如何在 Win32 中的两个子进程之间设置管道？
对于我的一生，我无法弄清楚为什么这不起作用。基本上，我创建了继承位设置为 true 的管道，并创建了两个子进程，并使用 STARTUPINFO 结构根据需要设置输入和输出句柄，但管道似乎已损坏（第二个进程没有向其中写入任何输出）控制台，即使输出是预期的）
我知道问题不在于我的测试程序 (BitTwiddler.exe)，因为我使用 CMD.exe 执行了相同的操作，并且一切都按预期进行。
下面是我所拥有的的最小复制品。我做错了什么？
#include "windows.h"
int main()
{
PROCESS_INFORMATION piSource, piDest;
HANDLE hPipeIn, hPipeOut;
HANDLE hIn = GetStdHandle(STD_INPUT_HANDLE);
HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
STARTUPINFOW suSource, suDest;
ZeroMemory(&suSource, sizeof(suSource));
ZeroMemory(&suDest, sizeof(suDest));
suSource.cb = suDest.cb = sizeof(STARTUPINFOW);
suSource.dwFlags = suDest.dwFlags = STARTF_USESTDHANDLES;
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = 0;
sa.bInheritHandle = TRUE;
if (CreatePipe(&hPipeIn, &hPipeOut, &sa, 0) == 0)
{
return GetLastError();
}
suSource.hStdInput = hIn;
suSource.hStdError = suSource.hStdOutput = hPipeIn;
suDest.hStdInput = hPipeOut;
suDest.hStdError = suDest.hStdOutput = hOut;
std::wstring cmdLineA(L"BitTwiddler 1"), cmdLineB(L"BitTwiddler 0");
cmdLineA.push_back(0); cmdLineB.push_back(0);
if (CreateProcessW(0, &cmdLineA[0], 0, 0, TRUE, 0, 0, 0, &suSource, &piSource) == 0)
{
return GetLastError();
}
CloseHandle(piSource.hThread);
if (CreateProcessW(0, &cmdLineB[0], 0, 0, TRUE, 0, 0, 0, &suDest, &piDest) == 0)
{
return GetLastError();
}
CloseHandle(piDest.hThread);
HANDLE hArray[2];
hArray[0] = piSource.hProcess;
hArray[1] = piDest.hProcess;
WaitForMultipleObjects(2, hArray, TRUE, INFINITE);
CloseHandle(hArray[0]);
CloseHandle(hArray[1]);
return 0;
}
（如果有人感兴趣，BitTwiddler 是
#include <windows.h>
#include <sstream>
#include <iostream>
#include <string>
int main(int argc, char *argv[])
{
std::size_t opt = 0;
argc--; argv++;
if (argc == 0)
{
return 0;
}
else
{
std::istringstream converter(*argv);
converter >> opt;
}
switch(opt)
{
case 0:
{
std::wstring currentLine;
while(std::getline(std::wcin, currentLine))
{
std::wcout << "Got somepin: " << currentLine << std::endl;
}
}
break;
case 1:
for (;;)
{
std::wcout << L"Hello World!" << std::endl;
Sleep(1000);
}
break;
case 2:
return -1;
default:
std::wcout << "Unknown option.";
return 0;
}
return 0;
}
：），但我真的认为这并不重要。
For the life of me I can't figure out why this is not working. Basically, I created the pipe with the inherit bit set to true, and created two child processes, and used the STARTUPINFO structure to set the input and output handles as one would need, but the pipe seems broken (the second process writes no output to the console, even though output is expected)
I know the problem does not lie in my test program (BitTwiddler.exe) because I performed the same operation using CMD.exe, and everything works as expected.
Below is a minimal reproduction of what I have. What have I done incorrectly?
