD_OLD_FIRST_INO+1) ninodes = EXT2_GOOD_OLD_FIRST_INO+1; ninodes_per_group = div_roundup(ninodes, ngroups); // minimum number because the first EXT2_GOOD_OLD_FIRST_INO-1 are reserved if (ninodes_per_group < 16) ninodes_per_group = 16; } // TODO: 5?/5 WE MUST NOT DEPEND ON WHETHER DEVICE IS /dev/zero 'ed OR NOT // TODO: 3/5 refuse if mounted // TODO: 4/5 compat options // TODO: 1/5 sanity checks // TODO: 0/5 more verbose error messages // TODO: 0/5 info printing // TODO: 2/5 bigendianness! Spot where it comes to play! sb->, gd-> // TODO: 2/5 reserved GDT: how to mark but not allocate? // TODO: 3/5 dir_index? // fill the superblock sb = xzalloc(blocksize); sb->s_rev_level = 1; // revision 1 filesystem sb->s_magic = EXT2_SUPER_MAGIC; sb->s_inode_size = sizeof(*inode); sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO; sb->s_log_block_size = sb->s_log_frag_size = blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE; // first 1024 bytes of the device are for boot record. If block size is 1024 bytes, then // the first block available for data is 1, otherwise 0 sb->s_first_data_block = first_data_block; // 0 or 1 // block and inode bitmaps occupy no more than one block, so maximum number of blocks is sb->s_blocks_per_group = sb->s_frags_per_group = blocks_per_group; timestamp = time(NULL); sb->s_mkfs_time = sb->s_wtime = sb->s_lastcheck = timestamp; sb->s_state = 1; sb->s_creator_os = EXT2_OS_LINUX; sb->s_checkinterval = 24*60*60 * 180; // 180 days sb->s_errors = EXT2_ERRORS_DEFAULT; sb->s_feature_compat = EXT2_FEATURE_COMPAT_SUPP | (EXT2_FEATURE_COMPAT_RESIZE_INO * ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT) | (EXT2_FEATURE_COMPAT_DIR_INDEX * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX) ; // e2fsprogs-1.41.9 doesn't like EXT2_FEATURE_INCOMPAT_WHITEOUT sb->s_feature_incompat = EXT2_FEATURE_INCOMPAT_FILETYPE;// | EXT2_FEATURE_INCOMPAT_WHITEOUT; sb->s_feature_ro_compat = EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER; sb->s_flags = EXT2_FLAGS_SIGNED_HASH * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX; generate_uuid(sb->s_uuid); if (ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX) { sb->s_def_hash_version = EXT2_HASH_HALF_MD4; generate_uuid((uint8_t *)sb->s_hash_seed); } /* * From e2fsprogs: add "jitter" to the superblock's check interval so that we * don't check all the filesystems at the same time. We use a * kludgy hack of using the UUID to derive a random jitter value. */ sb->s_max_mnt_count = EXT2_DFL_MAX_MNT_COUNT + (sb->s_uuid[ARRAY_SIZE(sb->s_uuid)-1] % EXT2_DFL_MAX_MNT_COUNT); sb->s_blocks_count = nblocks; // reserve blocks for superuser sb->s_r_blocks_count = ((uint64_t) nblocks * nreserved) / 100; gdtsz = div_roundup(ngroups, EXT2_DESC_PER_BLOCK(sb)); /* * From e2fsprogs: Calculate the number of GDT blocks to reserve for online * filesystem growth. * The absolute maximum number of GDT blocks we can reserve is determined by * the number of block pointers that can fit into a single block. */ /* We set it at 1024x the current filesystem size, or * the upper block count limit (2^32), whichever is lower. */ if (ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT) { uint32_t rgdtsz = 0xFFFFFFFF; // maximum block number if (nblocks < rgdtsz / 1024) rgdtsz = nblocks * 1024; rgdtsz = div_roundup(rgdtsz - first_data_block, blocks_per_group); rgdtsz = div_roundup(rgdtsz, EXT2_DESC_PER_BLOCK(sb)) - gdtsz; if (rgdtsz > EXT2_ADDR_PER_BLOCK(sb)) rgdtsz = EXT2_ADDR_PER_BLOCK(sb); STORE_LE(sb->s_reserved_gdt_blocks, rgdtsz); gdtsz += rgdtsz; } // N.B. a block group can have no more than 8*blocksize inodes if (ninodes_per_group > blocks_per_group) ninodes_per_group = blocks_per_group; // adjust inodes per group so they completely fill the inode table blocks in the descriptor ninodes_per_group = (div_roundup(ninodes_per_group * EXT2_INODE_SIZE(sb), blocksize) << blocksize_log2) / EXT2_INODE_SIZE(sb); // make sure the number of inodes per group is a multiple of 8 ninodes_per_group &= ~7; sb->s_inodes_per_group = ninodes_per_group;// = div_roundup(ninodes_per_group * sb->s_inode_size, blocksize); // total ninodes sb->s_inodes_count = ninodes_per_group * ngroups; itsz = ninodes_per_group * sb->s_inode_size / blocksize; sb->s_free_inodes_count = sb->s_inodes_count - EXT2_GOOD_OLD_FIRST_INO; // write the label, if any if (opts & OPT_L) safe_strncpy((char *)sb->s_volume_name, label, sizeof(sb->s_volume_name)); #if 1 /* if (fs_param.s_blocks_count != s->s_blocks_count) fprintf(stderr, _("warning: %u blocks unused.\n\n"), fs_param.s_blocks_count - s->s_blocks_count); */ printf( "Filesystem label=%s\n" "OS type: Linux\n" "Block size=%u (log=%u)\n" "Fragment size=%u (log=%u)\n" "%u inodes, %u blocks\n" "%u blocks (%u%%) reserved for the super user\n" "First data block=%u\n" "Maximum filesystem blocks=%u\n" "%u block groups\n" "%u blocks per group, %u fragments per group\n" "%u inodes per group" , (char *)sb->s_volume_name , blocksize, sb->s_log_block_size , blocksize, sb->s_log_block_size , sb->s_inodes_count, sb->s_blocks_count , sb->s_r_blocks_count, nreserved , first_data_block , gdtsz * EXT2_DESC_PER_BLOCK(sb) * blocks_per_group , ngroups , blocks_per_group, blocks_per_group , ninodes_per_group ); { const char *fmt = "\nSuperblock backups stored on blocks:\n" "\t%u"; pos = first_data_block; for (i = 1; i < ngroups; i++) { pos += blocks_per_group; if (has_super(i)) { printf(fmt, (unsigned)pos); fmt = ", %u"; } } } bb_putchar('\n'); #endif if (opts & OPT_n) goto done; // fill group descriptors gd = xzalloc(gdtsz * blocksize); sb->s_free_blocks_count = 0; for (i = 0, pos = first_data_block, n = nblocks; i < ngroups; i++, pos += blocks_per_group, n -= blocks_per_group ) { uint32_t overhead = pos + (has_super(i) ? (1/*sb*/ + gdtsz) : 0); gd[i].bg_block_bitmap = overhead + 0; gd[i].bg_inode_bitmap = overhead + 1; gd[i].bg_inode_table = overhead + 2; overhead = overhead - pos + 1/*bbmp*/ + 1/*ibmp*/ + itsz; gd[i].bg_free_inodes_count = ninodes_per_group; //gd[i].bg_used_dirs_count = 0; // N.B. both root and lost+found dirs are within the first block group, thus +2 if (0 == i) { overhead += 2; gd[i].bg_used_dirs_count = 2; gd[i].bg_free_inodes_count -= EXT2_GOOD_OLD_FIRST_INO; } // N.B. the following is pure heuristics! // Likely to cope with 1024-byte blocks, when first block is for boot sectors if (ngroups-1 == i) { overhead += first_data_block; } gd[i].bg_free_blocks_count = (n < blocks_per_group ? n : blocks_per_group) - overhead; sb->s_free_blocks_count += gd[i].bg_free_blocks_count; } STORE_LE(sb->s_free_blocks_count, sb->s_free_blocks_count); // dump filesystem skeleton structures // printf("Writing superblocks and filesystem accounting information: "); buf = xmalloc(blocksize); for (i = 0, pos = first_data_block; i < ngroups; i++, pos += blocks_per_group) { uint32_t overhead = has_super(i) ? (1/*sb*/ + gdtsz) : 0; uint32_t start; uint32_t end; // dump superblock and group descriptors and their backups if (overhead) { // N.B. in fact, we want (has_super(i)) condition, but it is equal to (overhead != 0) and is cheaper // N.B. 1024 byte blocks are special PUT(((uint64_t)pos << blocksize_log2) + ((0 == i && 0 == first_data_block) ? 