layout.h

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

/*
 * layout.h - Ntfs on-disk layout structures.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2000-2005 Anton Altaparmakov
 * Copyright (c)      2005 Yura Pakhuchiy
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _NTFS_LAYOUT_H
#define _NTFS_LAYOUT_H

#include "types.h"
#include "endians.h"
#include "support.h"

/* The NTFS oem_id */
#define magicNTFS	const_cpu_to_le64(0x202020205346544e)	/* "NTFS    " */
#define NTFS_SB_MAGIC	0x5346544e				/* 'NTFS' */

/*
 * Location of bootsector on partition:
 *	The standard NTFS_BOOT_SECTOR is on sector 0 of the partition.
 *	On NT4 and above there is one backup copy of the boot sector to
 *	be found on the last sector of the partition (not normally accessible
 *	from within Windows as the bootsector contained number of sectors
 *	value is one less than the actual value!).
 *	On versions of NT 3.51 and earlier, the backup copy was located at
 *	number of sectors/2 (integer divide), i.e. in the middle of the volume.
 */

/**
 * struct BIOS_PARAMETER_BLOCK - BIOS parameter block (bpb) structure.
 */
typedef struct {
	u16 bytes_per_sector;		/* Size of a sector in bytes. */
	u8  sectors_per_cluster;	/* Size of a cluster in sectors. */
	u16 reserved_sectors;		/* zero */
	u8  fats;			/* zero */
	u16 root_entries;		/* zero */
	u16 sectors;			/* zero */
	u8  media_type;			/* 0xf8 = hard disk */
	u16 sectors_per_fat;		/* zero */
/*0x0d*/u16 sectors_per_track;		/* Required to boot Windows. */
/*0x0f*/u16 heads;			/* Required to boot Windows. */
/*0x11*/u32 hidden_sectors;		/* Offset to the start of the partition
					   relative to the disk in sectors.
					   Required to boot Windows. */
/*0x15*/u32 large_sectors;		/* zero */
/* sizeof() = 25 (0x19) bytes */
} __attribute__((__packed__)) BIOS_PARAMETER_BLOCK;

/**
 * struct NTFS_BOOT_SECTOR - NTFS boot sector structure.
 */
typedef struct {
	u8  jump[3];			/* Irrelevant (jump to boot up code).*/
	u64 oem_id;			/* Magic "NTFS    ". */
/*0x0b*/BIOS_PARAMETER_BLOCK bpb;	/* See BIOS_PARAMETER_BLOCK. */
	u8 physical_drive;		/* 0x00 floppy, 0x80 hard disk */
	u8 current_head;		/* zero */
	u8 extended_boot_signature; 	/* 0x80 */
	u8 reserved2;			/* zero */
/*0x28*/s64 number_of_sectors;		/* Number of sectors in volume. Gives
					   maximum volume size of 2^63 sectors.
					   Assuming standard sector size of 512
					   bytes, the maximum byte size is
					   approx. 4.7x10^21 bytes. (-; */
	s64 mft_lcn;			/* Cluster location of mft data. */
	s64 mftmirr_lcn;		/* Cluster location of copy of mft. */
	s8  clusters_per_mft_record;	/* Mft record size in clusters. */
	u8  reserved0[3];		/* zero */
	s8  clusters_per_index_record;	/* Index block size in clusters. */
	u8  reserved1[3];		/* zero */
	u64 volume_serial_number;	/* Irrelevant (serial number). */
	u32 checksum;			/* Boot sector checksum. */
/*0x54*/u8  bootstrap[426];		/* Irrelevant (boot up code). */
	u16 end_of_sector_marker;	/* End of bootsector magic. Always is
					   0xaa55 in little endian. */
/* sizeof() = 512 (0x200) bytes */
} __attribute__((__packed__)) NTFS_BOOT_SECTOR;

/**
 * enum NTFS_RECORD_TYPES -
 *
 * Magic identifiers present at the beginning of all ntfs record containing
 * records (like mft records for example).
 */
typedef enum {
	/* Found in $MFT/$DATA. */
	magic_FILE = const_cpu_to_le32(0x454c4946), /* Mft entry. */
	magic_INDX = const_cpu_to_le32(0x58444e49), /* Index buffer. */
	magic_HOLE = const_cpu_to_le32(0x454c4f48), /* ? (NTFS 3.0+?) */

	/* Found in $LogFile/$DATA. */
	magic_RSTR = const_cpu_to_le32(0x52545352), /* Restart page. */
	magic_RCRD = const_cpu_to_le32(0x44524352), /* Log record page. */

	/* Found in $LogFile/$DATA.  (May be found in $MFT/$DATA, also?) */
	magic_CHKD = const_cpu_to_le32(0x444b4843), /* Modified by chkdsk. */

	/* Found in all ntfs record containing records. */
	magic_BAAD = const_cpu_to_le32(0x44414142), /* Failed multi sector
						       transfer was detected. */

