DriveInfoInternal.cs

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namespace System.IO;
 
internal static class DriveInfoInternal
{
    public static string[] GetLogicalDrives()
    {
        int logicalDrives = Interop.Kernel32.GetLogicalDrives();
        if (logicalDrives == 0)
        {
            throw Win32Marshal.GetExceptionForLastWin32Error();
        }
        uint num = (uint)logicalDrives;
        int num2 = 0;
        while (num != 0)
        {
            if ((num & (true ? 1u : 0u)) != 0)
            {
                num2++;
            }
            num >>= 1;
        }
        string[] array = new string[num2];
        Span<char> span = stackalloc char[3] { 'A', ':', '\\' };
        num = (uint)logicalDrives;
        num2 = 0;
        while (num != 0)
        {
            if ((num & (true ? 1u : 0u)) != 0)
            {
                array[num2++] = span.ToString();
            }
            num >>= 1;
            span[0] += '\u0001';
        }
        return array;
    }
 
    public static string NormalizeDriveName(string driveName)
    {
        string text;
        if (driveName.Length == 1)
        {
            text = driveName + ":\\";
        }
        else
        {
            text = Path.GetPathRoot(driveName);
            if (string.IsNullOrEmpty(text) || text.StartsWith("\\\\", StringComparison.Ordinal))
            {
                throw new ArgumentException(SR.Arg_MustBeDriveLetterOrRootDir, "driveName");
            }
        }
        if (text.Length == 2 && text[1] == ':')
        {
            text += "\\";
        }
        char c = driveName[0];
        if ((c < 'A' || c > 'Z') && (c < 'a' || c > 'z'))
        {
            throw new ArgumentException(SR.Arg_MustBeDriveLetterOrRootDir, "driveName");
        }
        return text;
    }
}