1024 : 0), sb, 1024);//blocksize); PUT(((uint64_t)pos << blocksize_log2) + blocksize, gd, gdtsz * blocksize); } start = overhead + 1/*bbmp*/ + 1/*ibmp*/ + itsz; if (i == 0) start += 2; // for "/" and "/lost+found" end = blocks_per_group - (start + gd[i].bg_free_blocks_count); // mark preallocated blocks as allocated allocate(buf, blocksize, start, end); // dump block bitmap PUT((uint64_t)(pos + overhead) * blocksize, buf, blocksize); // mark preallocated inodes as allocated allocate(buf, blocksize, ninodes_per_group - gd[i].bg_free_inodes_count, blocks_per_group - ninodes_per_group ); // dump inode bitmap //PUT((uint64_t)(pos + overhead + 1) * blocksize, buf, blocksize); //but it's right after block bitmap, so we can just: xwrite(fd, buf, blocksize); } // zero boot sectors memset(buf, 0, blocksize); PUT(0, buf, 1024); // N.B. 1024 <= blocksize // zero inode tables for (i = 0; i < ngroups; ++i) for (n = 0; n < itsz; ++n) PUT((uint64_t)(gd[i].bg_inode_table + n) * blocksize, buf, blocksize); // prepare directory inode inode = (struct ext2_inode *)buf; STORE_LE(inode->i_mode, S_IFDIR | S_IRWXU | S_IRGRP | S_IROTH | S_IXGRP | S_IXOTH); STORE_LE(inode->i_mtime, timestamp); STORE_LE(inode->i_atime, timestamp); STORE_LE(inode->i_ctime, timestamp); STORE_LE(inode->i_size, blocksize); // N.B. inode->i_blocks stores the number of 512 byte data blocks. Why on Earth?! STORE_LE(inode->i_blocks, blocksize / 512); // dump root dir inode STORE_LE(inode->i_links_count, 3); // "/.", "/..", "/lost+found/.." point to this inode STORE_LE(inode->i_block[0], gd[0].bg_inode_table + itsz); PUT(((uint64_t)gd[0].bg_inode_table << blocksize_log2) + (EXT2_ROOT_INO-1) * sizeof(*inode), buf, sizeof(*inode)); // dump lost+found dir inode STORE_LE(inode->i_links_count, 2); // both "/lost+found" and "/lost+found/." point to this inode STORE_LE(inode->i_block[0], inode->i_block[0]+1); // use next block //= gd[0].bg_inode_table + itsz + 1; PUT(((uint64_t)gd[0].bg_inode_table << blocksize_log2) + (EXT2_GOOD_OLD_FIRST_INO-1) * sizeof(*inode), buf, sizeof(*inode)); // dump directories memset(buf, 0, blocksize); dir = (struct ext2_dir *)buf; // dump lost+found dir block STORE_LE(dir->inode1, EXT2_GOOD_OLD_FIRST_INO); STORE_LE(dir->rec_len1, 12); STORE_LE(dir->name_len1, 1); STORE_LE(dir->file_type1, EXT2_FT_DIR); dir->name1[0] = '.'; STORE_LE(dir->inode2, EXT2_ROOT_INO); STORE_LE(dir->rec_len2, blocksize - 12); STORE_LE(dir->name_len2, 2); STORE_LE(dir->file_type2, EXT2_FT_DIR); dir->name2[0] = '.'; dir->name2[1] = '.'; PUT((uint64_t)(gd[0].bg_inode_table + itsz + 1) * blocksize, buf, blocksize); // dump root dir block STORE_LE(dir->inode1, EXT2_ROOT_INO); STORE_LE(dir->rec_len2, 12); STORE_LE(dir->inode3, EXT2_GOOD_OLD_FIRST_INO); STORE_LE(dir->rec_len3, blocksize - 12 - 12); STORE_LE(dir->name_len3, 10); STORE_LE(dir->file_type3, EXT2_FT_DIR); strcpy(dir->name3, "lost+found"); PUT((uint64_t)(gd[0].bg_inode_table + itsz + 0) * blocksize, buf, blocksize); // bb_info_msg("done\n" // "This filesystem will be automatically checked every %u mounts or\n" // "180 days, whichever comes first. Use tune2fs -c or -i to override.", // sb->s_max_mnt_count // ); done: // cleanup if (ENABLE_FEATURE_CLEAN_UP) { free(buf); free(gd); free(sb); } xclose(fd); return EXIT_SUCCESS; }