对于我的生活,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结构来设置输入和输出句柄,但管道似乎已损坏(第二个进程没有输出到控制台,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,一切都按预期工作。
以下是我所拥有的最小复制品。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;
}
),但我认为这并不重要。
答案 0 :(得分:5)
你错放了读写结束:)
CreatePipe
有原型
BOOL CreatePipe(
PHANDLE hReadPipe, // can only read from this
PHANDLE hWritePipe, // can only write to this
LPSECURITY_ATTRIBUTES lpPipeAttributes,
DWORD nSize
);
您不能从只写句柄调用ReadFile
(或在您的情况下为std :: getline),反之亦然。如果您通过简单的std::getline
来电替换了ReadFile
来电,那么您会收到ACCESS_DENIED
错误,并确认此事实,因为子进程中的STD_INPUT_HANDLE
未被打开GENERIC_READ
。
修复方法如下:
suSource.hStdError = suSource.hStdOutput = hPipeOut; // must be the write pipe!
suDest.hStdInput = hPipeIn; // must be the read pipe.
也许你指定的名字令人困惑。如果按照形式参数调用它们,则错误会更清楚:
suSource.hStdError = suSource.hStdOutput = hReadPipe; // clearly wrong.
suDest.hStdInput = hWritePipe; // as above -- expects a read-handle.