a9d1e9daa5
The 0.95 VHDX spec defined PAYLOAD_BLOCK_UNMAPPED to be 5. The 1.00 VHDX spec redefines PAYLOAD_BLOCK_UNMAPPED to be 3 instead. The original value of 5 is now an undefined state in the spec, but it should be safe to treat it the same and return zeros for data read. This way, we can maintain compatibility with any images out in the wild that may have been created in accordance to the 0.95 spec. Reported-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 8a4d2da73a8dbc04cde62bea782fc09ff84b1cf1.1418018421.git.jcody@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
454 lines
19 KiB
C
454 lines
19 KiB
C
/*
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* Block driver for Hyper-V VHDX Images
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*
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* Copyright (c) 2013 Red Hat, Inc.,
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*
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* Authors:
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* Jeff Cody <jcody@redhat.com>
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*
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* This is based on the "VHDX Format Specification v1.00", published 8/25/2012
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* by Microsoft:
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* https://www.microsoft.com/en-us/download/details.aspx?id=34750
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#ifndef BLOCK_VHDX_H
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#define BLOCK_VHDX_H
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#define KiB (1 * 1024)
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#define MiB (KiB * 1024)
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#define GiB (MiB * 1024)
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#define TiB ((uint64_t) GiB * 1024)
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#define DEFAULT_LOG_SIZE 1048576 /* 1MiB */
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/* Structures and fields present in the VHDX file */
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/* The header section has the following blocks,
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* each block is 64KB:
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*
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* _____________________________________________________________________________
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* | File Id. | Header 1 | Header 2 | Region Table | Reserved (768KB) |
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* |----------|---------------|------------|--------------|--------------------|
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* | | | | | |
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* 0.........64KB...........128KB........192KB..........256KB................1MB
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*/
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#define VHDX_HEADER_BLOCK_SIZE (64 * 1024)
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#define VHDX_FILE_ID_OFFSET 0
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#define VHDX_HEADER1_OFFSET (VHDX_HEADER_BLOCK_SIZE * 1)
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#define VHDX_HEADER2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 2)
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#define VHDX_REGION_TABLE_OFFSET (VHDX_HEADER_BLOCK_SIZE * 3)
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#define VHDX_REGION_TABLE2_OFFSET (VHDX_HEADER_BLOCK_SIZE * 4)
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#define VHDX_HEADER_SECTION_END (1 * MiB)
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/*
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* A note on the use of MS-GUID fields. For more details on the GUID,
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* please see: https://en.wikipedia.org/wiki/Globally_unique_identifier.
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*
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* The VHDX specification only states that these are MS GUIDs, and which
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* bytes are data1-data4. It makes no mention of what algorithm should be used
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* to generate the GUID, nor what standard. However, looking at the specified
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* known GUID fields, it appears the GUIDs are:
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* Standard/DCE GUID type (noted by 10b in the MSB of byte 0 of .data4)
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* Random algorithm (noted by 0x4XXX for .data3)
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*/
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/* ---- HEADER SECTION STRUCTURES ---- */
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/* These structures are ones that are defined in the VHDX specification
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* document */
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#define VHDX_FILE_SIGNATURE 0x656C696678646876ULL /* "vhdxfile" in ASCII */
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typedef struct VHDXFileIdentifier {
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uint64_t signature; /* "vhdxfile" in ASCII */
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uint16_t creator[256]; /* optional; utf-16 string to identify
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the vhdx file creator. Diagnostic
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only */
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} VHDXFileIdentifier;
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/* the guid is a 16 byte unique ID - the definition for this used by
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* Microsoft is not just 16 bytes though - it is a structure that is defined,
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* so we need to follow it here so that endianness does not trip us up */
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typedef struct QEMU_PACKED MSGUID {
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uint32_t data1;
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uint16_t data2;
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uint16_t data3;
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uint8_t data4[8];
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} MSGUID;
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#define guid_eq(a, b) \
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(memcmp(&(a), &(b), sizeof(MSGUID)) == 0)
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#define VHDX_HEADER_SIZE (4 * 1024) /* although the vhdx_header struct in disk
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is only 582 bytes, for purposes of crc
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the header is the first 4KB of the 64KB
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block */
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/* The full header is 4KB, although the actual header data is much smaller.
