diff options
Diffstat (limited to 'util-linux/mkfs_ext2.c')
| -rw-r--r-- | util-linux/mkfs_ext2.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/util-linux/mkfs_ext2.c b/util-linux/mkfs_ext2.c new file mode 100644 index 000000000..0f5e0148f --- /dev/null +++ b/util-linux/mkfs_ext2.c @@ -0,0 +1,479 @@ +/* vi: set sw=4 ts=4: */ +/* + * mkfs_ext2: utility to create EXT2 filesystem + * inspired by genext2fs + * + * Busybox'ed (2009) by Vladimir Dronnikov <dronnikov@gmail.com> + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ +#include "libbb.h" +#include <linux/fs.h> +#include <linux/ext2_fs.h> +#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 inline int int_log2(int arg) +{ + int r = 0; + while ((arg >>= 1) != 0) + r++; + return r; +} + +// taken from mkfs_minix.c. libbb candidate? +static ALWAYS_INLINE unsigned div_roundup(uint32_t size, uint32_t n) +{ + return (size + n-1) / n; +} + +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! +} + +#if 0 +// TODO: get rid of FPU +static bool is_power_of(uint32_t x, uint16_t n) +{ +// return (!(x % n) && is_power_of(x / n, n)); + double z = logf(x)/logf(n); + return (z == (int)z); +} + +static bool has_super(uint32_t x) +{ + return (0 == x || 1 == x || is_power_of(x, 3) || is_power_of(x, 5) || is_power_of(x, 7)); +} + +#else + +static bool has_super(uint32_t x) +{ + 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 */, + }; + for (int i = sizeof(supers)/sizeof(supers[0]); --i >= 0; ) + if (x == supers[i]) + return 1; + return 0; +} +#endif + +/* 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, + 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) +{ + if (!(option_mask32 & OPT_n)) { + 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, blocksize; + unsigned nreserved = 5; + uint32_t nblocks; + uint32_t ngroups; + unsigned bytes_per_inode; + uint32_t nblocks_per_group; + uint32_t first_data_block; + uint32_t ninodes; + uint32_t ninodes_per_group; + uint32_t gdtsz, rgdtsz, 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; + + bs = EXT2_MIN_BLOCK_SIZE; + 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, &bytes_per_inode, NULL, NULL, NULL, NULL, + &nreserved, NULL, NULL, &label, NULL, NULL, NULL, NULL, NULL, NULL); + argv += optind; // argv[0] -- device + + // block size minimax, block size is a multiple of minimum + 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("-%c is bad", 'b'); + } + + // reserved blocks count + if (nreserved > 50) + bb_error_msg_and_die("-%c is bad", 'm'); + + // check the device is a block device + xstat(argv[0], &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"); + + // 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: 0/5 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 = int_log2(blocksize >> 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 + first_data_block = sb->s_first_data_block = (EXT2_MIN_BLOCK_SIZE == blocksize); + // block and inode bitmaps occupy no more than one block, so maximum number of blocks is + // number of bits in one block, i.e. 8*blocksize + nblocks_per_group = sb->s_blocks_per_group = sb->s_frags_per_group = sb->s_inodes_per_group = 8*blocksize; + 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_max_mnt_count = EXT2_DFL_MAX_MNT_COUNT; + 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); +#endif + /* + * 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. + */ + for (i = 0, n = 0; i < sizeof(sb->s_uuid); i++) + n += sb->s_uuid[i]; + sb->s_max_mnt_count += n % EXT2_DFL_MAX_MNT_COUNT; + + // open the device, get number of blocks + xmove_fd(xopen3(argv[0], O_WRONLY | O_CREAT, 0666), fd); + if (argv[1]) { + nblocks = xatou(argv[1]); + } else { + nblocks = ((uoff_t)xlseek(fd, 0, SEEK_END)) / blocksize; + xlseek(fd, 0, SEEK_SET); + } + sb->s_blocks_count = nblocks; + + // nblocks is the total number of blocks in the filesystem + if (nblocks < 8) + bb_error_msg_and_die("nblocks"); + // reserve