--- /dev/null
+/* 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;
+}
projects / oweals / busybox.git / commitdiff