Adding upstream version 6.1.22-dfsg.upstream/6.1.22-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2413 insertions, 0 deletions

diff --git a/src/VBox/Storage/VHDX.cpp b/src/VBox/Storage/VHDX.cpp
new file mode 100644
index 00000000..00459bc5
--- /dev/null
+++ b/src/VBox/Storage/VHDX.cpp
@@ -0,0 +1,2413 @@
+/* $Id: VHDX.cpp $ */
+/** @file
+ * VHDX - VHDX Disk image, Core Code.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP LOG_GROUP_VD_VHDX
+#include <VBox/vd-plugin.h>
+#include <VBox/err.h>
+
+#include <VBox/log.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/alloc.h>
+#include <iprt/path.h>
+#include <iprt/uuid.h>
+#include <iprt/crc.h>
+
+#include "VDBackends.h"
+#include "VDBackendsInline.h"
+
+
+/*********************************************************************************************************************************
+*   On disk data structures                                                                                                      *
+*********************************************************************************************************************************/
+
+/**
+ * VHDX file type identifier.
+ */
+#pragma pack(1)
+typedef struct VhdxFileIdentifier
+{
+    /** Signature. */
+    uint64_t    u64Signature;
+    /** Creator ID - UTF-16 string (not neccessarily null terminated). */
+    uint16_t    awszCreator[256];
+} VhdxFileIdentifier;
+#pragma pack()
+/** Pointer to an on disk VHDX file type identifier. */
+typedef VhdxFileIdentifier *PVhdxFileIdentifier;
+
+/** VHDX file type identifier signature ("vhdxfile"). */
+#define VHDX_FILE_IDENTIFIER_SIGNATURE UINT64_C(0x656c696678646876)
+/** Start offset of the VHDX file type identifier. */
+#define VHDX_FILE_IDENTIFIER_OFFSET    UINT64_C(0)
+
+/**
+ * VHDX header.
+ */
+#pragma pack(1)
+typedef struct VhdxHeader
+{
+    /** Signature. */
+    uint32_t    u32Signature;
+    /** Checksum. */
+    uint32_t    u32Checksum;
+    /** Sequence number. */
+    uint64_t    u64SequenceNumber;
+    /** File write UUID. */
+    RTUUID      UuidFileWrite;
+    /** Data write UUID. */
+    RTUUID      UuidDataWrite;
+    /** Log UUID. */
+    RTUUID      UuidLog;
+    /** Version of the log format. */
+    uint16_t    u16LogVersion;
+    /** VHDX format version. */
+    uint16_t    u16Version;
+    /** Length of the log region. */
+    uint32_t    u32LogLength;
+    /** Start offset of the log offset in the file. */
+    uint64_t    u64LogOffset;
+    /** Reserved bytes. */
+    uint8_t     u8Reserved[4016];
+} VhdxHeader;
+#pragma pack()
+/** Pointer to an on disk VHDX header. */
+typedef VhdxHeader *PVhdxHeader;
+
+/** VHDX header signature ("head"). */
+#define VHDX_HEADER_SIGNATURE    UINT32_C(0x64616568)
+/** Start offset of the first VHDX header. */
+#define VHDX_HEADER1_OFFSET      _64K
+/** Start offset of the second VHDX header. */
+#define VHDX_HEADER2_OFFSET      _128K
+/** Current Log format version. */
+#define VHDX_HEADER_LOG_VERSION  UINT16_C(0)
+/** Current VHDX format version. */
+#define VHDX_HEADER_VHDX_VERSION UINT16_C(1)
+
+/**
+ * VHDX region table header
+ */
+#pragma pack(1)
+typedef struct VhdxRegionTblHdr
+{
+    /** Signature. */
+    uint32_t    u32Signature;
+    /** Checksum. */
+    uint32_t    u32Checksum;
+    /** Number of region table entries following this header. */
+    uint32_t    u32EntryCount;
+    /** Reserved. */
+    uint32_t    u32Reserved;
+} VhdxRegionTblHdr;
+#pragma pack()
+/** Pointer to an on disk VHDX region table header. */
+typedef VhdxRegionTblHdr *PVhdxRegionTblHdr;
+
+/** VHDX region table header signature. */
+#define VHDX_REGION_TBL_HDR_SIGNATURE       UINT32_C(0x69676572)
+/** Maximum number of entries which can follow. */
+#define VHDX_REGION_TBL_HDR_ENTRY_COUNT_MAX UINT32_C(2047)
+/** Offset where the region table is stored (192 KB). */
+#define VHDX_REGION_TBL_HDR_OFFSET          UINT64_C(196608)
+/** Maximum size of the region table. */
+#define VHDX_REGION_TBL_SIZE_MAX            _64K
+
+/**
+ * VHDX region table entry.
+ */
+#pragma pack(1)
+typedef struct VhdxRegionTblEntry
+{
+    /** Object UUID. */
+    RTUUID      UuidObject;
+    /** File offset of the region. */
+    uint64_t    u64FileOffset;
+    /** Length of the region in bytes. */
+    uint32_t    u32Length;
+    /** Flags for this object. */
+    uint32_t    u32Flags;
+} VhdxRegionTblEntry;
+#pragma pack()
+/** Pointer to an on disk VHDX region table entry. */
+typedef struct VhdxRegionTblEntry *PVhdxRegionTblEntry;
+
+/** Flag whether this region is required. */
+#define VHDX_REGION_TBL_ENTRY_FLAGS_IS_REQUIRED RT_BIT_32(0)
+/** UUID for the BAT region. */
+#define VHDX_REGION_TBL_ENTRY_UUID_BAT          "2dc27766-f623-4200-9d64-115e9bfd4a08"
+/** UUID for the metadata region. */
+#define VHDX_REGION_TBL_ENTRY_UUID_METADATA     "8b7ca206-4790-4b9a-b8fe-575f050f886e"
+
+/**
+ * VHDX Log entry header.
+ */
+#pragma pack(1)
+typedef struct VhdxLogEntryHdr
+{
+    /** Signature. */
+    uint32_t    u32Signature;
+    /** Checksum. */
+    uint32_t    u32Checksum;
+    /** Total length of the entry in bytes. */
+    uint32_t    u32EntryLength;
+    /** Tail of the log entries. */
+    uint32_t    u32Tail;
+    /** Sequence number. */
+    uint64_t    u64SequenceNumber;
+    /** Number of descriptors in this log entry. */
+    uint32_t    u32DescriptorCount;
+    /** Reserved. */
+    uint32_t    u32Reserved;
+    /** Log UUID. */
+    RTUUID      UuidLog;
+    /** VHDX file size in bytes while the log entry was written. */
+    uint64_t    u64FlushedFileOffset;
+    /** File size in bytes all allocated file structures fit into when the
+     * log entry was written. */
+    uint64_t    u64LastFileOffset;
+} VhdxLogEntryHdr;
+#pragma pack()
+/** Pointer to an on disk VHDX log entry header. */
+typedef struct VhdxLogEntryHdr *PVhdxLogEntryHdr;
+
+/** VHDX log entry signature ("loge"). */
+#define VHDX_LOG_ENTRY_HEADER_SIGNATURE UINT32_C(0x65676f6c)
+
+/**
+ * VHDX log zero descriptor.
+ */
+#pragma pack(1)
+typedef struct VhdxLogZeroDesc
+{
+    /** Signature of this descriptor. */
+    uint32_t    u32ZeroSignature;
+    /** Reserved. */
+    uint32_t    u32Reserved;
+    /** Length of the section to zero. */
+    uint64_t    u64ZeroLength;
+    /** File offset to write zeros to. */
+    uint64_t    u64FileOffset;
+    /** Sequence number (must macht the field in the log entry header). */
+    uint64_t    u64SequenceNumber;
+} VhdxLogZeroDesc;
+#pragma pack()
+/** Pointer to an on disk VHDX log zero descriptor. */
+typedef struct VhdxLogZeroDesc *PVhdxLogZeroDesc;
+
+/** Signature of a VHDX log zero descriptor ("zero"). */
+#define VHDX_LOG_ZERO_DESC_SIGNATURE UINT32_C(0x6f72657a)
+
+/**
+ * VHDX log data descriptor.
+ */
+#pragma pack(1)
+typedef struct VhdxLogDataDesc
+{
+    /** Signature of this descriptor. */
+    uint32_t    u32DataSignature;
+    /** Trailing 4 bytes removed from the update. */
+    uint32_t    u32TrailingBytes;
+    /** Leading 8 bytes removed from the update. */
+    uint64_t    u64LeadingBytes;
+    /** File offset to write zeros to. */
+    uint64_t    u64FileOffset;
+    /** Sequence number (must macht the field in the log entry header). */
+    uint64_t    u64SequenceNumber;
+} VhdxLogDataDesc;
+#pragma pack()
+/** Pointer to an on disk VHDX log data descriptor. */
+typedef struct VhdxLogDataDesc *PVhdxLogDataDesc;
+
+/** Signature of a VHDX log data descriptor ("desc"). */
+#define VHDX_LOG_DATA_DESC_SIGNATURE UINT32_C(0x63736564)
+
+/**
+ * VHDX log data sector.
+ */
+#pragma pack(1)
+typedef struct VhdxLogDataSector
+{
+    /** Signature of the data sector. */
+    uint32_t    u32DataSignature;
+    /** 4 most significant bytes of the sequence number. */
+    uint32_t    u32SequenceHigh;
+    /** Raw data associated with the update. */
+    uint8_t     u8Data[4084];
+    /** 4 least significant bytes of the sequence number. */
+    uint32_t    u32SequenceLow;
+} VhdxLogDataSector;
+#pragma pack()
+/** Pointer to an on disk VHDX log data sector. */
+typedef VhdxLogDataSector *PVhdxLogDataSector;
+
+/** Signature of a VHDX log data sector ("data"). */
+#define VHDX_LOG_DATA_SECTOR_SIGNATURE UINT32_C(0x61746164)
+
+/**
+ * VHDX BAT entry.
+ */
+#pragma pack(1)
+typedef struct VhdxBatEntry
+{
+    /** The BAT entry, contains state and offset. */
+    uint64_t    u64BatEntry;
+} VhdxBatEntry;
+#pragma pack()
+typedef VhdxBatEntry *PVhdxBatEntry;
+
+/** Return the BAT state from a given entry. */
+#define VHDX_BAT_ENTRY_GET_STATE(bat) ((bat) & UINT64_C(0x7))
+/** Get the FileOffsetMB field from a given BAT entry. */
+#define VHDX_BAT_ENTRY_GET_FILE_OFFSET_MB(bat) (((bat) & UINT64_C(0xfffffffffff00000)) >> 20)
+/** Get a byte offset from the BAT entry. */
+#define VHDX_BAT_ENTRY_GET_FILE_OFFSET(bat) (VHDX_BAT_ENTRY_GET_FILE_OFFSET_MB(bat) * (uint64_t)_1M)
+
+/** Block not present and the data is undefined. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_NOT_PRESENT       (0)
+/** Data in this block is undefined. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_UNDEFINED         (1)
+/** Data in this block contains zeros. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_ZERO              (2)
+/** Block was unmapped by the application or system and data is either zero or
+ * the data before the block was unmapped. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_UNMAPPED          (3)
+/** Block data is in the file pointed to by the FileOffsetMB field. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_FULLY_PRESENT     (6)
+/** Block is partially present, use sector bitmap to get present sectors. */
+#define VHDX_BAT_ENTRY_PAYLOAD_BLOCK_PARTIALLY_PRESENT (7)
+
+/** The sector bitmap block is undefined and not allocated in the file. */
+#define VHDX_BAT_ENTRY_SB_BLOCK_NOT_PRESENT            (0)
+/** The sector bitmap block is defined at the file location. */
+#define VHDX_BAT_ENTRY_SB_BLOCK_PRESENT                (6)
+
+/**
+ * VHDX Metadata tabl header.
+ */
+#pragma pack(1)
+typedef struct VhdxMetadataTblHdr
+{
+    /** Signature. */
+    uint64_t    u64Signature;
+    /** Reserved. */
+    uint16_t    u16Reserved;
+    /** Number of entries in the table. */
+    uint16_t    u16EntryCount;
+    /** Reserved */
+    uint32_t    u32Reserved2[5];
+} VhdxMetadataTblHdr;
+#pragma pack()
+/** Pointer to an on disk metadata table header. */
+typedef VhdxMetadataTblHdr *PVhdxMetadataTblHdr;
+
+/** Signature of a VHDX metadata table header ("metadata"). */
+#define VHDX_METADATA_TBL_HDR_SIGNATURE       UINT64_C(0x617461646174656d)
+/** Maximum number of entries the metadata table can have. */
+#define VHDX_METADATA_TBL_HDR_ENTRY_COUNT_MAX UINT16_C(2047)
+
+/**
+ * VHDX Metadata table entry.