blocks for superuser + sb->s_r_blocks_count = ((uint64_t) nblocks * nreserved) / 100; + + // N.B. a block group can have no more than nblocks_per_group blocks + ngroups = div_roundup(nblocks - first_data_block, nblocks_per_group); + if (0 == ngroups) + bb_error_msg_and_die("ngroups"); + 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 + rgdtsz = 0xFFFFFFFF; // maximum block number + if (nblocks < rgdtsz / 1024) + rgdtsz = nblocks * 1024; + rgdtsz = div_roundup(rgdtsz - first_data_block, nblocks_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); + sb->s_reserved_gdt_blocks = rgdtsz; + //bb_info_msg("RSRVD[%u]", n); +#else + rgdtsz = 0; +#endif + + // ninodes is the total number of inodes (files) in the file system + if (!(opts & OPT_i)) { + bytes_per_inode = 16384; + if (nblocks < 512*1024) + bytes_per_inode = 4096; + if (nblocks < 3*1024) + bytes_per_inode = 8192; + } + ninodes = nblocks / (bytes_per_inode / blocksize); + if (ninodes < EXT2_GOOD_OLD_FIRST_INO+1) + ninodes = EXT2_GOOD_OLD_FIRST_INO+1; + ninodes_per_group = div_roundup(ninodes, ngroups); + if (ninodes_per_group < 16) + ninodes_per_group = 16; // minimum number because the first 10 are reserved + // N.B. a block group can have no more than 8*blocksize = sb->s_inodes_per_group inodes + if (ninodes_per_group > sb->s_inodes_per_group) + ninodes_per_group = sb->s_inodes_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) / 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 + 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)); + + // fill group descriptors + gd = xzalloc((gdtsz + rgdtsz) * blocksize); + sb->s_free_blocks_count = 0; + for (i = 0, pos = first_data_block, n = nblocks; + i < ngroups; + i++, pos += nblocks_per_group, n -= nblocks_per_group + ) { + uint32_t overhead = pos + has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); + 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; + // N.B. both root and lost+found dirs are within the first block group, thus +2 + //gd[i].bg_used_dirs_count = 0; + 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 < nblocks_per_group ? n : nblocks_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 + buf = xmalloc(blocksize); + for (i = 0, pos = first_data_block; i < ngroups; i++, pos += nblocks_per_group) { + uint32_t overhead = has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); + uint32_t start;// = has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); + 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 +//bb_info_msg("SUPER@[%d]", pos); + // N.B. 1024 byte blocks are special + PUT(blocksize * pos + 1024 * (0 == i && 0 == first_data_block), sb, blocksize); + PUT(blocksize * pos + blocksize, gd, (gdtsz + rgdtsz) * blocksize); + } + + start = overhead + 1/*bbmp*/ + 1/*ibmp*/ + itsz + (0 == i) * 2; // +2: /, /lost+found + end = nblocks_per_group - (start + gd[i].bg_free_blocks_count); + // mark preallocated blocks as allocated + allocate(buf, blocksize, start, end); + // dump block bitmap + PUT((pos + overhead) * blocksize, buf, blocksize); + + // mark preallocated inodes as allocated + allocate(buf, blocksize, + ninodes_per_group - gd[i].bg_free_inodes_count, + 8*blocksize - ninodes_per_group + ); + // dump inode bitmap + PUT((pos + overhead + 1) * blocksize, 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((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); + inode->i_mtime = 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(gd[0].bg_inode_table * blocksize + (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(gd[0].bg_inode_table * blocksize + (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((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((gd[0].bg_inode_table + itsz + 0) * blocksize, buf, blocksize); + + // cleanup + if (ENABLE_FEATURE_CLEAN_UP) { + free(buf); + free(gd); + free(sb); + close(fd); + } + + return EXIT_SUCCESS; +} |