libblkid/ext.c - android_bootable_recovery - Gitiles

 /*
  * Copyright (C) 1999, 2001 by Andries Brouwer
  * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
  * Copyright (C) 2008 Karel Zak <kzak@redhat.com>
  *
  * This file may be redistributed under the terms of the
  * GNU Lesser General Public License.
  */
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
 #include <ctype.h>
 #include <stdint.h>
 #ifdef __linux__
 #include <sys/utsname.h>
 #endif
 #include <time.h>

 #include "linux_version.h"
 #include "superblocks.h"

 struct ext2_super_block {
 	uint32_t		s_inodes_count;
 	uint32_t		s_blocks_count;
 	uint32_t		s_r_blocks_count;
 	uint32_t		s_free_blocks_count;
 	uint32_t		s_free_inodes_count;
 	uint32_t		s_first_data_block;
 	uint32_t		s_log_block_size;
 	uint32_t		s_dummy3[7];
 	unsigned char		s_magic[2];
 	uint16_t		s_state;
 	uint16_t		s_errors;
 	uint16_t		s_minor_rev_level;
 	uint32_t		s_lastcheck;
 	uint32_t		s_checkinterval;
 	uint32_t		s_creator_os;
 	uint32_t		s_rev_level;
 	uint16_t		s_def_resuid;
 	uint16_t		s_def_resgid;
 	uint32_t		s_first_ino;
 	uint16_t		s_inode_size;
 	uint16_t		s_block_group_nr;
 	uint32_t		s_feature_compat;
 	uint32_t		s_feature_incompat;
 	uint32_t		s_feature_ro_compat;
 	unsigned char		s_uuid[16];
 	char			s_volume_name[16];
 	char			s_last_mounted[64];
 	uint32_t		s_algorithm_usage_bitmap;
 	uint8_t			s_prealloc_blocks;
 	uint8_t			s_prealloc_dir_blocks;
 	uint16_t		s_reserved_gdt_blocks;
 	uint8_t			s_journal_uuid[16];
 	uint32_t		s_journal_inum;
 	uint32_t		s_journal_dev;
 	uint32_t		s_last_orphan;
 	uint32_t		s_hash_seed[4];
 	uint8_t			s_def_hash_version;
 	uint8_t			s_jnl_backup_type;
 	uint16_t		s_reserved_word_pad;
 	uint32_t		s_default_mount_opts;
 	uint32_t		s_first_meta_bg;
 	uint32_t		s_mkfs_time;
 	uint32_t		s_jnl_blocks[17];
 	uint32_t		s_blocks_count_hi;
 	uint32_t		s_r_blocks_count_hi;
 	uint32_t		s_free_blocks_hi;
 	uint16_t		s_min_extra_isize;
 	uint16_t		s_want_extra_isize;
 	uint32_t		s_flags;
 	uint16_t		s_raid_stride;
 	uint16_t		s_mmp_interval;
 	uint64_t		s_mmp_block;
 	uint32_t		s_raid_stripe_width;
 	uint32_t		s_reserved[163];
 } __attribute__((packed));

 /* magic string */
 #define EXT_SB_MAGIC				"\123\357"
 /* supper block offset */
 #define EXT_SB_OFF				0x400
 /* supper block offset in kB */
 #define EXT_SB_KBOFF				(EXT_SB_OFF >> 10)
 /* magic string offset within super block */
 #define EXT_MAG_OFF				0x38


 /* for s_flags */
 #define EXT2_FLAGS_TEST_FILESYS		0x0004

 /* for s_feature_compat */
 #define EXT3_FEATURE_COMPAT_HAS_JOURNAL		0x0004

 /* for s_feature_ro_compat */
 #define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
 #define EXT2_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
 #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR	0x0004
 #define EXT4_FEATURE_RO_COMPAT_HUGE_FILE	0x0008
 #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM		0x0010
 #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK	0x0020
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE	0x0040

 /* for s_feature_incompat */
 #define EXT2_FEATURE_INCOMPAT_FILETYPE		0x0002
 #define EXT3_FEATURE_INCOMPAT_RECOVER		0x0004
 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV	0x0008
 #define EXT2_FEATURE_INCOMPAT_META_BG		0x0010
 #define EXT4_FEATURE_INCOMPAT_EXTENTS		0x0040 /* extents support */
 #define EXT4_FEATURE_INCOMPAT_64BIT		0x0080
 #define EXT4_FEATURE_INCOMPAT_MMP		0x0100
 #define EXT4_FEATURE_INCOMPAT_FLEX_BG		0x0200

