2
* Copyright (C) 1999, 2001 by Andries Brouwer
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* Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
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* Copyright (C) 2008 Karel Zak <kzak@redhat.com>
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* This file may be redistributed under the terms of the
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* GNU Lesser General Public License.
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#include <sys/utsname.h>
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#include "linux_version.h"
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#include "superblocks.h"
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struct ext2_super_block {
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uint32_t s_inodes_count;
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uint32_t s_blocks_count;
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uint32_t s_r_blocks_count;
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uint32_t s_free_blocks_count;
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uint32_t s_free_inodes_count;
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uint32_t s_first_data_block;
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uint32_t s_log_block_size;
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unsigned char s_magic[2];
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uint16_t s_minor_rev_level;
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uint32_t s_checkinterval;
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uint32_t s_creator_os;
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uint16_t s_def_resuid;
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uint16_t s_def_resgid;
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uint16_t s_inode_size;
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uint16_t s_block_group_nr;
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uint32_t s_feature_compat;
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uint32_t s_feature_incompat;
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uint32_t s_feature_ro_compat;
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unsigned char s_uuid[16];
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char s_volume_name[16];
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char s_last_mounted[64];
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uint32_t s_algorithm_usage_bitmap;
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uint8_t s_prealloc_blocks;
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uint8_t s_prealloc_dir_blocks;
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uint16_t s_reserved_gdt_blocks;
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uint8_t s_journal_uuid[16];
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uint32_t s_journal_inum;
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uint32_t s_journal_dev;
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uint32_t s_last_orphan;
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uint32_t s_hash_seed[4];
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uint8_t s_def_hash_version;
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uint8_t s_jnl_backup_type;
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uint16_t s_reserved_word_pad;
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uint32_t s_default_mount_opts;
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uint32_t s_first_meta_bg;
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uint32_t s_jnl_blocks[17];
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uint32_t s_blocks_count_hi;
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uint32_t s_r_blocks_count_hi;
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uint32_t s_free_blocks_hi;
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uint16_t s_min_extra_isize;
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uint16_t s_want_extra_isize;
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uint16_t s_raid_stride;
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uint16_t s_mmp_interval;
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uint32_t s_raid_stripe_width;
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uint32_t s_reserved[163];
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} __attribute__((packed));
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#define EXT_SB_MAGIC "\123\357"
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/* supper block offset */
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#define EXT_SB_OFF 0x400
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/* supper block offset in kB */
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#define EXT_SB_KBOFF (EXT_SB_OFF >> 10)
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/* magic string offset within super block */
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#define EXT_MAG_OFF 0x38
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#define EXT2_FLAGS_TEST_FILESYS 0x0004
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/* for s_feature_compat */
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#define EXT3_FEATURE_COMPAT_HAS_JOURNAL 0x0004
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/* for s_feature_ro_compat */
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#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
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#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
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#define EXT2_FEATURE_RO_COMPAT_BTREE_DIR 0x0004
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#define EXT4_FEATURE_RO_COMPAT_HUGE_FILE 0x0008
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#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
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#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
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#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040
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/* for s_feature_incompat */
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#define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002
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#define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004
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#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008
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#define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
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#define EXT4_FEATURE_INCOMPAT_EXTENTS 0x0040 /* extents support */
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#define EXT4_FEATURE_INCOMPAT_64BIT 0x0080
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#define EXT4_FEATURE_INCOMPAT_MMP 0x0100
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#define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200
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#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
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EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
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EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
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#define EXT2_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE| \
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EXT2_FEATURE_INCOMPAT_META_BG)
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#define EXT2_FEATURE_INCOMPAT_UNSUPPORTED ~EXT2_FEATURE_INCOMPAT_SUPP
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#define EXT2_FEATURE_RO_COMPAT_UNSUPPORTED ~EXT2_FEATURE_RO_COMPAT_SUPP
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#define EXT3_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
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EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
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EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
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#define EXT3_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE| \
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EXT3_FEATURE_INCOMPAT_RECOVER| \
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EXT2_FEATURE_INCOMPAT_META_BG)
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#define EXT3_FEATURE_INCOMPAT_UNSUPPORTED ~EXT3_FEATURE_INCOMPAT_SUPP
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#define EXT3_FEATURE_RO_COMPAT_UNSUPPORTED ~EXT3_FEATURE_RO_COMPAT_SUPP
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* Check to see if a filesystem is in /proc/filesystems.
