path: root/src/VBox/Main/src-server/linux/HostHardwareLinux.cpp

/* $Id$ */
/** @file
 * VirtualBox Main - Code for handling hardware detection under Linux, VBoxSVC.
 */

/*
 * Copyright (C) 2008-2023 Oracle and/or its affiliates.
 *
 * This file is part of VirtualBox base platform packages, as
 * available from https://www.virtualbox.org.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, in version 3 of the
 * License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <https://www.gnu.org/licenses>.
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#define LOG_GROUP LOG_GROUP_MAIN
#include "HostHardwareLinux.h"

#include <VBox/err.h>
#include <VBox/log.h>

#include <iprt/asm.h>
#include <iprt/dir.h>
#include <iprt/env.h>
#include <iprt/file.h>
#include <iprt/mem.h>
#include <iprt/param.h>
#include <iprt/path.h>
#include <iprt/string.h>

#include <linux/cdrom.h>
#include <linux/fd.h>
#include <linux/major.h>

#include <linux/version.h>
#include <scsi/scsi.h>

#include <iprt/linux/sysfs.h>

#ifdef VBOX_USB_WITH_SYSFS
# ifdef VBOX_USB_WITH_INOTIFY
#  include <fcntl.h>        /* O_CLOEXEC */
#  include <poll.h>
#  include <signal.h>
#  include <unistd.h>
#  include <sys/inotify.h>
# endif
#endif

//#include <vector>

#include <errno.h>
#include <dirent.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/sysmacros.h>

/*
 * Define NVME constant here to allow building
 * on several kernel versions even if the
 * building host doesn't contain certain NVME
 * includes
 */
#define NVME_IOCTL_ID _IO('N', 0x40)


/*********************************************************************************************************************************
*   Global Variables                                                                                                             *
*********************************************************************************************************************************/
#ifdef TESTCASE
static bool testing() { return true; }
static bool fNoProbe = false;
static bool noProbe() { return fNoProbe; }
static void setNoProbe(bool val) { fNoProbe = val; }
#else
static bool testing() { return false; }
static bool noProbe() { return false; }
static void setNoProbe(bool val) { (void)val; }
#endif


/*********************************************************************************************************************************
*   Typedefs and Defines                                                                                                         *
*********************************************************************************************************************************/
typedef enum SysfsWantDevice_T
{
    DVD,
    Floppy,
    FixedDisk
} SysfsWantDevice_T;


/*********************************************************************************************************************************
*   Internal Functions                                                                                                           *
*********************************************************************************************************************************/
static int getDriveInfoFromEnv(const char *pcszVar, DriveInfoList *pList, bool isDVD, bool *pfSuccess) RT_NOTHROW_PROTO;
static int getDriveInfoFromSysfs(DriveInfoList *pList, SysfsWantDevice_T wantDevice, bool *pfSuccess) RT_NOTHROW_PROTO;


/**
 * Find the length of a string, ignoring trailing non-ascii or control
 * characters
 *
 * @note Code duplicated in HostHardwareFreeBSD.cpp
 */
static size_t strLenStripped(const char *pcsz) RT_NOTHROW_DEF
{
    size_t cch = 0;
    for (size_t i = 0; pcsz[i] != '\0'; ++i)
        if (pcsz[i] > 32 /*space*/ && pcsz[i] < 127 /*delete*/)
            cch = i;
    return cch + 1;
}


/**
 * Get the name of a floppy drive according to the Linux floppy driver.
 *
 * @returns true on success, false if the name was not available (i.e. the
 *          device was not readable, or the file name wasn't a PC floppy
 *          device)
 * @param  pcszNode  the path to the device node for the device
 * @param  Number    the Linux floppy driver number for the drive.  Required.
 * @param  pszName   where to store the name retrieved
 */
static bool floppyGetName(const char *pcszNode, unsigned Number, floppy_drive_name pszName) RT_NOTHROW_DEF
{
    AssertPtrReturn(pcszNode, false);
    AssertPtrReturn(pszName, false);
    AssertReturn(Number <= 7, false);
    RTFILE File;
    int vrc = RTFileOpen(&File, pcszNode, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_NONE | RTFILE_O_NON_BLOCK);
    if (RT_SUCCESS(vrc))
    {
        int iRcIoCtl;
        vrc = RTFileIoCtl(File, FDGETDRVTYP, pszName, 0, &iRcIoCtl);
        RTFileClose(File);
        if (RT_SUCCESS(vrc) && iRcIoCtl >= 0)
            return true;
    }
    return false;
}


/**
 * Create a UDI and a description for a floppy drive based on a number and the
 * driver's name for it.
 *
 * We deliberately return an ugly sequence of characters as the description
 * rather than an English language string to avoid translation issues.
 *
 * @returns true if we know the device to be valid, false otherwise
 * @param   pcszName     the floppy driver name for the device (optional)
 * @param   Number       the number of the floppy (0 to 3 on FDC 0, 4 to 7 on
 *                       FDC 1)
 * @param   pszDesc      where to store the device description (optional)
 * @param   cbDesc       the size of the buffer in @a pszDesc
 * @param   pszUdi       where to store the device UDI (optional)
 * @param   cbUdi        the size of the buffer in @a pszUdi
 */
static void floppyCreateDeviceStrings(const floppy_drive_name pcszName, unsigned Number,
                                      char *pszDesc, size_t cbDesc, char *pszUdi, size_t cbUdi) RT_NOTHROW_DEF
{
    AssertPtrNullReturnVoid(pcszName);
    AssertPtrNullReturnVoid(pszDesc);
    AssertReturnVoid(!pszDesc || cbDesc > 0);
    AssertPtrNullReturnVoid(pszUdi);
    AssertReturnVoid(!pszUdi || cbUdi > 0);
    AssertReturnVoid(Number <= 7);
    if (pcszName)
    {
        const char *pcszSize;
        switch(pcszName[0])
        {
            case 'd': case 'q': case 'h':
                pcszSize = "5.25\"";
                break;
            case 'D': case 'H': case 'E': case 'u':
                pcszSize = "3.5\"";
                break;
            default:
                pcszSize = "(unknown)";
        }
        if (pszDesc)
            RTStrPrintf(pszDesc, cbDesc, "%s %s K%s", pcszSize, &pcszName[1],
                        Number > 3 ? ", FDC 2" : "");
    }
    else
    {
        if (pszDesc)
            RTStrPrintf(pszDesc, cbDesc, "FDD %d%s", (Number & 4) + 1,
                        Number > 3 ? ", FDC 2" : "");
    }
    if (pszUdi)
        RTStrPrintf(pszUdi, cbUdi,
                    "/org/freedesktop/Hal/devices/platform_floppy_%u_storage",
                    Number);
}