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* But for the checksum calculation, it is over the entire 4KB structure,
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* not just the defined portion of it */
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#define VHDX_HEADER_SIGNATURE 0x64616568
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typedef struct QEMU_PACKED VHDXHeader {
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uint32_t signature; /* "head" in ASCII */
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uint32_t checksum; /* CRC-32C hash of the whole header */
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uint64_t sequence_number; /* Seq number of this header. Each
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VHDX file has 2 of these headers,
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and only the header with the highest
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sequence number is valid */
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MSGUID file_write_guid; /* 128 bit unique identifier. Must be
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updated to new, unique value before
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the first modification is made to
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file */
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MSGUID data_write_guid; /* 128 bit unique identifier. Must be
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updated to new, unique value before
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the first modification is made to
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visible data. Visbile data is
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defined as:
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- system & user metadata
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- raw block data
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- disk size
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- any change that will
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cause the virtual disk
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sector read to differ
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This does not need to change if
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blocks are re-arranged */
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MSGUID log_guid; /* 128 bit unique identifier. If zero,
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there is no valid log. If non-zero,
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log entries with this guid are
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valid. */
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uint16_t log_version; /* version of the log format. Must be
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set to zero */
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uint16_t version; /* version of the vhdx file. Currently,
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only supported version is "1" */
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uint32_t log_length; /* length of the log. Must be multiple
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of 1MB */
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uint64_t log_offset; /* byte offset in the file of the log.
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Must also be a multiple of 1MB */
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} VHDXHeader;
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/* Header for the region table block */
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#define VHDX_REGION_SIGNATURE 0x69676572 /* "regi" in ASCII */
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typedef struct QEMU_PACKED VHDXRegionTableHeader {
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uint32_t signature; /* "regi" in ASCII */
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uint32_t checksum; /* CRC-32C hash of the 64KB table */
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uint32_t entry_count; /* number of valid entries */
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uint32_t reserved;
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} VHDXRegionTableHeader;
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/* Individual region table entry. There may be a maximum of 2047 of these
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*
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* There are two known region table properties. Both are required.
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* BAT (block allocation table): 2DC27766F62342009D64115E9BFD4A08
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* Metadata: 8B7CA20647904B9AB8FE575F050F886E
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*/
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#define VHDX_REGION_ENTRY_REQUIRED 0x01 /* if set, parser must understand
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this entry in order to open
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file */
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typedef struct QEMU_PACKED VHDXRegionTableEntry {
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MSGUID guid; /* 128-bit unique identifier */
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uint64_t file_offset; /* offset of the object in the file.
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Must be multiple of 1MB */
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uint32_t length; /* length, in bytes, of the object */
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uint32_t data_bits;
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} VHDXRegionTableEntry;
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/* ---- LOG ENTRY STRUCTURES ---- */
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#define VHDX_LOG_MIN_SIZE (1024 * 1024)
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#define VHDX_LOG_SECTOR_SIZE 4096
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#define VHDX_LOG_HDR_SIZE 64
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#define VHDX_LOG_SIGNATURE 0x65676f6c
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typedef struct QEMU_PACKED VHDXLogEntryHeader {
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uint32_t signature; /* "loge" in ASCII */
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uint32_t checksum; /* CRC-32C hash of the 64KB table */
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uint32_t entry_length; /* length in bytes, multiple of 1MB */
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uint32_t tail; /* byte offset of first log entry of a
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seq, where this entry is the last
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entry */
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uint64_t sequence_number; /* incremented with each log entry.
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May not be zero. */
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uint32_t descriptor_count; /* number of descriptors in this log
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entry, must be >= 0 */
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uint32_t reserved;
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MSGUID log_guid; /* value of the log_guid from
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vhdx_header. If not found in
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vhdx_header, it is invalid */
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uint64_t flushed_file_offset; /* see spec for full details - this
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should be vhdx file size in bytes */
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uint64_t last_file_offset; /* size in bytes that all allocated
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file structures fit into */
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} VHDXLogEntryHeader;
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#define VHDX_LOG_DESC_SIZE 32
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#define VHDX_LOG_DESC_SIGNATURE 0x63736564
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#define VHDX_LOG_ZERO_SIGNATURE 0x6f72657a
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typedef struct QEMU_PACKED VHDXLogDescriptor {
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uint32_t signature; /* "zero" or "desc" in ASCII */
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union {
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uint32_t reserved; /* zero desc */
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uint32_t trailing_bytes; /* data desc: bytes 4092-4096 of the
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data sector */
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};
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union {
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uint64_t zero_length; /* zero desc: length of the section to
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zero */
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uint64_t leading_bytes; /* data desc: bytes 0-7 of the data
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sector */
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};
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uint64_t file_offset; /* file offset to write zeros - multiple
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of 4kB */
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uint64_t sequence_number; /* must match same field in
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vhdx_log_entry_header */
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} VHDXLogDescriptor;
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#define VHDX_LOG_DATA_SIGNATURE 0x61746164
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typedef struct QEMU_PACKED VHDXLogDataSector {
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uint32_t data_signature; /* "data" in ASCII */
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uint32_t sequence_high; /* 4 MSB of 8 byte sequence_number */
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uint8_t data[4084]; /* raw data, bytes 8-4091 (inclusive).