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* Returns 1 if found, 0 if not
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static int fs_proc_check(const char *fs_name)
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char buf[80], *cp, *t;
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f = fopen("/proc/filesystems", "r");
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if (!fgets(buf, sizeof(buf), f))
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while (*cp && !isspace(*cp))
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while (*cp && isspace(*cp))
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if ((t = strchr(cp, '\n')) != NULL)
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if ((t = strchr(cp, '\t')) != NULL)
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if ((t = strchr(cp, ' ')) != NULL)
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if (!strcmp(fs_name, cp)) {
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* Check to see if a filesystem is available as a module
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* Returns 1 if found, 0 if not
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static int check_for_modules(const char *fs_name)
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snprintf(buf, sizeof(buf), "/lib/modules/%s/modules.dep", uts.release);
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namesz = strlen(fs_name);
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if (!fgets(buf, sizeof(buf), f))
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if ((cp = strchr(buf, ':')) != NULL)
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if ((cp = strrchr(buf, '/')) == NULL)
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if (!strncmp(cp, fs_name, namesz) &&
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(!strcmp(cp + namesz, ".ko") ||
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!strcmp(cp + namesz, ".ko.gz"))) {
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#endif /* __linux__ */
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* Starting in 2.6.29, ext4 can be used to support filesystems
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#define EXT4_SUPPORTS_EXT2 KERNEL_VERSION(2, 6, 29)
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static int system_supports_ext2(void)
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static time_t last_check = 0;
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time_t now = time(0);
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if (ret != -1 || (now - last_check) < 5)
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ret = (fs_proc_check("ext2") || check_for_modules("ext2"));
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static int system_supports_ext4(void)
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static time_t last_check = 0;
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time_t now = time(0);
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if (ret != -1 || (now - last_check) < 5)
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ret = (fs_proc_check("ext4") || check_for_modules("ext4"));
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static int system_supports_ext4dev(void)
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static time_t last_check = 0;
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time_t now = time(0);
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if (ret != -1 || (now - last_check) < 5)
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ret = (fs_proc_check("ext4dev") || check_for_modules("ext4dev"));
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* reads superblock and returns:
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* fc = feature_compat
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* fi = feature_incompat
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* frc = feature_ro_compat
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static struct ext2_super_block *ext_get_super(
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blkid_probe pr, uint32_t *fc, uint32_t *fi, uint32_t *frc)
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struct ext2_super_block *es;
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es = (struct ext2_super_block *)
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blkid_probe_get_buffer(pr, EXT_SB_OFF, 0x200);
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*fc = le32_to_cpu(es->s_feature_compat);
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*fi = le32_to_cpu(es->s_feature_incompat);
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*frc = le32_to_cpu(es->s_feature_ro_compat);
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static void ext_get_info(blkid_probe pr, int ver, struct ext2_super_block *es)
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struct blkid_chain *chn = blkid_probe_get_chain(pr);
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DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n",
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le32_to_cpu(es->s_feature_compat),
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le32_to_cpu(es->s_feature_incompat),
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le32_to_cpu(es->s_feature_ro_compat)));
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if (strlen(es->s_volume_name))
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blkid_probe_set_label(pr, (unsigned char *) es->s_volume_name,
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sizeof(es->s_volume_name));
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blkid_probe_set_uuid(pr, es->s_uuid);
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if (le32_to_cpu(es->s_feature_compat) & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
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blkid_probe_set_uuid_as(pr, es->s_journal_uuid, "EXT_JOURNAL");
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if (ver != 2 && (chn->flags & BLKID_SUBLKS_SECTYPE) &&
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((le32_to_cpu(es->s_feature_incompat) & EXT2_FEATURE_INCOMPAT_UNSUPPORTED) == 0))
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blkid_probe_set_value(pr, "SEC_TYPE",
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(unsigned char *) "ext2",
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blkid_probe_sprintf_version(pr, "%u.%u",
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le32_to_cpu(es->s_rev_level),
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le16_to_cpu(es->s_minor_rev_level));
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static int probe_jbd(blkid_probe pr, const struct blkid_idmag *mag)
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struct ext2_super_block *es;
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es = ext_get_super(pr, NULL, &fi, NULL);
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return -BLKID_ERR_PARAM;
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if (!(fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))
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return -BLKID_ERR_PARAM;
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ext_get_info(pr, 2, es);
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static int probe_ext2(blkid_probe pr, const struct blkid_idmag *mag)
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struct ext2_super_block *es;
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uint32_t fc, frc, fi;
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es = ext_get_super(pr, &fc, &fi, &frc);
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return -BLKID_ERR_PARAM;
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/* Distinguish between ext3 and ext2 */
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if (fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL)
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return -BLKID_ERR_PARAM;
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/* Any features which ext2 doesn't understand */
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if ((frc & EXT2_FEATURE_RO_COMPAT_UNSUPPORTED) ||
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(fi & EXT2_FEATURE_INCOMPAT_UNSUPPORTED))
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return -BLKID_ERR_PARAM;
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* If ext2 is not present, but ext4 or ext4dev are, then
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* disclaim we are ext2
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if (!system_supports_ext2() &&
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(system_supports_ext4() || system_supports_ext4dev()) &&
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get_linux_version() >= EXT4_SUPPORTS_EXT2)
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return -BLKID_ERR_PARAM;
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ext_get_info(pr, 2, es);
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static int probe_ext3(blkid_probe pr, const struct blkid_idmag *mag)
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struct ext2_super_block *es;
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uint32_t fc, frc, fi;
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es = ext_get_super(pr, &fc, &fi, &frc);
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return -BLKID_ERR_PARAM;
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/* ext3 requires journal */
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if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL))
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return -BLKID_ERR_PARAM;
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/* Any features which ext3 doesn't understand */
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if ((frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) ||
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(fi & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
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return -BLKID_ERR_PARAM;
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ext_get_info(pr, 3, es);
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static int probe_ext4dev(blkid_probe pr, const struct blkid_idmag *mag)
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struct ext2_super_block *es;
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uint32_t fc, frc, fi;
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es = ext_get_super(pr, &fc, &fi, &frc);
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return -BLKID_ERR_PARAM;
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/* Distinguish from jbd */
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if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
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return -BLKID_ERR_PARAM;
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* If the filesystem does not have a journal and ext2 and ext4
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* is not present, then force this to be detected as an
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* ext4dev filesystem.