 #define EXT2_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
 					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
 					 EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
 #define EXT2_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE| \
 					 EXT2_FEATURE_INCOMPAT_META_BG)
 #define EXT2_FEATURE_INCOMPAT_UNSUPPORTED	~EXT2_FEATURE_INCOMPAT_SUPP
 #define EXT2_FEATURE_RO_COMPAT_UNSUPPORTED	~EXT2_FEATURE_RO_COMPAT_SUPP

 #define EXT3_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
 					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
 					 EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
 #define EXT3_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE| \
 					 EXT3_FEATURE_INCOMPAT_RECOVER| \
 					 EXT2_FEATURE_INCOMPAT_META_BG)
 #define EXT3_FEATURE_INCOMPAT_UNSUPPORTED	~EXT3_FEATURE_INCOMPAT_SUPP
 #define EXT3_FEATURE_RO_COMPAT_UNSUPPORTED	~EXT3_FEATURE_RO_COMPAT_SUPP

 /*
  * Check to see if a filesystem is in /proc/filesystems.
  * Returns 1 if found, 0 if not
  */
 static int fs_proc_check(const char *fs_name)
 {
 	FILE	*f;
 	char	buf[80], *cp, *t;

 	f = fopen("/proc/filesystems", "r");
 	if (!f)
 		return 0;
 	while (!feof(f)) {
 		if (!fgets(buf, sizeof(buf), f))
 			break;
 		cp = buf;
 		if (!isspace(*cp)) {
 			while (*cp && !isspace(*cp))
 				cp++;
 		}
 		while (*cp && isspace(*cp))
 			cp++;
 		if ((t = strchr(cp, '\n')) != NULL)
 			*t = 0;
 		if ((t = strchr(cp, '\t')) != NULL)
 			*t = 0;
 		if ((t = strchr(cp, ' ')) != NULL)
 			*t = 0;
 		if (!strcmp(fs_name, cp)) {
 			fclose(f);
 			return 1;
 		}
 	}
 	fclose(f);
 	return (0);
 }

 /*
  * Check to see if a filesystem is available as a module
  * Returns 1 if found, 0 if not
  */
 static int check_for_modules(const char *fs_name)
 {
 #ifdef __linux__
 	struct utsname	uts;
 	FILE		*f;
 	char		buf[1024], *cp;
 	int		namesz;

 	if (uname(&uts))
 		return 0;
 	snprintf(buf, sizeof(buf), "/lib/modules/%s/modules.dep", uts.release);

 	f = fopen(buf, "r");
 	if (!f)
 		return 0;

 	namesz = strlen(fs_name);

 	while (!feof(f)) {
 		if (!fgets(buf, sizeof(buf), f))
 			break;
 		if ((cp = strchr(buf, ':')) != NULL)
 			*cp = 0;
 		else
 			continue;
 		if ((cp = strrchr(buf, '/')) == NULL)
 			continue;
 		cp++;

 		if (!strncmp(cp, fs_name, namesz) &&
 		    (!strcmp(cp + namesz, ".ko") ||
 		     !strcmp(cp + namesz, ".ko.gz"))) {
 			fclose(f);
 			return 1;
 		}
 	}
 	fclose(f);
 #endif /* __linux__ */
 	return 0;
 }

 /*
  * Starting in 2.6.29, ext4 can be used to support filesystems
  * without a journal.
  */
 #define EXT4_SUPPORTS_EXT2 KERNEL_VERSION(2, 6, 29)

 static int system_supports_ext2(void)
 {
 	static time_t	last_check = 0;
 	static int	ret = -1;
 	time_t		now = time(0);

 	if (ret != -1 || (now - last_check) < 5)
 		return ret;
 	last_check = now;
 	ret = (fs_proc_check("ext2") || check_for_modules("ext2"));
 	return ret;
 }

 static int system_supports_ext4(void)
 {
 	static time_t	last_check = 0;
 	static int	ret = -1;
 	time_t		now = time(0);

 	if (ret != -1 || (now - last_check) < 5)
 		return ret;
 	last_check = now;
 	ret = (fs_proc_check("ext4") || check_for_modules("ext4"));
 	return ret;
 }

 static int system_supports_ext4dev(void)
 {
 	static time_t	last_check = 0;
 	static int	ret = -1;
 	time_t		now = time(0);

 	if (ret != -1 || (now - last_check) < 5)
 		return ret;
 	last_check = now;
 	ret = (fs_proc_check("ext4dev") || check_for_modules("ext4dev"));
 	return ret;
 }