/**
 * Check whether a device number might correspond to a CD-ROM device according
 * to Documentation/devices.txt in the Linux kernel source.
 *
 * @returns true if it might, false otherwise
 * @param   Number  the device number (major and minor combination)
 */
static bool isCdromDevNum(dev_t Number) RT_NOTHROW_DEF
{
    int major = major(Number);
    int minor = minor(Number);
    if (major == IDE0_MAJOR && !(minor & 0x3f))
        return true;
    if (major == SCSI_CDROM_MAJOR)
        return true;
    if (major == CDU31A_CDROM_MAJOR)
        return true;
    if (major == GOLDSTAR_CDROM_MAJOR)
        return true;
    if (major == OPTICS_CDROM_MAJOR)
        return true;
    if (major == SANYO_CDROM_MAJOR)
        return true;
    if (major == MITSUMI_X_CDROM_MAJOR)
        return true;
    if (major == IDE1_MAJOR && !(minor & 0x3f))
        return true;
    if (major == MITSUMI_CDROM_MAJOR)
        return true;
    if (major == CDU535_CDROM_MAJOR)
        return true;
    if (major == MATSUSHITA_CDROM_MAJOR)
        return true;
    if (major == MATSUSHITA_CDROM2_MAJOR)
        return true;
    if (major == MATSUSHITA_CDROM3_MAJOR)
        return true;
    if (major == MATSUSHITA_CDROM4_MAJOR)
        return true;
    if (major == AZTECH_CDROM_MAJOR)
        return true;
    if (major == 30 /* CM205_CDROM_MAJOR */)  /* no #define for some reason */
        return true;
    if (major == CM206_CDROM_MAJOR)
        return true;
    if (major == IDE3_MAJOR && !(minor & 0x3f))
        return true;
    if (major == 46 /* Parallel port ATAPI CD-ROM */)  /* no #define */
        return true;
    if (major == IDE4_MAJOR && !(minor & 0x3f))
        return true;
    if (major == IDE5_MAJOR && !(minor & 0x3f))
        return true;
    if (major == IDE6_MAJOR && !(minor & 0x3f))
        return true;
    if (major == IDE7_MAJOR && !(minor & 0x3f))
        return true;
    if (major == IDE8_MAJOR && !(minor & 0x3f))
        return true;
    if (major == IDE9_MAJOR && !(minor & 0x3f))
        return true;
    if (major == 113 /* VIOCD_MAJOR */)
        return true;
    return false;
}


/**
 * Send an SCSI INQUIRY command to a device and return selected information.
 *
 * @returns  iprt status code
 * @retval   VERR_TRY_AGAIN if the query failed but might succeed next time
 * @param pcszNode    the full path to the device node
 * @param pbType     where to store the SCSI device type on success (optional)
 * @param pszVendor  where to store the vendor id string on success (optional)
 * @param cbVendor   the size of the @a pszVendor buffer
 * @param pszModel   where to store the product id string on success (optional)
 * @param cbModel    the size of the @a pszModel buffer
 * @note check documentation on the SCSI INQUIRY command and the Linux kernel
 *       SCSI headers included above if you want to understand what is going
 *       on in this method.
 */
static int cdromDoInquiry(const char *pcszNode, uint8_t *pbType, char *pszVendor, size_t cbVendor,
                          char *pszModel, size_t cbModel) RT_NOTHROW_DEF
{
    LogRelFlowFunc(("pcszNode=%s, pbType=%p, pszVendor=%p, cbVendor=%zu, pszModel=%p, cbModel=%zu\n",
                    pcszNode, pbType, pszVendor, cbVendor, pszModel, cbModel));
    AssertPtrReturn(pcszNode, VERR_INVALID_POINTER);
    AssertPtrNullReturn(pbType, VERR_INVALID_POINTER);
    AssertPtrNullReturn(pszVendor, VERR_INVALID_POINTER);
    AssertPtrNullReturn(pszModel, VERR_INVALID_POINTER);

    RTFILE hFile = NIL_RTFILE;
    int vrc = RTFileOpen(&hFile, pcszNode, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_NONE | RTFILE_O_NON_BLOCK);
    if (RT_SUCCESS(vrc))
    {
        int                             iRcIoCtl         = 0;
        unsigned char                   auchResponse[96] = { 0 };
        struct cdrom_generic_command    CdromCommandReq;
        RT_ZERO(CdromCommandReq);
        CdromCommandReq.cmd[0]         = INQUIRY;
        CdromCommandReq.cmd[4]         = sizeof(auchResponse);
        CdromCommandReq.buffer         = auchResponse;
        CdromCommandReq.buflen         = sizeof(auchResponse);
        CdromCommandReq.data_direction = CGC_DATA_READ;
        CdromCommandReq.timeout        = 5000;  /* ms */
        vrc = RTFileIoCtl(hFile, CDROM_SEND_PACKET, &CdromCommandReq, 0, &iRcIoCtl);
        if (RT_SUCCESS(vrc) && iRcIoCtl < 0)
            vrc = RTErrConvertFromErrno(-CdromCommandReq.stat);
        RTFileClose(hFile);

        if (RT_SUCCESS(vrc))
        {
            if (pbType)
                *pbType = auchResponse[0] & 0x1f;
            if (pszVendor)
            {
                RTStrPrintf(pszVendor, cbVendor, "%.8s", &auchResponse[8] /* vendor id string */);
                RTStrPurgeEncoding(pszVendor);
            }
            if (pszModel)
            {
                RTStrPrintf(pszModel, cbModel, "%.16s", &auchResponse[16] /* product id string */);
                RTStrPurgeEncoding(pszModel);
            }
            LogRelFlowFunc(("returning success: type=%u, vendor=%.8s, product=%.16s\n",
                            auchResponse[0] & 0x1f, &auchResponse[8], &auchResponse[16]));
            return VINF_SUCCESS;
        }
    }
    LogRelFlowFunc(("returning %Rrc\n", vrc));
    return vrc;
}


