ext4_utils/make_ext4fs.c - platform/system/extras - Git at Google

 /*
  * Copyright (C) 2010 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "make_ext4fs.h"
 #include "ext4_utils.h"
 #include "allocate.h"
 #include "contents.h"
 #include "uuid.h"
 #include "wipe.h"

 #include <sparse/sparse.h>

 #include <assert.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/types.h>

 #ifdef USE_MINGW

 #include <winsock2.h>

 /* These match the Linux definitions of these flags.
    L_xx is defined to avoid conflicting with the win32 versions.
 */
 #define L_S_IRUSR 00400
 #define L_S_IWUSR 00200
 #define L_S_IXUSR 00100
 #define S_IRWXU (L_S_IRUSR | L_S_IWUSR | L_S_IXUSR)
 #define S_IRGRP 00040
 #define S_IWGRP 00020
 #define S_IXGRP 00010
 #define S_IRWXG (S_IRGRP | S_IWGRP | S_IXGRP)
 #define S_IROTH 00004
 #define S_IWOTH 00002
 #define S_IXOTH 00001
 #define S_IRWXO (S_IROTH | S_IWOTH | S_IXOTH)
 #define S_ISUID 0004000
 #define S_ISGID 0002000
 #define S_ISVTX 0001000

 #else

 #define O_BINARY 0

 #endif

 /* TODO: Not implemented:
    Allocating blocks in the same block group as the file inode
    Hash or binary tree directories
    Special files: sockets, devices, fifos
  */

 static int filter_dot(const struct dirent *d)
 {
 	return (strcmp(d->d_name, "..") && strcmp(d->d_name, "."));
 }

 static u32 build_default_directory_structure()
 {
 	u32 inode;
 	u32 root_inode;
 	struct dentry dentries = {
 			.filename = "lost+found",
 			.file_type = EXT4_FT_DIR,
 			.mode = S_IRWXU,
 			.uid = 0,
 			.gid = 0,
 			.mtime = 0,
 	};
 	root_inode = make_directory(0, 1, &dentries, 1);
 	inode = make_directory(root_inode, 0, NULL, 0);
 	*dentries.inode = inode;
 	inode_set_permissions(inode, dentries.mode,
 		dentries.uid, dentries.gid, dentries.mtime);

 	return root_inode;
 }

 #ifndef USE_MINGW
 /* Read a local directory and create the same tree in the generated filesystem.
    Calls itself recursively with each directory in the given directory */
 static u32 build_directory_structure(const char *full_path, const char *dir_path,
 		u32 dir_inode, fs_config_func_t fs_config_func,
 		struct selabel_handle *sehnd)
 {
 	int entries = 0;
 	struct dentry *dentries;
 	struct dirent **namelist;
 	struct stat stat;
 	int ret;
 	int i;
 	u32 inode;
 	u32 entry_inode;
 	u32 dirs = 0;

 	entries = scandir(full_path, &namelist, filter_dot, (void*)alphasort);
 	if (entries < 0) {
 		error_errno("scandir");
 		return EXT4_ALLOCATE_FAILED;
 	}

 	dentries = calloc(entries, sizeof(struct dentry));
 	if (dentries == NULL)
 		critical_error_errno("malloc");

 	for (i = 0; i < entries; i++) {
 		dentries[i].filename = strdup(namelist[i]->d_name);
 		if (dentries[i].filename == NULL)
 			critical_error_errno("strdup");

 		asprintf(&dentries[i].path, "%s/%s", dir_path, namelist[i]->d_name);
 		asprintf(&dentries[i].full_path, "%s/%s", full_path, namelist[i]->d_name);

 		free(namelist[i]);

 		ret = lstat(dentries[i].full_path, &stat);
 		if (ret < 0) {
 			error_errno("lstat");
 			i--;
 			entries--;
 			continue;
 		}