+ */
+#pragma pack(1)
+typedef struct VhdxMetadataTblEntry
+{
+    /** Item UUID. */
+    RTUUID      UuidItem;
+    /** Offset of the metadata item. */
+    uint32_t    u32Offset;
+    /** Length of the metadata item. */
+    uint32_t    u32Length;
+    /** Flags for the metadata item. */
+    uint32_t    u32Flags;
+    /** Reserved. */
+    uint32_t    u32Reserved;
+} VhdxMetadataTblEntry;
+#pragma pack()
+/** Pointer to an on disk metadata table entry. */
+typedef VhdxMetadataTblEntry *PVhdxMetadataTblEntry;
+
+/** FLag whether the metadata item is system or user metadata. */
+#define VHDX_METADATA_TBL_ENTRY_FLAGS_IS_USER     RT_BIT_32(0)
+/** FLag whether the metadata item is file or virtual disk metadata. */
+#define VHDX_METADATA_TBL_ENTRY_FLAGS_IS_VDISK    RT_BIT_32(1)
+/** FLag whether the backend must understand the metadata item to load the image. */
+#define VHDX_METADATA_TBL_ENTRY_FLAGS_IS_REQUIRED RT_BIT_32(2)
+
+/** File parameters item UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_FILE_PARAMS    "caa16737-fa36-4d43-b3b6-33f0aa44e76b"
+/** Virtual disk size item UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_VDISK_SIZE     "2fa54224-cd1b-4876-b211-5dbed83bf4b8"
+/** Page 83 UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_PAGE83_DATA    "beca12ab-b2e6-4523-93ef-c309e000c746"
+/** Logical sector size UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_LOG_SECT_SIZE  "8141bf1d-a96f-4709-ba47-f233a8faab5f"
+/** Physical sector size UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_PHYS_SECT_SIZE "cda348c7-445d-4471-9cc9-e9885251c556"
+/** Parent locator UUID. */
+#define VHDX_METADATA_TBL_ENTRY_ITEM_PARENT_LOCATOR "a8d35f2d-b30b-454d-abf7-d3d84834ab0c"
+
+/**
+ * VHDX File parameters metadata item.
+ */
+#pragma pack(1)
+typedef struct VhdxFileParameters
+{
+    /** Block size. */
+    uint32_t    u32BlockSize;
+    /** Flags. */
+    uint32_t    u32Flags;
+} VhdxFileParameters;
+#pragma pack()
+/** Pointer to an on disk VHDX file parameters metadata item. */
+typedef struct VhdxFileParameters *PVhdxFileParameters;
+
+/** Flag whether to leave blocks allocated in the file or if it is possible to unmap them. */
+#define VHDX_FILE_PARAMETERS_FLAGS_LEAVE_BLOCKS_ALLOCATED RT_BIT_32(0)
+/** Flag whether this file has a parent VHDX file. */
+#define VHDX_FILE_PARAMETERS_FLAGS_HAS_PARENT             RT_BIT_32(1)
+
+/**
+ * VHDX virtual disk size metadata item.
+ */
+#pragma pack(1)
+typedef struct VhdxVDiskSize
+{
+    /** Virtual disk size. */
+    uint64_t    u64VDiskSize;
+} VhdxVDiskSize;
+#pragma pack()
+/** Pointer to an on disk VHDX virtual disk size metadata item. */
+typedef struct VhdxVDiskSize *PVhdxVDiskSize;
+
+/**
+ * VHDX page 83 data metadata item.
+ */
+#pragma pack(1)
+typedef struct VhdxPage83Data
+{
+    /** UUID for the SCSI device. */
+    RTUUID      UuidPage83Data;
+} VhdxPage83Data;
+#pragma pack()
+/** Pointer to an on disk VHDX vpage 83 data metadata item. */
+typedef struct VhdxPage83Data *PVhdxPage83Data;
+
+/**
+ * VHDX virtual disk logical sector size.
+ */
+#pragma pack(1)
+typedef struct VhdxVDiskLogicalSectorSize
+{
+    /** Logical sector size. */
+    uint32_t    u32LogicalSectorSize;
+} VhdxVDiskLogicalSectorSize;
+#pragma pack()
+/** Pointer to an on disk VHDX virtual disk logical sector size metadata item. */
+typedef struct VhdxVDiskLogicalSectorSize *PVhdxVDiskLogicalSectorSize;
+
+/**
+ * VHDX virtual disk physical sector size.
+ */
+#pragma pack(1)
+typedef struct VhdxVDiskPhysicalSectorSize
+{
+    /** Physical sector size. */
+    uint64_t    u64PhysicalSectorSize;
+} VhdxVDiskPhysicalSectorSize;
+#pragma pack()
+/** Pointer to an on disk VHDX virtual disk physical sector size metadata item. */
+typedef struct VhdxVDiskPhysicalSectorSize *PVhdxVDiskPhysicalSectorSize;
+
+/**
+ * VHDX parent locator header.
+ */
+#pragma pack(1)
+typedef struct VhdxParentLocatorHeader
+{
+    /** Locator type UUID. */
+    RTUUID      UuidLocatorType;
+    /** Reserved. */
+    uint16_t    u16Reserved;
+    /** Number of key value pairs. */
+    uint16_t    u16KeyValueCount;
+} VhdxParentLocatorHeader;
+#pragma pack()
+/** Pointer to an on disk VHDX parent locator header metadata item. */
+typedef struct VhdxParentLocatorHeader *PVhdxParentLocatorHeader;
+
+/** VHDX parent locator type. */
+#define VHDX_PARENT_LOCATOR_TYPE_VHDX "b04aefb7-d19e-4a81-b789-25b8e9445913"
+
+/**
+ * VHDX parent locator entry.
+ */
+#pragma pack(1)
+typedef struct VhdxParentLocatorEntry
+{
+    /** Offset of the key. */
+    uint32_t    u32KeyOffset;
+    /** Offset of the value. */
+    uint32_t    u32ValueOffset;
+    /** Length of the key. */
+    uint16_t    u16KeyLength;
+    /** Length of the value. */
+    uint16_t    u16ValueLength;
+} VhdxParentLocatorEntry;
+#pragma pack()
+/** Pointer to an on disk VHDX parent locator entry. */
+typedef struct VhdxParentLocatorEntry *PVhdxParentLocatorEntry;
+
+
+/*********************************************************************************************************************************
+*   Constants And Macros, Structures and Typedefs                                                                                *
+*********************************************************************************************************************************/
+
+typedef enum VHDXMETADATAITEM
+{
+    VHDXMETADATAITEM_UNKNOWN = 0,
+    VHDXMETADATAITEM_FILE_PARAMS,
+    VHDXMETADATAITEM_VDISK_SIZE,
+    VHDXMETADATAITEM_PAGE83_DATA,
+    VHDXMETADATAITEM_LOGICAL_SECTOR_SIZE,
+    VHDXMETADATAITEM_PHYSICAL_SECTOR_SIZE,
+    VHDXMETADATAITEM_PARENT_LOCATOR,
+    VHDXMETADATAITEM_32BIT_HACK = 0x7fffffff
+} VHDXMETADATAITEM;
+
+/**
+ * Table to validate the metadata item UUIDs and the flags.
+ */
+typedef struct VHDXMETADATAITEMPROPS
+{
+    /** Item UUID. */
+    const char          *pszItemUuid;
+    /** Flag whether this is a user or system metadata item. */
+    bool                 fIsUser;
+    /** Flag whether this is a virtual disk or file metadata item. */
+    bool                 fIsVDisk;
+    /** Flag whether this metadata item is required to load the file. */
+    bool                 fIsRequired;
+    /** Metadata item enum associated with this UUID. */
+    VHDXMETADATAITEM     enmMetadataItem;
+} VHDXMETADATAITEMPROPS;
+
+/**
+ * VHDX image data structure.
+ */
+typedef struct VHDXIMAGE
+{
+    /** Image name. */
+    const char         *pszFilename;
+    /** Storage handle. */
+    PVDIOSTORAGE        pStorage;
+
+    /** Pointer to the per-disk VD interface list. */
+    PVDINTERFACE        pVDIfsDisk;
+    /** Pointer to the per-image VD interface list. */
+    PVDINTERFACE        pVDIfsImage;
+    /** Error interface. */
+    PVDINTERFACEERROR   pIfError;
+    /** I/O interface. */
+    PVDINTERFACEIOINT   pIfIo;
+
+    /** Open flags passed by VBoxHD layer. */
+    unsigned            uOpenFlags;
+    /** Image flags defined during creation or determined during open. */
+    unsigned            uImageFlags;
+    /** Version of the VHDX image format. */
+    unsigned            uVersion;
+    /** Total size of the image. */
+    uint64_t            cbSize;
+    /** Logical sector size of the image. */
+    uint32_t            cbLogicalSector;
+    /** Block size of the image. */
+    size_t              cbBlock;
+    /** Physical geometry of this image. */
+    VDGEOMETRY          PCHSGeometry;
+    /** Logical geometry of this image. */
+    VDGEOMETRY          LCHSGeometry;
+
+    /** The BAT. */
+    PVhdxBatEntry       paBat;
+    /** Chunk ratio. */
+    uint32_t            uChunkRatio;
+    /** The static region list. */
+    VDREGIONLIST        RegionList;
+} VHDXIMAGE, *PVHDXIMAGE;
+
+/**
+ * Endianess conversion direction.
+ */
+typedef enum VHDXECONV
+{
+    /** Host to file endianess. */
+    VHDXECONV_H2F = 0,
+    /** File to host endianess. */
+    VHDXECONV_F2H
+} VHDXECONV;
+
+/** Macros for endianess conversion. */
+#define SET_ENDIAN_U16(u16) (enmConv == VHDXECONV_H2F ? RT_H2LE_U16(u16) : RT_LE2H_U16(u16))
+#define SET_ENDIAN_U32(u32) (enmConv == VHDXECONV_H2F ? RT_H2LE_U32(u32) : RT_LE2H_U32(u32))
+#define SET_ENDIAN_U64(u64) (enmConv == VHDXECONV_H2F ? RT_H2LE_U64(u64) : RT_LE2H_U64(u64))
+
+
+/*********************************************************************************************************************************
+*   Static Variables                                                                                                             *
+*********************************************************************************************************************************/
+
+/**
+ * NULL-terminated array of supported file extensions.
+ */
+static const VDFILEEXTENSION s_aVhdxFileExtensions[] =
+{
+    {"vhdx", VDTYPE_HDD},
+    {NULL, VDTYPE_INVALID}
+};
+
+/**
+ * Static table to verify the metadata item properties and the flags.
+ */
+static const VHDXMETADATAITEMPROPS s_aVhdxMetadataItemProps[] =
+{
+    /* pcszItemUuid                               fIsUser, fIsVDisk, fIsRequired, enmMetadataItem */
+    {VHDX_METADATA_TBL_ENTRY_ITEM_FILE_PARAMS,    false,   false,    true,        VHDXMETADATAITEM_FILE_PARAMS},
+    {VHDX_METADATA_TBL_ENTRY_ITEM_VDISK_SIZE,     false,   true,     true,        VHDXMETADATAITEM_VDISK_SIZE},
+    {VHDX_METADATA_TBL_ENTRY_ITEM_PAGE83_DATA,    false,   true,     true,        VHDXMETADATAITEM_PAGE83_DATA},
+    {VHDX_METADATA_TBL_ENTRY_ITEM_LOG_SECT_SIZE,  false,   true,     true,        VHDXMETADATAITEM_LOGICAL_SECTOR_SIZE},
+    {VHDX_METADATA_TBL_ENTRY_ITEM_PHYS_SECT_SIZE, false,   true,     true,        VHDXMETADATAITEM_PHYSICAL_SECTOR_SIZE},
+    {VHDX_METADATA_TBL_ENTRY_ITEM_PARENT_LOCATOR, false,   false,    true,        VHDXMETADATAITEM_PARENT_LOCATOR}
+};
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+
+/**
+ * Converts the file identifier between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pFileIdentifierConv Where to store the converted file identifier.
+ * @param   pFileIdentifier     The file identifier to convert.
+ *
+ * @note It is safe to use the same pointer for pFileIdentifierConv and pFileIdentifier.
+ */
+DECLINLINE(void) vhdxConvFileIdentifierEndianess(VHDXECONV enmConv, PVhdxFileIdentifier pFileIdentifierConv,
+                                                 PVhdxFileIdentifier pFileIdentifier)
+{
+    pFileIdentifierConv->u64Signature = SET_ENDIAN_U64(pFileIdentifier->u64Signature);
+    for (unsigned i = 0; i < RT_ELEMENTS(pFileIdentifierConv->awszCreator); i++)
+        pFileIdentifierConv->awszCreator[i] = SET_ENDIAN_U16(pFileIdentifier->awszCreator[i]);
+}
+
+/**
+ * Converts a UUID between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pUuidConv           Where to store the converted UUID.