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see the data descriptor field for the
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other mising bytes */
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uint32_t sequence_low; /* 4 LSB of 8 byte sequence_number */
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} VHDXLogDataSector;
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/* block states - different state values depending on whether it is a
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* payload block, or a sector block. */
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#define PAYLOAD_BLOCK_NOT_PRESENT 0
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#define PAYLOAD_BLOCK_UNDEFINED 1
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#define PAYLOAD_BLOCK_ZERO 2
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#define PAYLOAD_BLOCK_UNMAPPED 3
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#define PAYLOAD_BLOCK_UNMAPPED_v095 5
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#define PAYLOAD_BLOCK_FULLY_PRESENT 6
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#define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7
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#define SB_BLOCK_NOT_PRESENT 0
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#define SB_BLOCK_PRESENT 6
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/* per the spec */
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#define VHDX_MAX_SECTORS_PER_BLOCK (1 << 23)
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/* upper 44 bits are the file offset in 1MB units lower 3 bits are the state
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other bits are reserved */
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#define VHDX_BAT_STATE_BIT_MASK 0x07
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#define VHDX_BAT_FILE_OFF_MASK 0xFFFFFFFFFFF00000ULL /* upper 44 bits */
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typedef uint64_t VHDXBatEntry;
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/* ---- METADATA REGION STRUCTURES ---- */
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#define VHDX_METADATA_ENTRY_SIZE 32
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#define VHDX_METADATA_MAX_ENTRIES 2047 /* not including the header */
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#define VHDX_METADATA_TABLE_MAX_SIZE \
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(VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1))
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#define VHDX_METADATA_SIGNATURE 0x617461646174656DULL /* "metadata" in ASCII */
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typedef struct QEMU_PACKED VHDXMetadataTableHeader {
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uint64_t signature; /* "metadata" in ASCII */
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uint16_t reserved;
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uint16_t entry_count; /* number table entries. <= 2047 */
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uint32_t reserved2[5];
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} VHDXMetadataTableHeader;
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#define VHDX_META_FLAGS_IS_USER 0x01 /* max 1024 entries */
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#define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02 /* virtual disk metadata if set,
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otherwise file metdata */
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#define VHDX_META_FLAGS_IS_REQUIRED 0x04 /* parse must understand this
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entry to open the file */
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typedef struct QEMU_PACKED VHDXMetadataTableEntry {
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MSGUID item_id; /* 128-bit identifier for metadata */
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uint32_t offset; /* byte offset of the metadata. At
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least 64kB. Relative to start of
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metadata region */
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/* note: if length = 0, so is offset */
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uint32_t length; /* length of metadata. <= 1MB. */
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uint32_t data_bits; /* least-significant 3 bits are flags,
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the rest are reserved (see above) */
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uint32_t reserved2;
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} VHDXMetadataTableEntry;
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#define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01 /* Do not change any blocks to
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be BLOCK_NOT_PRESENT.
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If set indicates a fixed
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size VHDX file */
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#define VHDX_PARAMS_HAS_PARENT 0x02 /* has parent / backing file */
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#define VHDX_BLOCK_SIZE_MIN (1 * MiB)
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#define VHDX_BLOCK_SIZE_MAX (256 * MiB)
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typedef struct QEMU_PACKED VHDXFileParameters {
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uint32_t block_size; /* size of each payload block, always
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power of 2, <= 256MB and >= 1MB. */
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uint32_t data_bits; /* least-significant 2 bits are flags,
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the rest are reserved (see above) */
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} VHDXFileParameters;
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#define VHDX_MAX_IMAGE_SIZE ((uint64_t) 64 * TiB)
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typedef struct QEMU_PACKED VHDXVirtualDiskSize {
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uint64_t virtual_disk_size; /* Size of the virtual disk, in bytes.
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Must be multiple of the sector size,
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max of 64TB */
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} VHDXVirtualDiskSize;
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typedef struct QEMU_PACKED VHDXPage83Data {
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MSGUID page_83_data; /* unique id for scsi devices that
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support page 0x83 */
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} VHDXPage83Data;
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typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize {
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uint32_t logical_sector_size; /* virtual disk sector size (in bytes).
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Can only be 512 or 4096 bytes */
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} VHDXVirtualDiskLogicalSectorSize;
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typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize {
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uint32_t physical_sector_size; /* physical sector size (in bytes).