 		dentries[i].size = stat.st_size;
 		dentries[i].mode = stat.st_mode & (S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO);
 		dentries[i].mtime = stat.st_mtime;
 		if (fs_config_func != NULL) {
 #ifdef ANDROID
 			unsigned int mode = 0;
 			unsigned int uid = 0;
 			unsigned int gid = 0;
 			int dir = S_ISDIR(stat.st_mode);
 			fs_config_func(dentries[i].path, dir, &uid, &gid, &mode);
 			dentries[i].mode = mode;
 			dentries[i].uid = uid;
 			dentries[i].gid = gid;
 #else
 			error("can't set android permissions - built without android support");
 #endif
 		}
 #ifdef HAVE_SELINUX
 		if (sehnd) {
 			char *sepath = NULL;
 			asprintf(&sepath, "/%s", dentries[i].path);
 			if (selabel_lookup(sehnd, &dentries[i].secon, sepath, stat.st_mode) < 0) {
 				error("cannot lookup security context for %s", sepath);
 			}
 			if (dentries[i].secon)
 				printf("Labeling %s as %s\n", sepath, dentries[i].secon);
 			free(sepath);
 		}
 #endif

 		if (S_ISREG(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_REG_FILE;
 		} else if (S_ISDIR(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_DIR;
 			dirs++;
 		} else if (S_ISCHR(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_CHRDEV;
 		} else if (S_ISBLK(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_BLKDEV;
 		} else if (S_ISFIFO(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_FIFO;
 		} else if (S_ISSOCK(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_SOCK;
 		} else if (S_ISLNK(stat.st_mode)) {
 			dentries[i].file_type = EXT4_FT_SYMLINK;
 			dentries[i].link = calloc(info.block_size, 1);
 			readlink(dentries[i].full_path, dentries[i].link, info.block_size - 1);
 		} else {
 			error("unknown file type on %s", dentries[i].path);
 			i--;
 			entries--;
 		}
 	}
 	free(namelist);

 	inode = make_directory(dir_inode, entries, dentries, dirs);

 	for (i = 0; i < entries; i++) {
 		if (dentries[i].file_type == EXT4_FT_REG_FILE) {
 			entry_inode = make_file(dentries[i].full_path, dentries[i].size);
 		} else if (dentries[i].file_type == EXT4_FT_DIR) {
 			entry_inode = build_directory_structure(dentries[i].full_path,
 					dentries[i].path, inode, fs_config_func, sehnd);
 		} else if (dentries[i].file_type == EXT4_FT_SYMLINK) {
 			entry_inode = make_link(dentries[i].full_path, dentries[i].link);
 		} else {
 			error("unknown file type on %s", dentries[i].path);
 			entry_inode = 0;
 		}
 		*dentries[i].inode = entry_inode;

 		ret = inode_set_permissions(entry_inode, dentries[i].mode,
 			dentries[i].uid, dentries[i].gid,
 			dentries[i].mtime);
 		if (ret)
 			error("failed to set permissions on %s\n", dentries[i].path);
 		ret = inode_set_selinux(entry_inode, dentries[i].secon);
 		if (ret)
 			error("failed to set SELinux context on %s\n", dentries[i].path);

 		free(dentries[i].path);
 		free(dentries[i].full_path);
 		free(dentries[i].link);
 		free((void *)dentries[i].filename);
 		free(dentries[i].secon);
 	}

 	free(dentries);
 	return inode;
 }
 #endif

 static u32 compute_block_size()
 {
 	return 4096;
 }

 static u32 compute_journal_blocks()
 {
 	u32 journal_blocks = DIV_ROUND_UP(info.len, info.block_size) / 64;
 	if (journal_blocks < 1024)
 		journal_blocks = 1024;
 	if (journal_blocks > 32768)
 		journal_blocks = 32768;
 	return journal_blocks;
 }

 static u32 compute_blocks_per_group()
 {
 	return info.block_size * 8;
 }

 static u32 compute_inodes()
 {
 	return DIV_ROUND_UP(info.len, info.block_size) / 4;
 }

 static u32 compute_inodes_per_group()
 {
 	u32 blocks = DIV_ROUND_UP(info.len, info.block_size);
 	u32 block_groups = DIV_ROUND_UP(blocks, info.blocks_per_group);
 	u32 inodes = DIV_ROUND_UP(info.inodes, block_groups);
 	inodes = ALIGN(inodes, (info.block_size / info.inode_size));

