Re: asking about pipe line

Tech-Archive recommends: Speed Up your PC by fixing your registry

Not quite right, see below...
On Fri, 30 Nov 2007 02:13:42 -0800 (PST), Baby Lion <BabyLion.Liang@xxxxxxxxx> wrote:

here is the corrected code


// tryPipe3.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "tryPipe3.h"
#include<iostream>
#include<string>
#include<fstream>
using namespace std;
#ifdef _DEBUG
#define new DEBUG_NEW
#endif


// The one and only application object

CWinApp theApp;

using namespace std;

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{

PROCESS_INFORMATION pi;



#define BUFSIZE 4096
char ReadBuf[BUFSIZE];

DWORD ReadNum;
HANDLE hReadFromChild;
HANDLE hWriteToParent;
HANDLE hReadFromParent;
HANDLE hWriteToChild;

SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};

BOOL bRet = CreatePipe(&hReadFromChild, &hWriteToParent, &sa, 0);
if (bRet)
printf("success!\n");
else
{
printf("error:%d\n", GetLastError());
return 0;
}

bRet = CreatePipe(&hReadFromParent,&hWriteToChild,&sa,0);//y null?
****
Yes, you want to use NULL for the security attributes here
****
if (bRet)
printf("success!\n");
else
{
printf("error:%d\n", GetLastError());
return 0;
}
HANDLE hWriteToChildDup;
::DuplicateHandle(GetCurrentProcess(), hWriteToChild,
GetCurrentProcess(), &hWriteToChildDup,
0, FALSE, DUPLICATE_SAME_ACCESS);
****
Create the pipes non-inheritable, then create inheritable duplicates, by using TRUE for
the inheritance flag
****
::CloseHandle(hWriteToChild);
HANDLE hReadFromChildDup;
::DuplicateHandle(GetCurrentProcess(), hReadFromChild,
GetCurrentProcess(), &hReadFromChildDup,
0, FALSE, DUPLICATE_SAME_ACCESS);
::CloseHandle(hReadFromChild);

HANDLE hWriteToStderr;
::DuplicateHandle(GetCurrentProcess(), hWriteToParent,
GetCurrentProcess(), &hWriteToStderr,
0, TRUE, DUPLICATE_SAME_ACCESS);


STARTUPINFO si ;
si.cb= sizeof(STARTUPINFO);
::GetStartupInfo(&si);
//si.dwFlags = STARTF_USESTDHANDLES;
si.dwFlags=STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;
si.hStdInput = hReadFromParent;
si.hStdOutput = hWriteToParent;
****
Instead of the original handles, which should be now non-inheritable, assign the
inheritable duplicates here
****
si.hStdError = hWriteToStderr;
si.wShowWindow = SW_HIDE;

bRet = CreateProcessA(NULL, "nc -w1 www.baidu.com 80", NULL, NULL,
TRUE, NULL, NULL, NULL, &si, &pi);

if (bRet)
printf("succeeded create process!\n");
else
{
printf("fail to create process:%d\n", GetLastError());
::CloseHandle(hWriteToParent);
::CloseHandle(hReadFromParent);
::CloseHandle(hWriteToStderr);
::CloseHandle(hReadFromChildDup);
::CloseHandle(hWriteToChildDup);
return 0;
}

::CloseHandle(hWriteToParent);
::CloseHandle(hReadFromParent);
****
You would close the inheritable duplicates instead
****
::CloseHandle(hWriteToStderr);

DWORD count1;
char str1[] = "c\n\ra\n\rb\n\r";
string toWrite;
ifstream fin("baidu.txt");
while(!fin.eof())
{
string temp;
getline(fin,temp);
toWrite.append(temp+string("\n"));
****
Why not just send it directly to the child pipe here? Why create a separate string
variable, and concatenate everything?
****
cout<<temp<<endl;
}
fin.close();

WriteFile(hWriteToChildDup,toWrite.c_str(),toWrite.length(),&count1,NULL);
printf("delta len%d\n",toWrite.c_str()-count1);
::CloseHandle(hWriteToChildDup);
while (ReadFile(hReadFromChildDup, ReadBuf, BUFSIZE-1,&ReadNum,
NULL))
{
ReadBuf[ReadNum]='\0';
printf("get from pipe[\n%s\n]read%dbytes\n", ReadBuf, ReadNum);
}

if (GetLastError() == ERROR_BROKEN_PIPE) // ????????
printf("pipe closed by the sub-process\n");
else
printf("error :%d\n", GetLastError());

::CloseHandle(hReadFromChildDup);

::CloseHandle(pi.hProcess);
::CloseHandle(pi.hThread);
return 0;
}
Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
.

Relevant Pages

  • Re: asking about pipe line
    ... using namespace std; ... ::DuplicateHandle, hReadFromChild, ... GetCurrentProcess(), &hReadFromChildDup, ... ::DuplicateHandle, hWriteToParent, ...
    (microsoft.public.vc.mfc)
  • Re: asking about pipe line
    ... using namespace std; ... HANDLE hReadFromParent; ... if (bRet) ... ::DuplicateHandle, hWriteToParent, ...
    (microsoft.public.vc.mfc)