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() 会阻塞，即使我提供了一个 OVERLAPPED 结构。
MobyDX
问问题
10705 次
3 回答
28
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>
static volatile long 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(),
InterlockedIncrement(&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 );
}
于 2009-01-07T09:38:12.957 回答
12
首先需要了解 - 什么是匿名管道以及匿名管道和命名管道之间存在什么区别。
真的只存在单一管道类型（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。两者都只是管道。
所谓的匿名管道 - 这是win7之前的特殊/随机命名管道，真正的未命名管道从win7开始。
当 msdn 写道“匿名管道是单向管道”时- 这是谎言。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”时。- 这是谎言。当然管道支持异步 io。管道的名称不影响这一点。
在win7之前，真正的未命名管道甚至根本不存在。CreatePipe函数使用Win32Pipes.%08x.%08x格式创建“匿名管道”的名称。
static LONG PipeSerialNumber;
WCHAR name[64];
swprintf(name, L"\\Device\\NamedPipe\\Win32Pipes.%08x.%08x",
GetCurrentProcessId(), InterlockedIncrement(&PipeSerialNumber));
从win7开始CreatePipe 使用另一种技术（相对文件打开）创建管道对 - 现在它真的是匿名的。
例如代码女巫创建管道对，其中一个管道是异步的且不可继承。另一个管道是同步的和可继承的。两个管道都是双工的（支持读写）
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();
}
于 2018-07-20T18:27:18.867 回答