	/*
	 * Found in $LogFile/$DATA when a page is full or 0xff bytes and is
	 * thus not initialized.  User has to initialize the page before using
	 * it.
	 */
	magic_empty = const_cpu_to_le32(0xffffffff),/* Record is empty and has
						       to be initialized before
						       it can be used. */
} NTFS_RECORD_TYPES;

/*
 * Generic magic comparison macros. Finally found a use for the ## preprocessor
 * operator! (-8
 */
#define ntfs_is_magic(x, m)	(   (u32)(x) == (u32)magic_##m )
#define ntfs_is_magicp(p, m)	( *(u32*)(p) == (u32)magic_##m )

/*
 * Specialised magic comparison macros for the NTFS_RECORD_TYPES defined above.
 */
#define ntfs_is_file_record(x)	( ntfs_is_magic (x, FILE) )
#define ntfs_is_file_recordp(p)	( ntfs_is_magicp(p, FILE) )
#define ntfs_is_mft_record(x)	( ntfs_is_file_record(x) )
#define ntfs_is_mft_recordp(p)	( ntfs_is_file_recordp(p) )
#define ntfs_is_indx_record(x)	( ntfs_is_magic (x, INDX) )
#define ntfs_is_indx_recordp(p)	( ntfs_is_magicp(p, INDX) )
#define ntfs_is_hole_record(x)	( ntfs_is_magic (x, HOLE) )
#define ntfs_is_hole_recordp(p)	( ntfs_is_magicp(p, HOLE) )

#define ntfs_is_rstr_record(x)	( ntfs_is_magic (x, RSTR) )
#define ntfs_is_rstr_recordp(p)	( ntfs_is_magicp(p, RSTR) )
#define ntfs_is_rcrd_record(x)	( ntfs_is_magic (x, RCRD) )
#define ntfs_is_rcrd_recordp(p)	( ntfs_is_magicp(p, RCRD) )

#define ntfs_is_chkd_record(x)	( ntfs_is_magic (x, CHKD) )
#define ntfs_is_chkd_recordp(p)	( ntfs_is_magicp(p, CHKD) )

#define ntfs_is_baad_record(x)	( ntfs_is_magic (x, BAAD) )
#define ntfs_is_baad_recordp(p)	( ntfs_is_magicp(p, BAAD) )

#define ntfs_is_empty_record(x)		( ntfs_is_magic (x, empty) )
#define ntfs_is_empty_recordp(p)	( ntfs_is_magicp(p, empty) )


#define NTFS_BLOCK_SIZE		512
#define NTFS_BLOCK_SIZE_BITS	9

/**
 * struct NTFS_RECORD -
 *
 * The Update Sequence Array (usa) is an array of the u16 values which belong
 * to the end of each sector protected by the update sequence record in which
 * this array is contained. Note that the first entry is the Update Sequence
 * Number (usn), a cyclic counter of how many times the protected record has
 * been written to disk. The values 0 and -1 (ie. 0xffff) are not used. All
 * last u16's of each sector have to be equal to the usn (during reading) or
 * are set to it (during writing). If they are not, an incomplete multi sector
 * transfer has occurred when the data was written.
 * The maximum size for the update sequence array is fixed to:
 *	maximum size = usa_ofs + (usa_count * 2) = 510 bytes
 * The 510 bytes comes from the fact that the last u16 in the array has to
 * (obviously) finish before the last u16 of the first 512-byte sector.
 * This formula can be used as a consistency check in that usa_ofs +
 * (usa_count * 2) has to be less than or equal to 510.
 */
typedef struct {
	NTFS_RECORD_TYPES magic;/* A four-byte magic identifying the
				   record type and/or status. */
	u16 usa_ofs;		/* Offset to the Update Sequence Array (usa)
				   from the start of the ntfs record. */
	u16 usa_count;		/* Number of u16 sized entries in the usa
				   including the Update Sequence Number (usn),
				   thus the number of fixups is the usa_count
				   minus 1. */
} __attribute__((__packed__)) NTFS_RECORD;

