source: vbox/trunk/include/VBox/vd-cache-plugin.h@ 36638

/** @file
 * Internal hard disk format support API for VBoxHDD cache images.
 */

/*
 * Copyright (C) 2006-2010 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.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */

#ifndef __VBoxHDD_CachePlugin_h__
#define __VBoxHDD_CachePlugin_h__

#include <VBox/vd.h>

/**
 * Cache format backend interface used by VBox HDD Container implementation.
 */
typedef struct VDCACHEBACKEND
{
    /**
     * The name of the backend (constant string).
     */
    const char *pszBackendName;

    /**
     * The size of the structure.
     */
    uint32_t cbSize;

    /**
     * The capabilities of the backend.
     */
    uint64_t uBackendCaps;

    /**
     * Pointer to a NULL-terminated array of strings, containing the supported
     * file extensions. Note that some backends do not work on files, so this
     * pointer may just contain NULL.
     */
    const char * const *papszFileExtensions;

    /**
     * Pointer to an array of structs describing each supported config key.
     * Terminated by a NULL config key. Note that some backends do not support
     * the configuration interface, so this pointer may just contain NULL.
     * Mandatory if the backend sets VD_CAP_CONFIG.
     */
    PCVDCONFIGINFO paConfigInfo;

    /**
     * Handle of loaded plugin library, NIL_RTLDRMOD for static backends.
     */
    RTLDRMOD hPlugin;

    /**
     * Probes the given image.
     *
     * @returns VBox status code.
     * @param   pszFilename     Name of the image file.
     * @param   pVDIfsDisk      Pointer to the per-disk VD interface list.
     * @param   pVDIfsImage     Pointer to the per-image VD interface list.
     */
    DECLR3CALLBACKMEMBER(int, pfnProbe, (const char *pszFilename, PVDINTERFACE pVDIfsDisk, PVDINTERFACE pVDIfsImage));

    /**
     * Open a cache image.
     *
     * @returns VBox status code.
     * @param   pszFilename     Name of the image file to open. Guaranteed to be available and
     *                          unchanged during the lifetime of this image.
     * @param   uOpenFlags      Image file open mode, see VD_OPEN_FLAGS_* constants.
     * @param   pVDIfsDisk      Pointer to the per-disk VD interface list.
     * @param   pVDIfsImage     Pointer to the per-image VD interface list.
     * @param   ppBackendData   Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(int, pfnOpen, (const char *pszFilename, unsigned uOpenFlags,
                                        PVDINTERFACE pVDIfsDisk, PVDINTERFACE pVDIfsImage,
                                        void **ppBackendData));

    /**
     * Create a cache image.
     *
     * @returns VBox status code.
     * @param   pszFilename     Name of the image file to create. Guaranteed to be available and
     *                          unchanged during the lifetime of this image.
     * @param   cbSize          Image size in bytes.
     * @param   uImageFlags     Flags specifying special image features.
     * @param   pszComment      Pointer to image comment. NULL is ok.
     * @param   pUuid           New UUID of the image. Not NULL.
     * @param   uOpenFlags      Image file open mode, see VD_OPEN_FLAGS_* constants.
     * @param   uPercentStart   Starting value for progress percentage.
     * @param   uPercentSpan    Span for varying progress percentage.
     * @param   pVDIfsDisk      Pointer to the per-disk VD interface list.
     * @param   pVDIfsImage     Pointer to the per-image VD interface list.
     * @param   pVDIfsOperation Pointer to the per-operation VD interface list.
     * @param   ppBackendData   Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(int, pfnCreate, (const char *pszFilename, uint64_t cbSize,
                                          unsigned uImageFlags, const char *pszComment,
                                          PCRTUUID pUuid, unsigned uOpenFlags,
                                          unsigned uPercentStart, unsigned uPercentSpan,
                                          PVDINTERFACE pVDIfsDisk,
                                          PVDINTERFACE pVDIfsImage,
                                          PVDINTERFACE pVDIfsOperation,
                                          void **ppBackendData));

