296 lines
13 KiB
C
296 lines
13 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* logfile.h - Defines for NTFS kernel journal ($LogFile) handling. Part of
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* the Linux-NTFS project.
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*
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* Copyright (c) 2000-2005 Anton Altaparmakov
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*/
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#ifndef _LINUX_NTFS_LOGFILE_H
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#define _LINUX_NTFS_LOGFILE_H
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#ifdef NTFS_RW
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#include <linux/fs.h>
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#include "types.h"
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#include "endian.h"
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#include "layout.h"
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/*
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* Journal ($LogFile) organization:
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*
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* Two restart areas present in the first two pages (restart pages, one restart
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* area in each page). When the volume is dismounted they should be identical,
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* except for the update sequence array which usually has a different update
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* sequence number.
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*
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* These are followed by log records organized in pages headed by a log record
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* header going up to log file size. Not all pages contain log records when a
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* volume is first formatted, but as the volume ages, all records will be used.
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* When the log file fills up, the records at the beginning are purged (by
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* modifying the oldest_lsn to a higher value presumably) and writing begins
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* at the beginning of the file. Effectively, the log file is viewed as a
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* circular entity.
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*
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* NOTE: Windows NT, 2000, and XP all use log file version 1.1 but they accept
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* versions <= 1.x, including 0.-1. (Yes, that is a minus one in there!) We
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* probably only want to support 1.1 as this seems to be the current version
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* and we don't know how that differs from the older versions. The only
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* exception is if the journal is clean as marked by the two restart pages
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* then it doesn't matter whether we are on an earlier version. We can just
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* reinitialize the logfile and start again with version 1.1.
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*/
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/* Some $LogFile related constants. */
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#define MaxLogFileSize 0x100000000ULL
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#define DefaultLogPageSize 4096
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#define MinLogRecordPages 48
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/*
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* Log file restart page header (begins the restart area).
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*/
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typedef struct {
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/*Ofs*/
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/* 0 NTFS_RECORD; -- Unfolded here as gcc doesn't like unnamed structs. */
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/* 0*/ NTFS_RECORD_TYPE magic; /* The magic is "RSTR". */
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/* 4*/ le16 usa_ofs; /* See NTFS_RECORD definition in layout.h.
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When creating, set this to be immediately
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after this header structure (without any
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alignment). */
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/* 6*/ le16 usa_count; /* See NTFS_RECORD definition in layout.h. */
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/* 8*/ leLSN chkdsk_lsn; /* The last log file sequence number found by
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chkdsk. Only used when the magic is changed
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to "CHKD". Otherwise this is zero. */
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/* 16*/ le32 system_page_size; /* Byte size of system pages when the log file
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was created, has to be >= 512 and a power of
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2. Use this to calculate the required size
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of the usa (usa_count) and add it to usa_ofs.
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Then verify that the result is less than the
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value of the restart_area_offset. */
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/* 20*/ le32 log_page_size; /* Byte size of log file pages, has to be >=
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512 and a power of 2. The default is 4096
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and is used when the system page size is
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between 4096 and 8192. Otherwise this is
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set to the system page size instead. */
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/* 24*/ le16 restart_area_offset;/* Byte offset from the start of this header to
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the RESTART_AREA. Value has to be aligned
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to 8-byte boundary. When creating, set this
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to be after the usa. */
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/* 26*/ sle16 minor_ver; /* Log file minor version. Only check if major
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version is 1. */
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/* 28*/ sle16 major_ver; /* Log file major version. We only support
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version 1.1. */
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/* sizeof() = 30 (0x1e) bytes */
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} __attribute__ ((__packed__)) RESTART_PAGE_HEADER;
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/*
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* Constant for the log client indices meaning that there are no client records
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* in this particular client array. Also inside the client records themselves,
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* this means that there are no client records preceding or following this one.
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*/
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#define LOGFILE_NO_CLIENT cpu_to_le16(0xffff)
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#define LOGFILE_NO_CLIENT_CPU 0xffff
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/*
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* These are the so far known RESTART_AREA_* flags (16-bit) which contain
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* information about the log file in which they are present.
