subProcPipe01.cpp

#include <tchar.h>
#include <windows.h>
#pragma warning(disable : 4800)
#define BUFSIZE 4096
HANDLE g_hChildStd_OUT_Rd = NULL;
HANDLE g_hChildStd_OUT_Wr = NULL;
HANDLE g_hChildStd_ERR_Rd = NULL;
HANDLE g_hChildStd_ERR_Wr = NULL;

PROCESS_INFORMATION CreateChildProcess(char szCmdline[])//Create a child process
{
    PROCESS_INFORMATION piProcInfo;
    STARTUPINFO siStartInfo;
    bool bSuccess = FALSE;
    ZeroMemory(&piProcInfo, sizeof(PROCESS_INFORMATION));
    ZeroMemory(&siStartInfo, sizeof(STARTUPINFO));
    siStartInfo.cb = sizeof(STARTUPINFO);
    siStartInfo.hStdOutput = g_hChildStd_OUT_Wr;
    siStartInfo.dwFlags |= STARTF_USESTDHANDLES;
    bSuccess = CreateProcess(NULL, szCmdline, NULL, NULL, TRUE, CREATE_NO_WINDOW, NULL, NULL, &siStartInfo, &piProcInfo);
    CloseHandle(g_hChildStd_OUT_Wr);
    if(!bSuccess)
    {
        exit(1);
    }
    return piProcInfo;
}

std::string ReadFromPipe(PROCESS_INFORMATION piProcInfo)//Read output from the child process's pipe for STDOUT and write to the parent process's pipe for STDOUT
{
    DWORD dwRead;
    CHAR chBuf[BUFSIZE];
    bool bSuccess = FALSE;
    std::string out = "";
    for(;;)
    {
        bSuccess=ReadFile(g_hChildStd_OUT_Rd, chBuf, BUFSIZE, &dwRead, NULL);
        if(!bSuccess || dwRead == 0)
        {
            break;
        }
        std::string s(chBuf, dwRead);
        out += s;
    }
    return out;
}

int main(int argc, char *argv[])
{
    std::string command;
    SECURITY_ATTRIBUTES sa;
    sa.nLength = sizeof(SECURITY_ATTRIBUTES);
    sa.bInheritHandle = TRUE;
    sa.lpSecurityDescriptor = NULL;
    if(!CreatePipe(&g_hChildStd_OUT_Rd, &g_hChildStd_OUT_Wr, &sa, 0))
    {
        exit(1);
    }
    if(!SetHandleInformation(g_hChildStd_OUT_Rd, HANDLE_FLAG_INHERIT, 0))
    {
        exit(1);
    }
    PROCESS_INFORMATION piProcInfo = CreateChildProcess("cmd.exe /c dism /online /get-featureinfo /featurename:Microsoft-Windows-Subsystem-Linux | findstr /R /C:\"tat\"");
    command = ReadFromPipe(piProcInfo);
}   std::cout<<command<<std::endl;