+ * @param   pUuid               The UUID to convert.
+ *
+ * @note It is safe to use the same pointer for pUuidConv and pUuid.
+ */
+DECLINLINE(void) vhdxConvUuidEndianess(VHDXECONV enmConv, PRTUUID pUuidConv, PRTUUID pUuid)
+{
+    RT_NOREF1(enmConv);
+#if 1
+    /** @todo r=andy Code looks temporary disabled to me, fixes strict release builds:
+     *        "accessing 16 bytes at offsets 0 and 0 overlaps 16 bytes at offset 0 [-Werror=restrict]" */
+    RTUUID uuidTmp;
+    memcpy(&uuidTmp,  pUuid,    sizeof(RTUUID));
+    memcpy(pUuidConv, &uuidTmp, sizeof(RTUUID));
+#else
+    pUuidConv->Gen.u32TimeLow              = SET_ENDIAN_U32(pUuid->Gen.u32TimeLow);
+    pUuidConv->Gen.u16TimeMid              = SET_ENDIAN_U16(pUuid->Gen.u16TimeMid);
+    pUuidConv->Gen.u16TimeHiAndVersion     = SET_ENDIAN_U16(pUuid->Gen.u16TimeHiAndVersion);
+    pUuidConv->Gen.u8ClockSeqHiAndReserved = pUuid->Gen.u8ClockSeqHiAndReserved;
+    pUuidConv->Gen.u8ClockSeqLow           = pUuid->Gen.u8ClockSeqLow;
+    for (unsigned i = 0; i < RT_ELEMENTS(pUuidConv->Gen.au8Node); i++)
+        pUuidConv->Gen.au8Node[i] = pUuid->Gen.au8Node[i];
+#endif
+}
+
+/**
+ * Converts a VHDX header between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pHdrConv            Where to store the converted header.
+ * @param   pHdr                The VHDX header to convert.
+ *
+ * @note It is safe to use the same pointer for pHdrConv and pHdr.
+ */
+DECLINLINE(void) vhdxConvHeaderEndianess(VHDXECONV enmConv, PVhdxHeader pHdrConv, PVhdxHeader pHdr)
+{
+    pHdrConv->u32Signature      = SET_ENDIAN_U32(pHdr->u32Signature);
+    pHdrConv->u32Checksum       = SET_ENDIAN_U32(pHdr->u32Checksum);
+    pHdrConv->u64SequenceNumber = SET_ENDIAN_U64(pHdr->u64SequenceNumber);
+    vhdxConvUuidEndianess(enmConv, &pHdrConv->UuidFileWrite, &pHdrConv->UuidFileWrite);
+    vhdxConvUuidEndianess(enmConv, &pHdrConv->UuidDataWrite, &pHdrConv->UuidDataWrite);
+    vhdxConvUuidEndianess(enmConv, &pHdrConv->UuidLog, &pHdrConv->UuidLog);
+    pHdrConv->u16LogVersion     = SET_ENDIAN_U16(pHdr->u16LogVersion);
+    pHdrConv->u16Version        = SET_ENDIAN_U16(pHdr->u16Version);
+    pHdrConv->u32LogLength      = SET_ENDIAN_U32(pHdr->u32LogLength);
+    pHdrConv->u64LogOffset      = SET_ENDIAN_U64(pHdr->u64LogOffset);
+}
+
+/**
+ * Converts a VHDX region table header between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pRegTblHdrConv      Where to store the converted header.
+ * @param   pRegTblHdr          The VHDX region table header to convert.
+ *
+ * @note It is safe to use the same pointer for pRegTblHdrConv and pRegTblHdr.
+ */
+DECLINLINE(void) vhdxConvRegionTblHdrEndianess(VHDXECONV enmConv, PVhdxRegionTblHdr pRegTblHdrConv,
+                                               PVhdxRegionTblHdr pRegTblHdr)
+{
+    pRegTblHdrConv->u32Signature  = SET_ENDIAN_U32(pRegTblHdr->u32Signature);
+    pRegTblHdrConv->u32Checksum   = SET_ENDIAN_U32(pRegTblHdr->u32Checksum);
+    pRegTblHdrConv->u32EntryCount = SET_ENDIAN_U32(pRegTblHdr->u32EntryCount);
+    pRegTblHdrConv->u32Reserved   = SET_ENDIAN_U32(pRegTblHdr->u32Reserved);
+}
+
+/**
+ * Converts a VHDX region table entry between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pRegTblEntConv      Where to store the converted region table entry.
+ * @param   pRegTblEnt          The VHDX region table entry to convert.
+ *
+ * @note It is safe to use the same pointer for pRegTblEntConv and pRegTblEnt.
+ */
+DECLINLINE(void) vhdxConvRegionTblEntryEndianess(VHDXECONV enmConv, PVhdxRegionTblEntry pRegTblEntConv,
+                                                 PVhdxRegionTblEntry pRegTblEnt)
+{
+    vhdxConvUuidEndianess(enmConv, &pRegTblEntConv->UuidObject, &pRegTblEnt->UuidObject);
+    pRegTblEntConv->u64FileOffset = SET_ENDIAN_U64(pRegTblEnt->u64FileOffset);
+    pRegTblEntConv->u32Length     = SET_ENDIAN_U32(pRegTblEnt->u32Length);
+    pRegTblEntConv->u32Flags      = SET_ENDIAN_U32(pRegTblEnt->u32Flags);
+}
+
+#if 0 /* unused */
+
+/**
+ * Converts a VHDX log entry header between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pLogEntryHdrConv    Where to store the converted log entry header.
+ * @param   pLogEntryHdr        The VHDX log entry header to convert.
+ *
+ * @note It is safe to use the same pointer for pLogEntryHdrConv and pLogEntryHdr.
+ */
+DECLINLINE(void) vhdxConvLogEntryHdrEndianess(VHDXECONV enmConv, PVhdxLogEntryHdr pLogEntryHdrConv,
+                                              PVhdxLogEntryHdr pLogEntryHdr)
+{
+    pLogEntryHdrConv->u32Signature         = SET_ENDIAN_U32(pLogEntryHdr->u32Signature);
+    pLogEntryHdrConv->u32Checksum          = SET_ENDIAN_U32(pLogEntryHdr->u32Checksum);
+    pLogEntryHdrConv->u32EntryLength       = SET_ENDIAN_U32(pLogEntryHdr->u32EntryLength);
+    pLogEntryHdrConv->u32Tail              = SET_ENDIAN_U32(pLogEntryHdr->u32Tail);
+    pLogEntryHdrConv->u64SequenceNumber    = SET_ENDIAN_U64(pLogEntryHdr->u64SequenceNumber);
+    pLogEntryHdrConv->u32DescriptorCount   = SET_ENDIAN_U32(pLogEntryHdr->u32DescriptorCount);
+    pLogEntryHdrConv->u32Reserved          = SET_ENDIAN_U32(pLogEntryHdr->u32Reserved);
+    vhdxConvUuidEndianess(enmConv, &pLogEntryHdrConv->UuidLog, &pLogEntryHdr->UuidLog);
+    pLogEntryHdrConv->u64FlushedFileOffset = SET_ENDIAN_U64(pLogEntryHdr->u64FlushedFileOffset);
+}
+
+/**
+ * Converts a VHDX log zero descriptor between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pLogZeroDescConv    Where to store the converted log zero descriptor.
+ * @param   pLogZeroDesc        The VHDX log zero descriptor to convert.
+ *
+ * @note It is safe to use the same pointer for pLogZeroDescConv and pLogZeroDesc.
+ */
+DECLINLINE(void) vhdxConvLogZeroDescEndianess(VHDXECONV enmConv, PVhdxLogZeroDesc pLogZeroDescConv,
+                                              PVhdxLogZeroDesc pLogZeroDesc)
+{
+    pLogZeroDescConv->u32ZeroSignature  = SET_ENDIAN_U32(pLogZeroDesc->u32ZeroSignature);
+    pLogZeroDescConv->u32Reserved       = SET_ENDIAN_U32(pLogZeroDesc->u32Reserved);
+    pLogZeroDescConv->u64ZeroLength     = SET_ENDIAN_U64(pLogZeroDesc->u64ZeroLength);
+    pLogZeroDescConv->u64FileOffset     = SET_ENDIAN_U64(pLogZeroDesc->u64FileOffset);
+    pLogZeroDescConv->u64SequenceNumber = SET_ENDIAN_U64(pLogZeroDesc->u64SequenceNumber);
+}
+
+
+/**
+ * Converts a VHDX log data descriptor between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pLogDataDescConv    Where to store the converted log data descriptor.
+ * @param   pLogDataDesc        The VHDX log data descriptor to convert.
+ *
+ * @note It is safe to use the same pointer for pLogDataDescConv and pLogDataDesc.
+ */
+DECLINLINE(void) vhdxConvLogDataDescEndianess(VHDXECONV enmConv, PVhdxLogDataDesc pLogDataDescConv,
+                                              PVhdxLogDataDesc pLogDataDesc)
+{
+    pLogDataDescConv->u32DataSignature  = SET_ENDIAN_U32(pLogDataDesc->u32DataSignature);
+    pLogDataDescConv->u32TrailingBytes  = SET_ENDIAN_U32(pLogDataDesc->u32TrailingBytes);
+    pLogDataDescConv->u64LeadingBytes   = SET_ENDIAN_U64(pLogDataDesc->u64LeadingBytes);
+    pLogDataDescConv->u64FileOffset     = SET_ENDIAN_U64(pLogDataDesc->u64FileOffset);
+    pLogDataDescConv->u64SequenceNumber = SET_ENDIAN_U64(pLogDataDesc->u64SequenceNumber);
+}
+
+
+/**
+ * Converts a VHDX log data sector between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pLogDataSectorConv  Where to store the converted log data sector.
+ * @param   pLogDataSector      The VHDX log data sector to convert.
+ *
+ * @note It is safe to use the same pointer for pLogDataSectorConv and pLogDataSector.
+ */
+DECLINLINE(void) vhdxConvLogDataSectorEndianess(VHDXECONV enmConv, PVhdxLogDataSector pLogDataSectorConv,
+                                                PVhdxLogDataSector pLogDataSector)
+{
+    pLogDataSectorConv->u32DataSignature = SET_ENDIAN_U32(pLogDataSector->u32DataSignature);
+    pLogDataSectorConv->u32SequenceHigh  = SET_ENDIAN_U32(pLogDataSector->u32SequenceHigh);
+    pLogDataSectorConv->u32SequenceLow   = SET_ENDIAN_U32(pLogDataSector->u32SequenceLow);
+}
+
+#endif /* unused */
+
+/**
+ * Converts a BAT between file and host endianess.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   paBatEntriesConv    Where to store the converted BAT.
+ * @param   paBatEntries        The VHDX BAT to convert.
+ * @param   cBatEntries         Number of entries in the BAT.
+ *
+ * @note It is safe to use the same pointer for paBatEntriesConv and paBatEntries.
+ */
+DECLINLINE(void) vhdxConvBatTableEndianess(VHDXECONV enmConv, PVhdxBatEntry paBatEntriesConv,
+                                           PVhdxBatEntry paBatEntries, uint32_t cBatEntries)
+{
+    for (uint32_t i = 0; i < cBatEntries; i++)
+        paBatEntriesConv[i].u64BatEntry = SET_ENDIAN_U64(paBatEntries[i].u64BatEntry);
+}
+
+/**
+ * Converts a VHDX metadata table header between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv             Direction of the conversion.
+ * @param   pMetadataTblHdrConv Where to store the converted metadata table header.
+ * @param   pMetadataTblHdr     The VHDX metadata table header to convert.
+ *
+ * @note It is safe to use the same pointer for pMetadataTblHdrConv and pMetadataTblHdr.
+ */
+DECLINLINE(void) vhdxConvMetadataTblHdrEndianess(VHDXECONV enmConv, PVhdxMetadataTblHdr pMetadataTblHdrConv,
+                                                 PVhdxMetadataTblHdr pMetadataTblHdr)
+{
+    pMetadataTblHdrConv->u64Signature  = SET_ENDIAN_U64(pMetadataTblHdr->u64Signature);
+    pMetadataTblHdrConv->u16Reserved   = SET_ENDIAN_U16(pMetadataTblHdr->u16Reserved);
+    pMetadataTblHdrConv->u16EntryCount = SET_ENDIAN_U16(pMetadataTblHdr->u16EntryCount);
+    for (unsigned i = 0; i < RT_ELEMENTS(pMetadataTblHdr->u32Reserved2); i++)
+        pMetadataTblHdrConv->u32Reserved2[i] = SET_ENDIAN_U32(pMetadataTblHdr->u32Reserved2[i]);
+}
+
+/**
+ * Converts a VHDX metadata table entry between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv               Direction of the conversion.