 	/* After properly rounding up the number of inodes/group,
 	 * make sure to update the total inodes field in the info struct.
 	 */
 	info.inodes = inodes * block_groups;

 	return inodes;
 }

 static u32 compute_bg_desc_reserve_blocks()
 {
 	u32 blocks = DIV_ROUND_UP(info.len, info.block_size);
 	u32 block_groups = DIV_ROUND_UP(blocks, info.blocks_per_group);
 	u32 bg_desc_blocks = DIV_ROUND_UP(block_groups * sizeof(struct ext2_group_desc),
 			info.block_size);

 	u32 bg_desc_reserve_blocks =
 			DIV_ROUND_UP(block_groups * 1024 * sizeof(struct ext2_group_desc),
 					info.block_size) - bg_desc_blocks;

 	if (bg_desc_reserve_blocks > info.block_size / sizeof(u32))
 		bg_desc_reserve_blocks = info.block_size / sizeof(u32);

 	return bg_desc_reserve_blocks;
 }

 void reset_ext4fs_info() {
     // Reset all the global data structures used by make_ext4fs so it
     // can be called again.
     memset(&info, 0, sizeof(info));
     memset(&aux_info, 0, sizeof(aux_info));

     if (info.sparse_file) {
         sparse_file_destroy(info.sparse_file);
         info.sparse_file = NULL;
     }
 }

 int make_ext4fs(const char *filename, s64 len,
                 const char *mountpoint, struct selabel_handle *sehnd)
 {
 	int fd;
 	int status;

 	reset_ext4fs_info();
 	info.len = len;

 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
 	if (fd < 0) {
 		error_errno("open");
 		return EXIT_FAILURE;
 	}

 	status = make_ext4fs_internal(fd, NULL, mountpoint, NULL, 0, 0, 0, 1, 0, sehnd);
 	close(fd);

 	return status;
 }

 int make_ext4fs_internal(int fd, const char *directory,
                          const char *mountpoint, fs_config_func_t fs_config_func, int gzip,
                          int sparse, int crc, int wipe, int init_itabs,
                          struct selabel_handle *sehnd)
 {
 	u32 root_inode_num;
 	u16 root_mode;

 	if (setjmp(setjmp_env))
 		return EXIT_FAILURE; /* Handle a call to longjmp() */

 	if (info.len <= 0)
 		info.len = get_file_size(fd);

 	if (info.len <= 0) {
 		fprintf(stderr, "Need size of filesystem\n");
 		return EXIT_FAILURE;
 	}

 	if (info.block_size <= 0)
 		info.block_size = compute_block_size();

 	/* Round down the filesystem length to be a multiple of the block size */
 	info.len &= ~((u64)info.block_size - 1);

 	if (info.journal_blocks == 0)
 		info.journal_blocks = compute_journal_blocks();

 	if (info.no_journal == 0)
 		info.feat_compat = EXT4_FEATURE_COMPAT_HAS_JOURNAL;
 	else
 		info.journal_blocks = 0;

 	if (info.blocks_per_group <= 0)
 		info.blocks_per_group = compute_blocks_per_group();

 	if (info.inodes <= 0)
 		info.inodes = compute_inodes();

 	if (info.inode_size <= 0)
 		info.inode_size = 256;

 	if (info.label == NULL)
 		info.label = "";

 	info.inodes_per_group = compute_inodes_per_group();

 	info.feat_compat |=
 			EXT4_FEATURE_COMPAT_RESIZE_INODE;

 	info.feat_ro_compat |=
 			EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER |
 			EXT4_FEATURE_RO_COMPAT_LARGE_FILE;

 	info.feat_incompat |=
 			EXT4_FEATURE_INCOMPAT_EXTENTS |
 			EXT4_FEATURE_INCOMPAT_FILETYPE;


 	info.bg_desc_reserve_blocks = compute_bg_desc_reserve_blocks();

 	printf("Creating filesystem with parameters:\n");
 	printf("    Size: %llu\n", info.len);
 	printf("    Block size: %d\n", info.block_size);
 	printf("    Blocks per group: %d\n", info.blocks_per_group);
 	printf("    Inodes per group: %d\n", info.inodes_per_group);
 	printf("    Inode size: %d\n", info.inode_size);
 	printf("    Journal blocks: %d\n", info.journal_blocks);
 	printf("    Label: %s\n", info.label);

 	ext4_create_fs_aux_info();

 	printf("    Blocks: %llu\n", aux_info.len_blocks);
 	printf("    Block groups: %d\n", aux_info.groups);
 	printf("    Reserved block group size: %d\n", info.bg_desc_reserve_blocks);

 	info.sparse_file = sparse_file_new(info.block_size, info.len);

 	block_allocator_init();

 	ext4_fill_in_sb();

 	if (reserve_inodes(0, 10) == EXT4_ALLOCATE_FAILED)
 		error("failed to reserve first 10 inodes");

 	if (info.feat_compat & EXT4_FEATURE_COMPAT_HAS_JOURNAL)
 		ext4_create_journal_inode();

 	if (info.feat_compat & EXT4_FEATURE_COMPAT_RESIZE_INODE)
 		ext4_create_resize_inode();