 static int system_supports_ext4_ext2(void)
 {
 #ifdef __linux__
 	return get_linux_version() >= EXT4_SUPPORTS_EXT2;
 #else
 	return 0;
 #endif
 }
 /*
  * reads superblock and returns:
  *	fc = feature_compat
  *	fi = feature_incompat
  *	frc = feature_ro_compat
  */
 static struct ext2_super_block *ext_get_super(
 		blkid_probe pr, uint32_t *fc, uint32_t *fi, uint32_t *frc)
 {
 	struct ext2_super_block *es;

 	es = (struct ext2_super_block *)
 			blkid_probe_get_buffer(pr, EXT_SB_OFF, 0x200);
 	if (!es)
 		return NULL;
 	if (fc)
 		*fc = le32_to_cpu(es->s_feature_compat);
 	if (fi)
 		*fi = le32_to_cpu(es->s_feature_incompat);
 	if (frc)
 		*frc = le32_to_cpu(es->s_feature_ro_compat);

 	return es;
 }

 static void ext_get_info(blkid_probe pr, int ver, struct ext2_super_block *es)
 {
 	struct blkid_chain *chn = blkid_probe_get_chain(pr);

 	DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n",
 		   le32_to_cpu(es->s_feature_compat),
 		   le32_to_cpu(es->s_feature_incompat),
 		   le32_to_cpu(es->s_feature_ro_compat)));

 	if (strlen(es->s_volume_name))
 		blkid_probe_set_label(pr, (unsigned char *) es->s_volume_name,
 					sizeof(es->s_volume_name));
 	blkid_probe_set_uuid(pr, es->s_uuid);

 	if (le32_to_cpu(es->s_feature_compat) & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
 		blkid_probe_set_uuid_as(pr, es->s_journal_uuid, "EXT_JOURNAL");

 	if (ver != 2 && (chn->flags & BLKID_SUBLKS_SECTYPE) &&
 	    ((le32_to_cpu(es->s_feature_incompat) & EXT2_FEATURE_INCOMPAT_UNSUPPORTED) == 0))
 		blkid_probe_set_value(pr, "SEC_TYPE",
 				(unsigned char *) "ext2",
 				sizeof("ext2"));

 	blkid_probe_sprintf_version(pr, "%u.%u",
 		le32_to_cpu(es->s_rev_level),
 		le16_to_cpu(es->s_minor_rev_level));
 }


 static int probe_jbd(blkid_probe pr,
 		const struct blkid_idmag *mag __attribute__((__unused__)))
 {
 	struct ext2_super_block *es;
 	uint32_t fi;

 	es = ext_get_super(pr, NULL, &fi, NULL);
 	if (!es)
 		return -BLKID_ERR_PARAM;
 	if (!(fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))
 		return -BLKID_ERR_PARAM;

 	ext_get_info(pr, 2, es);
 	return 0;
 }

 static int probe_ext2(blkid_probe pr,
 		const struct blkid_idmag *mag __attribute__((__unused__)))
 {
 	struct ext2_super_block *es;
 	uint32_t fc, frc, fi;

 	es = ext_get_super(pr, &fc, &fi, &frc);
 	if (!es)
 		return -BLKID_ERR_PARAM;

 	/* Distinguish between ext3 and ext2 */
 	if (fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
 		return -BLKID_ERR_PARAM;

 	/* Any features which ext2 doesn't understand */
 	if ((frc & EXT2_FEATURE_RO_COMPAT_UNSUPPORTED) ||
 	    (fi  & EXT2_FEATURE_INCOMPAT_UNSUPPORTED))
 		return -BLKID_ERR_PARAM;

 	/*
 	 * If ext2 is not present, but ext4 or ext4dev are, then
 	 * disclaim we are ext2
 	 */
 	if (!system_supports_ext2() &&
 	    (system_supports_ext4() || system_supports_ext4dev()) &&
 	    system_supports_ext4_ext2())
 		return -BLKID_ERR_PARAM;

 	ext_get_info(pr, 2, es);
 	return 0;
 }

 static int probe_ext3(blkid_probe pr,
 		const struct blkid_idmag *mag __attribute__((__unused__)))
 {
 	struct ext2_super_block *es;
 	uint32_t fc, frc, fi;

 	es = ext_get_super(pr, &fc, &fi, &frc);
 	if (!es)
 		return -BLKID_ERR_PARAM;