+ * @param   pMetadataTblEntryConv Where to store the converted metadata table entry.
+ * @param   pMetadataTblEntry     The VHDX metadata table entry to convert.
+ *
+ * @note It is safe to use the same pointer for pMetadataTblEntryConv and pMetadataTblEntry.
+ */
+DECLINLINE(void) vhdxConvMetadataTblEntryEndianess(VHDXECONV enmConv, PVhdxMetadataTblEntry pMetadataTblEntryConv,
+                                                   PVhdxMetadataTblEntry pMetadataTblEntry)
+{
+    vhdxConvUuidEndianess(enmConv, &pMetadataTblEntryConv->UuidItem, &pMetadataTblEntry->UuidItem);
+    pMetadataTblEntryConv->u32Offset   = SET_ENDIAN_U32(pMetadataTblEntry->u32Offset);
+    pMetadataTblEntryConv->u32Length   = SET_ENDIAN_U32(pMetadataTblEntry->u32Length);
+    pMetadataTblEntryConv->u32Flags    = SET_ENDIAN_U32(pMetadataTblEntry->u32Flags);
+    pMetadataTblEntryConv->u32Reserved = SET_ENDIAN_U32(pMetadataTblEntry->u32Reserved);
+}
+
+/**
+ * Converts a VHDX file parameters item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv               Direction of the conversion.
+ * @param   pFileParamsConv       Where to store the converted file parameters item entry.
+ * @param   pFileParams           The VHDX file parameters item to convert.
+ *
+ * @note It is safe to use the same pointer for pFileParamsConv and pFileParams.
+ */
+DECLINLINE(void) vhdxConvFileParamsEndianess(VHDXECONV enmConv, PVhdxFileParameters pFileParamsConv,
+                                             PVhdxFileParameters pFileParams)
+{
+    pFileParamsConv->u32BlockSize = SET_ENDIAN_U32(pFileParams->u32BlockSize);
+    pFileParamsConv->u32Flags     = SET_ENDIAN_U32(pFileParams->u32Flags);
+}
+
+/**
+ * Converts a VHDX virtual disk size item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv               Direction of the conversion.
+ * @param   pVDiskSizeConv        Where to store the converted virtual disk size item entry.
+ * @param   pVDiskSize            The VHDX virtual disk size item to convert.
+ *
+ * @note It is safe to use the same pointer for pVDiskSizeConv and pVDiskSize.
+ */
+DECLINLINE(void) vhdxConvVDiskSizeEndianess(VHDXECONV enmConv, PVhdxVDiskSize pVDiskSizeConv,
+                                            PVhdxVDiskSize pVDiskSize)
+{
+    pVDiskSizeConv->u64VDiskSize  = SET_ENDIAN_U64(pVDiskSize->u64VDiskSize);
+}
+
+#if 0 /* unused */
+
+/**
+ * Converts a VHDX page 83 data item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv               Direction of the conversion.
+ * @param   pPage83DataConv       Where to store the converted page 83 data item entry.
+ * @param   pPage83Data           The VHDX page 83 data item to convert.
+ *
+ * @note It is safe to use the same pointer for pPage83DataConv and pPage83Data.
+ */
+DECLINLINE(void) vhdxConvPage83DataEndianess(VHDXECONV enmConv, PVhdxPage83Data pPage83DataConv,
+                                             PVhdxPage83Data pPage83Data)
+{
+    vhdxConvUuidEndianess(enmConv, &pPage83DataConv->UuidPage83Data, &pPage83Data->UuidPage83Data);
+}
+#endif /* unused */
+
+/**
+ * Converts a VHDX logical sector size item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv               Direction of the conversion.
+ * @param   pVDiskLogSectSizeConv Where to store the converted logical sector size item entry.
+ * @param   pVDiskLogSectSize     The VHDX logical sector size item to convert.
+ *
+ * @note It is safe to use the same pointer for pVDiskLogSectSizeConv and pVDiskLogSectSize.
+ */
+DECLINLINE(void) vhdxConvVDiskLogSectSizeEndianess(VHDXECONV enmConv, PVhdxVDiskLogicalSectorSize pVDiskLogSectSizeConv,
+                                                   PVhdxVDiskLogicalSectorSize pVDiskLogSectSize)
+{
+    pVDiskLogSectSizeConv->u32LogicalSectorSize = SET_ENDIAN_U32(pVDiskLogSectSize->u32LogicalSectorSize);
+}
+
+#if 0 /* unused */
+
+/**
+ * Converts a VHDX physical sector size item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv                Direction of the conversion.
+ * @param   pVDiskPhysSectSizeConv Where to store the converted physical sector size item entry.
+ * @param   pVDiskPhysSectSize     The VHDX physical sector size item to convert.
+ *
+ * @note It is safe to use the same pointer for pVDiskPhysSectSizeConv and pVDiskPhysSectSize.
+ */
+DECLINLINE(void) vhdxConvVDiskPhysSectSizeEndianess(VHDXECONV enmConv, PVhdxVDiskPhysicalSectorSize pVDiskPhysSectSizeConv,
+                                                    PVhdxVDiskPhysicalSectorSize pVDiskPhysSectSize)
+{
+    pVDiskPhysSectSizeConv->u64PhysicalSectorSize = SET_ENDIAN_U64(pVDiskPhysSectSize->u64PhysicalSectorSize);
+}
+
+
+/**
+ * Converts a VHDX parent locator header item between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv                Direction of the conversion.
+ * @param   pParentLocatorHdrConv  Where to store the converted parent locator header item entry.
+ * @param   pParentLocatorHdr      The VHDX parent locator header item to convert.
+ *
+ * @note It is safe to use the same pointer for pParentLocatorHdrConv and pParentLocatorHdr.
+ */
+DECLINLINE(void) vhdxConvParentLocatorHeaderEndianness(VHDXECONV enmConv, PVhdxParentLocatorHeader pParentLocatorHdrConv,
+                                                       PVhdxParentLocatorHeader pParentLocatorHdr)
+{
+    vhdxConvUuidEndianess(enmConv, &pParentLocatorHdrConv->UuidLocatorType, &pParentLocatorHdr->UuidLocatorType);
+    pParentLocatorHdrConv->u16Reserved      = SET_ENDIAN_U16(pParentLocatorHdr->u16Reserved);
+    pParentLocatorHdrConv->u16KeyValueCount = SET_ENDIAN_U16(pParentLocatorHdr->u16KeyValueCount);
+}
+
+
+/**
+ * Converts a VHDX parent locator entry between file and host endianness.
+ *
+ * @returns nothing.
+ * @param   enmConv                 Direction of the conversion.
+ * @param   pParentLocatorEntryConv Where to store the converted parent locator entry.
+ * @param   pParentLocatorEntry     The VHDX parent locator entry to convert.
+ *
+ * @note It is safe to use the same pointer for pParentLocatorEntryConv and pParentLocatorEntry.
+ */
+DECLINLINE(void) vhdxConvParentLocatorEntryEndianess(VHDXECONV enmConv, PVhdxParentLocatorEntry pParentLocatorEntryConv,
+                                                     PVhdxParentLocatorEntry pParentLocatorEntry)
+{
+    pParentLocatorEntryConv->u32KeyOffset   = SET_ENDIAN_U32(pParentLocatorEntry->u32KeyOffset);
+    pParentLocatorEntryConv->u32ValueOffset = SET_ENDIAN_U32(pParentLocatorEntry->u32ValueOffset);
+    pParentLocatorEntryConv->u16KeyLength   = SET_ENDIAN_U16(pParentLocatorEntry->u16KeyLength);
+    pParentLocatorEntryConv->u16ValueLength = SET_ENDIAN_U16(pParentLocatorEntry->u16ValueLength);
+}
+
+#endif /* unused */
+
+/**
+ * Internal. Free all allocated space for representing an image except pImage,
+ * and optionally delete the image from disk.
+ */
+static int vhdxFreeImage(PVHDXIMAGE pImage, bool fDelete)
+{
+    int rc = VINF_SUCCESS;
+
+    /* Freeing a never allocated image (e.g. because the open failed) is
+     * not signalled as an error. After all nothing bad happens. */
+    if (pImage)
+    {
+        if (pImage->pStorage)
+        {
+            rc = vdIfIoIntFileClose(pImage->pIfIo, pImage->pStorage);
+            pImage->pStorage = NULL;
+        }
+
+        if (pImage->paBat)
+        {
+            RTMemFree(pImage->paBat);
+            pImage->paBat = NULL;
+        }
+
+        if (fDelete && pImage->pszFilename)
+            vdIfIoIntFileDelete(pImage->pIfIo, pImage->pszFilename);
+    }
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Loads all required fields from the given VHDX header.
+ * The header must be converted to the host endianess and validated already.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   pHdr      The header to load.
+ */
+static int vhdxLoadHeader(PVHDXIMAGE pImage, PVhdxHeader pHdr)
+{
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p pHdr=%#p\n", pImage, pHdr));
+
+    /*
+     * Most fields in the header are not required because the backend implements
+     * readonly access only so far.
+     * We just have to check that the log is empty, we have to refuse to load the
+     * image otherwsie because replaying the log is not implemented.
+     */
+    if (pHdr->u16Version == VHDX_HEADER_VHDX_VERSION)
+    {
+        /* Check that the log UUID is zero. */
+        pImage->uVersion = pHdr->u16Version;
+        if (!RTUuidIsNull(&pHdr->UuidLog))
+            rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                           "VHDX: Image \'%s\' has a non empty log which is not supported",
+                           pImage->pszFilename);
+    }
+    else
+        rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                       "VHDX: Image \'%s\' uses an unsupported version (%u) of the VHDX format",
+                       pImage->pszFilename, pHdr->u16Version);
+
+    LogFlowFunc(("return rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Determines the current header and loads it.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ */
+static int vhdxFindAndLoadCurrentHeader(PVHDXIMAGE pImage)
+{
+    PVhdxHeader pHdr1, pHdr2;
+    uint32_t u32ChkSum = 0;
+    uint32_t u32ChkSumSaved = 0;
+    bool fHdr1Valid = false;
+    bool fHdr2Valid = false;
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p\n", pImage));
+
+    /*
+     * The VHDX format defines two headers at different offsets to provide failure
+     * consistency. Only one header is current. This can be determined using the
+     * sequence number and checksum fields in the header.
+     */
+    pHdr1 = (PVhdxHeader)RTMemAllocZ(sizeof(VhdxHeader));
+    pHdr2 = (PVhdxHeader)RTMemAllocZ(sizeof(VhdxHeader));
+
+    if (pHdr1 && pHdr2)
+    {
+        /* Read the first header. */
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, VHDX_HEADER1_OFFSET,
+                                   pHdr1, sizeof(*pHdr1));
+        if (RT_SUCCESS(rc))
+        {
+            vhdxConvHeaderEndianess(VHDXECONV_F2H, pHdr1, pHdr1);
+
+            /* Validate checksum. */
+            u32ChkSumSaved = pHdr1->u32Checksum;
+            pHdr1->u32Checksum = 0;
+            u32ChkSum = RTCrc32C(pHdr1, sizeof(VhdxHeader));
+
+            if (   pHdr1->u32Signature == VHDX_HEADER_SIGNATURE
+                && u32ChkSum == u32ChkSumSaved)
+                fHdr1Valid = true;
+        }
+
+        /* Try to read the second header in any case (even if reading the first failed). */
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, VHDX_HEADER2_OFFSET,
+                                   pHdr2, sizeof(*pHdr2));
+        if (RT_SUCCESS(rc))
+        {
+            vhdxConvHeaderEndianess(VHDXECONV_F2H, pHdr2, pHdr2);
+
+            /* Validate checksum. */
+            u32ChkSumSaved = pHdr2->u32Checksum;
+            pHdr2->u32Checksum = 0;
+            u32ChkSum = RTCrc32C(pHdr2, sizeof(VhdxHeader));
+
+            if (   pHdr2->u32Signature == VHDX_HEADER_SIGNATURE
+                && u32ChkSum == u32ChkSumSaved)
+                fHdr2Valid = true;
+        }
+
+        /* Determine the current header. */
+        if (fHdr1Valid != fHdr2Valid)
+        {
+            /* Only one header is valid - use it. */
+            rc = vhdxLoadHeader(pImage, fHdr1Valid ? pHdr1 : pHdr2);
+        }
+        else if (!fHdr1Valid && !fHdr2Valid)
+        {
+            /* Crap, both headers are corrupt, refuse to load the image. */
+            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                           "VHDX: Can not load the image because both headers are corrupt");
+        }
+        else
+        {
+            /* Both headers are valid. Use the sequence number to find the current one. */
+            if (pHdr1->u64SequenceNumber > pHdr2->u64SequenceNumber)
+                rc = vhdxLoadHeader(pImage, pHdr1);
+            else
+                rc = vhdxLoadHeader(pImage, pHdr2);
+        }
+    }
+    else
+        rc = vdIfError(pImage->pIfError, VERR_NO_MEMORY, RT_SRC_POS,
+                       "VHDX: Out of memory while allocating memory for the header");
+
+    if (pHdr1)
+        RTMemFree(pHdr1);
+    if (pHdr2)
+        RTMemFree(pHdr2);
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Loads the BAT region.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   offRegion Start offset of the region.