/**
 * Initialise the device strings (description and UDI) for a DVD drive based on
 * vendor and model name strings.
 *
 * @param pcszVendor  the vendor ID string
 * @param pcszModel   the product ID string
 * @param pszDesc    where to store the description string (optional)
 * @param cbDesc     the size of the buffer in @a pszDesc
 * @param pszUdi     where to store the UDI string (optional)
 * @param cbUdi      the size of the buffer in @a pszUdi
 *
 * @note  Used for more than DVDs these days.
 */
static void dvdCreateDeviceStrings(const char *pcszVendor, const char *pcszModel,
                                   char *pszDesc, size_t cbDesc, char *pszUdi, size_t cbUdi) RT_NOEXCEPT
{
    AssertPtrReturnVoid(pcszVendor);
    AssertPtrReturnVoid(pcszModel);
    AssertPtrNullReturnVoid(pszDesc);
    AssertReturnVoid(!pszDesc || cbDesc > 0);
    AssertPtrNullReturnVoid(pszUdi);
    AssertReturnVoid(!pszUdi || cbUdi > 0);

    size_t cchModel = strLenStripped(pcszModel);
    /*
     * Vendor and Model strings can contain trailing spaces.
     * Create trimmed copy of them because we should not modify
     * original strings.
     */
    char* pszStartTrimmed = RTStrStripL(pcszVendor);
    char* pszVendor = RTStrDup(pszStartTrimmed);
    RTStrStripR(pszVendor);
    pszStartTrimmed = RTStrStripL(pcszModel);
    char* pszModel = RTStrDup(pszStartTrimmed);
    RTStrStripR(pszModel);

    size_t cbVendor = strlen(pszVendor);

    /* Create a cleaned version of the model string for the UDI string. */
    char szCleaned[128];
    for (unsigned i = 0; i < sizeof(szCleaned) && pcszModel[i] != '\0'; ++i)
        if (   (pcszModel[i] >= '0' && pcszModel[i] <= '9')
            || (pcszModel[i] >= 'A' && pcszModel[i] <= 'z'))
            szCleaned[i] = pcszModel[i];
        else
            szCleaned[i] = '_';
    szCleaned[RT_MIN(cchModel, sizeof(szCleaned) - 1)] = '\0';

    /* Construct the description string as "Vendor Product" */
    if (pszDesc)
    {
        if (cbVendor > 0)
        {
            RTStrPrintf(pszDesc, cbDesc, "%.*s %s", cbVendor, pszVendor, strlen(pszModel) > 0 ? pszModel : "(unknown drive model)");
            RTStrPurgeEncoding(pszDesc);
        }
        else
            RTStrCopy(pszDesc, cbDesc, pszModel);
    }
    /* Construct the UDI string */
    if (pszUdi)
    {
        if (cchModel > 0)
            RTStrPrintf(pszUdi, cbUdi, "/org/freedesktop/Hal/devices/storage_model_%s", szCleaned);
        else
            pszUdi[0] = '\0';
    }
}


/**
 * Check whether the device is the NVME device.
 * @returns true on success, false if the name was not available (i.e. the
 *          device was not readable, or the file name wasn't a NVME device)
 * @param  pcszNode     the path to the device node for the device
 */
static bool probeNVME(const char *pcszNode) RT_NOTHROW_DEF
{
    AssertPtrReturn(pcszNode, false);
    RTFILE File;
    int vrc = RTFileOpen(&File, pcszNode, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_NONE | RTFILE_O_NON_BLOCK);
    if (RT_SUCCESS(vrc))
    {
        int iRcIoCtl;
        vrc = RTFileIoCtl(File, NVME_IOCTL_ID, NULL, 0, &iRcIoCtl);
        RTFileClose(File);
        if (RT_SUCCESS(vrc) && iRcIoCtl >= 0)
            return true;
    }
    return false;
}

/**
 * Check whether a device node points to a valid device and create a UDI and
 * a description for it, and store the device number, if it does.
 *
 * @returns true if the device is valid, false otherwise
 * @param   pcszNode   the path to the device node
 * @param   isDVD     are we looking for a DVD device (or a floppy device)?
 * @param   pDevice   where to store the device node (optional)
 * @param   pszDesc   where to store the device description (optional)
 * @param   cbDesc    the size of the buffer in @a pszDesc
 * @param   pszUdi    where to store the device UDI (optional)
 * @param   cbUdi     the size of the buffer in @a pszUdi
 */
static bool devValidateDevice(const char *pcszNode, bool isDVD, dev_t *pDevice,
                              char *pszDesc, size_t cbDesc, char *pszUdi, size_t cbUdi) RT_NOTHROW_DEF
{
    AssertPtrReturn(pcszNode, false);
    AssertPtrNullReturn(pDevice, false);
    AssertPtrNullReturn(pszDesc, false);
    AssertReturn(!pszDesc || cbDesc > 0, false);
    AssertPtrNullReturn(pszUdi, false);
    AssertReturn(!pszUdi || cbUdi > 0, false);

    RTFSOBJINFO ObjInfo;
    if (RT_FAILURE(RTPathQueryInfo(pcszNode, &ObjInfo, RTFSOBJATTRADD_UNIX)))
        return false;
    if (!RTFS_IS_DEV_BLOCK(ObjInfo.Attr.fMode))
        return false;
    if (pDevice)
        *pDevice = ObjInfo.Attr.u.Unix.Device;

    if (isDVD)
    {
        char szVendor[128], szModel[128];
        uint8_t u8Type;
        if (!isCdromDevNum(ObjInfo.Attr.u.Unix.Device))
            return false;
        if (RT_FAILURE(cdromDoInquiry(pcszNode, &u8Type,
                                      szVendor, sizeof(szVendor),
                                      szModel, sizeof(szModel))))
            return false;
        if (u8Type != TYPE_ROM)
            return false;
        dvdCreateDeviceStrings(szVendor, szModel, pszDesc, cbDesc, pszUdi, cbUdi);
    }
    else
    {
        /* Floppies on Linux are legacy devices with hardcoded majors and minors */
        if (major(ObjInfo.Attr.u.Unix.Device) != FLOPPY_MAJOR)
            return false;

