Question

是否可以将重叠I / O与匿名管道一起使用？ CreatePipe（）没有任何指定FILE_FLAG_OVERLAPPED的方法，所以我假设ReadFile（）将阻塞，即使我提供了OVERLAPPED结构。

Answer 1

这是一个匿名管道函数的实现，可以指定FILE_FLAG_OVERLAPPED：

/******************************************************************************\
*       This is a part of the Microsoft Source Code Samples. 
*       Copyright 1995 - 1997 Microsoft Corporation.
*       All rights reserved. 
*       This source code is only intended as a supplement to 
*       Microsoft Development Tools and/or WinHelp documentation.
*       See these sources for detailed information regarding the 
*       Microsoft samples programs.
\******************************************************************************/

/*++
Copyright (c) 1997  Microsoft Corporation
Module Name:
    pipeex.c
Abstract:
    CreatePipe-like function that lets one or both handles be overlapped
Author:
    Dave Hart  Summer 1997
Revision History:
--*/

#include <windows.h>
#include <stdio.h>

ULONG PipeSerialNumber;

BOOL
APIENTRY
MyCreatePipeEx(
    OUT LPHANDLE lpReadPipe,
    OUT LPHANDLE lpWritePipe,
    IN LPSECURITY_ATTRIBUTES lpPipeAttributes,
    IN DWORD nSize,
    DWORD dwReadMode,
    DWORD dwWriteMode
    )

/*++
Routine Description:
    The CreatePipeEx API is used to create an anonymous pipe I/O device.
    Unlike CreatePipe FILE_FLAG_OVERLAPPED may be specified for one or
    both handles.
    Two handles to the device are created.  One handle is opened for
    reading and the other is opened for writing.  These handles may be
    used in subsequent calls to ReadFile and WriteFile to transmit data
    through the pipe.
Arguments:
    lpReadPipe - Returns a handle to the read side of the pipe.  Data
        may be read from the pipe by specifying this handle value in a
        subsequent call to ReadFile.
    lpWritePipe - Returns a handle to the write side of the pipe.  Data
        may be written to the pipe by specifying this handle value in a
        subsequent call to WriteFile.
    lpPipeAttributes - An optional parameter that may be used to specify
        the attributes of the new pipe.  If the parameter is not
        specified, then the pipe is created without a security
        descriptor, and the resulting handles are not inherited on
        process creation.  Otherwise, the optional security attributes
        are used on the pipe, and the inherit handles flag effects both
        pipe handles.
    nSize - Supplies the requested buffer size for the pipe.  This is
        only a suggestion and is used by the operating system to
        calculate an appropriate buffering mechanism.  A value of zero
        indicates that the system is to choose the default buffering
        scheme.
Return Value:
    TRUE - The operation was successful.
    FALSE/NULL - The operation failed. Extended error status is available
        using GetLastError.
--*/

{
  HANDLE ReadPipeHandle, WritePipeHandle;
  DWORD dwError;
  UCHAR PipeNameBuffer[ MAX_PATH ];

  //
  // Only one valid OpenMode flag - FILE_FLAG_OVERLAPPED
  //

  if ((dwReadMode | dwWriteMode) & (~FILE_FLAG_OVERLAPPED)) {
    SetLastError(ERROR_INVALID_PARAMETER);
    return FALSE;
  }

  //
  //  Set the default timeout to 120 seconds
  //

  if (nSize == 0) {
    nSize = 4096;
  }

  sprintf( PipeNameBuffer,
           "\\\\.\\Pipe\\RemoteExeAnon.%08x.%08x",
           GetCurrentProcessId(),
           PipeSerialNumber++
         );

  ReadPipeHandle = CreateNamedPipeA(
                       PipeNameBuffer,
                       PIPE_ACCESS_INBOUND | dwReadMode,
                       PIPE_TYPE_BYTE | PIPE_WAIT,
                       1,             // Number of pipes
                       nSize,         // Out buffer size
                       nSize,         // In buffer size
                       120 * 1000,    // Timeout in ms
                       lpPipeAttributes
                       );

  if (! ReadPipeHandle) {
    return FALSE;
  }

  WritePipeHandle = CreateFileA(
                      PipeNameBuffer,
                      GENERIC_WRITE,
                      0,                         // No sharing
                      lpPipeAttributes,
                      OPEN_EXISTING,
                      FILE_ATTRIBUTE_NORMAL | dwWriteMode,
                      NULL                       // Template file
                    );

  if (INVALID_HANDLE_VALUE == WritePipeHandle) {
    dwError = GetLastError();
    CloseHandle( ReadPipeHandle );
    SetLastError(dwError);
    return FALSE;
  }

  *lpReadPipe = ReadPipeHandle;
  *lpWritePipe = WritePipeHandle;
  return( TRUE );
}