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*/
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enum {
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RESTART_VOLUME_IS_CLEAN = cpu_to_le16(0x0002),
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RESTART_SPACE_FILLER = cpu_to_le16(0xffff), /* gcc: Force enum bit width to 16. */
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} __attribute__ ((__packed__));
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typedef le16 RESTART_AREA_FLAGS;
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/*
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* Log file restart area record. The offset of this record is found by adding
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* the offset of the RESTART_PAGE_HEADER to the restart_area_offset value found
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* in it. See notes at restart_area_offset above.
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*/
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typedef struct {
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/*Ofs*/
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/* 0*/ leLSN current_lsn; /* The current, i.e. last LSN inside the log
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when the restart area was last written.
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This happens often but what is the interval?
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Is it just fixed time or is it every time a
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check point is written or somethine else?
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On create set to 0. */
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/* 8*/ le16 log_clients; /* Number of log client records in the array of
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log client records which follows this
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restart area. Must be 1. */
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/* 10*/ le16 client_free_list; /* The index of the first free log client record
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in the array of log client records.
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LOGFILE_NO_CLIENT means that there are no
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free log client records in the array.
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If != LOGFILE_NO_CLIENT, check that
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log_clients > client_free_list. On Win2k
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and presumably earlier, on a clean volume
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this is != LOGFILE_NO_CLIENT, and it should
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be 0, i.e. the first (and only) client
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record is free and thus the logfile is
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closed and hence clean. A dirty volume
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would have left the logfile open and hence
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this would be LOGFILE_NO_CLIENT. On WinXP
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and presumably later, the logfile is always
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open, even on clean shutdown so this should
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always be LOGFILE_NO_CLIENT. */
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/* 12*/ le16 client_in_use_list;/* The index of the first in-use log client
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record in the array of log client records.
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LOGFILE_NO_CLIENT means that there are no
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in-use log client records in the array. If
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!= LOGFILE_NO_CLIENT check that log_clients
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> client_in_use_list. On Win2k and
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presumably earlier, on a clean volume this
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is LOGFILE_NO_CLIENT, i.e. there are no
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client records in use and thus the logfile
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is closed and hence clean. A dirty volume
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would have left the logfile open and hence
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this would be != LOGFILE_NO_CLIENT, and it
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should be 0, i.e. the first (and only)
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client record is in use. On WinXP and
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presumably later, the logfile is always
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open, even on clean shutdown so this should
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always be 0. */
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/* 14*/ RESTART_AREA_FLAGS flags;/* Flags modifying LFS behaviour. On Win2k
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and presumably earlier this is always 0. On
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WinXP and presumably later, if the logfile
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was shutdown cleanly, the second bit,
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RESTART_VOLUME_IS_CLEAN, is set. This bit
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is cleared when the volume is mounted by
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WinXP and set when the volume is dismounted,
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thus if the logfile is dirty, this bit is
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clear. Thus we don't need to check the
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Windows version to determine if the logfile
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is clean. Instead if the logfile is closed,
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we know it must be clean. If it is open and
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this bit is set, we also know it must be
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clean. If on the other hand the logfile is
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open and this bit is clear, we can be almost
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certain that the logfile is dirty. */
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/* 16*/ le32 seq_number_bits; /* How many bits to use for the sequence
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number. This is calculated as 67 - the
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number of bits required to store the logfile
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size in bytes and this can be used in with
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the specified file_size as a consistency
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check. */
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/* 20*/ le16 restart_area_length;/* Length of the restart area including the
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client array. Following checks required if
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version matches. Otherwise, skip them.
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restart_area_offset + restart_area_length
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has to be <= system_page_size. Also,
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restart_area_length has to be >=
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client_array_offset + (log_clients *
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sizeof(log client record)). */
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/* 22*/ le16 client_array_offset;/* Offset from the start of this record to
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the first log client record if versions are
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matched. When creating, set this to be
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after this restart area structure, aligned
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to 8-bytes boundary. If the versions do not
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match, this is ignored and the offset is
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assumed to be (sizeof(RESTART_AREA) + 7) &
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~7, i.e. rounded up to first 8-byte
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boundary. Either way, client_array_offset
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has to be aligned to an 8-byte boundary.
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Also, restart_area_offset +
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client_array_offset has to be <= 510.