    /**
     * Close a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   fDelete         If true, delete the image from the host disk.
     */
    DECLR3CALLBACKMEMBER(int, pfnClose, (void *pBackendData, bool fDelete));

    /**
     * Read data from a cache image. The area read never crosses a block
     * boundary.
     *
     * @returns VBox status code.
     * @returns VERR_VD_BLOCK_FREE if this image contains no data for this block.
     * @param   pBackendData    Opaque state data for this image.
     * @param   uOffset         Offset to start reading from.
     * @param   pvBuf           Where to store the read bits.
     * @param   cbRead          Number of bytes to read.
     * @param   pcbActuallyRead Pointer to returned number of bytes read.
     */
    DECLR3CALLBACKMEMBER(int, pfnRead, (void *pBackendData, uint64_t uOffset, void *pvBuf,
                                        size_t cbRead, size_t *pcbActuallyRead));

    /**
     * Write data to a cache image. The area written never crosses a block
     * boundary.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   uOffset         Offset to start writing to.
     * @param   pvBuf           Where to retrieve the written bits.
     * @param   cbWrite         Number of bytes to write.
     * @param   pcbWriteProcess Pointer to returned number of bytes that could
     *                          be processed.
     */
    DECLR3CALLBACKMEMBER(int, pfnWrite, (void *pBackendData, uint64_t uOffset,
                                         const void *pvBuf, size_t cbWrite,
                                         size_t *pcbWriteProcess));

    /**
     * Flush data to disk.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(int, pfnFlush, (void *pBackendData));

    /**
     * Get the version of a cache image.
     *
     * @returns version of cache image.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(unsigned, pfnGetVersion, (void *pBackendData));

    /**
     * Get the capacity of a cache image.
     *
     * @returns size of cache image in bytes.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(uint64_t, pfnGetSize, (void *pBackendData));

    /**
     * Get the file size of a cache image.
     *
     * @returns size of cache image in bytes.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(uint64_t, pfnGetFileSize, (void *pBackendData));

    /**
     * Get the image flags of a cache image.
     *
     * @returns image flags of cache image.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(unsigned, pfnGetImageFlags, (void *pBackendData));

    /**
     * Get the open flags of a cache image.
     *
     * @returns open flags of cache image.
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(unsigned, pfnGetOpenFlags, (void *pBackendData));

    /**
     * Set the open flags of a cache image. May cause the image to be locked
     * in a different mode or be reopened (which can fail).
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   uOpenFlags      New open flags for this image.
     */
    DECLR3CALLBACKMEMBER(int, pfnSetOpenFlags, (void *pBackendData, unsigned uOpenFlags));

    /**
     * Get comment of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pszComment      Where to store the comment.
     * @param   cbComment       Size of the comment buffer.
     */
    DECLR3CALLBACKMEMBER(int, pfnGetComment, (void *pBackendData, char *pszComment, size_t cbComment));

    /**
     * Set comment of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pszComment      Where to get the comment from. NULL resets comment.
     *                          The comment is silently truncated if the image format
     *                          limit is exceeded.
     */
    DECLR3CALLBACKMEMBER(int, pfnSetComment, (void *pBackendData, const char *pszComment));

    /**
     * Get UUID of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pUuid           Where to store the image UUID.
     */
    DECLR3CALLBACKMEMBER(int, pfnGetUuid, (void *pBackendData, PRTUUID pUuid));

    /**
     * Set UUID of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pUuid           Where to get the image UUID from.
     */
    DECLR3CALLBACKMEMBER(int, pfnSetUuid, (void *pBackendData, PCRTUUID pUuid));

    /**
     * Get last modification UUID of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pUuid           Where to store the image modification UUID.
     */
    DECLR3CALLBACKMEMBER(int, pfnGetModificationUuid, (void *pBackendData, PRTUUID pUuid));

