Affichage des chemins d’accès aux volumes

  • Article

L’exemple C++ suivant montre comment afficher tous les chemins d’accès pour chaque volume et appareil. Pour chaque volume du système, l’exemple localise le volume, obtient le nom de l’appareil, obtient tous les chemins d’accès pour ce volume et affiche les chemins d’accès.

#include <windows.h>
#include <stdio.h>

void DisplayVolumePaths(
        __in PWCHAR VolumeName
        )
{
    DWORD  CharCount = MAX_PATH + 1;
    PWCHAR Names     = NULL;
    PWCHAR NameIdx   = NULL;
    BOOL   Success   = FALSE;

    for (;;) 
    {
        //
        //  Allocate a buffer to hold the paths.
        Names = (PWCHAR) new BYTE [CharCount * sizeof(WCHAR)];

        if ( !Names ) 
        {
            //
            //  If memory can't be allocated, return.
            return;
        }

        //
        //  Obtain all of the paths
        //  for this volume.
        Success = GetVolumePathNamesForVolumeNameW(
            VolumeName, Names, CharCount, &CharCount
            );

        if ( Success ) 
        {
            break;
        }

        if ( GetLastError() != ERROR_MORE_DATA ) 
        {
            break;
        }

        //
        //  Try again with the
        //  new suggested size.
        delete [] Names;
        Names = NULL;
    }

    if ( Success )
    {
        //
        //  Display the various paths.
        for ( NameIdx = Names; 
              NameIdx[0] != L'\0'; 
              NameIdx += wcslen(NameIdx) + 1 ) 
        {
            wprintf(L"  %s", NameIdx);
        }
        wprintf(L"\n");
    }

    if ( Names != NULL ) 
    {
        delete [] Names;
        Names = NULL;
    }

    return;
}

void __cdecl wmain(void)
{
    DWORD  CharCount            = 0;
    WCHAR  DeviceName[MAX_PATH] = L"";
    DWORD  Error                = ERROR_SUCCESS;
    HANDLE FindHandle           = INVALID_HANDLE_VALUE;
    BOOL   Found                = FALSE;
    size_t Index                = 0;
    BOOL   Success              = FALSE;
    WCHAR  VolumeName[MAX_PATH] = L"";

    //
    //  Enumerate all volumes in the system.
    FindHandle = FindFirstVolumeW(VolumeName, ARRAYSIZE(VolumeName));

    if (FindHandle == INVALID_HANDLE_VALUE)
    {
        Error = GetLastError();
        wprintf(L"FindFirstVolumeW failed with error code %d\n", Error);
        return;
    }

    for (;;)
    {
        //
        //  Skip the \\?\ prefix and remove the trailing backslash.
        Index = wcslen(VolumeName) - 1;

        if (VolumeName[0]     != L'\\' ||
            VolumeName[1]     != L'\\' ||
            VolumeName[2]     != L'?'  ||
            VolumeName[3]     != L'\\' ||
            VolumeName[Index] != L'\\') 
        {
            Error = ERROR_BAD_PATHNAME;
            wprintf(L"FindFirstVolumeW/FindNextVolumeW returned a bad path: %s\n", VolumeName);
            break;
        }

        //
        //  QueryDosDeviceW does not allow a trailing backslash,
        //  so temporarily remove it.
        VolumeName[Index] = L'\0';

        CharCount = QueryDosDeviceW(&VolumeName[4], DeviceName, ARRAYSIZE(DeviceName)); 

        VolumeName[Index] = L'\\';

        if ( CharCount == 0 ) 
        {
            Error = GetLastError();
            wprintf(L"QueryDosDeviceW failed with error code %d\n", Error);
            break;
        }

        wprintf(L"\nFound a device:\n %s", DeviceName);
        wprintf(L"\nVolume name: %s", VolumeName);
        wprintf(L"\nPaths:");
        DisplayVolumePaths(VolumeName);

        //
        //  Move on to the next volume.
        Success = FindNextVolumeW(FindHandle, VolumeName, ARRAYSIZE(VolumeName));

        if ( !Success ) 
        {
            Error = GetLastError();

            if (Error != ERROR_NO_MORE_FILES) 
            {
                wprintf(L"FindNextVolumeW failed with error code %d\n", Error);
                break;
            }

            //
            //  Finished iterating
            //  through all the volumes.
            Error = ERROR_SUCCESS;
            break;
        }
    }

    FindVolumeClose(FindHandle);
    FindHandle = INVALID_HANDLE_VALUE;

    return;
}

Voici un exemple de sortie de l’exécution de l’application. Pour chaque volume, la sortie inclut un chemin d’accès de périphérique de volume, un chemin d’accès GUID de volume et une lettre de lecteur.

Found a device:
 \Device\HarddiskVolume2
Volume name: \\?\Volume{4c1b02c1-d990-11dc-99ae-806e6f6e6963}\
Paths:  C:\

Found a device:
 \Device\CdRom0
Volume name: \\?\Volume{4c1b02c4-d990-11dc-99ae-806e6f6e6963}\
Paths:  D:\

FindFirstVolume

FindNextVolume

FindVolumeClose

GetVolumePathNamesForVolumeName

QueryDosDevice