 	/* ext3 requires journal */
 	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 		return -BLKID_ERR_PARAM;

 	/* Any features which ext3 doesn't understand */
 	if ((frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) ||
 	    (fi  & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
 		return -BLKID_ERR_PARAM;

 	ext_get_info(pr, 3, es);
 	return 0;
 }


 static int probe_ext4dev(blkid_probe pr,
 		const struct blkid_idmag *mag __attribute__((__unused__)))
 {
 	struct ext2_super_block *es;
 	uint32_t fc, frc, fi;

 	es = ext_get_super(pr, &fc, &fi, &frc);
 	if (!es)
 		return -BLKID_ERR_PARAM;

 	/* Distinguish from jbd */
 	if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
 		return -BLKID_ERR_PARAM;

 	/*
 	 * If the filesystem does not have a journal and ext2 and ext4
 	 * is not present, then force this to be detected as an
 	 * ext4dev filesystem.
 	 */
 	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
 	    !system_supports_ext2() && !system_supports_ext4() &&
 	    system_supports_ext4dev() &&
 	    system_supports_ext4_ext2())
 		goto force_ext4dev;

 	/*
 	 * If the filesystem is marked as OK for use by in-development
 	 * filesystem code, but ext4dev is not supported, and ext4 is,
 	 * then don't call ourselves ext4dev, since we should be
 	 * detected as ext4 in that case.
 	 *
 	 * If the filesystem is marked as in use by production
 	 * filesystem, then it can only be used by ext4 and NOT by
 	 * ext4dev, so always disclaim we are ext4dev in that case.
 	 */
 	if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
 		if (!system_supports_ext4dev() && system_supports_ext4())
 			return -BLKID_ERR_PARAM;
 	} else
 		return -BLKID_ERR_PARAM;

 force_ext4dev:
 	ext_get_info(pr, 4, es);
 	return 0;
 }

 static int probe_ext4(blkid_probe pr,
 		const struct blkid_idmag *mag __attribute__((__unused__)))
 {
 	struct ext2_super_block *es;
 	uint32_t fc, frc, fi;

 	es = ext_get_super(pr, &fc, &fi, &frc);
 	if (!es)
 		return -1;

 	/* Distinguish from jbd */
 	if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
 		return -BLKID_ERR_PARAM;

 	/*
 	 * If the filesystem does not have a journal and ext2 is not
 	 * present, then force this to be detected as an ext2
 	 * filesystem.
 	 */
 	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
 	    !system_supports_ext2() && system_supports_ext4() &&
 	    system_supports_ext4_ext2())
 		goto force_ext4;

 	/* Ext4 has at least one feature which ext3 doesn't understand */
 	if (!(frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) &&
 	    !(fi  & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
 		return -BLKID_ERR_PARAM;

 force_ext4:
 	/*
 	 * If the filesystem is a OK for use by in-development
 	 * filesystem code, and ext4dev is supported or ext4 is not
 	 * supported, then don't call ourselves ext4, so we can redo
 	 * the detection and mark the filesystem as ext4dev.
 	 *
 	 * If the filesystem is marked as in use by production
 	 * filesystem, then it can only be used by ext4 and NOT by
 	 * ext4dev.
 	 */
 	if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
 		if (system_supports_ext4dev() || !system_supports_ext4())
 			return -BLKID_ERR_PARAM;
 	}

 	ext_get_info(pr, 4, es);
 	return 0;
 }

 #define BLKID_EXT_MAGICS \
 	{ \
 		{	 \
 			.magic = EXT_SB_MAGIC, \
 			.len = sizeof(EXT_SB_MAGIC) - 1, \
 			.kboff = EXT_SB_KBOFF, \
 			.sboff = EXT_MAG_OFF \
 		}, \
 		{ NULL } \
 	}

 const struct blkid_idinfo jbd_idinfo =
 {
 	.name		= "jbd",
 	.usage		= BLKID_USAGE_OTHER,
 	.probefunc	= probe_jbd,
 	.magics		= BLKID_EXT_MAGICS
 };

 const struct blkid_idinfo ext2_idinfo =
 {
 	.name		= "ext2",
 	.usage		= BLKID_USAGE_FILESYSTEM,
 	.probefunc	= probe_ext2,
 	.magics		= BLKID_EXT_MAGICS
 };

 const struct blkid_idinfo ext3_idinfo =
 {
 	.name		= "ext3",
 	.usage		= BLKID_USAGE_FILESYSTEM,
 	.probefunc	= probe_ext3,
 	.magics		= BLKID_EXT_MAGICS
 };