+ * @param   cbRegion  Size of the region.
+ */
+static int vhdxLoadBatRegion(PVHDXIMAGE pImage, uint64_t offRegion,
+                             size_t cbRegion)
+{
+    int rc = VINF_SUCCESS;
+    uint32_t cDataBlocks;
+    uint32_t uChunkRatio;
+    uint32_t cSectorBitmapBlocks;
+    uint32_t cBatEntries;
+    uint32_t cbBatEntries;
+    PVhdxBatEntry paBatEntries = NULL;
+
+    LogFlowFunc(("pImage=%#p\n", pImage));
+
+    /* Calculate required values first. */
+    uint64_t uChunkRatio64 = (RT_BIT_64(23) * pImage->cbLogicalSector) / pImage->cbBlock;
+    uChunkRatio = (uint32_t)uChunkRatio64; Assert(uChunkRatio == uChunkRatio64);
+    uint64_t cDataBlocks64 = pImage->cbSize / pImage->cbBlock;
+    cDataBlocks = (uint32_t)cDataBlocks64; Assert(cDataBlocks == cDataBlocks64);
+
+    if (pImage->cbSize % pImage->cbBlock)
+        cDataBlocks++;
+
+    cSectorBitmapBlocks = cDataBlocks / uChunkRatio;
+    if (cDataBlocks % uChunkRatio)
+        cSectorBitmapBlocks++;
+
+    cBatEntries = cDataBlocks + (cDataBlocks - 1)/uChunkRatio;
+    cbBatEntries = cBatEntries * sizeof(VhdxBatEntry);
+
+    if (cbBatEntries <= cbRegion)
+    {
+        /*
+         * Load the complete BAT region first, convert to host endianess and process
+         * it afterwards. The SB entries can be removed because they are not needed yet.
+         */
+        paBatEntries = (PVhdxBatEntry)RTMemAlloc(cbBatEntries);
+        if (paBatEntries)
+        {
+            rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offRegion,
+                                       paBatEntries, cbBatEntries);
+            if (RT_SUCCESS(rc))
+            {
+                vhdxConvBatTableEndianess(VHDXECONV_F2H, paBatEntries, paBatEntries,
+                                          cBatEntries);
+
+                /* Go through the table and validate it. */
+                for (unsigned i = 0; i < cBatEntries; i++)
+                {
+                    if (   i != 0
+                        && (i % uChunkRatio) == 0)
+                    {
+/**
+ * Disabled the verification because there are images out there with the sector bitmap
+ * marked as present. The entry is never accessed and the image is readonly anyway,
+ * so no harm done.
+ */
+#if 0
+                        /* Sector bitmap block. */
+                        if (   VHDX_BAT_ENTRY_GET_STATE(paBatEntries[i].u64BatEntry)
+                            != VHDX_BAT_ENTRY_SB_BLOCK_NOT_PRESENT)
+                        {
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: Sector bitmap block at entry %u of image \'%s\' marked as present, violation of the specification",
+                                           i, pImage->pszFilename);
+                            break;
+                        }
+#endif
+                    }
+                    else
+                    {
+                        /* Payload block. */
+                        if (   VHDX_BAT_ENTRY_GET_STATE(paBatEntries[i].u64BatEntry)
+                            == VHDX_BAT_ENTRY_PAYLOAD_BLOCK_PARTIALLY_PRESENT)
+                        {
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: Payload block at entry %u of image \'%s\' marked as partially present, violation of the specification",
+                                           i, pImage->pszFilename);
+                            break;
+                        }
+                    }
+                }
+
+                if (RT_SUCCESS(rc))
+                {
+                    pImage->paBat       = paBatEntries;
+                    pImage->uChunkRatio = uChunkRatio;
+                }
+            }
+            else
+                rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                               "VHDX: Error reading the BAT from image \'%s\'",
+                               pImage->pszFilename);
+        }
+        else
+            rc = vdIfError(pImage->pIfError, VERR_NO_MEMORY, RT_SRC_POS,
+                           "VHDX: Out of memory allocating memory for %u BAT entries of image \'%s\'",
+                           cBatEntries, pImage->pszFilename);
+    }
+    else
+        rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                       "VHDX: Mismatch between calculated number of BAT entries and region size (expected %u got %u) for image \'%s\'",
+                       cbBatEntries, cbRegion, pImage->pszFilename);
+
+    if (   RT_FAILURE(rc)
+        && paBatEntries)
+        RTMemFree(paBatEntries);
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Load the file parameters metadata item from the file.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   offItem   File offset where the data is stored.
+ * @param   cbItem    Size of the item in the file.
+ */
+static int vhdxLoadFileParametersMetadata(PVHDXIMAGE pImage, uint64_t offItem, size_t cbItem)
+{
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p offItem=%llu cbItem=%zu\n", pImage, offItem, cbItem));
+
+    if (cbItem != sizeof(VhdxFileParameters))
+        rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                       "VHDX: File parameters item size mismatch (expected %u got %zu) in image \'%s\'",
+                       sizeof(VhdxFileParameters), cbItem, pImage->pszFilename);
+    else
+    {
+        VhdxFileParameters FileParameters;
+
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offItem,
+                                   &FileParameters, sizeof(FileParameters));
+        if (RT_SUCCESS(rc))
+        {
+            vhdxConvFileParamsEndianess(VHDXECONV_F2H, &FileParameters, &FileParameters);
+            pImage->cbBlock = FileParameters.u32BlockSize;
+
+            /** @todo No support for differencing images yet. */
+            if (FileParameters.u32Flags & VHDX_FILE_PARAMETERS_FLAGS_HAS_PARENT)
+                rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                               "VHDX: Image \'%s\' is a differencing image which is not supported yet",
+                               pImage->pszFilename);
+        }
+        else
+            rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                           "VHDX: Reading the file parameters metadata item from image \'%s\' failed",
+                           pImage->pszFilename);
+    }
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Load the virtual disk size metadata item from the file.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   offItem   File offset where the data is stored.
+ * @param   cbItem    Size of the item in the file.
+ */
+static int vhdxLoadVDiskSizeMetadata(PVHDXIMAGE pImage, uint64_t offItem, size_t cbItem)
+{
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p offItem=%llu cbItem=%zu\n", pImage, offItem, cbItem));
+
+    if (cbItem != sizeof(VhdxVDiskSize))
+        rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                       "VHDX: Virtual disk size item size mismatch (expected %u got %zu) in image \'%s\'",
+                       sizeof(VhdxVDiskSize), cbItem, pImage->pszFilename);
+    else
+    {
+        VhdxVDiskSize VDiskSize;
+
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offItem,
+                                   &VDiskSize, sizeof(VDiskSize));
+        if (RT_SUCCESS(rc))
+        {
+            vhdxConvVDiskSizeEndianess(VHDXECONV_F2H, &VDiskSize, &VDiskSize);
+            pImage->cbSize = VDiskSize.u64VDiskSize;
+        }
+        else
+            rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                           "VHDX: Reading the virtual disk size metadata item from image \'%s\' failed",
+                           pImage->pszFilename);
+    }
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Load the logical sector size metadata item from the file.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   offItem   File offset where the data is stored.
+ * @param   cbItem    Size of the item in the file.
+ */
+static int vhdxLoadVDiskLogSectorSizeMetadata(PVHDXIMAGE pImage, uint64_t offItem, size_t cbItem)
+{
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p offItem=%llu cbItem=%zu\n", pImage, offItem, cbItem));
+
+    if (cbItem != sizeof(VhdxVDiskLogicalSectorSize))
+        rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                       "VHDX: Virtual disk logical sector size item size mismatch (expected %u got %zu) in image \'%s\'",
+                       sizeof(VhdxVDiskLogicalSectorSize), cbItem, pImage->pszFilename);
+    else
+    {
+        VhdxVDiskLogicalSectorSize VDiskLogSectSize;
+
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offItem,
+                                   &VDiskLogSectSize, sizeof(VDiskLogSectSize));
+        if (RT_SUCCESS(rc))
+        {
+            vhdxConvVDiskLogSectSizeEndianess(VHDXECONV_F2H, &VDiskLogSectSize,
+                                              &VDiskLogSectSize);
+            pImage->cbLogicalSector = VDiskLogSectSize.u32LogicalSectorSize;
+        }
+        else
+            rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                           "VHDX: Reading the virtual disk logical sector size metadata item from image \'%s\' failed",
+                           pImage->pszFilename);
+    }
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Loads the metadata region.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ * @param   offRegion Start offset of the region.
+ * @param   cbRegion  Size of the region.
+ */
+static int vhdxLoadMetadataRegion(PVHDXIMAGE pImage, uint64_t offRegion,
+                                  size_t cbRegion)
+{
+    VhdxMetadataTblHdr MetadataTblHdr;
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p\n", pImage));
+
+    /* Load the header first. */
+    rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offRegion,
+                               &MetadataTblHdr, sizeof(MetadataTblHdr));
+    if (RT_SUCCESS(rc))
+    {
+        vhdxConvMetadataTblHdrEndianess(VHDXECONV_F2H, &MetadataTblHdr, &MetadataTblHdr);
+
+        /* Validate structure. */
+        if (MetadataTblHdr.u64Signature != VHDX_METADATA_TBL_HDR_SIGNATURE)
+            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                           "VHDX: Incorrect metadata table header signature for image \'%s\'",
+                           pImage->pszFilename);
+        else if (MetadataTblHdr.u16EntryCount > VHDX_METADATA_TBL_HDR_ENTRY_COUNT_MAX)
+            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                           "VHDX: Incorrect entry count in metadata table header of image \'%s\'",
+                           pImage->pszFilename);
+        else if (cbRegion < (MetadataTblHdr.u16EntryCount * sizeof(VhdxMetadataTblEntry) + sizeof(VhdxMetadataTblHdr)))
+            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                           "VHDX: Metadata table of image \'%s\' exceeds region size",
+                           pImage->pszFilename);
+
+        if (RT_SUCCESS(rc))
+        {
+            uint64_t offMetadataTblEntry = offRegion + sizeof(VhdxMetadataTblHdr);
+
+            for (unsigned i = 0; i < MetadataTblHdr.u16EntryCount; i++)
+            {
+                uint64_t offMetadataItem = 0;
+                VHDXMETADATAITEM enmMetadataItem = VHDXMETADATAITEM_UNKNOWN;
+                VhdxMetadataTblEntry MetadataTblEntry;
+
+                rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, offMetadataTblEntry,
+                                           &MetadataTblEntry, sizeof(MetadataTblEntry));
+                if (RT_FAILURE(rc))
+                {
+                    rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                                   "VHDX: Reading metadata table entry from image \'%s\' failed",
+                                   pImage->pszFilename);
+                    break;
+                }
+
+                vhdxConvMetadataTblEntryEndianess(VHDXECONV_F2H, &MetadataTblEntry, &MetadataTblEntry);
+
+                /* Check whether the flags match the expectations. */
+                for (unsigned idxProp = 0; idxProp < RT_ELEMENTS(s_aVhdxMetadataItemProps); idxProp++)
+                {
+                    if (!RTUuidCompareStr(&MetadataTblEntry.UuidItem,
+                                          s_aVhdxMetadataItemProps[idxProp].pszItemUuid))
+                    {
+                        /*
+                         * Check for specification violations and bail out, except
+                         * for the required flag of the physical sector size metadata item.
+                         * Early images had the required flag not set opposed to the specification.
+                         * We don't want to brerak those images.
