private static bool IsDefined(char driveLetter)
{
var drive = driveLetter + ":";
var target = new StringBuilder(SubstituteDrive.MAX_PATH);
return(0 != SubstituteDrive.QueryDosDevice(drive, target, target.Capacity));
}
/// <summary>
/// Gets a <see cref="SubstitutionDrve"/> for the next available drive letter.
/// </summary>
/// <param name="targetPath">The path to the folder to map to a drive letter.</param>
/// <returns>A <see cref="SubstitutionDrive"/> for the <paramref name="targetPath"/>.</returns>
internal static SubstituteDrive Next(string targetPath)
{
for (var c = 'C'; c <= 'Z'; ++c)
{
if (!SubstituteDrive.IsDefined(c))
{
return(new SubstituteDrive(c, targetPath));
}
}
throw new InvalidOperationException("No drive letters are available.");
}
/// <summary>
/// Remove the drive substitution.
/// </summary>
public void Dispose()
{
if (null != this.DriveLetter)
{
SubstituteDrive.DefineDosDevice(DefineDosDeviceFlags.RemoveExactMatch, this.DriveLetter, this.TargetPath);
this.DriveLetter = null;
this.TargetPath = null;
GC.SuppressFinalize(this);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="SubstituteDrive"/> class.
/// </summary>
/// <param name="driveLetter">The drive letter to use for the substitution.</param>
/// <param name="targetPath">The path to the folder to map to a drive letter.</param>
/// <exception cref="ArgumentException">The <paramref name="driveLetter"/> is already defined.</exception>
/// <exception cref="Win32Exception">An error occurred when creating a drive subistution.</exception>
internal SubstituteDrive(char driveLetter, string targetPath)
{
Contract.Requires('C' <= driveLetter && 'Z' >= driveLetter);
Contract.Requires(!string.IsNullOrEmpty(targetPath));
driveLetter = char.ToUpperInvariant(driveLetter);
if (SubstituteDrive.IsDefined(driveLetter))
{
throw new ArgumentException("The drive letter is already defined.", "driveLetter");
}
this.DriveLetter = driveLetter + ":";
this.TargetPath = targetPath;
if (!SubstituteDrive.DefineDosDevice(DefineDosDeviceFlags.None, this.DriveLetter, this.TargetPath))
{
// Throw last error.
throw new Win32Exception();
}
}