 #ifdef USE_MINGW
 	// Windows needs only 'create an empty fs image' functionality
 	assert(!directory);
 	root_inode_num = build_default_directory_structure();
 #else
 	if (directory)
 		root_inode_num = build_directory_structure(directory, mountpoint, 0,
                         fs_config_func, sehnd);
 	else
 		root_inode_num = build_default_directory_structure();
 #endif

 	root_mode = S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH;
 	inode_set_permissions(root_inode_num, root_mode, 0, 0, 0);

 #ifdef HAVE_SELINUX
 	if (sehnd) {
 		char *sepath = NULL;
 		char *secontext = NULL;

 		if (mountpoint[0] == '/')
 			sepath = strdup(mountpoint);
 		else
 			asprintf(&sepath, "/%s", mountpoint);
 		if (!sepath)
 			critical_error_errno("malloc");
 		if (selabel_lookup(sehnd, &secontext, sepath, S_IFDIR) < 0) {
 			error("cannot lookup security context for %s", sepath);
 		}
 		if (secontext) {
 			printf("Labeling %s as %s\n", sepath, secontext);
 			inode_set_selinux(root_inode_num, secontext);
 		}
 		free(sepath);
 		freecon(secontext);
 	}
 #endif

 	ext4_update_free();

 	if (init_itabs)
 		init_unused_inode_tables();

 	ext4_queue_sb();

 	printf("Created filesystem with %d/%d inodes and %d/%d blocks\n",
 			aux_info.sb->s_inodes_count - aux_info.sb->s_free_inodes_count,
 			aux_info.sb->s_inodes_count,
 			aux_info.sb->s_blocks_count_lo - aux_info.sb->s_free_blocks_count_lo,
 			aux_info.sb->s_blocks_count_lo);

 	if (wipe)
 		wipe_block_device(fd, info.len);

 	write_ext4_image(fd, gzip, sparse, crc);

 	sparse_file_destroy(info.sparse_file);
 	info.sparse_file = NULL;

 	return 0;
 }
	/*
	* Copyright (C) 2010 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "make_ext4fs.h"
	#include "ext4_utils.h"
	#include "allocate.h"
	#include "contents.h"
	#include "uuid.h"
	#include "wipe.h"

	#include <sparse/sparse.h>

	#include <assert.h>
	#include <dirent.h>
	#include <fcntl.h>
	#include <libgen.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>
	#include <sys/stat.h>
	#include <sys/types.h>

	#ifdef USE_MINGW

	#include <winsock2.h>

	/* These match the Linux definitions of these flags.
	L_xx is defined to avoid conflicting with the win32 versions.
	*/
	#define L_S_IRUSR 00400
	#define L_S_IWUSR 00200
	#define L_S_IXUSR 00100
	#define S_IRWXU (L_S_IRUSR \| L_S_IWUSR \| L_S_IXUSR)
	#define S_IRGRP 00040
	#define S_IWGRP 00020
	#define S_IXGRP 00010
	#define S_IRWXG (S_IRGRP \| S_IWGRP \| S_IXGRP)
	#define S_IROTH 00004
	#define S_IWOTH 00002
	#define S_IXOTH 00001
	#define S_IRWXO (S_IROTH \| S_IWOTH \| S_IXOTH)
	#define S_ISUID 0004000
	#define S_ISGID 0002000
	#define S_ISVTX 0001000

	#else

	#define O_BINARY 0

	#endif

	/* TODO: Not implemented:
	Allocating blocks in the same block group as the file inode
	Hash or binary tree directories
	Special files: sockets, devices, fifos
	*/

	static int filter_dot(const struct dirent *d)
	{
	return (strcmp(d->d_name, "..") && strcmp(d->d_name, "."));
	}

	static u32 build_default_directory_structure()
	{
	u32 inode;
	u32 root_inode;
	struct dentry dentries = {
	.filename = "lost+found",
	.file_type = EXT4_FT_DIR,
	.mode = S_IRWXU,
	.uid = 0,
	.gid = 0,
	.mtime = 0,
	};
	root_inode = make_directory(0, 1, &dentries, 1);
	inode = make_directory(root_inode, 0, NULL, 0);
	*dentries.inode = inode;
	inode_set_permissions(inode, dentries.mode,
	dentries.uid, dentries.gid, dentries.mtime);

