c++ pipe实现父子进程通信

1、父子进程通信pipe编程流程

-创建管道

-设置进程的输出到管道

-创建进程

-关闭管道写句柄

-读管道读句柄，把数据读到一个buffer里

2、注意事项

-读管道数据的时候，一定要关闭写句柄；

-父子进程通信时，句柄的传递多通过继承来完成，父进程允许这些句柄为子进程继承；创建子进程，是否继承的属性要设置为true；

 

 // pdfprintconsole.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include "pch.h"
#include <iostream>
#include <windows.h>
#include<tchar.h>
#include <string.h>

int main()
{



    int page_index = 0;
    char currentbuff[1000] = { 0 };
    char cachfilename[1000] = { 0 };
    char printcommand[1000] = { 0 };
    char command[500] = { 0 };
    handle handle = 0;
    bool                btest = 0;
    security_attributes sa = { 0 };
    dword               dwnumberofbytesread = 0;
    char szbuffer[10000] = { 0 };
    dword ret = 0;
    handle   hpipeoutputread = null;
    handle    hpipeoutputwrite = null;
    
    startupinfoa si = { 0 };
    process_information pi = { 0 };    

    sa.binherithandle = true; // true为管道可以被子进程所继承  
    sa.lpsecuritydescriptor = null; // 默认为null
    sa.nlength = sizeof(security_attributes);
    // create pipe for standard output redirection.
    createpipe(&hpipeoutputread,  // read handle
        &hpipeoutputwrite, // write handle
        &sa,      // security attributes
        0      // number of bytes reserved for pipe - 0 default
    );
    // make child process use hpipeoutputwrite as standard out,
        // and make sure it does not show on screen.
    si.cb = sizeof(si);
    si.dwflags = startf_useshowwindow | startf_usestdhandles;
    si.wshowwindow = sw_hide;
    //si.hstdinput = hpipeinputread;
    si.hstdoutput = hpipeoutputwrite;
    si.hstderror = hpipeoutputwrite;
    //strcpy_s(command, " -printer \"fx docucentre s2011\" -paper 9 -printermargins c:\\users\\qj\\desktop\\f3044688ce88a4b0a78c16ba85076570-5378-0010-0.png");
    strcpy_s(command," -printer \"fx docucentre s2011\" -listpapers");
    //一共执行三次
    for (int i = 0; i < 3; i++)
    {

        if (!createprocessa("c:\\users\\qj\\source\\repos\\windowsformsapp1\\x64\\debug\\pdfprint.exe", command, null, null, true, null, null, null, &si, &pi))
        {
            //afxmessagebox("缺失pdfprint.exe文件",0,0);        
            break;
        }
        else
        {
            handle hprocess = pi.hprocess;
            //等待进程退出    //closehandle(hpipeoutputread);
            while (waitforsingleobject(hprocess, infinite) != wait_object_0);
            getexitcodeprocess(hprocess, &ret);
            //如果ret!=0,异常退出；

            //
            closehandle(hpipeoutputwrite);
            while (true)
            {
                btest = readfile(
                    hpipeoutputread,      // handle of the read end of our pipe
                    &szbuffer,            // address of buffer that receives data
                    sizeof(szbuffer),                  // number of bytes to read
                    &dwnumberofbytesread, // address of number of bytes read
                    null                  // non-overlapped.
                );
            
                if (!btest)
                {
                    break;
                }
                // do something with data.
                szbuffer[dwnumberofbytesread] = 0;  // null terminate
            }
            if (!ret)
            {
                printf("123%s456\nbtest:%d\n", szbuffer, btest);
                closehandle(hprocess);            
                closehandle(hpipeoutputread);
                break;
            }




        }
    }
    //std::cout << "hello world!\n"; 
    system("pause");
}