layout.h

Linux Kernel 2.6.9 for OMAP1710

#define MSEQNO_LE(x)	((u16)((le64_to_cpu(x) >> 48) & 0xffff))

#define IS_ERR_MREF(x)	(((x) & 0x0000800000000000ULL) ? 1 : 0)
#define ERR_MREF(x)	((u64)((s64)(x)))
#define MREF_ERR(x)	((int)((s64)(x)))

/*
 * The mft record header present at the beginning of every record in the mft.
 * This is followed by a sequence of variable length attribute records which
 * is terminated by an attribute of type AT_END which is a truncated attribute
 * in that it only consists of the attribute type code AT_END and none of the
 * other members of the attribute structure are present.
 */
typedef struct {
/*Ofs*/
/*  0	NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */
	NTFS_RECORD_TYPE magic;	/* Usually the magic is "FILE". */
	le16 usa_ofs;		/* See NTFS_RECORD definition above. */
	le16 usa_count;		/* See NTFS_RECORD definition above. */

/*  8*/	le64 lsn;		/* $LogFile sequence number for this record.
				   Changed every time the record is modified. */
/* 16*/	le16 sequence_number;	/* Number of times this mft record has been
				   reused. (See description for MFT_REF
				   above.) NOTE: The increment (skipping zero)
				   is done when the file is deleted. NOTE: If
				   this is zero it is left zero. */
/* 18*/	le16 link_count;	/* Number of hard links, i.e. the number of
				   directory entries referencing this record.
				   NOTE: Only used in mft base records.
				   NOTE: When deleting a directory entry we
				   check the link_count and if it is 1 we
				   delete the file. Otherwise we delete the
				   FILE_NAME_ATTR being referenced by the
				   directory entry from the mft record and
				   decrement the link_count.
				   FIXME: Careful with Win32 + DOS names! */
/* 20*/	le16 attrs_offset;	/* Byte offset to the first attribute in this
				   mft record from the start of the mft record.
				   NOTE: Must be aligned to 8-byte boundary. */
/* 22*/	MFT_RECORD_FLAGS flags;	/* Bit array of MFT_RECORD_FLAGS. When a file
				   is deleted, the MFT_RECORD_IN_USE flag is
				   set to zero. */
/* 24*/	le32 bytes_in_use;	/* Number of bytes used in this mft record.
				   NOTE: Must be aligned to 8-byte boundary. */
/* 28*/	le32 bytes_allocated;	/* Number of bytes allocated for this mft
				   record. This should be equal to the mft
				   record size. */
/* 32*/	leMFT_REF base_mft_record;/* This is zero for base mft records.
				   When it is not zero it is a mft reference
				   pointing to the base mft record to which
				   this record belongs (this is then used to
				   locate the attribute list attribute present
				   in the base record which describes this
				   extension record and hence might need
				   modification when the extension record
				   itself is modified, also locating the
				   attribute list also means finding the other
				   potential extents, belonging to the non-base
				   mft record). */
/* 40*/	le16 next_attr_instance;/* The instance number that will be assigned to
				   the next attribute added to this mft record.
				   NOTE: Incremented each time after it is used.
				   NOTE: Every time the mft record is reused
				   this number is set to zero.  NOTE: The first
				   instance number is always 0. */
/* sizeof() = 42 bytes */
/* NTFS 3.1+ (Windows XP and above) introduce the following additions. */
/* 42*/ //le16 reserved;	/* Reserved/alignment. */
/* 44*/ //le32 mft_record_number;/* Number of this mft record. */
/* sizeof() = 48 bytes */
/*
 * When (re)using the mft record, we place the update sequence array at this
 * offset, i.e. before we start with the attributes. This also makes sense,
 * otherwise we could run into problems with the update sequence array
 * containing in itself the last two bytes of a sector which would mean that
 * multi sector transfer protection wouldn't work. As you can't protect data
 * by overwriting it since you then can't get it back...
 * When reading we obviously use the data from the ntfs record header.
 */
} __attribute__ ((__packed__)) MFT_RECORD;