	return root_inode;
	}

	#ifndef USE_MINGW
	/* Read a local directory and create the same tree in the generated filesystem.
	Calls itself recursively with each directory in the given directory */
	static u32 build_directory_structure(const char full_path, const char dir_path,
	u32 dir_inode, fs_config_func_t fs_config_func,
	struct selabel_handle *sehnd)
	{
	int entries = 0;
	struct dentry *dentries;
	struct dirent **namelist;
	struct stat stat;
	int ret;
	int i;
	u32 inode;
	u32 entry_inode;
	u32 dirs = 0;

	entries = scandir(full_path, &namelist, filter_dot, (void*)alphasort);
	if (entries < 0) {
	error_errno("scandir");
	return EXT4_ALLOCATE_FAILED;
	}

	dentries = calloc(entries, sizeof(struct dentry));
	if (dentries == NULL)
	critical_error_errno("malloc");

	for (i = 0; i < entries; i++) {
	dentries[i].filename = strdup(namelist[i]->d_name);
	if (dentries[i].filename == NULL)
	critical_error_errno("strdup");

	asprintf(&dentries[i].path, "%s/%s", dir_path, namelist[i]->d_name);
	asprintf(&dentries[i].full_path, "%s/%s", full_path, namelist[i]->d_name);

	free(namelist[i]);

	ret = lstat(dentries[i].full_path, &stat);
	if (ret < 0) {
	error_errno("lstat");
	i--;
	entries--;
	continue;
	}

	dentries[i].size = stat.st_size;
	dentries[i].mode = stat.st_mode & (S_ISUID\|S_ISGID\|S_ISVTX\|S_IRWXU\|S_IRWXG\|S_IRWXO);
	dentries[i].mtime = stat.st_mtime;
	if (fs_config_func != NULL) {
	#ifdef ANDROID
	unsigned int mode = 0;
	unsigned int uid = 0;
	unsigned int gid = 0;
	int dir = S_ISDIR(stat.st_mode);
	fs_config_func(dentries[i].path, dir, &uid, &gid, &mode);
	dentries[i].mode = mode;
	dentries[i].uid = uid;
	dentries[i].gid = gid;
	#else
	error("can't set android permissions - built without android support");
	#endif
	}
	#ifdef HAVE_SELINUX
	if (sehnd) {
	char *sepath = NULL;
	asprintf(&sepath, "/%s", dentries[i].path);
	if (selabel_lookup(sehnd, &dentries[i].secon, sepath, stat.st_mode) < 0) {
	error("cannot lookup security context for %s", sepath);
	}
	if (dentries[i].secon)
	printf("Labeling %s as %s\n", sepath, dentries[i].secon);
	free(sepath);
	}
	#endif

	if (S_ISREG(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_REG_FILE;
	} else if (S_ISDIR(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_DIR;
	dirs++;
	} else if (S_ISCHR(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_CHRDEV;
	} else if (S_ISBLK(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_BLKDEV;
	} else if (S_ISFIFO(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_FIFO;
	} else if (S_ISSOCK(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_SOCK;
	} else if (S_ISLNK(stat.st_mode)) {
	dentries[i].file_type = EXT4_FT_SYMLINK;
	dentries[i].link = calloc(info.block_size, 1);
	readlink(dentries[i].full_path, dentries[i].link, info.block_size - 1);
	} else {
	error("unknown file type on %s", dentries[i].path);
	i--;
	entries--;
	}
	}
	free(namelist);

	inode = make_directory(dir_inode, entries, dentries, dirs);

	for (i = 0; i < entries; i++) {
	if (dentries[i].file_type == EXT4_FT_REG_FILE) {
	entry_inode = make_file(dentries[i].full_path, dentries[i].size);
	} else if (dentries[i].file_type == EXT4_FT_DIR) {
	entry_inode = build_directory_structure(dentries[i].full_path,
	dentries[i].path, inode, fs_config_func, sehnd);
	} else if (dentries[i].file_type == EXT4_FT_SYMLINK) {
	entry_inode = make_link(dentries[i].full_path, dentries[i].link);
	} else {
	error("unknown file type on %s", dentries[i].path);
	entry_inode = 0;
	}
	*dentries[i].inode = entry_inode;

	ret = inode_set_permissions(entry_inode, dentries[i].mode,
	dentries[i].uid, dentries[i].gid,
	dentries[i].mtime);
	if (ret)
	error("failed to set permissions on %s\n", dentries[i].path);
	ret = inode_set_selinux(entry_inode, dentries[i].secon);
	if (ret)
	error("failed to set SELinux context on %s\n", dentries[i].path);

	free(dentries[i].path);
	free(dentries[i].full_path);
	free(dentries[i].link);
	free((void *)dentries[i].filename);
	free(dentries[i].secon);
	}

	free(dentries);
	return inode;
	}
	#endif

	static u32 compute_block_size()
	{
	return 4096;
	}

	static u32 compute_journal_blocks()
	{
	u32 journal_blocks = DIV_ROUND_UP(info.len, info.block_size) / 64;
	if (journal_blocks < 1024)
	journal_blocks = 1024;
	if (journal_blocks > 32768)
	journal_blocks = 32768;
	return journal_blocks;
	}

	static u32 compute_blocks_per_group()
	{
	return info.block_size * 8;
	}

	static u32 compute_inodes()
	{
	return DIV_ROUND_UP(info.len, info.block_size) / 4;
	}

	static u32 compute_inodes_per_group()
	{
	u32 blocks = DIV_ROUND_UP(info.len, info.block_size);
	u32 block_groups = DIV_ROUND_UP(blocks, info.blocks_per_group);
	u32 inodes = DIV_ROUND_UP(info.inodes, block_groups);
	inodes = ALIGN(inodes, (info.block_size / info.inode_size));

	/* After properly rounding up the number of inodes/group,
	* make sure to update the total inodes field in the info struct.
	*/
	info.inodes = inodes * block_groups;

	return inodes;
	}

	static u32 compute_bg_desc_reserve_blocks()
	{
	u32 blocks = DIV_ROUND_UP(info.len, info.block_size);
	u32 block_groups = DIV_ROUND_UP(blocks, info.blocks_per_group);
	u32 bg_desc_blocks = DIV_ROUND_UP(block_groups * sizeof(struct ext2_group_desc),
	info.block_size);

	u32 bg_desc_reserve_blocks =
	DIV_ROUND_UP(block_groups * 1024 * sizeof(struct ext2_group_desc),
	info.block_size) - bg_desc_blocks;

	if (bg_desc_reserve_blocks > info.block_size / sizeof(u32))
	bg_desc_reserve_blocks = info.block_size / sizeof(u32);

	return bg_desc_reserve_blocks;
	}

	void reset_ext4fs_info() {
	// Reset all the global data structures used by make_ext4fs so it
	// can be called again.
	memset(&info, 0, sizeof(info));
	memset(&aux_info, 0, sizeof(aux_info));

	if (info.sparse_file) {
	sparse_file_destroy(info.sparse_file);
	info.sparse_file = NULL;
	}
	}

	int make_ext4fs(const char *filename, s64 len,
	const char mountpoint, struct selabel_handle sehnd)
	{
	int fd;
	int status;

	reset_ext4fs_info();
	info.len = len;

	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC \| O_BINARY, 0644);
	if (fd < 0) {
	error_errno("open");
	return EXIT_FAILURE;
	}

	status = make_ext4fs_internal(fd, NULL, mountpoint, NULL, 0, 0, 0, 1, 0, sehnd);
	close(fd);

	return status;
	}

	int make_ext4fs_internal(int fd, const char *directory,
	const char *mountpoint, fs_config_func_t fs_config_func, int gzip,
	int sparse, int crc, int wipe, int init_itabs,
	struct selabel_handle *sehnd)
	{
	u32 root_inode_num;
	u16 root_mode;

	if (setjmp(setjmp_env))
	return EXIT_FAILURE; /* Handle a call to longjmp() */

	if (info.len <= 0)
	info.len = get_file_size(fd);

	if (info.len <= 0) {
	fprintf(stderr, "Need size of filesystem\n");
	return EXIT_FAILURE;
	}

	if (info.block_size <= 0)
	info.block_size = compute_block_size();