 const struct blkid_idinfo ext4_idinfo =
 {
 	.name		= "ext4",
 	.usage		= BLKID_USAGE_FILESYSTEM,
 	.probefunc	= probe_ext4,
 	.magics		= BLKID_EXT_MAGICS
 };

 const struct blkid_idinfo ext4dev_idinfo =
 {
 	.name		= "ext4dev",
 	.usage		= BLKID_USAGE_FILESYSTEM,
 	.probefunc	= probe_ext4dev,
 	.magics		= BLKID_EXT_MAGICS
 };
	/*
	* Copyright (C) 1999, 2001 by Andries Brouwer
	* Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
	* Copyright (C) 2008 Karel Zak <kzak@redhat.com>
	*
	* This file may be redistributed under the terms of the
	* GNU Lesser General Public License.
	*/
	#include <stdio.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <string.h>
	#include <errno.h>
	#include <ctype.h>
	#include <stdint.h>
	#ifdef __linux__
	#include <sys/utsname.h>
	#endif
	#include <time.h>

	#include "linux_version.h"
	#include "superblocks.h"

	struct ext2_super_block {
	uint32_t s_inodes_count;
	uint32_t s_blocks_count;
	uint32_t s_r_blocks_count;
	uint32_t s_free_blocks_count;
	uint32_t s_free_inodes_count;
	uint32_t s_first_data_block;
	uint32_t s_log_block_size;
	uint32_t s_dummy3[7];
	unsigned char s_magic[2];
	uint16_t s_state;
	uint16_t s_errors;
	uint16_t s_minor_rev_level;
	uint32_t s_lastcheck;
	uint32_t s_checkinterval;
	uint32_t s_creator_os;
	uint32_t s_rev_level;
	uint16_t s_def_resuid;
	uint16_t s_def_resgid;
	uint32_t s_first_ino;
	uint16_t s_inode_size;
	uint16_t s_block_group_nr;
	uint32_t s_feature_compat;
	uint32_t s_feature_incompat;
	uint32_t s_feature_ro_compat;
	unsigned char s_uuid[16];
	char s_volume_name[16];
	char s_last_mounted[64];
	uint32_t s_algorithm_usage_bitmap;
	uint8_t s_prealloc_blocks;
	uint8_t s_prealloc_dir_blocks;
	uint16_t s_reserved_gdt_blocks;
	uint8_t s_journal_uuid[16];
	uint32_t s_journal_inum;
	uint32_t s_journal_dev;
	uint32_t s_last_orphan;
	uint32_t s_hash_seed[4];
	uint8_t s_def_hash_version;
	uint8_t s_jnl_backup_type;
	uint16_t s_reserved_word_pad;
	uint32_t s_default_mount_opts;
	uint32_t s_first_meta_bg;
	uint32_t s_mkfs_time;
	uint32_t s_jnl_blocks[17];
	uint32_t s_blocks_count_hi;
	uint32_t s_r_blocks_count_hi;
	uint32_t s_free_blocks_hi;
	uint16_t s_min_extra_isize;
	uint16_t s_want_extra_isize;
	uint32_t s_flags;
	uint16_t s_raid_stride;
	uint16_t s_mmp_interval;
	uint64_t s_mmp_block;
	uint32_t s_raid_stripe_width;
	uint32_t s_reserved[163];
	} __attribute__((packed));

	/* magic string */
	#define EXT_SB_MAGIC "\123\357"
	/* supper block offset */
	#define EXT_SB_OFF 0x400
	/* supper block offset in kB */
	#define EXT_SB_KBOFF (EXT_SB_OFF >> 10)
	/* magic string offset within super block */
	#define EXT_MAG_OFF 0x38



	/* for s_flags */
	#define EXT2_FLAGS_TEST_FILESYS 0x0004

	/* for s_feature_compat */
	#define EXT3_FEATURE_COMPAT_HAS_JOURNAL 0x0004

	/* for s_feature_ro_compat */
	#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
	#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
	#define EXT2_FEATURE_RO_COMPAT_BTREE_DIR 0x0004
	#define EXT4_FEATURE_RO_COMPAT_HUGE_FILE 0x0008
	#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
	#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
	#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040

	/* for s_feature_incompat */
	#define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002
	#define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004
	#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008
	#define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
	#define EXT4_FEATURE_INCOMPAT_EXTENTS 0x0040 /* extents support */
	#define EXT4_FEATURE_INCOMPAT_64BIT 0x0080
	#define EXT4_FEATURE_INCOMPAT_MMP 0x0100
	#define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200