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if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
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!system_supports_ext2() && !system_supports_ext4() &&
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system_supports_ext4dev() &&
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get_linux_version() >= EXT4_SUPPORTS_EXT2)
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* If the filesystem is marked as OK for use by in-development
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* filesystem code, but ext4dev is not supported, and ext4 is,
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* then don't call ourselves ext4dev, since we should be
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* detected as ext4 in that case.
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* If the filesystem is marked as in use by production
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* filesystem, then it can only be used by ext4 and NOT by
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* ext4dev, so always disclaim we are ext4dev in that case.
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if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
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if (!system_supports_ext4dev() && system_supports_ext4())
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return -BLKID_ERR_PARAM;
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return -BLKID_ERR_PARAM;
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ext_get_info(pr, 4, es);
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static int probe_ext4(blkid_probe pr, const struct blkid_idmag *mag)
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struct ext2_super_block *es;
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uint32_t fc, frc, fi;
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es = ext_get_super(pr, &fc, &fi, &frc);
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/* Distinguish from jbd */
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if (fi & EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
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return -BLKID_ERR_PARAM;
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* If the filesystem does not have a journal and ext2 is not
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* present, then force this to be detected as an ext2
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if (!(fc & EXT3_FEATURE_COMPAT_HAS_JOURNAL) &&
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!system_supports_ext2() && system_supports_ext4() &&
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get_linux_version() >= EXT4_SUPPORTS_EXT2)
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/* Ext4 has at least one feature which ext3 doesn't understand */
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if (!(frc & EXT3_FEATURE_RO_COMPAT_UNSUPPORTED) &&
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!(fi & EXT3_FEATURE_INCOMPAT_UNSUPPORTED))
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return -BLKID_ERR_PARAM;
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* If the filesystem is a OK for use by in-development
459
* filesystem code, and ext4dev is supported or ext4 is not
460
* supported, then don't call ourselves ext4, so we can redo
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* the detection and mark the filesystem as ext4dev.
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* If the filesystem is marked as in use by production
464
* filesystem, then it can only be used by ext4 and NOT by
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if (le32_to_cpu(es->s_flags) & EXT2_FLAGS_TEST_FILESYS) {
468
if (system_supports_ext4dev() || !system_supports_ext4())
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return -BLKID_ERR_PARAM;
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ext_get_info(pr, 4, es);
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#define BLKID_EXT_MAGICS \
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.magic = EXT_SB_MAGIC, \
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.len = sizeof(EXT_SB_MAGIC) - 1, \
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.kboff = EXT_SB_KBOFF, \
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.sboff = EXT_MAG_OFF \
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const struct blkid_idinfo jbd_idinfo =
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.usage = BLKID_USAGE_OTHER,
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.probefunc = probe_jbd,
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.magics = BLKID_EXT_MAGICS
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const struct blkid_idinfo ext2_idinfo =
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.usage = BLKID_USAGE_FILESYSTEM,
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.probefunc = probe_ext2,
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.magics = BLKID_EXT_MAGICS
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const struct blkid_idinfo ext3_idinfo =
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.usage = BLKID_USAGE_FILESYSTEM,
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.probefunc = probe_ext3,
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.magics = BLKID_EXT_MAGICS
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const struct blkid_idinfo ext4_idinfo =
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.usage = BLKID_USAGE_FILESYSTEM,
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.probefunc = probe_ext4,
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.magics = BLKID_EXT_MAGICS
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const struct blkid_idinfo ext4dev_idinfo =
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.usage = BLKID_USAGE_FILESYSTEM,
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.probefunc = probe_ext4dev,
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.magics = BLKID_EXT_MAGICS
added
removed
shlibs/blkid/src/superblocks/ext.c