/**
 * enum NTFS_SYSTEM_FILES - System files mft record numbers.
 *
 * All these files are always marked as used in the bitmap attribute of the
 * mft; presumably in order to avoid accidental allocation for random other
 * mft records. Also, the sequence number for each of the system files is
 * always equal to their mft record number and it is never modified.
 */
typedef enum {
	FILE_MFT	= 0,	/* Master file table (mft). Data attribute
				   contains the entries and bitmap attribute
				   records which ones are in use (bit==1). */
	FILE_MFTMirr	= 1,	/* Mft mirror: copy of first four mft records
				   in data attribute. If cluster size > 4kiB,
				   copy of first N mft records, with
					N = cluster_size / mft_record_size. */
	FILE_LogFile	= 2,	/* Journalling log in data attribute. */
	FILE_Volume	= 3,	/* Volume name attribute and volume information
				   attribute (flags and ntfs version). Windows
				   refers to this file as volume DASD (Direct
				   Access Storage Device). */
	FILE_AttrDef	= 4,	/* Array of attribute definitions in data
				   attribute. */
	FILE_root	= 5,	/* Root directory. */
	FILE_Bitmap	= 6,	/* Allocation bitmap of all clusters (lcns) in
				   data attribute. */
	FILE_Boot	= 7,	/* Boot sector (always at cluster 0) in data
				   attribute. */
	FILE_BadClus	= 8,	/* Contains all bad clusters in the non-resident
				   data attribute. */
	FILE_Secure	= 9,	/* Shared security descriptors in data attribute
				   and two indexes into the descriptors.
				   Appeared in Windows 2000. Before that, this
				   file was named $Quota but was unused. */
	FILE_UpCase	= 10,	/* Uppercase equivalents of all 65536 Unicode
				   characters in data attribute. */
	FILE_Extend	= 11,	/* Directory containing other system files (eg.
				   $ObjId, $Quota, $Reparse and $UsnJrnl). This
				   is new to NTFS3.0. */
	FILE_reserved12	= 12,	/* Reserved for future use (records 12-15). */
	FILE_reserved13	= 13,
	FILE_reserved14	= 14,
	FILE_reserved15	= 15,
	FILE_first_user	= 16,	/* First user file, used as test limit for
				   whether to allow opening a file or not. */
} NTFS_SYSTEM_FILES;

/**
 * enum MFT_RECORD_FLAGS -
 *
 * These are the so far known MFT_RECORD_* flags (16-bit) which contain
 * information about the mft record in which they are present.
 * 
 * MFT_RECORD_IS_4 exists on all $Extend sub-files.
 * It seems that it marks it is a metadata file with MFT record >24, however,
 * it is unknown if it is limited to metadata files only.
 *
 * MFT_RECORD_IS_VIEW_INDEX exists on every metafile with a non directory
 * index, that means an INDEX_ROOT and an INDEX_ALLOCATION with a name other
 * than "$I30". It is unknown if it is limited to metadata files only.
 */
typedef enum {
	MFT_RECORD_IN_USE		= const_cpu_to_le16(0x0001),
	MFT_RECORD_IS_DIRECTORY		= const_cpu_to_le16(0x0002),
	MFT_RECORD_IS_4			= const_cpu_to_le16(0x0004),
	MFT_RECORD_IS_VIEW_INDEX	= const_cpu_to_le16(0x0008),
	MFT_REC_SPACE_FILLER		= 0xffff, /* Just to make flags
						     16-bit. */
} __attribute__((__packed__)) MFT_RECORD_FLAGS;

/*
 * mft references (aka file references or file record segment references) are
 * used whenever a structure needs to refer to a record in the mft.
 *
 * A reference consists of a 48-bit index into the mft and a 16-bit sequence
 * number used to detect stale references.
 *
 * For error reporting purposes we treat the 48-bit index as a signed quantity.
 *
 * The sequence number is a circular counter (skipping 0) describing how many
 * times the referenced mft record has been (re)used. This has to match the
 * sequence number of the mft record being referenced, otherwise the reference
 * is considered stale and removed (FIXME: only ntfsck or the driver itself?).
 *
 * If the sequence number is zero it is assumed that no sequence number
 * consistency checking should be performed.
 *
 * FIXME: Since inodes are 32-bit as of now, the driver needs to always check
 * for high_part being 0 and if not either BUG(), cause a panic() or handle
 * the situation in some other way. This shouldn't be a problem as a volume has
 * to become HUGE in order to need more than 32-bits worth of mft records.
 * Assuming the standard mft record size of 1kb only the records (never mind
 * the non-resident attributes, etc.) would require 4Tb of space on their own
 * for the first 32 bits worth of records. This is only if some strange person
 * doesn't decide to foul play and make the mft sparse which would be a really
 * horrible thing to do as it would trash our current driver implementation. )-:
 * Do I hear screams "we want 64-bit inodes!" ?!? (-;
 *
 * FIXME: The mft zone is defined as the first 12% of the volume. This space is
 * reserved so that the mft can grow contiguously and hence doesn't become
 * fragmented. Volume free space includes the empty part of the mft zone and
 * when the volume's free 88% are used up, the mft zone is shrunk by a factor
 * of 2, thus making more space available for more files/data. This process is
 * repeated every time there is no more free space except for the mft zone until
 * there really is no more free space.
 */

/*
 * Typedef the MFT_REF as a 64-bit value for easier handling.
 * Also define two unpacking macros to get to the reference (MREF) and
 * sequence number (MSEQNO) respectively.
 * The _LE versions are to be applied on little endian MFT_REFs.
 * Note: The _LE versions will return a CPU endian formatted value!
 */
#define MFT_REF_MASK_CPU 0x0000ffffffffffffULL
#define MFT_REF_MASK_LE const_cpu_to_le64(MFT_REF_MASK_CPU)

typedef u64 MFT_REF;

#define MK_MREF(m, s)	((MFT_REF)(((MFT_REF)(s) << 48) |		\