+                         */
+                        if (   !!(MetadataTblEntry.u32Flags & VHDX_METADATA_TBL_ENTRY_FLAGS_IS_USER)
+                            != s_aVhdxMetadataItemProps[idxProp].fIsUser)
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: User flag of metadata item does not meet expectations \'%s\'",
+                                           pImage->pszFilename);
+                        else if (   !!(MetadataTblEntry.u32Flags & VHDX_METADATA_TBL_ENTRY_FLAGS_IS_VDISK)
+                                 != s_aVhdxMetadataItemProps[idxProp].fIsVDisk)
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: Virtual disk flag of metadata item does not meet expectations \'%s\'",
+                                           pImage->pszFilename);
+                        else if (      !!(MetadataTblEntry.u32Flags & VHDX_METADATA_TBL_ENTRY_FLAGS_IS_REQUIRED)
+                                    != s_aVhdxMetadataItemProps[idxProp].fIsRequired
+                                 && (s_aVhdxMetadataItemProps[idxProp].enmMetadataItem != VHDXMETADATAITEM_PHYSICAL_SECTOR_SIZE))
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: Required flag of metadata item does not meet expectations \'%s\'",
+                                           pImage->pszFilename);
+                        else
+                            enmMetadataItem = s_aVhdxMetadataItemProps[idxProp].enmMetadataItem;
+
+                        break;
+                    }
+                }
+
+                if (RT_FAILURE(rc))
+                    break;
+
+                offMetadataItem = offRegion + MetadataTblEntry.u32Offset;
+
+                switch (enmMetadataItem)
+                {
+                    case VHDXMETADATAITEM_FILE_PARAMS:
+                    {
+                        rc = vhdxLoadFileParametersMetadata(pImage, offMetadataItem,
+                                                            MetadataTblEntry.u32Length);
+                        break;
+                    }
+                    case VHDXMETADATAITEM_VDISK_SIZE:
+                    {
+                        rc = vhdxLoadVDiskSizeMetadata(pImage, offMetadataItem,
+                                                       MetadataTblEntry.u32Length);
+                        break;
+                    }
+                    case VHDXMETADATAITEM_PAGE83_DATA:
+                    {
+                        /*
+                         * Nothing to do here for now (marked as required but
+                         * there is no API to pass this information to the caller)
+                         * so far.
+                         */
+                        break;
+                    }
+                    case VHDXMETADATAITEM_LOGICAL_SECTOR_SIZE:
+                    {
+                        rc = vhdxLoadVDiskLogSectorSizeMetadata(pImage, offMetadataItem,
+                                                                MetadataTblEntry.u32Length);
+                        break;
+                    }
+                    case VHDXMETADATAITEM_PHYSICAL_SECTOR_SIZE:
+                    {
+                        /*
+                         * Nothing to do here for now (marked as required but
+                         * there is no API to pass this information to the caller)
+                         * so far.
+                         */
+                        break;
+                    }
+                    case VHDXMETADATAITEM_PARENT_LOCATOR:
+                    {
+                        rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                                       "VHDX: Image \'%s\' is a differencing image which is not supported yet",
+                                       pImage->pszFilename);
+                        break;
+                    }
+                    case VHDXMETADATAITEM_UNKNOWN:
+                    default:
+                        if (MetadataTblEntry.u32Flags & VHDX_METADATA_TBL_ENTRY_FLAGS_IS_REQUIRED)
+                            rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                                           "VHDX: Unsupported but required metadata item in image \'%s\'",
+                                           pImage->pszFilename);
+                }
+
+                if (RT_FAILURE(rc))
+                    break;
+
+                offMetadataTblEntry += sizeof(MetadataTblEntry);
+            }
+        }
+    }
+    else
+        rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                       "VHDX: Reading the metadata table header for image \'%s\' failed",
+                       pImage->pszFilename);
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Loads the region table and the associated regions.
+ *
+ * @returns VBox status code.
+ * @param   pImage    Image instance data.
+ */
+static int vhdxLoadRegionTable(PVHDXIMAGE pImage)
+{
+    uint8_t *pbRegionTbl = NULL;
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p\n", pImage));
+
+    /* Load the complete region table into memory. */
+    pbRegionTbl = (uint8_t *)RTMemTmpAlloc(VHDX_REGION_TBL_SIZE_MAX);
+    if (pbRegionTbl)
+    {
+        rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, VHDX_REGION_TBL_HDR_OFFSET,
+                                   pbRegionTbl, VHDX_REGION_TBL_SIZE_MAX);
+        if (RT_SUCCESS(rc))
+        {
+            PVhdxRegionTblHdr pRegionTblHdr;
+            VhdxRegionTblHdr RegionTblHdr;
+            uint32_t u32ChkSum = 0;
+
+            /*
+             * Copy the region table header to a dedicated structure where we can
+             * convert it to host endianess.
+             */
+            memcpy(&RegionTblHdr, pbRegionTbl, sizeof(RegionTblHdr));
+            vhdxConvRegionTblHdrEndianess(VHDXECONV_F2H, &RegionTblHdr, &RegionTblHdr);
+
+            /* Set checksum field to 0 during crc computation. */
+            pRegionTblHdr = (PVhdxRegionTblHdr)pbRegionTbl;
+            pRegionTblHdr->u32Checksum = 0;
+
+            /* Verify the region table integrity. */
+            u32ChkSum = RTCrc32C(pbRegionTbl, VHDX_REGION_TBL_SIZE_MAX);
+
+            if (RegionTblHdr.u32Signature != VHDX_REGION_TBL_HDR_SIGNATURE)
+                rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                               "VHDX: Invalid signature for region table header of image \'%s\'",
+                               pImage->pszFilename);
+            else if (u32ChkSum != RegionTblHdr.u32Checksum)
+                rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                               "VHDX: CRC32 checksum mismatch for the region table of image \'%s\' (expected %#x got %#x)",
+                               pImage->pszFilename, RegionTblHdr.u32Checksum, u32ChkSum);
+            else if (RegionTblHdr.u32EntryCount > VHDX_REGION_TBL_HDR_ENTRY_COUNT_MAX)
+                rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                               "VHDX: Invalid entry count field in the region table header of image \'%s\'",
+                               pImage->pszFilename);
+
+            if (RT_SUCCESS(rc))
+            {
+                /* Parse the region table entries. */
+                PVhdxRegionTblEntry pRegTblEntry = (PVhdxRegionTblEntry)(pbRegionTbl + sizeof(VhdxRegionTblHdr));
+                VhdxRegionTblEntry RegTblEntryBat; /* BAT region table entry. */
+                bool fBatRegPresent = false;
+                RT_ZERO(RegTblEntryBat); /* Maybe uninitialized, gcc. */
+
+                for (unsigned i = 0; i < RegionTblHdr.u32EntryCount; i++)
+                {
+                    vhdxConvRegionTblEntryEndianess(VHDXECONV_F2H, pRegTblEntry, pRegTblEntry);
+
+                    /* Check the uuid for known regions. */
+                    if (!RTUuidCompareStr(&pRegTblEntry->UuidObject, VHDX_REGION_TBL_ENTRY_UUID_BAT))
+                    {
+                        /*
+                         * Save the BAT region and process it later.
+                         * It may come before the metadata region but needs the block size.
+                         */
+                        if (pRegTblEntry->u32Flags & VHDX_REGION_TBL_ENTRY_FLAGS_IS_REQUIRED)
+                        {
+                            fBatRegPresent = true;
+                            RegTblEntryBat.u32Length = pRegTblEntry->u32Length;
+                            RegTblEntryBat.u64FileOffset = pRegTblEntry->u64FileOffset;
+                        }
+                        else
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: BAT region not marked as required in image \'%s\'",
+                                           pImage->pszFilename);
+                    }
+                    else if (!RTUuidCompareStr(&pRegTblEntry->UuidObject, VHDX_REGION_TBL_ENTRY_UUID_METADATA))
+                    {
+                        if (pRegTblEntry->u32Flags & VHDX_REGION_TBL_ENTRY_FLAGS_IS_REQUIRED)
+                            rc = vhdxLoadMetadataRegion(pImage, pRegTblEntry->u64FileOffset, pRegTblEntry->u32Length);
+                        else
+                            rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                           "VHDX: Metadata region not marked as required in image \'%s\'",
+                                           pImage->pszFilename);
+                    }
+                    else if (pRegTblEntry->u32Flags & VHDX_REGION_TBL_ENTRY_FLAGS_IS_REQUIRED)
+                    {
+                        /* The region is not known but marked as required, fail to load the image. */
+                        rc = vdIfError(pImage->pIfError, VERR_NOT_SUPPORTED, RT_SRC_POS,
+                                       "VHDX: Unknown required region in image \'%s\'",
+                                       pImage->pszFilename);
+                    }
+
+                    if (RT_FAILURE(rc))
+                        break;
+
+                    pRegTblEntry++;
+                }
+
+                if (fBatRegPresent)
+                    rc = vhdxLoadBatRegion(pImage, RegTblEntryBat.u64FileOffset, RegTblEntryBat.u32Length);
+                else
+                    rc = vdIfError(pImage->pIfError, VERR_VD_GEN_INVALID_HEADER, RT_SRC_POS,
+                                   "VHDX: BAT region in image \'%s\' is missing",
+                                   pImage->pszFilename);
+            }
+        }
+        else
+            rc = vdIfError(pImage->pIfError, rc, RT_SRC_POS,
+                           "VHDX: Reading the region table for image \'%s\' failed",
+                           pImage->pszFilename);
+    }
+    else
+        rc = vdIfError(pImage->pIfError, VERR_NO_MEMORY, RT_SRC_POS,
+                       "VHDX: Out of memory allocating memory for the region table of image \'%s\'",
+                       pImage->pszFilename);
+
+    if (pbRegionTbl)
+        RTMemTmpFree(pbRegionTbl);
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+/**
+ * Internal: Open an image, constructing all necessary data structures.
+ */
+static int vhdxOpenImage(PVHDXIMAGE pImage, unsigned uOpenFlags)
+{
+    uint64_t cbFile = 0;
+    VhdxFileIdentifier FileIdentifier;
+    int rc = VINF_SUCCESS;
+
+    LogFlowFunc(("pImage=%#p uOpenFlags=%#x\n", pImage, uOpenFlags));
+    pImage->uOpenFlags = uOpenFlags;
+
+    pImage->pIfError = VDIfErrorGet(pImage->pVDIfsDisk);
+    pImage->pIfIo = VDIfIoIntGet(pImage->pVDIfsImage);
+    AssertPtrReturn(pImage->pIfIo, VERR_INVALID_PARAMETER);
+
+    /* Refuse write access, it is not implemented so far. */
+    if (!(uOpenFlags & VD_OPEN_FLAGS_READONLY))
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Open the image.
+     */
+    rc = vdIfIoIntFileOpen(pImage->pIfIo, pImage->pszFilename,
+                           VDOpenFlagsToFileOpenFlags(uOpenFlags,
+                                                      false /* fCreate */),
+                           &pImage->pStorage);
+
+    /* Do NOT signal an appropriate error here, as the VD layer has the
+     * choice of retrying the open if it failed. */
+    if (RT_SUCCESS(rc))
+        rc = vdIfIoIntFileGetSize(pImage->pIfIo, pImage->pStorage, &cbFile);
+
+    if (RT_SUCCESS(rc))
+    {
+        if (cbFile > sizeof(FileIdentifier))
+        {
+            rc = vdIfIoIntFileReadSync(pImage->pIfIo, pImage->pStorage, VHDX_FILE_IDENTIFIER_OFFSET,
+                                       &FileIdentifier, sizeof(FileIdentifier));
+            if (RT_SUCCESS(rc))
+            {
+                vhdxConvFileIdentifierEndianess(VHDXECONV_F2H, &FileIdentifier,
+                                                &FileIdentifier);
+                if (FileIdentifier.u64Signature != VHDX_FILE_IDENTIFIER_SIGNATURE)
+                    rc = VERR_VD_GEN_INVALID_HEADER;
+                else
+                    rc = vhdxFindAndLoadCurrentHeader(pImage);
+
+                /* Load the region table. */
+                if (RT_SUCCESS(rc))
+                    rc = vhdxLoadRegionTable(pImage);
+            }
+        }
+        else
+            rc = VERR_VD_GEN_INVALID_HEADER;
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        PVDREGIONDESC pRegion = &pImage->RegionList.aRegions[0];
+        pImage->RegionList.fFlags   = 0;
+        pImage->RegionList.cRegions = 1;
+
+        pRegion->offRegion            = 0; /* Disk start. */
+        pRegion->cbBlock              = pImage->cbLogicalSector;
+        pRegion->enmDataForm          = VDREGIONDATAFORM_RAW;
+        pRegion->enmMetadataForm      = VDREGIONMETADATAFORM_NONE;
+        pRegion->cbData               = pImage->cbLogicalSector;
+        pRegion->cbMetadata           = 0;
+        pRegion->cRegionBlocksOrBytes = pImage->cbSize;
+    }
+    else
+        vhdxFreeImage(pImage, false);
+
+    LogFlowFunc(("returns rc=%Rrc\n", rc));
+    return rc;
+}
+
+
+/** @copydoc VDIMAGEBACKEND::pfnProbe */
+static DECLCALLBACK(int) vhdxProbe(const char *pszFilename, PVDINTERFACE pVDIfsDisk,
+                                   PVDINTERFACE pVDIfsImage, VDTYPE enmDesiredType, VDTYPE *penmType)
+{
+    RT_NOREF(pVDIfsDisk, enmDesiredType);
+    LogFlowFunc(("pszFilename=\"%s\" pVDIfsDisk=%#p pVDIfsImage=%#p\n", pszFilename, pVDIfsDisk, pVDIfsImage));
+    PVDIOSTORAGE pStorage = NULL;
+    uint64_t cbFile;
+    int rc = VINF_SUCCESS;
+    VhdxFileIdentifier FileIdentifier;
+
+    PVDINTERFACEIOINT pIfIo = VDIfIoIntGet(pVDIfsImage);
+    AssertPtrReturn(pIfIo, VERR_INVALID_PARAMETER);
+
+    if (   !VALID_PTR(pszFilename)
+        || !*pszFilename)
+        rc = VERR_INVALID_PARAMETER;
+    else
+    {
+        /*
+         * Open the file and read the file identifier.
