/// <summary>
/// For a file extension (with leading period) and a verb (or null for default
/// verb), returns the (full?) path to the executable file that is assigned to
/// that extension/verb. Returns null if an error occurs.
/// </summary>
public static string GetExecutablePath(string extension, string verb)
{
int capacity = 270;
attempt: // we may need to retry with a different (larger) value for "capacity"
StringBuilder buffer = new StringBuilder(capacity); // the buffer that will hold the result
int hresult = Shlwapi.AssocQueryString(ASSOCF.NOTRUNCATE, ASSOCSTR.EXECUTABLE, extension, verb, buffer, ref capacity);
switch (hresult)
{
case HRESULT.S_OK:
return(buffer.ToString()); // success; return the path
// failure; buffer was too small
case HRESULT.E_POINTER:
case HRESULT.S_FALSE:
// the capacity variable now holds the number of chars necessary (AssocQueryString
// assigns it). it should work if we try again.
goto attempt;
// failure. the default case will catch all, but I'm explicitly
// calling out the two failure codes I know about in case we need
// them someday.
case HRESULT.E_INVALIDARG:
case HRESULT.E_FAILED:
default:
return(null);
}
}
/// <summary>
/// Gets the friendly type string for an extension.
/// </summary>
public static string GetTypeNameForExtension(string extension)
{
if (extension != null)
{
extension = extension.Trim();
}
int capacity = 270;
attempt:
StringBuilder builder = new StringBuilder(capacity);
int hresult = Shlwapi.AssocQueryString(ASSOCF.NOTRUNCATE, ASSOCSTR.FRIENDLYDOCNAME, extension, null, builder, ref capacity);
switch (hresult)
{
case HRESULT.S_OK:
return(builder.ToString());
case HRESULT.E_POINTER:
case HRESULT.S_FALSE:
// the capacity variable now holds the number of chars necessary. try again
goto attempt;
case HRESULT.E_INVALIDARG:
case HRESULT.E_FAILED:
default:
break;
}
if (extension == null || extension == string.Empty)
{
return("Unknown");
}
else
{
return(extension.TrimStart('.').ToUpper(CultureInfo.InvariantCulture) + " File");
}
}