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Can only be 512 or 4096 bytes */
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} VHDXVirtualDiskPhysicalSectorSize;
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typedef struct QEMU_PACKED VHDXParentLocatorHeader {
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MSGUID locator_type; /* type of the parent virtual disk. */
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uint16_t reserved;
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uint16_t key_value_count; /* number of key/value pairs for this
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locator */
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} VHDXParentLocatorHeader;
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/* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */
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typedef struct QEMU_PACKED VHDXParentLocatorEntry {
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uint32_t key_offset; /* offset in metadata for key, > 0 */
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uint32_t value_offset; /* offset in metadata for value, >0 */
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uint16_t key_length; /* length of entry key, > 0 */
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uint16_t value_length; /* length of entry value, > 0 */
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} VHDXParentLocatorEntry;
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/* ----- END VHDX SPECIFICATION STRUCTURES ---- */
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typedef struct VHDXMetadataEntries {
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VHDXMetadataTableEntry file_parameters_entry;
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VHDXMetadataTableEntry virtual_disk_size_entry;
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VHDXMetadataTableEntry page83_data_entry;
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VHDXMetadataTableEntry logical_sector_size_entry;
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VHDXMetadataTableEntry phys_sector_size_entry;
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VHDXMetadataTableEntry parent_locator_entry;
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uint16_t present;
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} VHDXMetadataEntries;
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typedef struct VHDXLogEntries {
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uint64_t offset;
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uint64_t length;
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uint32_t write;
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uint32_t read;
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VHDXLogEntryHeader *hdr;
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void *desc_buffer;
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uint64_t sequence;
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uint32_t tail;
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} VHDXLogEntries;
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typedef struct VHDXRegionEntry {
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uint64_t start;
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uint64_t end;
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QLIST_ENTRY(VHDXRegionEntry) entries;
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} VHDXRegionEntry;
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typedef struct BDRVVHDXState {
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CoMutex lock;
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int curr_header;
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VHDXHeader *headers[2];
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VHDXRegionTableHeader rt;
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VHDXRegionTableEntry bat_rt; /* region table for the BAT */
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VHDXRegionTableEntry metadata_rt; /* region table for the metadata */
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VHDXMetadataTableHeader metadata_hdr;
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VHDXMetadataEntries metadata_entries;
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VHDXFileParameters params;
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uint32_t block_size;
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uint32_t block_size_bits;
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uint32_t sectors_per_block;
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uint32_t sectors_per_block_bits;
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uint64_t virtual_disk_size;
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uint32_t logical_sector_size;
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uint32_t physical_sector_size;
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uint64_t chunk_ratio;
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uint32_t chunk_ratio_bits;
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uint32_t logical_sector_size_bits;
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uint32_t bat_entries;
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VHDXBatEntry *bat;
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uint64_t bat_offset;
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bool first_visible_write;
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MSGUID session_guid;
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VHDXLogEntries log;
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VHDXParentLocatorHeader parent_header;
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VHDXParentLocatorEntry *parent_entries;
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Error *migration_blocker;
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bool log_replayed_on_open;
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QLIST_HEAD(VHDXRegionHead, VHDXRegionEntry) regions;
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} BDRVVHDXState;
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void vhdx_guid_generate(MSGUID *guid);
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int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s, bool rw,
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MSGUID *log_guid);
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uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset);
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uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
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int crc_offset);
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bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset);
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int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
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Error **errp);
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int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
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void *data, uint32_t length, uint64_t offset);
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static inline void leguid_to_cpus(MSGUID *guid)
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{
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le32_to_cpus(&guid->data1);
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le16_to_cpus(&guid->data2);
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le16_to_cpus(&guid->data3);
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}
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static inline void cpu_to_leguids(MSGUID *guid)
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{
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cpu_to_le32s(&guid->data1);
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cpu_to_le16s(&guid->data2);
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cpu_to_le16s(&guid->data3);
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}
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void vhdx_header_le_import(VHDXHeader *h);
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void vhdx_header_le_export(VHDXHeader *orig_h, VHDXHeader *new_h);
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void vhdx_log_desc_le_import(VHDXLogDescriptor *d);
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void vhdx_log_desc_le_export(VHDXLogDescriptor *d);
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void vhdx_log_data_le_import(VHDXLogDataSector *d);
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void vhdx_log_data_le_export(VHDXLogDataSector *d);
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void vhdx_log_entry_hdr_le_import(VHDXLogEntryHeader *hdr);
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void vhdx_log_entry_hdr_le_export(VHDXLogEntryHeader *hdr);
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void vhdx_region_header_le_import(VHDXRegionTableHeader *hdr);
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void vhdx_region_header_le_export(VHDXRegionTableHeader *hdr);
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void vhdx_region_entry_le_import(VHDXRegionTableEntry *e);
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void vhdx_region_entry_le_export(VHDXRegionTableEntry *e);
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void vhdx_metadata_header_le_import(VHDXMetadataTableHeader *hdr);
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void vhdx_metadata_header_le_export(VHDXMetadataTableHeader *hdr);
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void vhdx_metadata_entry_le_import(VHDXMetadataTableEntry *e);
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void vhdx_metadata_entry_le_export(VHDXMetadataTableEntry *e);
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int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s);
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#endif
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