	#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER\| \
	EXT2_FEATURE_RO_COMPAT_LARGE_FILE\| \
	EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
	#define EXT2_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE\| \
	EXT2_FEATURE_INCOMPAT_META_BG)
	#define EXT2_FEATURE_INCOMPAT_UNSUPPORTED ~EXT2_FEATURE_INCOMPAT_SUPP
	#define EXT2_FEATURE_RO_COMPAT_UNSUPPORTED ~EXT2_FEATURE_RO_COMPAT_SUPP

	#define EXT3_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER\| \
	EXT2_FEATURE_RO_COMPAT_LARGE_FILE\| \
	EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
	#define EXT3_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE\| \
	EXT3_FEATURE_INCOMPAT_RECOVER\| \
	EXT2_FEATURE_INCOMPAT_META_BG)
	#define EXT3_FEATURE_INCOMPAT_UNSUPPORTED ~EXT3_FEATURE_INCOMPAT_SUPP
	#define EXT3_FEATURE_RO_COMPAT_UNSUPPORTED ~EXT3_FEATURE_RO_COMPAT_SUPP

	/*
	* Check to see if a filesystem is in /proc/filesystems.
	* Returns 1 if found, 0 if not
	*/
	static int fs_proc_check(const char *fs_name)
	{
	FILE *f;
	char buf[80], cp, t;

	f = fopen("/proc/filesystems", "r");
	if (!f)
	return 0;
	while (!feof(f)) {
	if (!fgets(buf, sizeof(buf), f))
	break;
	cp = buf;
	if (!isspace(*cp)) {
	while (cp && !isspace(cp))
	cp++;
	}
	while (cp && isspace(cp))
	cp++;
	if ((t = strchr(cp, '\n')) != NULL)
	*t = 0;
	if ((t = strchr(cp, '\t')) != NULL)
	*t = 0;
	if ((t = strchr(cp, ' ')) != NULL)
	*t = 0;
	if (!strcmp(fs_name, cp)) {
	fclose(f);
	return 1;
	}
	}
	fclose(f);
	return (0);
	}

	/*
	* Check to see if a filesystem is available as a module
	* Returns 1 if found, 0 if not
	*/
	static int check_for_modules(const char *fs_name)
	{
	#ifdef __linux__
	struct utsname uts;
	FILE *f;
	char buf[1024], *cp;
	int namesz;

	if (uname(&uts))
	return 0;
	snprintf(buf, sizeof(buf), "/lib/modules/%s/modules.dep", uts.release);

	f = fopen(buf, "r");
	if (!f)
	return 0;

	namesz = strlen(fs_name);

	while (!feof(f)) {
	if (!fgets(buf, sizeof(buf), f))
	break;
	if ((cp = strchr(buf, ':')) != NULL)
	*cp = 0;
	else
	continue;
	if ((cp = strrchr(buf, '/')) == NULL)
	continue;
	cp++;

	if (!strncmp(cp, fs_name, namesz) &&
	(!strcmp(cp + namesz, ".ko") \|\|
	!strcmp(cp + namesz, ".ko.gz"))) {
	fclose(f);
	return 1;
	}
	}
	fclose(f);
	#endif /* __linux__ */
	return 0;
	}

	/*
	* Starting in 2.6.29, ext4 can be used to support filesystems
	* without a journal.
	*/
	#define EXT4_SUPPORTS_EXT2 KERNEL_VERSION(2, 6, 29)

	static int system_supports_ext2(void)
	{
	static time_t last_check = 0;
	static int ret = -1;
	time_t now = time(0);

	if (ret != -1 \|\| (now - last_check) < 5)
	return ret;
	last_check = now;
	ret = (fs_proc_check("ext2") \|\| check_for_modules("ext2"));
	return ret;
	}

	static int system_supports_ext4(void)
	{
	static time_t last_check = 0;
	static int ret = -1;
	time_t now = time(0);

	if (ret != -1 \|\| (now - last_check) < 5)
	return ret;
	last_check = now;
	ret = (fs_proc_check("ext4") \|\| check_for_modules("ext4"));
	return ret;
	}

	static int system_supports_ext4dev(void)
	{
	static time_t last_check = 0;
	static int ret = -1;
	time_t now = time(0);

	if (ret != -1 \|\| (now - last_check) < 5)
	return ret;
	last_check = now;
	ret = (fs_proc_check("ext4dev") \|\| check_for_modules("ext4dev"));
	return ret;
	}