+         */
+        rc = vdIfIoIntFileOpen(pIfIo, pszFilename,
+                               VDOpenFlagsToFileOpenFlags(VD_OPEN_FLAGS_READONLY,
+                                                          false /* fCreate */),
+                               &pStorage);
+        if (RT_SUCCESS(rc))
+        {
+            rc = vdIfIoIntFileGetSize(pIfIo, pStorage, &cbFile);
+            if (RT_SUCCESS(rc))
+            {
+                if (cbFile > sizeof(FileIdentifier))
+                {
+                    rc = vdIfIoIntFileReadSync(pIfIo, pStorage, VHDX_FILE_IDENTIFIER_OFFSET,
+                                               &FileIdentifier, sizeof(FileIdentifier));
+                    if (RT_SUCCESS(rc))
+                    {
+                        vhdxConvFileIdentifierEndianess(VHDXECONV_F2H, &FileIdentifier,
+                                                        &FileIdentifier);
+                        if (FileIdentifier.u64Signature != VHDX_FILE_IDENTIFIER_SIGNATURE)
+                            rc = VERR_VD_GEN_INVALID_HEADER;
+                        else
+                            *penmType = VDTYPE_HDD;
+                    }
+                }
+                else
+                    rc = VERR_VD_GEN_INVALID_HEADER;
+            }
+        }
+
+        if (pStorage)
+            vdIfIoIntFileClose(pIfIo, pStorage);
+    }
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnOpen */
+static DECLCALLBACK(int) vhdxOpen(const char *pszFilename, unsigned uOpenFlags,
+                                  PVDINTERFACE pVDIfsDisk, PVDINTERFACE pVDIfsImage,
+                                  VDTYPE enmType, void **ppBackendData)
+{
+    LogFlowFunc(("pszFilename=\"%s\" uOpenFlags=%#x pVDIfsDisk=%#p pVDIfsImage=%#p enmType=%u ppBackendData=%#p\n", pszFilename, uOpenFlags, pVDIfsDisk, pVDIfsImage, enmType, ppBackendData));
+    int rc;
+    PVHDXIMAGE pImage;
+
+    NOREF(enmType); /**< @todo r=klaus make use of the type info. */
+
+    /* Check open flags. All valid flags are supported. */
+    if (   uOpenFlags & ~VD_OPEN_FLAGS_MASK
+        || !VALID_PTR(pszFilename)
+        || !*pszFilename)
+        rc = VERR_INVALID_PARAMETER;
+    else
+    {
+        pImage = (PVHDXIMAGE)RTMemAllocZ(RT_UOFFSETOF(VHDXIMAGE, RegionList.aRegions[1]));
+        if (!pImage)
+            rc = VERR_NO_MEMORY;
+        else
+        {
+            pImage->pszFilename = pszFilename;
+            pImage->pStorage = NULL;
+            pImage->pVDIfsDisk = pVDIfsDisk;
+            pImage->pVDIfsImage = pVDIfsImage;
+
+            rc = vhdxOpenImage(pImage, uOpenFlags);
+            if (RT_SUCCESS(rc))
+                *ppBackendData = pImage;
+            else
+                RTMemFree(pImage);
+        }
+    }
+
+    LogFlowFunc(("returns %Rrc (pBackendData=%#p)\n", rc, *ppBackendData));
+    return rc;
+}
+
+/** @interface_method_impl{VDIMAGEBACKEND,pfnCreate} */
+static DECLCALLBACK(int) vhdxCreate(const char *pszFilename, uint64_t cbSize,
+                                    unsigned uImageFlags, const char *pszComment,
+                                    PCVDGEOMETRY pPCHSGeometry, PCVDGEOMETRY pLCHSGeometry,
+                                    PCRTUUID pUuid, unsigned uOpenFlags,
+                                    unsigned uPercentStart, unsigned uPercentSpan,
+                                    PVDINTERFACE pVDIfsDisk, PVDINTERFACE pVDIfsImage,
+                                    PVDINTERFACE pVDIfsOperation, VDTYPE enmType,
+                                    void **ppBackendData)
+{
+    RT_NOREF8(pszFilename, cbSize, uImageFlags, pszComment, pPCHSGeometry, pLCHSGeometry, pUuid, uOpenFlags);
+    RT_NOREF7(uPercentStart, uPercentSpan, pVDIfsDisk, pVDIfsImage, pVDIfsOperation, enmType, ppBackendData);
+    LogFlowFunc(("pszFilename=\"%s\" cbSize=%llu uImageFlags=%#x pszComment=\"%s\" pPCHSGeometry=%#p pLCHSGeometry=%#p Uuid=%RTuuid uOpenFlags=%#x uPercentStart=%u uPercentSpan=%u pVDIfsDisk=%#p pVDIfsImage=%#p pVDIfsOperation=%#p enmType=%u ppBackendData=%#p",
+                 pszFilename, cbSize, uImageFlags, pszComment, pPCHSGeometry, pLCHSGeometry, pUuid, uOpenFlags, uPercentStart, uPercentSpan, pVDIfsDisk, pVDIfsImage, pVDIfsOperation, enmType, ppBackendData));
+    int rc = VERR_NOT_SUPPORTED;
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnRename */
+static DECLCALLBACK(int) vhdxRename(void *pBackendData, const char *pszFilename)
+{
+    LogFlowFunc(("pBackendData=%#p pszFilename=%#p\n", pBackendData, pszFilename));
+    int rc = VINF_SUCCESS;
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+
+    /* Check arguments. */
+    if (   !pImage
+        || !pszFilename
+        || !*pszFilename)
+        rc = VERR_INVALID_PARAMETER;
+    else
+    {
+        /* Close the image. */
+        rc = vhdxFreeImage(pImage, false);
+        if (RT_SUCCESS(rc))
+        {
+            /* Rename the file. */
+            rc = vdIfIoIntFileMove(pImage->pIfIo, pImage->pszFilename, pszFilename, 0);
+            if (RT_FAILURE(rc))
+            {
+                /* The move failed, try to reopen the original image. */
+                int rc2 = vhdxOpenImage(pImage, pImage->uOpenFlags);
+                if (RT_FAILURE(rc2))
+                    rc = rc2;
+            }
+            else
+            {
+                /* Update pImage with the new information. */
+                pImage->pszFilename = pszFilename;
+
+                /* Open the old image with new name. */
+                rc = vhdxOpenImage(pImage, pImage->uOpenFlags);
+            }
+        }
+    }
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnClose */
+static DECLCALLBACK(int) vhdxClose(void *pBackendData, bool fDelete)
+{
+    LogFlowFunc(("pBackendData=%#p fDelete=%d\n", pBackendData, fDelete));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc;
+
+    rc = vhdxFreeImage(pImage, fDelete);
+    RTMemFree(pImage);
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnRead */
+static DECLCALLBACK(int) vhdxRead(void *pBackendData, uint64_t uOffset, size_t cbToRead,
+                                  PVDIOCTX pIoCtx, size_t *pcbActuallyRead)
+{
+    LogFlowFunc(("pBackendData=%#p uOffset=%llu pIoCtx=%#p cbToRead=%zu pcbActuallyRead=%#p\n",
+                 pBackendData, uOffset, pIoCtx, cbToRead, pcbActuallyRead));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc = VINF_SUCCESS;
+
+    AssertPtr(pImage);
+    Assert(uOffset % 512 == 0);
+    Assert(cbToRead % 512 == 0);
+
+    if (   uOffset + cbToRead > pImage->cbSize
+        || cbToRead == 0)
+        rc = VERR_INVALID_PARAMETER;
+    else
+    {
+        uint32_t idxBat = (uint32_t)(uOffset / pImage->cbBlock); Assert(idxBat == uOffset / pImage->cbBlock);
+        uint32_t offRead = uOffset % pImage->cbBlock;
+        uint64_t uBatEntry;
+
+        idxBat += idxBat / pImage->uChunkRatio; /* Add interleaving sector bitmap entries. */
+        uBatEntry = pImage->paBat[idxBat].u64BatEntry;
+
+        cbToRead = RT_MIN(cbToRead, pImage->cbBlock - offRead);
+
+        switch (VHDX_BAT_ENTRY_GET_STATE(uBatEntry))
+        {
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_NOT_PRESENT:
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_UNDEFINED:
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_ZERO:
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_UNMAPPED:
+            {
+                vdIfIoIntIoCtxSet(pImage->pIfIo, pIoCtx, 0, cbToRead);
+                break;
+            }
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_FULLY_PRESENT:
+            {
+                uint64_t offFile = VHDX_BAT_ENTRY_GET_FILE_OFFSET(uBatEntry) + offRead;
+                rc = vdIfIoIntFileReadUser(pImage->pIfIo, pImage->pStorage, offFile,
+                                           pIoCtx, cbToRead);
+                break;
+            }
+            case VHDX_BAT_ENTRY_PAYLOAD_BLOCK_PARTIALLY_PRESENT:
+            default:
+                rc = VERR_INVALID_PARAMETER;
+                break;
+        }
+
+        if (pcbActuallyRead)
+            *pcbActuallyRead = cbToRead;
+    }
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnWrite */
+static DECLCALLBACK(int) vhdxWrite(void *pBackendData, uint64_t uOffset,  size_t cbToWrite,
+                                   PVDIOCTX pIoCtx, size_t *pcbWriteProcess, size_t *pcbPreRead,
+                                   size_t *pcbPostRead, unsigned fWrite)
+{
+    RT_NOREF5(pIoCtx, pcbWriteProcess, pcbPreRead, pcbPostRead, fWrite);
+    LogFlowFunc(("pBackendData=%#p uOffset=%llu pIoCtx=%#p cbToWrite=%zu pcbWriteProcess=%#p pcbPreRead=%#p pcbPostRead=%#p\n",
+                 pBackendData, uOffset, pIoCtx, cbToWrite, pcbWriteProcess, pcbPreRead, pcbPostRead));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc;
+
+    AssertPtr(pImage);
+    Assert(uOffset % 512 == 0);
+    Assert(cbToWrite % 512 == 0);
+
+    if (pImage->uOpenFlags & VD_OPEN_FLAGS_READONLY)
+        rc = VERR_VD_IMAGE_READ_ONLY;
+    else if (   uOffset + cbToWrite > pImage->cbSize
+             || cbToWrite == 0)
+        rc = VERR_INVALID_PARAMETER;
+    else
+        rc = VERR_NOT_SUPPORTED;
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnFlush */
+static DECLCALLBACK(int) vhdxFlush(void *pBackendData, PVDIOCTX pIoCtx)
+{
+    RT_NOREF1(pIoCtx);
+    LogFlowFunc(("pBackendData=%#p pIoCtx=%#p\n", pBackendData, pIoCtx));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc;
+
+    if (pImage->uOpenFlags & VD_OPEN_FLAGS_READONLY)
+        rc = VERR_VD_IMAGE_READ_ONLY;
+    else
+        rc = VERR_NOT_SUPPORTED;
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetVersion */
+static DECLCALLBACK(unsigned) vhdxGetVersion(void *pBackendData)
+{
+    LogFlowFunc(("pBackendData=%#p\n", pBackendData));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+        return pImage->uVersion;
+    else
+        return 0;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetFileSize */
+static DECLCALLBACK(uint64_t) vhdxGetFileSize(void *pBackendData)
+{
+    LogFlowFunc(("pBackendData=%#p\n", pBackendData));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    uint64_t cb = 0;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+    {