/*
 * System defined attributes (32-bit).  Each attribute type has a corresponding
 * attribute name (Unicode string of maximum 64 character length) as described
 * by the attribute definitions present in the data attribute of the $AttrDef
 * system file.  On NTFS 3.0 volumes the names are just as the types are named
 * in the below defines exchanging AT_ for the dollar sign ($).  If that is not
 * a revealing choice of symbol I do not know what is... (-;
 */
enum {
	AT_UNUSED			= const_cpu_to_le32(         0),
	AT_STANDARD_INFORMATION		= const_cpu_to_le32(      0x10),
	AT_ATTRIBUTE_LIST		= const_cpu_to_le32(      0x20),
	AT_FILE_NAME			= const_cpu_to_le32(      0x30),
	AT_OBJECT_ID			= const_cpu_to_le32(      0x40),
	AT_SECURITY_DESCRIPTOR		= const_cpu_to_le32(      0x50),
	AT_VOLUME_NAME			= const_cpu_to_le32(      0x60),
	AT_VOLUME_INFORMATION		= const_cpu_to_le32(      0x70),
	AT_DATA				= const_cpu_to_le32(      0x80),
	AT_INDEX_ROOT			= const_cpu_to_le32(      0x90),
	AT_INDEX_ALLOCATION		= const_cpu_to_le32(      0xa0),
	AT_BITMAP			= const_cpu_to_le32(      0xb0),
	AT_REPARSE_POINT		= const_cpu_to_le32(      0xc0),
	AT_EA_INFORMATION		= const_cpu_to_le32(      0xd0),
	AT_EA				= const_cpu_to_le32(      0xe0),
	AT_PROPERTY_SET			= const_cpu_to_le32(      0xf0),
	AT_LOGGED_UTILITY_STREAM	= const_cpu_to_le32(     0x100),
	AT_FIRST_USER_DEFINED_ATTRIBUTE	= const_cpu_to_le32(    0x1000),
	AT_END				= const_cpu_to_le32(0xffffffff)
};

typedef le32 ATTR_TYPE;

/*
 * The collation rules for sorting views/indexes/etc (32-bit).
 *
 * COLLATION_BINARY - Collate by binary compare where the first byte is most
 *	significant.
 * COLLATION_UNICODE_STRING - Collate Unicode strings by comparing their binary
 *	Unicode values, except that when a character can be uppercased, the
 *	upper case value collates before the lower case one.
 * COLLATION_FILE_NAME - Collate file names as Unicode strings. The collation
 *	is done very much like COLLATION_UNICODE_STRING. In fact I have no idea
 *	what the difference is. Perhaps the difference is that file names
 *	would treat some special characters in an odd way (see
 *	unistr.c::ntfs_collate_names() and unistr.c::legal_ansi_char_array[]
 *	for what I mean but COLLATION_UNICODE_STRING would not give any special
 *	treatment to any characters at all, but this is speculation.
 * COLLATION_NTOFS_ULONG - Sorting is done according to ascending le32 key
 *	values. E.g. used for $SII index in FILE_Secure, which sorts by
 *	security_id (le32).
 * COLLATION_NTOFS_SID - Sorting is done according to ascending SID values.
 *	E.g. used for $O index in FILE_Extend/$Quota.
 * COLLATION_NTOFS_SECURITY_HASH - Sorting is done first by ascending hash
 *	values and second by ascending security_id values. E.g. used for $SDH
 *	index in FILE_Secure.
 * COLLATION_NTOFS_ULONGS - Sorting is done according to a sequence of ascending
 *	le32 key values. E.g. used for $O index in FILE_Extend/$ObjId, which
 *	sorts by object_id (16-byte), by splitting up the object_id in four
 *	le32 values and using them as individual keys. E.g. take the following
 *	two security_ids, stored as follows on disk:
 *		1st: a1 61 65 b7 65 7b d4 11 9e 3d 00 e0 81 10 42 59
 *		2nd: 38 14 37 d2 d2 f3 d4 11 a5 21 c8 6b 79 b1 97 45
 *	To compare them, they are split into four le32 values each, like so:
 *		1st: 0xb76561a1 0x11d47b65 0xe0003d9e 0x59421081
 *		2nd: 0xd2371438 0x11d4f3d2 0x6bc821a5 0x4597b179
 *	Now, it is apparent why the 2nd object_id collates after the 1st: the
 *	first le32 value of the 1st object_id is less than the first le32 of
 *	the 2nd object_id. If the first le32 values of both object_ids were
 *	equal then the second le32 values would be compared, etc.
 */
enum {
	COLLATION_BINARY		= const_cpu_to_le32(0x00),
	COLLATION_FILE_NAME		= const_cpu_to_le32(0x01),
	COLLATION_UNICODE_STRING	= const_cpu_to_le32(0x02),
	COLLATION_NTOFS_ULONG		= const_cpu_to_le32(0x10),
	COLLATION_NTOFS_SID		= const_cpu_to_le32(0x11),
	COLLATION_NTOFS_SECURITY_HASH	= const_cpu_to_le32(0x12),
	COLLATION_NTOFS_ULONGS		= const_cpu_to_le32(0x13)
};