        unsigned Number;
        switch (minor(ObjInfo.Attr.u.Unix.Device))
        {
            case 0: case 1: case 2: case 3:
                Number = minor(ObjInfo.Attr.u.Unix.Device);
                break;
            case 128: case 129: case 130: case 131:
                Number = minor(ObjInfo.Attr.u.Unix.Device) - 128 + 4;
                break;
            default:
                return false;
        }

        floppy_drive_name szName;
        if (!floppyGetName(pcszNode, Number, szName))
            return false;
        floppyCreateDeviceStrings(szName, Number, pszDesc, cbDesc, pszUdi, cbUdi);
    }
    return true;
}


int VBoxMainDriveInfo::updateDVDs() RT_NOEXCEPT
{
    LogFlowThisFunc(("entered\n"));
    int vrc;
    try
    {
        mDVDList.clear();
        /* Always allow the user to override our auto-detection using an
         * environment variable. */
        bool fSuccess = false;  /* Have we succeeded in finding anything yet? */
        vrc = getDriveInfoFromEnv("VBOX_CDROM", &mDVDList, true /* isDVD */, &fSuccess);
        setNoProbe(false);
        if (RT_SUCCESS(vrc) && (!fSuccess || testing()))
            vrc = getDriveInfoFromSysfs(&mDVDList, DVD, &fSuccess);
        if (RT_SUCCESS(vrc) && testing())
        {
            setNoProbe(true);
            vrc = getDriveInfoFromSysfs(&mDVDList, DVD, &fSuccess);
        }
    }
    catch (std::bad_alloc &e)
    {
        vrc = VERR_NO_MEMORY;
    }
    LogFlowThisFunc(("vrc=%Rrc\n", vrc));
    return vrc;
}

int VBoxMainDriveInfo::updateFloppies() RT_NOEXCEPT
{
    LogFlowThisFunc(("entered\n"));
    int vrc;
    try
    {
        mFloppyList.clear();
        bool fSuccess = false;  /* Have we succeeded in finding anything yet? */
        vrc = getDriveInfoFromEnv("VBOX_FLOPPY", &mFloppyList, false /* isDVD */, &fSuccess);
        setNoProbe(false);
        if (RT_SUCCESS(vrc) && (!fSuccess || testing()))
            vrc = getDriveInfoFromSysfs(&mFloppyList, Floppy, &fSuccess);
        if (RT_SUCCESS(vrc) && testing())
        {
            setNoProbe(true);
            vrc = getDriveInfoFromSysfs(&mFloppyList, Floppy, &fSuccess);
        }
    }
    catch (std::bad_alloc &)
    {
        vrc = VERR_NO_MEMORY;
    }
    LogFlowThisFunc(("vrc=%Rrc\n", vrc));
    return vrc;
}

int VBoxMainDriveInfo::updateFixedDrives() RT_NOEXCEPT
{
    LogFlowThisFunc(("entered\n"));
    int vrc;
    try
    {
        mFixedDriveList.clear();
        setNoProbe(false);
        bool fSuccess = false;  /* Have we succeeded in finding anything yet? */
        vrc = getDriveInfoFromSysfs(&mFixedDriveList, FixedDisk, &fSuccess);
        if (RT_SUCCESS(vrc) && testing())
        {
            setNoProbe(true);
            vrc = getDriveInfoFromSysfs(&mFixedDriveList, FixedDisk, &fSuccess);
        }
    }
    catch (std::bad_alloc &)
    {
        vrc = VERR_NO_MEMORY;
    }
    LogFlowThisFunc(("vrc=%Rrc\n", vrc));
    return vrc;
}


/**
 * Extract the names of drives from an environment variable and add them to a
 * list if they are valid.
 *
 * @returns iprt status code
 * @param   pcszVar     the name of the environment variable.  The variable
 *                     value should be a list of device node names, separated
 *                     by ':' characters.
 * @param   pList      the list to append the drives found to
 * @param   isDVD      are we looking for DVD drives or for floppies?
 * @param   pfSuccess  this will be set to true if we found at least one drive
 *                     and to false otherwise.  Optional.
 *
 * @note    This is duplicated in HostHardwareFreeBSD.cpp.
 */
static int getDriveInfoFromEnv(const char *pcszVar, DriveInfoList *pList, bool isDVD, bool *pfSuccess) RT_NOTHROW_DEF
{
    AssertPtrReturn(pcszVar, VERR_INVALID_POINTER);
    AssertPtrReturn(pList, VERR_INVALID_POINTER);
    AssertPtrNullReturn(pfSuccess, VERR_INVALID_POINTER);
    LogFlowFunc(("pcszVar=%s, pList=%p, isDVD=%d, pfSuccess=%p\n", pcszVar, pList, isDVD, pfSuccess));
    int vrc = VINF_SUCCESS;
    bool success = false;
    char *pszFreeMe = RTEnvDupEx(RTENV_DEFAULT, pcszVar);

    try
    {
        char *pszCurrent = pszFreeMe;
        while (pszCurrent && *pszCurrent != '\0')
        {
            char *pszNext = strchr(pszCurrent, ':');
            if (pszNext)
                *pszNext++ = '\0';

            char szReal[RTPATH_MAX];
            char szDesc[256], szUdi[256];
            if (   RT_SUCCESS(RTPathReal(pszCurrent, szReal, sizeof(szReal)))
                && devValidateDevice(szReal, isDVD, NULL, szDesc, sizeof(szDesc), szUdi, sizeof(szUdi)))
            {
                pList->push_back(DriveInfo(szReal, szUdi, szDesc));
                success = true;
            }
            pszCurrent = pszNext;
        }
        if (pfSuccess != NULL)
            *pfSuccess = success;
    }
    catch (std::bad_alloc &)
    {
        vrc = VERR_NO_MEMORY;
    }
    RTStrFree(pszFreeMe);
    LogFlowFunc(("vrc=%Rrc, success=%d\n", vrc, success));
    return vrc;
}