#include "windows.h"
int main()
{
PROCESS_INFORMATION piSource, piDest;
HANDLE hPipeIn, hPipeOut;
HANDLE hIn = GetStdHandle(STD_INPUT_HANDLE);
HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
STARTUPINFOW suSource, suDest;
ZeroMemory(&suSource, sizeof(suSource));
ZeroMemory(&suDest, sizeof(suDest));
suSource.cb = suDest.cb = sizeof(STARTUPINFOW);
suSource.dwFlags = suDest.dwFlags = STARTF_USESTDHANDLES;
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(sa);
sa.lpSecurityDescriptor = 0;
sa.bInheritHandle = TRUE;
if (CreatePipe(&hPipeIn, &hPipeOut, &sa, 0) == 0)
{
return GetLastError();
}
suSource.hStdInput = hIn;
suSource.hStdError = suSource.hStdOutput = hPipeIn;
suDest.hStdInput = hPipeOut;
suDest.hStdError = suDest.hStdOutput = hOut;
std::wstring cmdLineA(L"BitTwiddler 1"), cmdLineB(L"BitTwiddler 0");
cmdLineA.push_back(0); cmdLineB.push_back(0);
if (CreateProcessW(0, &cmdLineA[0], 0, 0, TRUE, 0, 0, 0, &suSource, &piSource) == 0)
{
return GetLastError();
}
CloseHandle(piSource.hThread);
if (CreateProcessW(0, &cmdLineB[0], 0, 0, TRUE, 0, 0, 0, &suDest, &piDest) == 0)
{
return GetLastError();
}
CloseHandle(piDest.hThread);
HANDLE hArray[2];
hArray[0] = piSource.hProcess;
hArray[1] = piDest.hProcess;
WaitForMultipleObjects(2, hArray, TRUE, INFINITE);
CloseHandle(hArray[0]);
CloseHandle(hArray[1]);
return 0;
}
(In case anyone's interested, BitTwiddler is:
#include <windows.h>
#include <sstream>
#include <iostream>
#include <string>
int main(int argc, char *argv[])
{
std::size_t opt = 0;
argc--; argv++;
if (argc == 0)
{
return 0;
}
else
{
std::istringstream converter(*argv);
converter >> opt;
}
switch(opt)
{
case 0:
{
std::wstring currentLine;
while(std::getline(std::wcin, currentLine))
{
std::wcout << "Got somepin: " << currentLine << std::endl;
}
}
break;
case 1:
for (;;)
{
std::wcout << L"Hello World!" << std::endl;
Sleep(1000);
}
break;
case 2:
return -1;
default:
std::wcout << "Unknown option.";
return 0;
}
return 0;
}
), but I really don't think that matters.
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评论（2）
您放错了读取和写入端:)
CreatePipe具有原型您无法从只写句柄调用
ReadFile（或在您的情况下为 std::getline），反之亦然。如果您将std::getline调用替换为简单的ReadFile调用，则会收到ACCESS_DENIED错误，这证实了这一事实，因为您的子进程中的STD_INPUT_HANDLE未针对GENERIC_READ打开。修复方法如下：
也许您指定的名称令人困惑。如果你按照形参调用它们，错误会更清楚：
You misplaced the read and write ends :)
CreatePipehas the prototypeYou can't call
ReadFile(or in your case std::getline) from a Write-only handle, and vice versa. If you replaced yourstd::getlinecalls with a simpleReadFilecall, you'd get anACCESS_DENIEDerror, confirming this fact, since yourSTD_INPUT_HANDLEin the child process was not opened forGENERIC_READ.The fix is as follows:
Perhaps the names you assigned are confusing. If you called them as per the formal parameters, the error would be clearer:
我对你的问题投了赞成票，因为这是一个非常重要的问题。自从几年前我从 FamTrinli 的演示中学习 Windows 编程以来，CreateProcess 一直是 Win32 API 中最难的函数之一。如果没有，那是最难的。
CreateProcess 有很多参数。每个参数都需要仔细阅读文档才能正确使用。很多论证结构复杂；例如 SECURITY_ATTRIBUTES 和 STARTUPINFO。 STARTUPINFO 结构中的 HANDLE 名称可能会令人困惑。当你迷茫的时候。使用 CreateProcess 涉及的步骤。是否需要立即关闭句柄（注意：不需要）。而进程之间的实际通信可能会导致死锁。
使用 CreateProcess 多年后，我对该 API 进行了广泛的研究和测试。然后我设计了一个包含所有这些知识的库。该库是我的 Jav/win32 库的一部分。该库类似于Java 的Process 类。
我无法在这里发布所有源代码。如果您对源代码感兴趣，我可以通过电子邮件发送给您。让 Cpp 成为编程的首选。
Jav/win32/Process.h
src/Jav/win32/Process.cpp
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I upvoted your question as it is a very important one. Since I learnt Windows programming from FamTrinli's demos years ago, CreateProcess has been one of the harddest functions of the Win32 API. If not, the harddest.
CreateProcess has alot of arguments. Each argument requires careful reading of the documentation to properly use. Alot of arguments are complicated structures; such as SECURITY_ATTRIBUTES and STARTUPINFO. The names for the HANDLE(s) in STARTUPINFO structure can be confusing. As you were confused. The steps that are involved in using CreateProcess. whether or not you need to immediately close the handles(nb: you don't). And the actual communication between the processes can cause deadlocks.
After using CreateProcess for years I did an extensive research and testing of the API. I then designed a library that encapsulates all that knowledge. This library is apart of my Jav/win32 library. This library is similar to Java's Process class.
I am not able to post every last bit of source code here. If you are interested in the source code I can email it to you. Keeping Cpp a goto for programming.
Jav/win32/Process.h
src/Jav/win32/Process.cpp
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