192 lines
8.4 KiB
C
192 lines
8.4 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling.
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* Part of the Linux-NTFS project.
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*
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* Copyright (c) 2005 Anton Altaparmakov
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*/
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#ifndef _LINUX_NTFS_USNJRNL_H
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#define _LINUX_NTFS_USNJRNL_H
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#ifdef NTFS_RW
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#include "types.h"
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#include "endian.h"
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#include "layout.h"
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#include "volume.h"
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/*
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* Transaction log ($UsnJrnl) organization:
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*
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* The transaction log records whenever a file is modified in any way. So for
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* example it will record that file "blah" was written to at a particular time
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* but not what was written. If will record that a file was deleted or
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* created, that a file was truncated, etc. See below for all the reason
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* codes used.
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*
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* The transaction log is in the $Extend directory which is in the root
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* directory of each volume. If it is not present it means transaction
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* logging is disabled. If it is present it means transaction logging is
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* either enabled or in the process of being disabled in which case we can
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* ignore it as it will go away as soon as Windows gets its hands on it.
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*
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* To determine whether the transaction logging is enabled or in the process
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* of being disabled, need to check the volume flags in the
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* $VOLUME_INFORMATION attribute in the $Volume system file (which is present
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* in the root directory and has a fixed mft record number, see layout.h).
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* If the flag VOLUME_DELETE_USN_UNDERWAY is set it means the transaction log
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* is in the process of being disabled and if this flag is clear it means the
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* transaction log is enabled.
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*
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* The transaction log consists of two parts; the $DATA/$Max attribute as well
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* as the $DATA/$J attribute. $Max is a header describing the transaction
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* log whilst $J is the transaction log data itself as a sequence of variable
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* sized USN_RECORDs (see below for all the structures).
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*
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* We do not care about transaction logging at this point in time but we still
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* need to let windows know that the transaction log is out of date. To do
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* this we need to stamp the transaction log. This involves setting the
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* lowest_valid_usn field in the $DATA/$Max attribute to the usn to be used
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* for the next added USN_RECORD to the $DATA/$J attribute as well as
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* generating a new journal_id in $DATA/$Max.
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*
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* The journal_id is as of the current version (2.0) of the transaction log
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* simply the 64-bit timestamp of when the journal was either created or last
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* stamped.
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*
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* To determine the next usn there are two ways. The first is to parse
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* $DATA/$J and to find the last USN_RECORD in it and to add its record_length
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* to its usn (which is the byte offset in the $DATA/$J attribute). The
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* second is simply to take the data size of the attribute. Since the usns
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* are simply byte offsets into $DATA/$J, this is exactly the next usn. For
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* obvious reasons we use the second method as it is much simpler and faster.
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*
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* As an aside, note that to actually disable the transaction log, one would
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* need to set the VOLUME_DELETE_USN_UNDERWAY flag (see above), then go
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* through all the mft records on the volume and set the usn field in their
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* $STANDARD_INFORMATION attribute to zero. Once that is done, one would need
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* to delete the transaction log file, i.e. \$Extent\$UsnJrnl, and finally,
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* one would need to clear the VOLUME_DELETE_USN_UNDERWAY flag.
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*
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* Note that if a volume is unmounted whilst the transaction log is being
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* disabled, the process will continue the next time the volume is mounted.
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* This is why we can safely mount read-write when we see a transaction log
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* in the process of being deleted.
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*/
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/* Some $UsnJrnl related constants. */
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#define UsnJrnlMajorVer 2
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#define UsnJrnlMinorVer 0
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/*
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* $DATA/$Max attribute. This is (always?) resident and has a fixed size of
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* 32 bytes. It contains the header describing the transaction log.
