/// <summary>
/// Turns HRESULT errors into the appropriate exception (that maps with existing .NET behavior as much as possible).
/// There are additional IOException derived errors for ease of client error handling.
/// </summary>
public static Exception GetIoExceptionForHResult(HRESULT hr, string path = null)
{
string message = path == null
? $"{HResultToString(hr)}"
: $"{HResultToString(hr)} '{path}'";
switch (hr)
{
case HRESULT.E_ACCESSDENIED:
return(new UnauthorizedAccessException(message));
case HRESULT.E_INVALIDARG:
return(new ArgumentException(message));
default:
if (ErrorMacros.HRESULT_FACILITY(hr) == Facility.WIN32)
{
return(WindowsErrorToException((WindowsError)ErrorMacros.HRESULT_CODE(hr), message, path));
}
else
{
return(new IOException(message, (int)hr));
}
}
}
// .NET's Win32Exception impements the error code lookup on FormatMessage using FORMAT_MESSAGE_FROM_SYSTEM.
// It won't handle Network Errors (NERR_BASE..MAX_NERR), which come from NETMSG.DLL.
public static string FormatMessage(
uint messageId,
IntPtr source,
FormatMessageFlags flags,
params string[] args)
{
using (StringBuffer buffer = new StringBuffer())
{
// Don't use line breaks
flags |= FormatMessageFlags.FORMAT_MESSAGE_MAX_WIDTH_MASK;
if (args == null || args.Length == 0)
{
flags |= FormatMessageFlags.FORMAT_MESSAGE_IGNORE_INSERTS;
}
WindowsError lastError = WindowsError.ERROR_INSUFFICIENT_BUFFER;
uint capacity = byte.MaxValue;
uint result = 0;
while (lastError == WindowsError.ERROR_INSUFFICIENT_BUFFER && capacity <= short.MaxValue)
{
buffer.EnsureCharCapacity(capacity);
result = Imports.FormatMessageW(
dwFlags: flags,
lpSource: source,
dwMessageId: messageId,
// Do the default language lookup
dwLanguageId: 0,
lpBuffer: buffer.DangerousGetHandle(),
nSize: buffer.CharCapacity,
Arguments: args);
if (result == 0)
{
lastError = Errors.GetLastError();
capacity = (uint)Math.Min(capacity * 2, short.MaxValue);
}
else
{
buffer.Length = result;
return(buffer.ToString());
}
}
throw new IOException("Failed to get error string.", (int)ErrorMacros.HRESULT_FROM_WIN32(lastError));
}
}
private static Exception WindowsErrorToException(WindowsError error, string message, string path)
{
switch (error)
{
case WindowsError.ERROR_FILE_NOT_FOUND:
return(new FileNotFoundException(message, path));
case WindowsError.ERROR_PATH_NOT_FOUND:
return(new DirectoryNotFoundException(message));
case WindowsError.ERROR_ACCESS_DENIED:
// Network access doesn't throw UnauthorizedAccess in .NET
case WindowsError.ERROR_NETWORK_ACCESS_DENIED:
return(new UnauthorizedAccessException(message));
case WindowsError.ERROR_FILENAME_EXCED_RANGE:
return(new PathTooLongException(message));
case WindowsError.ERROR_INVALID_DRIVE:
// Not available in Portable libraries
// return new DriveNotFoundException(message);
goto default;
case WindowsError.ERROR_OPERATION_ABORTED:
return(new OperationCanceledException(message));
case WindowsError.ERROR_NOT_READY:
return(new DriveNotReadyException(message));
case WindowsError.FVE_E_LOCKED_VOLUME:
return(new DriveLockedException(message));
case WindowsError.ERROR_INVALID_PARAMETER:
return(new ArgumentException(message));
case WindowsError.ERROR_NOT_SUPPORTED:
case WindowsError.ERROR_NOT_SUPPORTED_IN_APPCONTAINER:
return(new NotSupportedException(message));
case WindowsError.ERROR_ALREADY_EXISTS:
case WindowsError.ERROR_SHARING_VIOLATION:
case WindowsError.ERROR_FILE_EXISTS:
default:
return(new IOException(message, (int)ErrorMacros.HRESULT_FROM_WIN32(error)));
}
}
/// <summary>
/// Try to get the string for an HRESULT
/// </summary>
public static string HResultToString(HRESULT hr)
{
string message;
if (ErrorMacros.HRESULT_FACILITY(hr) == Facility.WIN32)
{
// Win32 Error, extract the code
message = ErrorMethods.FormatMessage(
messageId: (uint)ErrorMacros.HRESULT_CODE(hr),
source: IntPtr.Zero,
flags: FormatMessageFlags.FORMAT_MESSAGE_FROM_SYSTEM);
}
else
{
// Hope that we get a rational IErrorInfo
Exception exception = Marshal.GetExceptionForHR((int)hr);
message = exception.Message;
}
return($"HRESULT {(int)hr:D} [0x{(int)hr:X}]: {message}");
}