class SysfsBlockDev
{
public:
    SysfsBlockDev(const char *pcszName, SysfsWantDevice_T wantDevice) RT_NOEXCEPT
        : mpcszName(pcszName), mWantDevice(wantDevice), misConsistent(true), misValid(false)
    {
        if (findDeviceNode())
        {
            switch (mWantDevice)
            {
                case DVD:    validateAndInitForDVD(); break;
                case Floppy: validateAndInitForFloppy(); break;
                default:     validateAndInitForFixedDisk(); break;
            }
        }
    }
private:
    /** The name of the subdirectory of /sys/block for this device */
    const char *mpcszName;
    /** Are we looking for a floppy, a DVD or a fixed disk device? */
    SysfsWantDevice_T mWantDevice;
    /** The device node for the device */
    char mszNode[RTPATH_MAX];
    /** Does the sysfs entry look like we expect it too?  This is a canary
     * for future sysfs ABI changes. */
    bool misConsistent;
    /** Is this entry a valid specimen of what we are looking for? */
    bool misValid;
    /** Human readable drive description string */
    char mszDesc[256];
    /** Unique identifier for the drive.  Should be identical to hal's UDI for
     * the device.  May not be unique for two identical drives. */
    char mszUdi[256];
private:
    /* Private methods */

    /**
     * Fill in the device node member based on the /sys/block subdirectory.
     * @returns boolean success value
     */
    bool findDeviceNode() RT_NOEXCEPT
    {
        dev_t dev = 0;
        int vrc = RTLinuxSysFsReadDevNumFile(&dev, "block/%s/dev", mpcszName);
        if (RT_FAILURE(vrc) || dev == 0)
        {
            misConsistent = false;
            return false;
        }
        vrc = RTLinuxCheckDevicePath(dev, RTFS_TYPE_DEV_BLOCK, mszNode, sizeof(mszNode), "%s", mpcszName);
        return RT_SUCCESS(vrc);
    }

    /** Check whether the sysfs block entry is valid for a DVD device and
     * initialise the string data members for the object.  We try to get all
     * the information we need from sysfs if possible, to avoid unnecessarily
     * poking the device, and if that fails we fall back to an SCSI INQUIRY
     * command. */
    void validateAndInitForDVD() RT_NOEXCEPT
    {
        int64_t type = 0;
        int vrc = RTLinuxSysFsReadIntFile(10, &type, "block/%s/device/type", mpcszName);
        if (RT_SUCCESS(vrc) && type != TYPE_ROM)
            return;
        if (type == TYPE_ROM)
        {
            char szVendor[128];
            vrc = RTLinuxSysFsReadStrFile(szVendor, sizeof(szVendor), NULL, "block/%s/device/vendor", mpcszName);
            if (RT_SUCCESS(vrc))
            {
                char szModel[128];
                vrc = RTLinuxSysFsReadStrFile(szModel, sizeof(szModel), NULL, "block/%s/device/model", mpcszName);
                if (RT_SUCCESS(vrc))
                {
                    misValid = true;
                    dvdCreateDeviceStrings(szVendor, szModel, mszDesc, sizeof(mszDesc), mszUdi, sizeof(mszUdi));
                    return;
                }
            }
        }
        if (!noProbe())
            probeAndInitForDVD();
    }

    /** Try to find out whether a device is a DVD drive by sending it an
     * SCSI INQUIRY command.  If it is, initialise the string and validity
     * data members for the object based on the returned data.
     */
    void probeAndInitForDVD() RT_NOEXCEPT
    {
        AssertReturnVoid(mszNode[0] != '\0');
        uint8_t bType = 0;
        char szVendor[128] = "";
        char szModel[128] = "";
        int vrc = cdromDoInquiry(mszNode, &bType, szVendor, sizeof(szVendor), szModel, sizeof(szModel));
        if (RT_SUCCESS(vrc) && bType == TYPE_ROM)
        {
            misValid = true;
            dvdCreateDeviceStrings(szVendor, szModel, mszDesc, sizeof(mszDesc), mszUdi, sizeof(mszUdi));
        }
    }

    /** Check whether the sysfs block entry is valid for a floppy device and
     * initialise the string data members for the object.  Since we only
     * support floppies using the basic "floppy" driver, we check the driver
     * using the entry name and a driver-specific ioctl. */
    void validateAndInitForFloppy() RT_NOEXCEPT
    {
        floppy_drive_name szName;
        char szDriver[8];
        if (   mpcszName[0] != 'f'
            || mpcszName[1] != 'd'
            || mpcszName[2] < '0'
            || mpcszName[2] > '7'
            || mpcszName[3] != '\0')
            return;
        bool fHaveName = false;
        if (!noProbe())
            fHaveName = floppyGetName(mszNode, mpcszName[2] - '0', szName);
        int vrc = RTLinuxSysFsGetLinkDest(szDriver, sizeof(szDriver), NULL, "block/%s/%s", mpcszName, "device/driver");
        if (RT_SUCCESS(vrc))
        {
            if (RTStrCmp(szDriver, "floppy"))
                return;
        }
        else if (!fHaveName)
            return;
        floppyCreateDeviceStrings(fHaveName ? szName : NULL,
                                  mpcszName[2] - '0', mszDesc,
                                  sizeof(mszDesc), mszUdi, sizeof(mszUdi));
        misValid = true;
    }

    void validateAndInitForFixedDisk() RT_NOEXCEPT
    {
        /*
         * For current task only device path is needed. Therefore, device probing
         * is skipped and other fields are empty if there aren't files in the
         * device entry.
         */
        int64_t type = 0;
        int vrc = RTLinuxSysFsReadIntFile(10, &type, "block/%s/device/type", mpcszName);
        if (!RT_SUCCESS(vrc) || type != TYPE_DISK)
        {
            if (noProbe() || !probeNVME(mszNode))
            {
                char szDriver[16];
                vrc = RTLinuxSysFsGetLinkDest(szDriver, sizeof(szDriver), NULL, "block/%s/%s", mpcszName, "device/device/driver");
                if (RT_FAILURE(vrc) || RTStrCmp(szDriver, "nvme"))
                    return;
            }
        }
        char szVendor[128];
        char szModel[128];
        size_t cbRead = 0;
        vrc = RTLinuxSysFsReadStrFile(szVendor, sizeof(szVendor), &cbRead, "block/%s/device/vendor", mpcszName);
        szVendor[cbRead] = '\0';
        /* Assume the model is always present. Vendor is not present for NVME disks */
        cbRead = 0;
        vrc = RTLinuxSysFsReadStrFile(szModel, sizeof(szModel), &cbRead, "block/%s/device/model", mpcszName);
        szModel[cbRead] = '\0';
        if (RT_SUCCESS(vrc))
        {
            misValid = true;
            dvdCreateDeviceStrings(szVendor, szModel, mszDesc, sizeof(mszDesc), mszUdi, sizeof(mszUdi));
        }
    }

