怎么解决windows下管道阻塞的问题？

[welong]

程序很简单：
程序A：
#include "stdio.h"
int main()
{
int index = 0;
int i = 0;
for (i = 1; i <9988998; i++) {
printf("Current Count is %d\n", index++);

Sleep(10 * 999);
}
}

通过管道获取stdout时会卡死，究其原因，是因为windows的stdout输出是全缓冲的，只有缓冲区满了才会输出，但我要实现的有一行就输出一行，在命令行下可以这样，但用管道一直实现不了，在网上搜了很多代码，虽然说是异步获取，但也必须在缓冲区满了后才能输出，现在的问题是程序A我无法修改，上面只是个例子，实际功能比它复杂很多，但原理一样，也没办法把windows的命令行改为行缓冲，各位高手有什么好办法？

[宁南学者]

输出换行符，或者fflush 函数强制刷出可以吧？

[l357630798]

使用PeekNamedPipe查询管道内的数据，有则读取，没有则不读。主要是防止ReadFile堵塞。

[smwhotjay]

应该可以实现，类似 后门绑定cmd反弹那种。控制台的输入输出都接管了。

[赵4老师]

仅供参考：

#pragma comment(lib,"user32")
#include <stdio.h>
#include <string.h>
#include <windows.h>
int main() {
    SECURITY_ATTRIBUTES sa          = {0};
    STARTUPINFO         si          = {0};
    PROCESS_INFORMATION pi          = {0};
    HANDLE              hPipeOutputRead  = NULL;
    HANDLE              hPipeOutputWrite = NULL;
    HANDLE              hPipeInputRead   = NULL;
    HANDLE              hPipeInputWrite  = NULL;
    BOOL                bTest = 0;
    DWORD               dwNumberOfBytesRead = 0;
    DWORD               dwNumberOfBytesWrite = 0;
    CHAR                szMsg[100];
    CHAR                szBuffer[256];

    sa.nLength = sizeof(sa);
    sa.bInheritHandle = TRUE;
    sa.lpSecurityDescriptor = NULL;

    // 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
            );

    // Create pipe for standard input redirection.
    CreatePipe(&hPipeInputRead,  // read handle
            &hPipeInputWrite, // 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;

    CreateProcess (
          NULL, "cmd.exe",
          NULL, NULL,
          TRUE, 0,
          NULL, NULL,
          &si, &pi);

    // Now that handles have been inherited, close it to be safe.
    // You don't want to read or write to them accidentally.
    CloseHandle(hPipeOutputWrite);
    CloseHandle(hPipeInputRead);

    // Now test to capture DOS application output by reading
    // hPipeOutputRead.  Could also write to DOS application
    // standard input by writing to hPipeInputWrite.
    sprintf(szMsg, "ver\n");
    WriteFile(
          hPipeInputWrite,      // handle of the write end of our pipe
          &szMsg,               // address of buffer that send data
          strlen(szMsg),        // number of bytes to write
          &dwNumberOfBytesWrite,// address of number of bytes read
          NULL                  // non-overlapped.
          );

    while(TRUE)
    {
       bTest=ReadFile(
          hPipeOutputRead,      // handle of the read end of our pipe
          &szBuffer,            // address of buffer that receives data
          256,                  // number of bytes to read
          &dwNumberOfBytesRead, // address of number of bytes read
          NULL                  // non-overlapped.
          );

      if (!bTest){
          sprintf(szMsg, "Error #%d reading pipe.",GetLastError());
          printf("%s",szMsg);
          break;
      }

      // do something with data.
      szBuffer[dwNumberOfBytesRead] = 0;  // null terminate
      printf("%s",szBuffer);
      if ('>'==szBuffer[dwNumberOfBytesRead-1]) break;
    }

    sprintf(szMsg, "chcp\nexit\n");
    WriteFile(
          hPipeInputWrite,      // handle of the write end of our pipe
          &szMsg,               // address of buffer that send data
          strlen(szMsg),        // number of bytes to write
          &dwNumberOfBytesWrite,// address of number of bytes read
          NULL                  // non-overlapped.
          );

    while(TRUE)
    {
       bTest=ReadFile(
          hPipeOutputRead,      // handle of the read end of our pipe
          &szBuffer,            // address of buffer that receives data
          256,                  // number of bytes to read
          &dwNumberOfBytesRead, // address of number of bytes read
          NULL                  // non-overlapped.
          );

      if (!bTest){
          sprintf(szMsg, "Error #%d reading pipe.",GetLastError());
          printf("%s",szMsg);
          break;
      }

      // do something with data.
      szBuffer[dwNumberOfBytesRead] = 0;  // null terminate
      printf("%s",szBuffer);
    }

    // Wait for CONSPAWN to finish.
    WaitForSingleObject (pi.hProcess, INFINITE);

    // Close all remaining handles
    CloseHandle (pi.hProcess);
    CloseHandle (hPipeOutputRead);
    CloseHandle (hPipeInputWrite);

    return 0;
}
//C:\test>test
//Microsoft Windows [版本 5.2.3790]
//(C) 版权所有 1985-2003 Microsoft Corp.
//
//C:\test>ver
//
//Microsoft Windows [版本 5.2.3790]
//
//C:\test>chcp
//活动的代码页: 936
//
//C:\test>exit
//Error #109 reading pipe.
//C:\test>

[welong]

引用 1 楼 qq_36751214 的回复:

输出换行符，或者fflush 函数强制刷出可以吧？

我现在没有程序a的代码，上面的代码只是实现延时输出的功能，实际输出也是有延时的，但输出的内容和我写的不一样，是有用的数据。我能做的只能修改管道读取程序或者修改系统注册表

[liuxlyangjl_01]

今天遇到同样的问题，找遍了，没有在网上发现解决方案，抱着试试看的想法，终于找到了最好的解决方案。
无须命名管道，只需在读取前加上GetFileSizeEx判断即可，代码如下：
char buf[ 1024 ];
LARGE_INTEGER off;
::GetFileSizeEx( z_stdoutRd, &off );
if ( off.LowPart || off.HighPart )
{
DWORD readSize = 0;
BOOL b = ::ReadFile( z_stdoutRd, buf, 1024, &readSize, NULL );
buf[ readSize ] = 0;
::OutputDebugStringA( buf );
}

[还没淹死的鱼]

学习了。
最讨厌缓冲了。

[鑫森淼焱垚]

你要再另一端读，输入才不会卡。写满了就不会再写了，除非是异步io