Answer 2

没有。正如here所解释的那样，匿名管道不支持异步I / O.您需要使用命名管道。有一些示例代码可以在MSDN here和here上执行此操作。

Answer 3

首先需要了解-什么是Anonymous Pipes，什么是匿名与Named Pipes之间的区别。

仅存在单个管道类型（由 npfs.sys 实现）。除了名称之外，命名管道和匿名管道之间没有任何区别。两者都是唯一的管道。

所谓的匿名管道-这是Win7之前的特殊/随机命名管道，而真正的未命名管道则从Win7开始。

当msdn写下“匿名管道是单向管道” 时-这是谎言</ strong>。与任何管道一样，它可以是单向或双工的。当msdn写道“匿名管道不支持异步（重叠）读写操作。” -这是谎言</ strong>。当然，管道支持异步io。管道的名称不影响此。

在win7之前，真正的未命名管道根本不存在。 CreatePipe函数使用Win32Pipes.%08x.%08x格式创建“匿名管道”名称。

static LONG PipeSerialNumber; WCHAR name[64]; swprintf(name, L"\\Device\\NamedPipe\\Win32Pipes.%08x.%08x", GetCurrentProcessId(), InterlockedIncrement(&PipeSerialNumber));

从win7 CreatePipe开始，使用另一种技术（相对文件打开）来创建管道对-现在它确实是匿名的。

例如，代码女巫创建了一个管道对，其中一个管道是异步的且不可继承。另一个管道是同步且可继承的。两个管道都是双工的（支持读取和写入）

ULONG CreatePipeAnonymousPair7(PHANDLE phServerPipe, PHANDLE phClientPipe) { HANDLE hNamedPipe; IO_STATUS_BLOCK iosb; static UNICODE_STRING NamedPipe = RTL_CONSTANT_STRING(L"\\Device\\NamedPipe\\"); OBJECT_ATTRIBUTES oa = { sizeof(oa), 0, const_cast<PUNICODE_STRING>(&NamedPipe), OBJ_CASE_INSENSITIVE }; NTSTATUS status; if (0 <= (status = NtOpenFile(&hNamedPipe, SYNCHRONIZE, &oa, &iosb, FILE_SHARE_VALID_FLAGS, 0))) { oa.RootDirectory = hNamedPipe; static LARGE_INTEGER timeout = { 0, MINLONG }; static UNICODE_STRING empty = {}; oa.ObjectName = ∅ if (0 <= (status = ZwCreateNamedPipeFile(phServerPipe, FILE_READ_ATTRIBUTES|FILE_READ_DATA| FILE_WRITE_ATTRIBUTES|FILE_WRITE_DATA| FILE_CREATE_PIPE_INSTANCE, &oa, &iosb, FILE_SHARE_READ|FILE_SHARE_WRITE, FILE_CREATE, 0, FILE_PIPE_BYTE_STREAM_TYPE, FILE_PIPE_BYTE_STREAM_MODE, FILE_PIPE_QUEUE_OPERATION, 1, 0, 0, &timeout))) { oa.RootDirectory = *phServerPipe; oa.Attributes = OBJ_CASE_INSENSITIVE|OBJ_INHERIT; if (0 > (status = NtOpenFile(phClientPipe, SYNCHRONIZE|FILE_READ_ATTRIBUTES|FILE_READ_DATA| FILE_WRITE_ATTRIBUTES|FILE_WRITE_DATA, &oa, &iosb, FILE_SHARE_VALID_FLAGS, FILE_SYNCHRONOUS_IO_NONALERT))) { NtClose(oa.RootDirectory); } } NtClose(hNamedPipe); } return RtlNtStatusToDosError(status); } ULONG CreatePipeAnonymousPair(PHANDLE phServerPipe, PHANDLE phClientPipe) { static char flag_supported = -1; if (flag_supported < 0) { ULONG dwMajorVersion, dwMinorVersion; RtlGetNtVersionNumbers(&dwMajorVersion, &dwMinorVersion, 0); flag_supported = _WIN32_WINNT_WIN7 <= ((dwMajorVersion << 8)| dwMinorVersion); } if (flag_supported) { return CreatePipeAnonymousPair7(phServerPipe, phClientPipe); } static LONG PipeSerialNumber; WCHAR name[64]; swprintf(name, L"\\\\?\\pipe\\Win32Pipes.%08x.%08x", GetCurrentProcessId(), InterlockedIncrement(&PipeSerialNumber)); HANDLE hClient, hServer = CreateNamedPipeW(name, PIPE_ACCESS_DUPLEX|FILE_READ_DATA|FILE_WRITE_DATA|FILE_FLAG_OVERLAPPED, PIPE_TYPE_BYTE|PIPE_READMODE_BYTE, 1, 0, 0, 0, 0); if (hServer != INVALID_HANDLE_VALUE) { static SECURITY_ATTRIBUTES sa = { sizeof(sa), 0, TRUE }; hClient = CreateFileW(name, FILE_GENERIC_READ|FILE_GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, &sa, OPEN_EXISTING, 0, 0); if (hClient != INVALID_HANDLE_VALUE) { *phServerPipe = hServer, *phClientPipe = hClient; return NOERROR; } CloseHandle(hServer); } return GetLastError(); }

匿名管道上重叠的I / O.

3 个答案: