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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Buffers;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Win32.SafeHandles;
using System.Runtime.CompilerServices;
namespace System.IO
{
public partial class FileStream : Stream
{
private SafeFileHandle OpenHandle(FileMode mode, FileShare share, FileOptions options)
{
Interop.Kernel32.SECURITY_ATTRIBUTES secAttrs = GetSecAttrs(share);
int fAccess =
((_access & FileAccess.Read) == FileAccess.Read ? GENERIC_READ : 0) |
((_access & FileAccess.Write) == FileAccess.Write ? GENERIC_WRITE : 0);
// Our Inheritable bit was stolen from Windows, but should be set in
// the security attributes class. Don't leave this bit set.
share &= ~FileShare.Inheritable;
// Must use a valid Win32 constant here...
if (mode == FileMode.Append)
mode = FileMode.OpenOrCreate;
int flagsAndAttributes = (int)options;
// For mitigating local elevation of privilege attack through named pipes
// make sure we always call CreateFile with SECURITY_ANONYMOUS so that the
// named pipe server can't impersonate a high privileged client security context
flagsAndAttributes |= (Interop.Kernel32.SecurityOptions.SECURITY_SQOS_PRESENT | Interop.Kernel32.SecurityOptions.SECURITY_ANONYMOUS);
// Don't pop up a dialog for reading from an empty floppy drive
uint oldMode = Interop.Kernel32.SetErrorMode(Interop.Kernel32.SEM_FAILCRITICALERRORS);
try
{
SafeFileHandle fileHandle = Interop.Kernel32.CreateFile(_path, fAccess, share, ref secAttrs, mode, flagsAndAttributes, IntPtr.Zero);
fileHandle.IsAsync = _useAsyncIO;
if (fileHandle.IsInvalid)
{
// Return a meaningful exception with the full path.
// NT5 oddity - when trying to open "C:\" as a Win32FileStream,
// we usually get ERROR_PATH_NOT_FOUND from the OS. We should
// probably be consistent w/ every other directory.
int errorCode = Marshal.GetLastWin32Error();
if (errorCode == Interop.Errors.ERROR_PATH_NOT_FOUND && _path.Length == PathInternal.GetRootLength(_path))
errorCode = Interop.Errors.ERROR_ACCESS_DENIED;
throw Win32Marshal.GetExceptionForWin32Error(errorCode, _path);
}
int fileType = Interop.Kernel32.GetFileType(fileHandle);
if (fileType != Interop.Kernel32.FileTypes.FILE_TYPE_DISK)
{
fileHandle.Dispose();
throw new NotSupportedException(SR.NotSupported_FileStreamOnNonFiles);
}
return fileHandle;
}
finally
{
Interop.Kernel32.SetErrorMode(oldMode);
}
}
}
}
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