public:
    bool isConsistent() const RT_NOEXCEPT
    {
        return misConsistent;
    }
    bool isValid() const RT_NOEXCEPT
    {
        return misValid;
    }
    const char *getDesc() const RT_NOEXCEPT
    {
        return mszDesc;
    }
    const char *getUdi() const RT_NOEXCEPT
    {
        return mszUdi;
    }
    const char *getNode() const RT_NOEXCEPT
    {
        return mszNode;
    }
};


/**
 * Helper function to query the sysfs subsystem for information about DVD
 * drives attached to the system.
 * @returns iprt status code
 * @param   pList       where to add information about the drives detected
 * @param   wantDevice  The kind of devices we're looking for.
 * @param   pfSuccess   Did we find anything?
 *
 * @returns IPRT status code
 * @throws  Nothing.
 */
static int getDriveInfoFromSysfs(DriveInfoList *pList, SysfsWantDevice_T wantDevice, bool *pfSuccess) RT_NOTHROW_DEF
{
    AssertPtrReturn(pList, VERR_INVALID_POINTER);
    AssertPtrNullReturn(pfSuccess, VERR_INVALID_POINTER); /* Valid or Null */
    LogFlowFunc (("pList=%p, wantDevice=%u, pfSuccess=%p\n",
                  pList, (unsigned)wantDevice, pfSuccess));
    if (!RTPathExists("/sys"))
        return VINF_SUCCESS;

    bool fSuccess = true;
    unsigned cFound = 0;
    RTDIR hDir = NIL_RTDIR;
    int vrc = RTDirOpen(&hDir, "/sys/block");
    /* This might mean that sysfs semantics have changed */
    AssertReturn(vrc != VERR_FILE_NOT_FOUND, VINF_SUCCESS);
    if (RT_SUCCESS(vrc))
    {
        for (;;)
        {
            RTDIRENTRY entry;
            vrc = RTDirRead(hDir, &entry, NULL);
            Assert(vrc != VERR_BUFFER_OVERFLOW);  /* Should never happen... */
            if (RT_FAILURE(vrc))  /* Including overflow and no more files */
                break;
            if (entry.szName[0] == '.')
                continue;
            SysfsBlockDev dev(entry.szName, wantDevice);
            /* This might mean that sysfs semantics have changed */
            AssertBreakStmt(dev.isConsistent(), fSuccess = false);
            if (!dev.isValid())
                continue;
            try
            {
                pList->push_back(DriveInfo(dev.getNode(), dev.getUdi(), dev.getDesc()));
            }
            catch (std::bad_alloc &e)
            {
                vrc = VERR_NO_MEMORY;
                break;
            }
            ++cFound;
        }
        RTDirClose(hDir);
    }
    if (vrc == VERR_NO_MORE_FILES)
        vrc = VINF_SUCCESS;
    else if (RT_FAILURE(vrc))
        /* Clean up again */
        while (cFound-- > 0)
            pList->pop_back();
    if (pfSuccess)
        *pfSuccess = fSuccess;
    LogFlow (("vrc=%Rrc, fSuccess=%u\n", vrc, (unsigned)fSuccess));
    return vrc;
}


/** Helper for readFilePathsFromDir().  Adds a path to the vector if it is not
 * NULL and not a dotfile (".", "..", ".*"). */
static int maybeAddPathToVector(const char *pcszPath, const char *pcszEntry, VECTOR_PTR(char *) *pvecpchDevs) RT_NOTHROW_DEF
{
    if (!pcszPath)
        return 0;
    if (pcszEntry[0] == '.')
        return 0;
    char *pszPath = RTStrDup(pcszPath);
    if (pszPath)
    {
        int vrc = VEC_PUSH_BACK_PTR(pvecpchDevs, char *, pszPath);
        if (RT_SUCCESS(vrc))
            return 0;
    }
    return ENOMEM;
}

/**
 * Helper for readFilePaths().
 *
 * Adds the entries from the open directory @a pDir to the vector @a pvecpchDevs
 * using either the full path or the realpath() and skipping hidden files
 * and files on which realpath() fails.
 */
static int readFilePathsFromDir(const char *pcszPath, DIR *pDir, VECTOR_PTR(char *) *pvecpchDevs, int withRealPath) RT_NOTHROW_DEF
{
    struct dirent entry, *pResult;
    int err;

#if RT_GNUC_PREREQ(4, 6)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
    for (err = readdir_r(pDir, &entry, &pResult);
         pResult != NULL && err == 0;
         err = readdir_r(pDir, &entry, &pResult))
#if RT_GNUC_PREREQ(4, 6)
# pragma GCC diagnostic pop
#endif
    {
        /* We (implicitly) require that PATH_MAX be defined */
        char szPath[PATH_MAX + 1], szRealPath[PATH_MAX + 1], *pszPath;
        if (snprintf(szPath, sizeof(szPath), "%s/%s", pcszPath,
                     entry.d_name) < 0)
            return errno;
        if (withRealPath)
            pszPath = realpath(szPath, szRealPath);
        else
            pszPath = szPath;
        if ((err = maybeAddPathToVector(pszPath, entry.d_name, pvecpchDevs)))
            return err;
    }
    return err;
}