	/* Round down the filesystem length to be a multiple of the block size */
	info.len &= ~((u64)info.block_size - 1);

	if (info.journal_blocks == 0)
	info.journal_blocks = compute_journal_blocks();

	if (info.no_journal == 0)
	info.feat_compat = EXT4_FEATURE_COMPAT_HAS_JOURNAL;
	else
	info.journal_blocks = 0;

	if (info.blocks_per_group <= 0)
	info.blocks_per_group = compute_blocks_per_group();

	if (info.inodes <= 0)
	info.inodes = compute_inodes();

	if (info.inode_size <= 0)
	info.inode_size = 256;

	if (info.label == NULL)
	info.label = "";

	info.inodes_per_group = compute_inodes_per_group();

	info.feat_compat \|=
	EXT4_FEATURE_COMPAT_RESIZE_INODE;

	info.feat_ro_compat \|=
	EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER \|
	EXT4_FEATURE_RO_COMPAT_LARGE_FILE;

	info.feat_incompat \|=
	EXT4_FEATURE_INCOMPAT_EXTENTS \|
	EXT4_FEATURE_INCOMPAT_FILETYPE;


	info.bg_desc_reserve_blocks = compute_bg_desc_reserve_blocks();

	printf("Creating filesystem with parameters:\n");
	printf(" Size: %llu\n", info.len);
	printf(" Block size: %d\n", info.block_size);
	printf(" Blocks per group: %d\n", info.blocks_per_group);
	printf(" Inodes per group: %d\n", info.inodes_per_group);
	printf(" Inode size: %d\n", info.inode_size);
	printf(" Journal blocks: %d\n", info.journal_blocks);
	printf(" Label: %s\n", info.label);

	ext4_create_fs_aux_info();

	printf(" Blocks: %llu\n", aux_info.len_blocks);
	printf(" Block groups: %d\n", aux_info.groups);
	printf(" Reserved block group size: %d\n", info.bg_desc_reserve_blocks);

	info.sparse_file = sparse_file_new(info.block_size, info.len);

	block_allocator_init();

	ext4_fill_in_sb();

	if (reserve_inodes(0, 10) == EXT4_ALLOCATE_FAILED)
	error("failed to reserve first 10 inodes");

	if (info.feat_compat & EXT4_FEATURE_COMPAT_HAS_JOURNAL)
	ext4_create_journal_inode();

	if (info.feat_compat & EXT4_FEATURE_COMPAT_RESIZE_INODE)
	ext4_create_resize_inode();

	#ifdef USE_MINGW
	// Windows needs only 'create an empty fs image' functionality
	assert(!directory);
	root_inode_num = build_default_directory_structure();
	#else
	if (directory)
	root_inode_num = build_directory_structure(directory, mountpoint, 0,
	fs_config_func, sehnd);
	else
	root_inode_num = build_default_directory_structure();
	#endif

	root_mode = S_IRWXU \| S_IRGRP \| S_IXGRP \| S_IROTH \| S_IXOTH;
	inode_set_permissions(root_inode_num, root_mode, 0, 0, 0);

	#ifdef HAVE_SELINUX
	if (sehnd) {
	char *sepath = NULL;
	char *secontext = NULL;

	if (mountpoint[0] == '/')
	sepath = strdup(mountpoint);
	else
	asprintf(&sepath, "/%s", mountpoint);
	if (!sepath)
	critical_error_errno("malloc");
	if (selabel_lookup(sehnd, &secontext, sepath, S_IFDIR) < 0) {
	error("cannot lookup security context for %s", sepath);
	}
	if (secontext) {
	printf("Labeling %s as %s\n", sepath, secontext);
	inode_set_selinux(root_inode_num, secontext);
	}
	free(sepath);
	freecon(secontext);
	}
	#endif

	ext4_update_free();

	if (init_itabs)
	init_unused_inode_tables();

	ext4_queue_sb();

	printf("Created filesystem with %d/%d inodes and %d/%d blocks\n",
	aux_info.sb->s_inodes_count - aux_info.sb->s_free_inodes_count,
	aux_info.sb->s_inodes_count,
	aux_info.sb->s_blocks_count_lo - aux_info.sb->s_free_blocks_count_lo,
	aux_info.sb->s_blocks_count_lo);

	if (wipe)
	wipe_block_device(fd, info.len);

	write_ext4_image(fd, gzip, sparse, crc);

	sparse_file_destroy(info.sparse_file);
	info.sparse_file = NULL;

	return 0;
	}