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*/
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typedef struct {
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/*Ofs*/
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/* 0*/sle64 maximum_size; /* The maximum on-disk size of the $DATA/$J
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attribute. */
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/* 8*/sle64 allocation_delta; /* Number of bytes by which to increase the
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size of the $DATA/$J attribute. */
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/*0x10*/sle64 journal_id; /* Current id of the transaction log. */
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/*0x18*/leUSN lowest_valid_usn; /* Lowest valid usn in $DATA/$J for the
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current journal_id. */
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/* sizeof() = 32 (0x20) bytes */
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} __attribute__ ((__packed__)) USN_HEADER;
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/*
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* Reason flags (32-bit). Cumulative flags describing the change(s) to the
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* file since it was last opened. I think the names speak for themselves but
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* if you disagree check out the descriptions in the Linux NTFS project NTFS
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* documentation: http://www.linux-ntfs.org/
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*/
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enum {
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USN_REASON_DATA_OVERWRITE = cpu_to_le32(0x00000001),
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USN_REASON_DATA_EXTEND = cpu_to_le32(0x00000002),
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USN_REASON_DATA_TRUNCATION = cpu_to_le32(0x00000004),
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USN_REASON_NAMED_DATA_OVERWRITE = cpu_to_le32(0x00000010),
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USN_REASON_NAMED_DATA_EXTEND = cpu_to_le32(0x00000020),
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USN_REASON_NAMED_DATA_TRUNCATION= cpu_to_le32(0x00000040),
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USN_REASON_FILE_CREATE = cpu_to_le32(0x00000100),
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USN_REASON_FILE_DELETE = cpu_to_le32(0x00000200),
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USN_REASON_EA_CHANGE = cpu_to_le32(0x00000400),
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USN_REASON_SECURITY_CHANGE = cpu_to_le32(0x00000800),
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USN_REASON_RENAME_OLD_NAME = cpu_to_le32(0x00001000),
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USN_REASON_RENAME_NEW_NAME = cpu_to_le32(0x00002000),
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USN_REASON_INDEXABLE_CHANGE = cpu_to_le32(0x00004000),
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USN_REASON_BASIC_INFO_CHANGE = cpu_to_le32(0x00008000),
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USN_REASON_HARD_LINK_CHANGE = cpu_to_le32(0x00010000),
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USN_REASON_COMPRESSION_CHANGE = cpu_to_le32(0x00020000),
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USN_REASON_ENCRYPTION_CHANGE = cpu_to_le32(0x00040000),
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USN_REASON_OBJECT_ID_CHANGE = cpu_to_le32(0x00080000),
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USN_REASON_REPARSE_POINT_CHANGE = cpu_to_le32(0x00100000),
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USN_REASON_STREAM_CHANGE = cpu_to_le32(0x00200000),
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USN_REASON_CLOSE = cpu_to_le32(0x80000000),
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};
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typedef le32 USN_REASON_FLAGS;
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/*
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* Source info flags (32-bit). Information about the source of the change(s)
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* to the file. For detailed descriptions of what these mean, see the Linux
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* NTFS project NTFS documentation:
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* http://www.linux-ntfs.org/
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*/
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enum {
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USN_SOURCE_DATA_MANAGEMENT = cpu_to_le32(0x00000001),
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USN_SOURCE_AUXILIARY_DATA = cpu_to_le32(0x00000002),
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USN_SOURCE_REPLICATION_MANAGEMENT = cpu_to_le32(0x00000004),
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};
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typedef le32 USN_SOURCE_INFO_FLAGS;
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/*
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* $DATA/$J attribute. This is always non-resident, is marked as sparse, and
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* is of variabled size. It consists of a sequence of variable size
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* USN_RECORDS. The minimum allocated_size is allocation_delta as
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* specified in $DATA/$Max. When the maximum_size specified in $DATA/$Max is
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* exceeded by more than allocation_delta bytes, allocation_delta bytes are
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* allocated and appended to the $DATA/$J attribute and an equal number of
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* bytes at the beginning of the attribute are freed and made sparse. Note the
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* making sparse only happens at volume checkpoints and hence the actual
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* $DATA/$J size can exceed maximum_size + allocation_delta temporarily.
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*/
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typedef struct {
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/*Ofs*/
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/* 0*/le32 length; /* Byte size of this record (8-byte
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aligned). */
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/* 4*/le16 major_ver; /* Major version of the transaction log used
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for this record. */
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/* 6*/le16 minor_ver; /* Minor version of the transaction log used
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for this record. */
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/* 8*/leMFT_REF mft_reference;/* The mft reference of the file (or
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directory) described by this record. */
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/*0x10*/leMFT_REF parent_directory;/* The mft reference of the parent
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directory of the file described by this
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record. */
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/*0x18*/leUSN usn; /* The usn of this record. Equals the offset
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within the $DATA/$J attribute. */
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/*0x20*/sle64 time; /* Time when this record was created. */
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/*0x28*/USN_REASON_FLAGS reason;/* Reason flags (see above). */
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/*0x2c*/USN_SOURCE_INFO_FLAGS source_info;/* Source info flags (see above). */
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/*0x30*/le32 security_id; /* File security_id copied from
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$STANDARD_INFORMATION. */
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/*0x34*/FILE_ATTR_FLAGS file_attributes; /* File attributes copied from
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$STANDARD_INFORMATION or $FILE_NAME (not
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sure which). */
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/*0x38*/le16 file_name_size; /* Size of the file name in bytes. */
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/*0x3a*/le16 file_name_offset; /* Offset to the file name in bytes from the
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start of this record. */
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/*0x3c*/ntfschar file_name[0]; /* Use when creating only. When reading use
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file_name_offset to determine the location
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of the name. */
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/* sizeof() = 60 (0x3c) bytes */
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} __attribute__ ((__packed__)) USN_RECORD;
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extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol);
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#endif /* NTFS_RW */
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#endif /* _LINUX_NTFS_USNJRNL_H */
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