typedef le32 COLLATION_RULE;

/*
 * The flags (32-bit) describing attribute properties in the attribute
 * definition structure.  FIXME: This information is from Regis's information
 * and, according to him, it is not certain and probably incomplete.
 * The INDEXABLE flag is fairly certainly correct as only the file name
 * attribute has this flag set and this is the only attribute indexed in NT4.
 */
enum {
	INDEXABLE	    = const_cpu_to_le32(0x02), /* Attribute can be
							  indexed. */
	NEED_TO_REGENERATE  = const_cpu_to_le32(0x40), /* Need to regenerate
							  during regeneration
							  phase. */
	CAN_BE_NON_RESIDENT = const_cpu_to_le32(0x80), /* Attribute can be
							  non-resident. */
};

typedef le32 ATTR_DEF_FLAGS;

/*
 * The data attribute of FILE_AttrDef contains a sequence of attribute
 * definitions for the NTFS volume. With this, it is supposed to be safe for an
 * older NTFS driver to mount a volume containing a newer NTFS version without
 * damaging it (that's the theory. In practice it's: not damaging it too much).
 * Entries are sorted by attribute type. The flags describe whether the
 * attribute can be resident/non-resident and possibly other things, but the
 * actual bits are unknown.
 */
typedef struct {
/*hex ofs*/
/*  0*/	ntfschar name[0x40];		/* Unicode name of the attribute. Zero
					   terminated. */
/* 80*/	ATTR_TYPE type;			/* Type of the attribute. */
/* 84*/	le32 display_rule;		/* Default display rule.
					   FIXME: What does it mean? (AIA) */
/* 88*/ COLLATION_RULE collation_rule;	/* Default collation rule. */
/* 8c*/	ATTR_DEF_FLAGS flags;		/* Flags describing the attribute. */
/* 90*/	le64 min_size;			/* Optional minimum attribute size. */
/* 98*/	le64 max_size;			/* Maximum size of attribute. */
/* sizeof() = 0xa0 or 160 bytes */
} __attribute__ ((__packed__)) ATTR_DEF;

/*
 * Attribute flags (16-bit).
 */
enum {
	ATTR_IS_COMPRESSED    = const_cpu_to_le16(0x0001),
	ATTR_COMPRESSION_MASK = const_cpu_to_le16(0x00ff), /* Compression method
							      mask.  Also, first
							      illegal value. */
	ATTR_IS_ENCRYPTED     = const_cpu_to_le16(0x4000),
	ATTR_IS_SPARSE	      = const_cpu_to_le16(0x8000),
} __attribute__ ((__packed__));

typedef le16 ATTR_FLAGS;