	static int system_supports_ext4_ext2(void)
	{
	#ifdef __linux__
	return get_linux_version() >= EXT4_SUPPORTS_EXT2;
	#else
	return 0;
	#endif
	}
	/*
	* reads superblock and returns:
	* fc = feature_compat
	* fi = feature_incompat
	* frc = feature_ro_compat
	*/
	static struct ext2_super_block *ext_get_super(
	blkid_probe pr, uint32_t fc, uint32_t fi, uint32_t *frc)
	{
	struct ext2_super_block *es;

	es = (struct ext2_super_block *)
	blkid_probe_get_buffer(pr, EXT_SB_OFF, 0x200);
	if (!es)
	return NULL;
	if (fc)
	*fc = le32_to_cpu(es->s_feature_compat);
	if (fi)
	*fi = le32_to_cpu(es->s_feature_incompat);
	if (frc)
	*frc = le32_to_cpu(es->s_feature_ro_compat);

	return es;
	}

	static void ext_get_info(blkid_probe pr, int ver, struct ext2_super_block *es)
	{
	struct blkid_chain *chn = blkid_probe_get_chain(pr);

	DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n",
	le32_to_cpu(es->s_feature_compat),
	le32_to_cpu(es->s_feature_incompat),
	le32_to_cpu(es->s_feature_ro_compat)));

	if (strlen(es->s_volume_name))
	blkid_probe_set_label(pr, (unsigned char *) es->s_volume_name,
	sizeof(es->s_volume_name));
	blkid_probe_set_uuid(pr, es->s_uuid);

	if (le32_to_cpu(es->s_feature_compat) & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
	blkid_probe_set_uuid_as(pr, es->s_journal_uuid, "EXT_JOURNAL");

	if (ver != 2 && (chn->flags & BLKID_SUBLKS_SECTYPE) &&
	((le32_to_cpu(es->s_feature_incompat) & EXT2_FEATURE_INCOMPAT_UNSUPPORTED) == 0))
	blkid_probe_set_value(pr, "SEC_TYPE",
	(unsigned char *) "ext2",
	sizeof("ext2"));

	blkid_probe_sprintf_version(pr, "%u.%u",
	le32_to_cpu(es->s_rev_level),
	le16_to_cpu(es->s_minor_rev_level));
	}


	static int probe_jbd(blkid_probe pr,
	const struct blkid_idmag *mag __attribute__((__unused__)))
	{
	struct ext2_super_block *es;
	uint32_t fi;

	es = ext_get_super(pr, NULL, &fi, NULL);
	if (!es)
	return -BLKID_ERR_PARAM;
	if (!(fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))
	return -BLKID_ERR_PARAM;

	ext_get_info(pr, 2, es);
	return 0;
	}

	static int probe_ext2(blkid_probe pr,
	const struct blkid_idmag *mag __attribute__((__unused__)))
	{
	struct ext2_super_block *es;
	uint32_t fc, frc, fi;

	es = ext_get_super(pr, &fc, &fi, &frc);
	if (!es)
	return -BLKID_ERR_PARAM;

	/* Distinguish between ext3 and ext2 */
	if (fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
	return -BLKID_ERR_PARAM;

	/* Any features which ext2 doesn't understand */
	if ((frc & EXT2_FEATURE_RO_COMPAT_UNSUPPORTED) \|\|
	(fi & EXT2_FEATURE_INCOMPAT_UNSUPPORTED))
	return -BLKID_ERR_PARAM;

	/*
	* If ext2 is not present, but ext4 or ext4dev are, then
	* disclaim we are ext2
	*/
	if (!system_supports_ext2() &&
	(system_supports_ext4() \|\| system_supports_ext4dev()) &&
	system_supports_ext4_ext2())
	return -BLKID_ERR_PARAM;

	ext_get_info(pr, 2, es);
	return 0;
	}

	static int probe_ext3(blkid_probe pr,
	const struct blkid_idmag *mag __attribute__((__unused__)))
	{
	struct ext2_super_block *es;
	uint32_t fc, frc, fi;

	es = ext_get_super(pr, &fc, &fi, &frc);
	if (!es)
	return -BLKID_ERR_PARAM;

	/* ext3 requires journal */
	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL))
	return -BLKID_ERR_PARAM;