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Finally, client_array_offset + (log_clients
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* sizeof(log client record)) has to be <=
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system_page_size. On Win2k and presumably
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earlier, this is 0x30, i.e. immediately
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following this record. On WinXP and
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presumably later, this is 0x40, i.e. there
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are 16 extra bytes between this record and
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the client array. This probably means that
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the RESTART_AREA record is actually bigger
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in WinXP and later. */
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/* 24*/ sle64 file_size; /* Usable byte size of the log file. If the
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restart_area_offset + the offset of the
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file_size are > 510 then corruption has
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occurred. This is the very first check when
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starting with the restart_area as if it
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fails it means that some of the above values
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will be corrupted by the multi sector
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transfer protection. The file_size has to
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be rounded down to be a multiple of the
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log_page_size in the RESTART_PAGE_HEADER and
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then it has to be at least big enough to
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store the two restart pages and 48 (0x30)
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log record pages. */
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/* 32*/ le32 last_lsn_data_length;/* Length of data of last LSN, not including
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the log record header. On create set to
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0. */
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/* 36*/ le16 log_record_header_length;/* Byte size of the log record header.
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If the version matches then check that the
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value of log_record_header_length is a
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multiple of 8, i.e.
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(log_record_header_length + 7) & ~7 ==
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log_record_header_length. When creating set
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it to sizeof(LOG_RECORD_HEADER), aligned to
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8 bytes. */
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/* 38*/ le16 log_page_data_offset;/* Offset to the start of data in a log record
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page. Must be a multiple of 8. On create
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set it to immediately after the update
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sequence array of the log record page. */
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/* 40*/ le32 restart_log_open_count;/* A counter that gets incremented every
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time the logfile is restarted which happens
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at mount time when the logfile is opened.
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When creating set to a random value. Win2k
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sets it to the low 32 bits of the current
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system time in NTFS format (see time.h). */
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/* 44*/ le32 reserved; /* Reserved/alignment to 8-byte boundary. */
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/* sizeof() = 48 (0x30) bytes */
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} __attribute__ ((__packed__)) RESTART_AREA;
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/*
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* Log client record. The offset of this record is found by adding the offset
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* of the RESTART_AREA to the client_array_offset value found in it.
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*/
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typedef struct {
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/*Ofs*/
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/* 0*/ leLSN oldest_lsn; /* Oldest LSN needed by this client. On create
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set to 0. */
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/* 8*/ leLSN client_restart_lsn;/* LSN at which this client needs to restart
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the volume, i.e. the current position within
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the log file. At present, if clean this
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should = current_lsn in restart area but it
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probably also = current_lsn when dirty most
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of the time. At create set to 0. */
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/* 16*/ le16 prev_client; /* The offset to the previous log client record
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in the array of log client records.
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LOGFILE_NO_CLIENT means there is no previous
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client record, i.e. this is the first one.
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This is always LOGFILE_NO_CLIENT. */
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/* 18*/ le16 next_client; /* The offset to the next log client record in
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the array of log client records.
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LOGFILE_NO_CLIENT means there are no next
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client records, i.e. this is the last one.
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This is always LOGFILE_NO_CLIENT. */
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/* 20*/ le16 seq_number; /* On Win2k and presumably earlier, this is set
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to zero every time the logfile is restarted
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and it is incremented when the logfile is
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closed at dismount time. Thus it is 0 when
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dirty and 1 when clean. On WinXP and
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presumably later, this is always 0. */
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/* 22*/ u8 reserved[6]; /* Reserved/alignment. */
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/* 28*/ le32 client_name_length;/* Length of client name in bytes. Should
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always be 8. */
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/* 32*/ ntfschar client_name[64];/* Name of the client in Unicode. Should
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always be "NTFS" with the remaining bytes
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set to 0. */
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/* sizeof() = 160 (0xa0) bytes */
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} __attribute__ ((__packed__)) LOG_CLIENT_RECORD;
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extern bool ntfs_check_logfile(struct inode *log_vi,
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RESTART_PAGE_HEADER **rp);
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extern bool ntfs_is_logfile_clean(struct inode *log_vi,
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const RESTART_PAGE_HEADER *rp);
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extern bool ntfs_empty_logfile(struct inode *log_vi);
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#endif /* NTFS_RW */
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#endif /* _LINUX_NTFS_LOGFILE_H */
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