GetFinalPathNameByHandleW が XP でも使いたい

GetFinalPathNameByHandleW が使いたかったけど、XP には無かった…
…だけならわざわざ作りはしなかったけれども、c:\tmp の ディレクトリハンドルの GUID を取得した際に FindFirst/NextVolume で列挙したボリューム郡を指していない GUID を返してきたため、しぶしぶ作った。

static HRESULT GetVolumeNameForVolumeSerialNumberW(
    const DWORD dwVolumeSerialNumber, 
    CStringW &result);
static HRESULT GetVolumePathNamesForVolumeNameW(
    LPCWSTR szVolumeName,
    std::vector<CStringW> &VolumePaths);

HRESULT GetFinalPathNameByHandleW2(HANDLE hFile, DWORD dwFlags, CStringW &result) {
    BYTE data[sizeof(DWORD) + sizeof(WCHAR) * 32767];   //  32767 is a NTFS maximum filename length
    const DWORD fileNameMask = FILE_NAME_NORMALIZED | FILE_NAME_OPENED;
    const DWORD volumeNameMask = VOLUME_NAME_DOS | VOLUME_NAME_GUID | VOLUME_NAME_NT | VOLUME_NAME_NONE;
    CStringW trail;
    CStringW foundVolume;

    BOOL rc;
    HRESULT hr;

    DWORD dwVolumeSerialNumber;

    rc = GetFileInformationByHandleEx(hFile, FileNameInfo, &data, sizeof(data));
    if (rc == FALSE) {
        return HRESULT_FROM_WIN32(GetLastError());
    }

    {
        FILE_NAME_INFO &fiName = (FILE_NAME_INFO &)data;
        trail = CStringW(fiName.FileName, fiName.FileNameLength / sizeof(WCHAR));
        if (trail[0] == L'\\') {
            trail.Delete(0, 1);
        }

        switch (dwFlags & fileNameMask) {
        case FILE_NAME_NORMALIZED:
            /// ?('_.)? need change?
            break;
        case FILE_NAME_OPENED:
            /// ?('_.)? need change?
            break;
        }
    }

    rc = GetVolumeInformationByHandleW(hFile,
                                       NULL, 0,
                                       &dwVolumeSerialNumber,
                                       NULL,
                                       NULL,
                                       NULL, 0);
    if (rc == FALSE) {
        return HRESULT_FROM_WIN32(GetLastError());
    }

    hr = GetVolumeNameForVolumeSerialNumber(dwVolumeSerialNumber, foundVolume);

    if (hr == S_OK) {
        switch (dwFlags & volumeNameMask) {
        case VOLUME_NAME_DOS:
            //  \\?\c:\ type.
            {
                std::vector<CStringW> VolumePaths;
                GetVolumePathNamesForVolumeNameW(foundVolume, VolumePaths);

                if (VolumePaths.size() == 0) {
                    // ?('_.)? no change? 
                    break;
                }

                CStringW shortest;
                DWORD lenShortest = (DWORD)(-1);

                for (int i = 0; i < VolumePaths.size(); i++) {
                    size_t len = VolumePaths[i].GetLength();

                    if (len < lenShortest) {
                        lenShortest = len;
                        shortest = VolumePaths[i];
                    }
                }

                foundVolume = CStringW(L"\\\\?\\") + shortest;
            }
            break;
        case VOLUME_NAME_GUID:
            //  \\?\Volume{guid}\ type. no change.
            break;
        case VOLUME_NAME_NT:
            /// don't know format. 調べるのタルい.
            throw "not impremented.";
            break;
        case VOLUME_NAME_NONE:
            /// don't know format. 調べるのタルい.
            throw "not impremented.";
            break;
        }

        hr = S_OK;
    }
    else {
        //  maybe network file handle.
        switch (dwFlags & volumeNameMask) {
        case VOLUME_NAME_DOS:
            //  \\?\UNC\server\share\ type
            hr = S_OK;
            throw "not impremented.";
            break;
        case VOLUME_NAME_GUID:
            /// error.
            hr = E_FAIL;
            break;
        case VOLUME_NAME_NT:
            /// don't know format. 調べるのタルい.
            hr = S_OK;
            throw "not impremented.";
            break;
        case VOLUME_NAME_NONE:
            /// don't know format. 調べるのタルい.
            hr = S_OK;
            throw "not impremented.";
            break;
        }
    }

    if (SUCCEEDED(hr)) {
        result = foundVolume;

        if (result[result.GetLength() - 1] != L'\\') {
            result += L"\\";
        }

        result += trail;
    }
    return hr;
}


static HRESULT GetVolumeNameForVolumeSerialNumber(const DWORD dwVolumeSerialNumber, CStringW &result) {
    WCHAR VolumeNameBuffer[1024];

    HANDLE hFindVolume = FindFirstVolume(VolumeNameBuffer, _countof(VolumeNameBuffer));
    if (hFindVolume == NULL || hFindVolume == INVALID_HANDLE_VALUE) {
        return HRESULT_FROM_WIN32(GetLastError());
    }

    DWORD err;
    do {
        DWORD vsn;
        GetVolumeInformationW(VolumeNameBuffer,
                              NULL, 0,
                              &vsn,
                              NULL,
                              NULL,
                              NULL, 0);

        if (vsn != dwVolumeSerialNumber) {
            continue;
        }

        assert(GetLastError() == ERROR_MORE_DATA);
        result = VolumeNameBuffer;
        break;
    }
    while (FindNextVolumeW(hFindVolume, VolumeNameBuffer, _countof(VolumeNameBuffer)));
    err = GetLastError();

    FindVolumeClose(hFindVolume);

    return
        err == ERROR_NO_MORE_FILES ? HRESULT_FROM_WIN32(ERROR_NOT_FOUND) :
        err == ERROR_MORE_DATA ? S_OK :
        HRESULT_FROM_WIN32(err);
}


static HRESULT GetVolumePathNamesForVolumeNameW(
    LPCWSTR szVolumeName,
    std::vector<CStringW> &VolumePaths
) {
    CHeapPtr<WCHAR> heapNames;
    DWORD count;

    SetLastError(ERROR_SUCCESS);
    ::GetVolumePathNamesForVolumeNameW(szVolumeName, NULL, 0, &count);
    DWORD lastError = GetLastError();

    if (lastError != ERROR_MORE_DATA) {
        return HRESULT_FROM_WIN32(lastError);
    }

    if (heapNames.Allocate(count) == false) {
        return HRESULT_FROM_WIN32(ERROR_OUTOFMEMORY);
    }

    SetLastError(ERROR_SUCCESS);
    BOOL
    rc = ::GetVolumePathNamesForVolumeNameW(szVolumeName, heapNames.m_pData, count, &count);

    if (rc == FALSE) {
        DWORD lastError = GetLastError();
        return HRESULT_FROM_WIN32(lastError);
    }

    for (WCHAR *NameIdx = heapNames.m_pData;
            NameIdx[0] != L'\0';
            NameIdx += wcslen(NameIdx) + 1) {
        VolumePaths.push_back(CStringW(NameIdx));
    }

    return S_OK;
}

known issue.

\\localpc\share\dir\subdir\tatoeba.bmp を開いた HANDLE を食わせてやると、本家では \\?\UNC\localpc\share\dir\subdir\tatoeba.bmp を返してくるけれど、この関数では \\C:\test\sharedir\localpc\share\dir\subdir\tatoeba.bmp を返してくる。

follow link.

C++ - GetFinalPathNameByHandleW が 2000 でも使いたい