	/* Any features which ext3 doesn't understand */
	if ((frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) \|\|
	(fi & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
	return -BLKID_ERR_PARAM;

	ext_get_info(pr, 3, es);
	return 0;
	}


	static int probe_ext4dev(blkid_probe pr,
	const struct blkid_idmag *mag __attribute__((__unused__)))
	{
	struct ext2_super_block *es;
	uint32_t fc, frc, fi;

	es = ext_get_super(pr, &fc, &fi, &frc);
	if (!es)
	return -BLKID_ERR_PARAM;

	/* Distinguish from jbd */
	if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
	return -BLKID_ERR_PARAM;

	/*
	* If the filesystem does not have a journal and ext2 and ext4
	* is not present, then force this to be detected as an
	* ext4dev filesystem.
	*/
	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
	!system_supports_ext2() && !system_supports_ext4() &&
	system_supports_ext4dev() &&
	system_supports_ext4_ext2())
	goto force_ext4dev;

	/*
	* If the filesystem is marked as OK for use by in-development
	* filesystem code, but ext4dev is not supported, and ext4 is,
	* then don't call ourselves ext4dev, since we should be
	* detected as ext4 in that case.
	*
	* If the filesystem is marked as in use by production
	* filesystem, then it can only be used by ext4 and NOT by
	* ext4dev, so always disclaim we are ext4dev in that case.
	*/
	if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
	if (!system_supports_ext4dev() && system_supports_ext4())
	return -BLKID_ERR_PARAM;
	} else
	return -BLKID_ERR_PARAM;

	force_ext4dev:
	ext_get_info(pr, 4, es);
	return 0;
	}

	static int probe_ext4(blkid_probe pr,
	const struct blkid_idmag *mag __attribute__((__unused__)))
	{
	struct ext2_super_block *es;
	uint32_t fc, frc, fi;

	es = ext_get_super(pr, &fc, &fi, &frc);
	if (!es)
	return -1;

	/* Distinguish from jbd */
	if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
	return -BLKID_ERR_PARAM;

	/*
	* If the filesystem does not have a journal and ext2 is not
	* present, then force this to be detected as an ext2
	* filesystem.
	*/
	if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
	!system_supports_ext2() && system_supports_ext4() &&
	system_supports_ext4_ext2())
	goto force_ext4;

	/* Ext4 has at least one feature which ext3 doesn't understand */
	if (!(frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) &&
	!(fi & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
	return -BLKID_ERR_PARAM;

	force_ext4:
	/*
	* If the filesystem is a OK for use by in-development
	* filesystem code, and ext4dev is supported or ext4 is not
	* supported, then don't call ourselves ext4, so we can redo
	* the detection and mark the filesystem as ext4dev.
	*
	* If the filesystem is marked as in use by production
	* filesystem, then it can only be used by ext4 and NOT by
	* ext4dev.
	*/
	if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
	if (system_supports_ext4dev() \|\| !system_supports_ext4())
	return -BLKID_ERR_PARAM;
	}

	ext_get_info(pr, 4, es);
	return 0;
	}

	#define BLKID_EXT_MAGICS \
	{ \
	{ \
	.magic = EXT_SB_MAGIC, \
	.len = sizeof(EXT_SB_MAGIC) - 1, \
	.kboff = EXT_SB_KBOFF, \
	.sboff = EXT_MAG_OFF \
	}, \
	{ NULL } \
	}

	const struct blkid_idinfo jbd_idinfo =
	{
	.name = "jbd",
	.usage = BLKID_USAGE_OTHER,
	.probefunc = probe_jbd,
	.magics = BLKID_EXT_MAGICS
	};

	const struct blkid_idinfo ext2_idinfo =
	{
	.name = "ext2",
	.usage = BLKID_USAGE_FILESYSTEM,
	.probefunc = probe_ext2,
	.magics = BLKID_EXT_MAGICS
	};

	const struct blkid_idinfo ext3_idinfo =
	{
	.name = "ext3",
	.usage = BLKID_USAGE_FILESYSTEM,
	.probefunc = probe_ext3,
	.magics = BLKID_EXT_MAGICS
	};

	const struct blkid_idinfo ext4_idinfo =
	{
	.name = "ext4",
	.usage = BLKID_USAGE_FILESYSTEM,
	.probefunc = probe_ext4,
	.magics = BLKID_EXT_MAGICS
	};

	const struct blkid_idinfo ext4dev_idinfo =
	{
	.name = "ext4dev",
	.usage = BLKID_USAGE_FILESYSTEM,
	.probefunc = probe_ext4dev,
	.magics = BLKID_EXT_MAGICS
	};