/*
 * Attribute compression.
 *
 * Only the data attribute is ever compressed in the current ntfs driver in
 * Windows. Further, compression is only applied when the data attribute is
 * non-resident. Finally, to use compression, the maximum allowed cluster size
 * on a volume is 4kib.
 *
 * The compression method is based on independently compressing blocks of X
 * clusters, where X is determined from the compression_unit value found in the
 * non-resident attribute record header (more precisely: X = 2^compression_unit
 * clusters). On Windows NT/2k, X always is 16 clusters (compression_unit = 4).
 *
 * There are three different cases of how a compression block of X clusters
 * can be stored:
 *
 *   1) The data in the block is all zero (a sparse block):
 *	  This is stored as a sparse block in the runlist, i.e. the runlist
 *	  entry has length = X and lcn = -1. The mapping pairs array actually
 *	  uses a delta_lcn value length of 0, i.e. delta_lcn is not present at
 *	  all, which is then interpreted by the driver as lcn = -1.
 *	  NOTE: Even uncompressed files can be sparse on NTFS 3.0 volumes, then
 *	  the same principles apply as above, except that the length is not
 *	  restricted to being any particular value.
 *
 *   2) The data in the block is not compressed:
 *	  This happens when compression doesn't reduce the size of the block
 *	  in clusters. I.e. if compression has a small effect so that the
 *	  compressed data still occupies X clusters, then the uncompressed data
 *	  is stored in the block.
 *	  This case is recognised by the fact that the runlist entry has
 *	  length = X and lcn >= 0. The mapping pairs array stores this as
 *	  normal with a run length of X and some specific delta_lcn, i.e.
 *	  delta_lcn has to be present.
 *
 *   3) The data in the block is compressed:
 *	  The common case. This case is recognised by the fact that the run
 *	  list entry has length L < X and lcn >= 0. The mapping pairs array
 *	  stores this as normal with a run length of X and some specific
 *	  delta_lcn, i.e. delta_lcn has to be present. This runlist entry is
 *	  immediately followed by a sparse entry with length = X - L and
 *	  lcn = -1. The latter entry is to make up the vcn counting to the
 *	  full compression block size X.
 *
 * In fact, life is more complicated because adjacent entries of the same type
 * can be coalesced. This means that one has to keep track of the number of
 * clusters handled and work on a basis of X clusters at a time being one
 * block. An example: if length L > X this means that this particular runlist
 * entry contains a block of length X and part of one or more blocks of length
 * L - X. Another example: if length L < X, this does not necessarily mean that
 * the block is compressed as it might be that the lcn changes inside the block
 * and hence the following runlist entry describes the continuation of the
 * potentially compressed block. The block would be compressed if the
 * following runlist entry describes at least X - L sparse clusters, thus
 * making up the compression block length as described in point 3 above. (Of
 * course, there can be several runlist entries with small lengths so that the
 * sparse entry does not follow the first data containing entry with
 * length < X.)
 *
 * NOTE: At the end of the compressed attribute value, there most likely is not
 * just the right amount of data to make up a compression block, thus this data
 * is not even attempted to be compressed. It is just stored as is, unless
 * the number of clusters it occupies is reduced when compressed in which case
 * it is stored as a compressed compression block, complete with sparse
 * clusters at the end.
 */

/*
 * Flags of resident attributes (8-bit).
 */
enum {
	RESIDENT_ATTR_IS_INDEXED = 0x01, /* Attribute is referenced in an index
					    (has implications for deleting and
					    modifying the attribute). */
} __attribute__ ((__packed__));

typedef u8 RESIDENT_ATTR_FLAGS;

/*
 * Attribute record header. Always aligned to 8-byte boundary.
 */
typedef struct {
/*Ofs*/
/*  0*/	ATTR_TYPE type;		/* The (32-bit) type of the attribute. */
/*  4*/	le32 length;		/* Byte size of the resident part of the
				   attribute (aligned to 8-byte boundary).
				   Used to get to the next attribute. */
/*  8*/	u8 non_resident;	/* If 0, attribute is resident.
				   If 1, attribute is non-resident. */
/*  9*/	u8 name_length;		/* Unicode character size of name of attribute.
				   0 if unnamed. */
/* 10*/	le16 name_offset;	/* If name_length != 0, the byte offset to the
				   beginning of the name from the attribute
				   record. Note that the name is stored as a
				   Unicode string. When creating, place offset
				   just at the end of the record header. Then,
				   follow with attribute value or mapping pairs
				   array, resident and non-resident attributes
				   respectively, aligning to an 8-byte
				   boundary. */
/* 12*/	ATTR_FLAGS flags;	/* Flags describing the attribute. */