/**
 * Helper for walkDirectory to dump the names of a directory's entries into a
 * vector of char pointers.
 *
 * @returns zero on success or (positive) posix error value.
 * @param   pcszPath      the path to dump.
 * @param   pvecpchDevs   an empty vector of char pointers - must be cleaned up
 *                        by the caller even on failure.
 * @param   withRealPath  whether to canonicalise the filename with realpath
 */
static int readFilePaths(const char *pcszPath, VECTOR_PTR(char *) *pvecpchDevs, int withRealPath) RT_NOTHROW_DEF
{
    AssertPtrReturn(pvecpchDevs, EINVAL);
    AssertReturn(VEC_SIZE_PTR(pvecpchDevs) == 0, EINVAL);
    AssertPtrReturn(pcszPath, EINVAL);

    DIR *pDir = opendir(pcszPath);
    if (!pDir)
        return RTErrConvertFromErrno(errno);
    int err = readFilePathsFromDir(pcszPath, pDir, pvecpchDevs, withRealPath);
    if (closedir(pDir) < 0 && !err)
        err = errno;
    return RTErrConvertFromErrno(err);
}


class hotplugNullImpl : public VBoxMainHotplugWaiterImpl
{
public:
    hotplugNullImpl(const char *) {}
    virtual ~hotplugNullImpl (void) {}
    /** @copydoc VBoxMainHotplugWaiter::Wait */
    virtual int Wait (RTMSINTERVAL cMillies)
    {
        NOREF(cMillies);
        return VERR_NOT_SUPPORTED;
    }
    /** @copydoc VBoxMainHotplugWaiter::Interrupt */
    virtual void Interrupt (void) {}
    virtual int getStatus(void)
    {
        return VERR_NOT_SUPPORTED;
    }

};

#ifdef VBOX_USB_WITH_SYSFS
# ifdef VBOX_USB_WITH_INOTIFY
/** Class wrapper around an inotify watch (or a group of them to be precise).
 */
typedef struct inotifyWatch
{
    /** The native handle of the inotify fd. */
    int mhInotify;
} inotifyWatch;

/** The flags we pass to inotify - modify, create, delete, change permissions
 */
#define MY_IN_FLAGS (IN_CREATE | IN_DELETE | IN_MODIFY | IN_ATTRIB)
AssertCompile(MY_IN_FLAGS == 0x306);

static int iwAddWatch(inotifyWatch *pSelf, const char *pcszPath)
{
    errno = 0;
    if (   inotify_add_watch(pSelf->mhInotify, pcszPath, MY_IN_FLAGS) >= 0
        || errno == EACCES)
        return VINF_SUCCESS;
    /* Other errors listed in the manpage can be treated as fatal */
    return RTErrConvertFromErrno(errno);
}

/** Object initialisation */
static int iwInit(inotifyWatch *pSelf)
{
    AssertPtr(pSelf);
    pSelf->mhInotify = -1;
    int fd = inotify_init1(IN_CLOEXEC | IN_NONBLOCK);
    if (fd >= 0)
    {
        pSelf->mhInotify = fd;
        return VINF_SUCCESS;
    }
    Assert(errno > 0);
    return RTErrConvertFromErrno(errno);
}

static void iwTerm(inotifyWatch *pSelf)
{
    AssertPtrReturnVoid(pSelf);
    if (pSelf->mhInotify != -1)
    {
        close(pSelf->mhInotify);
        pSelf->mhInotify = -1;
    }
}

static int iwGetFD(inotifyWatch *pSelf)
{
    AssertPtrReturn(pSelf, -1);
    return pSelf->mhInotify;
}

# define SYSFS_WAKEUP_STRING "Wake up!"

class hotplugInotifyImpl : public VBoxMainHotplugWaiterImpl
{
    /** Pipe used to interrupt wait(), the read end. */
    int mhWakeupPipeR;
    /** Pipe used to interrupt wait(), the write end. */
    int mhWakeupPipeW;
    /** The inotify watch set */
    inotifyWatch mWatches;
    /** Flag to mark that the Wait() method is currently being called, and to
     * ensure that it isn't called multiple times in parallel. */
    volatile uint32_t mfWaiting;
    /** The root of the USB devices tree. */
    const char *mpcszDevicesRoot;
    /** iprt result code from object initialisation.  Should be AssertReturn-ed
     * on at the start of all methods.  I went this way because I didn't want
     * to deal with exceptions. */
    int mStatus;
    /** ID values associates with the wakeup pipe and the FAM socket for polling
     */
    enum
    {
        RPIPE_ID = 0,
        INOTIFY_ID,
        MAX_POLLID
    };

    /** Clean up any resources in use, gracefully skipping over any which have
     * not yet been allocated or already cleaned up.  Intended to be called
     * from the destructor or after a failed initialisation. */
    void term(void);

    int drainInotify();

    /** Read the wakeup string from the wakeup pipe */
    int drainWakeupPipe(void);
public:
    hotplugInotifyImpl(const char *pcszDevicesRoot);
    virtual ~hotplugInotifyImpl(void)
    {
        term();
#ifdef DEBUG
        /** The first call to term should mark all resources as freed, so this
         * should be a semantic no-op. */
        term();
#endif
    }
    /** Is inotify available and working on this system?  If so we expect that
     * this implementation will be usable. */
    static bool Available(void)
    {
        int const fd = inotify_init1(IN_CLOEXEC | IN_NONBLOCK);
        if (fd >= 0)
            close(fd);
        return fd >= 0;
    }

    virtual int getStatus(void)
    {
        return mStatus;
    }

    /** @copydoc VBoxMainHotplugWaiter::Wait */
    virtual int Wait(RTMSINTERVAL);
    /** @copydoc VBoxMainHotplugWaiter::Interrupt */
    virtual void Interrupt(void);
};

/** Simplified version of RTPipeCreate */
static int pipeCreateSimple(int *phPipeRead, int *phPipeWrite)
{
    AssertPtrReturn(phPipeRead, VERR_INVALID_POINTER);
    AssertPtrReturn(phPipeWrite, VERR_INVALID_POINTER);

    /*
     * Create the pipe and set the close-on-exec flag.
     * ASSUMES we're building and running on Linux 2.6.27 or later (pipe2).
     */
    int aFds[2] = {-1, -1};
    if (pipe2(aFds, O_CLOEXEC))
        return RTErrConvertFromErrno(errno);

    *phPipeRead  = aFds[0];
    *phPipeWrite = aFds[1];