+        uint64_t cbFile;
+        if (pImage->pStorage)
+        {
+            int rc = vdIfIoIntFileGetSize(pImage->pIfIo, pImage->pStorage, &cbFile);
+            if (RT_SUCCESS(rc))
+                cb = cbFile;
+        }
+    }
+
+    LogFlowFunc(("returns %lld\n", cb));
+    return cb;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetPCHSGeometry */
+static DECLCALLBACK(int) vhdxGetPCHSGeometry(void *pBackendData,
+                                             PVDGEOMETRY pPCHSGeometry)
+{
+    LogFlowFunc(("pBackendData=%#p pPCHSGeometry=%#p\n", pBackendData, pPCHSGeometry));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+    {
+        if (pImage->PCHSGeometry.cCylinders)
+        {
+            *pPCHSGeometry = pImage->PCHSGeometry;
+            rc = VINF_SUCCESS;
+        }
+        else
+            rc = VERR_VD_GEOMETRY_NOT_SET;
+    }
+    else
+        rc = VERR_VD_NOT_OPENED;
+
+    LogFlowFunc(("returns %Rrc (PCHS=%u/%u/%u)\n", rc, pPCHSGeometry->cCylinders, pPCHSGeometry->cHeads, pPCHSGeometry->cSectors));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnSetPCHSGeometry */
+static DECLCALLBACK(int) vhdxSetPCHSGeometry(void *pBackendData,
+                                             PCVDGEOMETRY pPCHSGeometry)
+{
+    LogFlowFunc(("pBackendData=%#p pPCHSGeometry=%#p PCHS=%u/%u/%u\n", pBackendData, pPCHSGeometry, pPCHSGeometry->cCylinders, pPCHSGeometry->cHeads, pPCHSGeometry->cSectors));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc = VINF_SUCCESS;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+    {
+        if (pImage->uOpenFlags & VD_OPEN_FLAGS_READONLY)
+            rc = VERR_VD_IMAGE_READ_ONLY;
+        else
+            pImage->PCHSGeometry = *pPCHSGeometry;
+    }
+    else
+        rc = VERR_VD_NOT_OPENED;
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetLCHSGeometry */
+static DECLCALLBACK(int) vhdxGetLCHSGeometry(void *pBackendData,
+                                             PVDGEOMETRY pLCHSGeometry)
+{
+     LogFlowFunc(("pBackendData=%#p pLCHSGeometry=%#p\n", pBackendData, pLCHSGeometry));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc = VINF_SUCCESS;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+    {
+        if (pImage->LCHSGeometry.cCylinders)
+            *pLCHSGeometry = pImage->LCHSGeometry;
+        else
+            rc = VERR_VD_GEOMETRY_NOT_SET;
+    }
+    else
+        rc = VERR_VD_NOT_OPENED;
+
+    LogFlowFunc(("returns %Rrc (LCHS=%u/%u/%u)\n", rc, pLCHSGeometry->cCylinders, pLCHSGeometry->cHeads, pLCHSGeometry->cSectors));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnSetLCHSGeometry */
+static DECLCALLBACK(int) vhdxSetLCHSGeometry(void *pBackendData,
+                                             PCVDGEOMETRY pLCHSGeometry)
+{
+    LogFlowFunc(("pBackendData=%#p pLCHSGeometry=%#p LCHS=%u/%u/%u\n", pBackendData, pLCHSGeometry, pLCHSGeometry->cCylinders, pLCHSGeometry->cHeads, pLCHSGeometry->cSectors));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc = VINF_SUCCESS;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+    {
+        if (pImage->uOpenFlags & VD_OPEN_FLAGS_READONLY)
+            rc = VERR_VD_IMAGE_READ_ONLY;
+        else
+            pImage->LCHSGeometry = *pLCHSGeometry;
+    }
+    else
+        rc = VERR_VD_NOT_OPENED;
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnQueryRegions */
+static DECLCALLBACK(int) vhdxQueryRegions(void *pBackendData, PCVDREGIONLIST *ppRegionList)
+{
+    LogFlowFunc(("pBackendData=%#p ppRegionList=%#p\n", pBackendData, ppRegionList));
+    PVHDXIMAGE pThis = (PVHDXIMAGE)pBackendData;
+
+    AssertPtrReturn(pThis, VERR_VD_NOT_OPENED);
+
+    *ppRegionList = &pThis->RegionList;
+    LogFlowFunc(("returns %Rrc\n", VINF_SUCCESS));
+    return VINF_SUCCESS;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnRegionListRelease */
+static DECLCALLBACK(void) vhdxRegionListRelease(void *pBackendData, PCVDREGIONLIST pRegionList)
+{
+    RT_NOREF1(pRegionList);
+    LogFlowFunc(("pBackendData=%#p pRegionList=%#p\n", pBackendData, pRegionList));
+    PVHDXIMAGE pThis = (PVHDXIMAGE)pBackendData;
+    AssertPtr(pThis); RT_NOREF(pThis);
+
+    /* Nothing to do here. */
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetImageFlags */
+static DECLCALLBACK(unsigned) vhdxGetImageFlags(void *pBackendData)
+{
+    LogFlowFunc(("pBackendData=%#p\n", pBackendData));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    unsigned uImageFlags;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+        uImageFlags = pImage->uImageFlags;
+    else
+        uImageFlags = 0;
+
+    LogFlowFunc(("returns %#x\n", uImageFlags));
+    return uImageFlags;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetOpenFlags */
+static DECLCALLBACK(unsigned) vhdxGetOpenFlags(void *pBackendData)
+{
+    LogFlowFunc(("pBackendData=%#p\n", pBackendData));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    unsigned uOpenFlags;
+
+    AssertPtr(pImage);
+
+    if (pImage)
+        uOpenFlags = pImage->uOpenFlags;
+    else
+        uOpenFlags = 0;
+
+    LogFlowFunc(("returns %#x\n", uOpenFlags));
+    return uOpenFlags;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnSetOpenFlags */
+static DECLCALLBACK(int) vhdxSetOpenFlags(void *pBackendData, unsigned uOpenFlags)
+{
+    LogFlowFunc(("pBackendData=%#p\n uOpenFlags=%#x", pBackendData, uOpenFlags));
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+    int rc = VINF_SUCCESS;
+
+    /* Image must be opened and the new flags must be valid. */
+    if (!pImage || (uOpenFlags & ~(VD_OPEN_FLAGS_READONLY | VD_OPEN_FLAGS_INFO | VD_OPEN_FLAGS_SKIP_CONSISTENCY_CHECKS)))
+        rc = VERR_INVALID_PARAMETER;
+    else
+    {
+        /* Implement this operation via reopening the image. */
+        rc = vhdxFreeImage(pImage, false);
+        if (RT_SUCCESS(rc))
+            rc = vhdxOpenImage(pImage, uOpenFlags);
+    }
+
+    LogFlowFunc(("returns %Rrc\n", rc));
+    return rc;
+}
+
+/** @copydoc VDIMAGEBACKEND::pfnGetComment */
+VD_BACKEND_CALLBACK_GET_COMMENT_DEF_NOT_SUPPORTED(vhdxGetComment);
+
+/** @copydoc VDIMAGEBACKEND::pfnSetComment */
+VD_BACKEND_CALLBACK_SET_COMMENT_DEF_NOT_SUPPORTED(vhdxSetComment, PVHDXIMAGE);
+
+/** @copydoc VDIMAGEBACKEND::pfnGetUuid */
+VD_BACKEND_CALLBACK_GET_UUID_DEF_NOT_SUPPORTED(vhdxGetUuid);
+
+/** @copydoc VDIMAGEBACKEND::pfnSetUuid */
+VD_BACKEND_CALLBACK_SET_UUID_DEF_NOT_SUPPORTED(vhdxSetUuid, PVHDXIMAGE);
+
+/** @copydoc VDIMAGEBACKEND::pfnGetModificationUuid */
+VD_BACKEND_CALLBACK_GET_UUID_DEF_NOT_SUPPORTED(vhdxGetModificationUuid);
+
+/** @copydoc VDIMAGEBACKEND::pfnSetModificationUuid */
+VD_BACKEND_CALLBACK_SET_UUID_DEF_NOT_SUPPORTED(vhdxSetModificationUuid, PVHDXIMAGE);
+
+/** @copydoc VDIMAGEBACKEND::pfnGetParentUuid */
+VD_BACKEND_CALLBACK_GET_UUID_DEF_NOT_SUPPORTED(vhdxGetParentUuid);
+
+/** @copydoc VDIMAGEBACKEND::pfnSetParentUuid */
+VD_BACKEND_CALLBACK_SET_UUID_DEF_NOT_SUPPORTED(vhdxSetParentUuid, PVHDXIMAGE);
+
+/** @copydoc VDIMAGEBACKEND::pfnGetParentModificationUuid */
+VD_BACKEND_CALLBACK_GET_UUID_DEF_NOT_SUPPORTED(vhdxGetParentModificationUuid);
+
+/** @copydoc VDIMAGEBACKEND::pfnSetParentModificationUuid */
+VD_BACKEND_CALLBACK_SET_UUID_DEF_NOT_SUPPORTED(vhdxSetParentModificationUuid, PVHDXIMAGE);
+
+/** @copydoc VDIMAGEBACKEND::pfnDump */
+static DECLCALLBACK(void) vhdxDump(void *pBackendData)
+{
+    PVHDXIMAGE pImage = (PVHDXIMAGE)pBackendData;
+
+    AssertPtr(pImage);
+    if (pImage)
+    {
+        vdIfErrorMessage(pImage->pIfError, "Header: Geometry PCHS=%u/%u/%u LCHS=%u/%u/%u cbSector=%u\n",
+                        pImage->PCHSGeometry.cCylinders, pImage->PCHSGeometry.cHeads, pImage->PCHSGeometry.cSectors,
+                        pImage->LCHSGeometry.cCylinders, pImage->LCHSGeometry.cHeads, pImage->LCHSGeometry.cSectors,
+                        pImage->cbLogicalSector);
+    }
+}
+
+
+const VDIMAGEBACKEND g_VhdxBackend =
+{
+    /* u32Version */
+    VD_IMGBACKEND_VERSION,
+    /* pszBackendName */
+    "VHDX",
+    /* uBackendCaps */
+    VD_CAP_FILE | VD_CAP_VFS,
+    /* paFileExtensions */
+    s_aVhdxFileExtensions,
+    /* paConfigInfo */
+    NULL,
+    /* pfnProbe */
+    vhdxProbe,
+    /* pfnOpen */
+    vhdxOpen,
+    /* pfnCreate */
+    vhdxCreate,
+    /* pfnRename */
+    vhdxRename,
+    /* pfnClose */
+    vhdxClose,
+    /* pfnRead */
+    vhdxRead,
+    /* pfnWrite */
+    vhdxWrite,
+    /* pfnFlush */
+    vhdxFlush,
+    /* pfnDiscard */
+    NULL,
+    /* pfnGetVersion */
+    vhdxGetVersion,
+    /* pfnGetFileSize */
+    vhdxGetFileSize,
+    /* pfnGetPCHSGeometry */
+    vhdxGetPCHSGeometry,
+    /* pfnSetPCHSGeometry */
+    vhdxSetPCHSGeometry,
+    /* pfnGetLCHSGeometry */
+    vhdxGetLCHSGeometry,
+    /* pfnSetLCHSGeometry */
+    vhdxSetLCHSGeometry,
+    /* pfnQueryRegions */
+    vhdxQueryRegions,
+    /* pfnRegionListRelease */
+    vhdxRegionListRelease,
+    /* pfnGetImageFlags */
+    vhdxGetImageFlags,
+    /* pfnGetOpenFlags */
+    vhdxGetOpenFlags,
+    /* pfnSetOpenFlags */
+    vhdxSetOpenFlags,
+    /* pfnGetComment */
+    vhdxGetComment,
+    /* pfnSetComment */
+    vhdxSetComment,
+    /* pfnGetUuid */
+    vhdxGetUuid,
+    /* pfnSetUuid */
+    vhdxSetUuid,
+    /* pfnGetModificationUuid */
+    vhdxGetModificationUuid,
+    /* pfnSetModificationUuid */
+    vhdxSetModificationUuid,
+    /* pfnGetParentUuid */
+    vhdxGetParentUuid,
+    /* pfnSetParentUuid */
+    vhdxSetParentUuid,
+    /* pfnGetParentModificationUuid */
+    vhdxGetParentModificationUuid,
+    /* pfnSetParentModificationUuid */
+    vhdxSetParentModificationUuid,
+    /* pfnDump */
+    vhdxDump,
+    /* pfnGetTimestamp */
+    NULL,
+    /* pfnGetParentTimestamp */
+    NULL,
+    /* pfnSetParentTimestamp */
+    NULL,
+    /* pfnGetParentFilename */
+    NULL,
+    /* pfnSetParentFilename */
+    NULL,
+    /* pfnComposeLocation */
+    genericFileComposeLocation,
+    /* pfnComposeName */
+    genericFileComposeName,
+    /* pfnCompact */
+    NULL,
+    /* pfnResize */
+    NULL,
+    /* pfnRepair */
+    NULL,
+    /* pfnTraverseMetadata */
+    NULL,
+    /* u32VersionEnd */
+    VD_IMGBACKEND_VERSION
+};