    /**
     * Set last modification UUID of a cache image.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pUuid           Where to get the image modification UUID from.
     */
    DECLR3CALLBACKMEMBER(int, pfnSetModificationUuid, (void *pBackendData, PCRTUUID pUuid));

    /**
     * Dump information about a cache image.
     *
     * @param   pBackendData    Opaque state data for this image.
     */
    DECLR3CALLBACKMEMBER(void, pfnDump, (void *pBackendData));

    /**
     * Start an asynchronous read request.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   uOffset         The offset of the virtual disk to read from.
     * @param   cbRead          How many bytes to read.
     * @param   pIoCtx          I/O context associated with this request.
     * @param   pcbActuallyRead Pointer to returned number of bytes read.
     */
    DECLR3CALLBACKMEMBER(int, pfnAsyncRead, (void *pBackendData, uint64_t uOffset, size_t cbRead,
                                             PVDIOCTX pIoCtx, size_t *pcbActuallyRead));

    /**
     * Start an asynchronous write request.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   uOffset         The offset of the virtual disk to write to.
     * @param   cbWrite         How many bytes to write.
     * @param   pIoCtx          I/O context associated with this request.
     * @param   pcbWriteProcess Pointer to returned number of bytes that could
     *                          be processed. In case the function returned
     *                          VERR_VD_BLOCK_FREE this is the number of bytes
     *                          that could be written in a full block write,
     *                          when prefixed/postfixed by the appropriate
     *                          amount of (previously read) padding data.
     */
    DECLR3CALLBACKMEMBER(int, pfnAsyncWrite, (void *pBackendData, uint64_t uOffset, size_t cbWrite,
                                              PVDIOCTX pIoCtx, size_t *pcbWriteProcess));

    /**
     * Flush data to disk.
     *
     * @returns VBox status code.
     * @param   pBackendData    Opaque state data for this image.
     * @param   pIoCtx          I/O context associated with this request.
     */
    DECLR3CALLBACKMEMBER(int, pfnAsyncFlush, (void *pBackendData, PVDIOCTX pIoCtx));

    /** Returns a human readable hard disk location string given a
     *  set of hard disk configuration keys. The returned string is an
     *  equivalent of the full file path for image-based hard disks.
     *  Mandatory for backends with no VD_CAP_FILE and NULL otherwise. */
    DECLR3CALLBACKMEMBER(int, pfnComposeLocation, (PVDINTERFACE pConfig, char **pszLocation));

    /** Returns a human readable hard disk name string given a
     *  set of hard disk configuration keys. The returned string is an
     *  equivalent of the file name part in the full file path for
     *  image-based hard disks. Mandatory for backends with no
     *  VD_CAP_FILE and NULL otherwise. */
    DECLR3CALLBACKMEMBER(int, pfnComposeName, (PVDINTERFACE pConfig, char **pszName));

} VDCACHEBACKEND;

/** Pointer to VD backend. */
typedef VDCACHEBACKEND *PVDCACHEBACKEND;

/** Constant pointer to VD backend. */
typedef const VDCACHEBACKEND *PCVDCACHEBACKEND;

/** Initialization entry point. */
typedef DECLCALLBACK(int) FNVDCACHEFORMATLOAD(PVDCACHEBACKEND *ppBackendTable);
typedef FNVDCACHEFORMATLOAD *PFNVDCACHEFORMATLOAD;
#define VD_CACHEFORMAT_LOAD_NAME "VDCacheFormatLoad"

/** The prefix to identify Storage Plugins. */
#define VD_CACHEFORMAT_PLUGIN_PREFIX "VDCache"
/** The size of the prefix excluding the '\\0' terminator. */
#define VD_CACHEFORMAT_PLUGIN_PREFIX_LENGTH (sizeof(VD_CACHEFORMAT_PLUGIN_PREFIX)-1)

#endif