    /*
     * Before we leave, make sure to shut up SIGPIPE.
     */
    signal(SIGPIPE, SIG_IGN);
    return VINF_SUCCESS;
}

hotplugInotifyImpl::hotplugInotifyImpl(const char *pcszDevicesRoot)
    : mhWakeupPipeR(-1), mhWakeupPipeW(-1), mfWaiting(0)
    , mpcszDevicesRoot(pcszDevicesRoot), mStatus(VERR_WRONG_ORDER)
{
#  ifdef DEBUG
    /* Excercise the code path (term() on a not-fully-initialised object) as
     * well as we can.  On an uninitialised object this method is a semantic
     * no-op. */
    mWatches.mhInotify = -1; /* term will access this variable */
    term();
    /* For now this probing method should only be used if nothing else is
     * available */
#  endif

    int vrc = iwInit(&mWatches);
    if (RT_SUCCESS(vrc))
    {
        vrc = iwAddWatch(&mWatches, mpcszDevicesRoot);
        if (RT_SUCCESS(vrc))
            vrc = pipeCreateSimple(&mhWakeupPipeR, &mhWakeupPipeW);
    }
    mStatus = vrc;
    if (RT_FAILURE(vrc))
        term();
}

void hotplugInotifyImpl::term(void)
{
    /** This would probably be a pending segfault, so die cleanly */
    AssertRelease(!mfWaiting);
    if (mhWakeupPipeR != -1)
    {
        close(mhWakeupPipeR);
        mhWakeupPipeR = -1;
    }
    if (mhWakeupPipeW != -1)
    {
        close(mhWakeupPipeW);
        mhWakeupPipeW = -1;
    }
    iwTerm(&mWatches);
}

int hotplugInotifyImpl::drainInotify()
{
    char chBuf[RTPATH_MAX + 256];  /* Should always be big enough */
    ssize_t cchRead;

    AssertRCReturn(mStatus, VERR_WRONG_ORDER);
    errno = 0;
    do
        cchRead = read(iwGetFD(&mWatches), chBuf, sizeof(chBuf));
    while (cchRead > 0);
    if (cchRead == 0)
        return VINF_SUCCESS;
    if (   cchRead < 0
        && (   errno == EAGAIN
#if EAGAIN != EWOULDBLOCK
            || errno == EWOULDBLOCK
#endif
            ))
        return VINF_SUCCESS;
    Assert(errno > 0);
    return RTErrConvertFromErrno(errno);
}

int hotplugInotifyImpl::drainWakeupPipe(void)
{
    char szBuf[sizeof(SYSFS_WAKEUP_STRING)];
    ssize_t cbRead;

    AssertRCReturn(mStatus, VERR_WRONG_ORDER);
    cbRead = read(mhWakeupPipeR, szBuf, sizeof(szBuf));
    Assert(cbRead > 0);
    NOREF(cbRead);
    return VINF_SUCCESS;
}

int hotplugInotifyImpl::Wait(RTMSINTERVAL aMillies)
{
    AssertRCReturn(mStatus, VERR_WRONG_ORDER);
    bool fEntered = ASMAtomicCmpXchgU32(&mfWaiting, 1, 0);
    AssertReturn(fEntered, VERR_WRONG_ORDER);

    VECTOR_PTR(char *) vecpchDevs;
    VEC_INIT_PTR(&vecpchDevs, char *, RTStrFree);
    int vrc = readFilePaths(mpcszDevicesRoot, &vecpchDevs, false);
    if (RT_SUCCESS(vrc))
    {
        char **ppszEntry;
        VEC_FOR_EACH(&vecpchDevs, char *, ppszEntry)
            if (RT_FAILURE(vrc = iwAddWatch(&mWatches, *ppszEntry)))
                break;

        if (RT_SUCCESS(vrc))
        {
            struct pollfd pollFD[MAX_POLLID];
            pollFD[RPIPE_ID].fd       = mhWakeupPipeR;
            pollFD[RPIPE_ID].events   = POLLIN;
            pollFD[INOTIFY_ID].fd     = iwGetFD(&mWatches);
            pollFD[INOTIFY_ID].events = POLLIN | POLLERR | POLLHUP;
            errno = 0;
            int cPolled = poll(pollFD, RT_ELEMENTS(pollFD), aMillies);
            if (cPolled < 0)
            {
                Assert(errno > 0);
                vrc = RTErrConvertFromErrno(errno);
            }
            else if (pollFD[RPIPE_ID].revents)
            {
                vrc = drainWakeupPipe();
                if (RT_SUCCESS(vrc))
                    vrc = VERR_INTERRUPTED;
            }
            else if ((pollFD[INOTIFY_ID].revents))
            {
                if (cPolled == 1)
                    vrc = drainInotify();
                else
                    AssertFailedStmt(vrc = VERR_INTERNAL_ERROR);
            }
            else
            {
                if (errno == 0 && cPolled == 0)
                    vrc = VERR_TIMEOUT;
                else
                    AssertFailedStmt(vrc = VERR_INTERNAL_ERROR);
            }
        }
    }

    mfWaiting = 0;
    VEC_CLEANUP_PTR(&vecpchDevs);
    return vrc;
}

void hotplugInotifyImpl::Interrupt(void)
{
    AssertRCReturnVoid(mStatus);
    ssize_t cbWritten = write(mhWakeupPipeW, SYSFS_WAKEUP_STRING,
                         sizeof(SYSFS_WAKEUP_STRING));
    if (cbWritten > 0)
        fsync(mhWakeupPipeW);
}

# endif /* VBOX_USB_WITH_INOTIFY */
#endif  /* VBOX_USB_WTH_SYSFS */

VBoxMainHotplugWaiter::VBoxMainHotplugWaiter(const char *pcszDevicesRoot)
{
    try
    {
#ifdef VBOX_USB_WITH_SYSFS
# ifdef VBOX_USB_WITH_INOTIFY
        if (hotplugInotifyImpl::Available())
        {
            mImpl = new hotplugInotifyImpl(pcszDevicesRoot);
            return;
        }
# endif /* VBOX_USB_WITH_INOTIFY */
#endif  /* VBOX_USB_WITH_SYSFS */
        mImpl = new hotplugNullImpl(pcszDevicesRoot);
    }
    catch (std::bad_alloc &e)
    { }
}