用管道将cmd.exe信息输出到窗口

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
void CParentDlg::OnBnClickedButton3()
{
	//创建管道
	SECURITY_ATTRIBUTES sa = {};
	sa.nLength = sizeof(sa);
	sa.bInheritHandle = TRUE;
	::CreatePipe(&m_hSelfRead, &m_hCmdWrite, &sa, 0);		
	::CreatePipe(&m_hCmdRead, &m_hSelfWrite, &sa, 0);

	//创建子进程
	STARTUPINFO si = {};
	si.cb = sizeof(si);
	si.dwFlags = STARTF_USESTDHANDLES;
	si.hStdInput = m_hCmdRead;
	si.hStdOutput = m_hCmdWrite;

	PROCESS_INFORMATION pi;
	ZeroMemory(&pi, sizeof(pi));
	// Start the child process. 
	if (!CreateProcess(NULL,   // No module name (use command line)
		"cmd.exe",        // Command line
		NULL,           // Process handle not inheritable
		NULL,           // Thread handle not inheritable
		TRUE,          // Set handle inheritance to FALSE
		0,              // No creation flags
		NULL,           // Use parent's environment block
		NULL,           // Use parent's starting directory 
		&si,            // Pointer to STARTUPINFO structure
		&pi)           // Pointer to PROCESS_INFORMATION structure
		)
	{
		printf("CreateProcess failed (%d).\n", GetLastError());
		return;
	}
	CloseHandle(pi.hProcess);
	CloseHandle(pi.hThread);
}


void CParentDlg::OnBnClickedButton4()
{
	CString strBuf;
	GetDlgItemText(EDT_COMD, strBuf);
	strBuf += "\r\n";
	BOOL bRet = WriteFile(m_hSelfWrite, strBuf.GetBuffer(), strBuf.GetLength(), NULL, NULL);
	if (!bRet)
	{
		AfxMessageBox("写入管道失败");
	}
}


void CParentDlg::OnBnClickedButton5()
{
	DWORD dwBytesAvail = 0;
	BOOL bRet = ::PeekNamedPipe(m_hSelfRead, NULL, 0, NULL, &dwBytesAvail, NULL);
	if (!bRet)
	{
		AfxMessageBox("无法查看管道剩余数据");
		return;
	}
	//管道中有数据再读
	if (dwBytesAvail > 0)
	{
		CString strBuf;
		DWORD dwBytesToRead = 0;
		BOOL bRet = ::ReadFile(
			m_hSelfRead,
			strBuf.GetBufferSetLength(MAXBYTE),
			MAXBYTE,
			&dwBytesToRead,
			NULL
		);
		if (!bRet)
		{
			AfxMessageBox("读取数据失败");
			return;
		}
		strBuf.ReleaseBuffer(dwBytesToRead);
		SetDlgItemText(EDT_SHOW, strBuf);
	}
}

分析：

1
2
3
4
5
6
7
8
9
::CreatePipe(&m_hSelfRead, &m_hCmdWrite, &sa, 0);		
::CreatePipe(&m_hCmdRead, &m_hSelfWrite, &sa, 0);

//创建子进程
STARTUPINFO si = {};
si.cb = sizeof(si);
si.dwFlags = STARTF_USESTDHANDLES;
si.hStdInput = m_hCmdRead;
si.hStdOutput = m_hCmdWrite;

第一个管道：::CreatePipe(&m_hSelfRead, &m_hCmdWrite, &sa, 0);

  • **m_hSelfRead**：父进程读取句柄。父进程通过这个句柄从管道中读取数据，即从子进程 cmd.exe 的输出中读取数据。
  • **m_hCmdWrite**：子进程写入句柄。子进程通过这个句柄向管道中写入数据，即将 cmd.exe 的输出写入管道。

第二个管道：::CreatePipe(&m_hCmdRead, &m_hSelfWrite, &sa, 0);

  • **m_hCmdRead**：子进程读取句柄。子进程通过这个句柄从管道中读取数据，即从父进程输入的数据。
  • **m_hSelfWrite**：父进程写入句柄。父进程通过这个句柄向管道中写入数据，即将命令输入到 cmd.exe。

在 STARTUPINFO 结构体中，si.hStdInput 和 si.hStdOutput 应该分别设置为用于输入和输出的管道句柄，以便父进程可以通过这些句柄与子进程 cmd.exe 进行通信。正确的设置方式：

  1. **si.hStdInput**：设置为子进程的读取句柄 m_hCmdRead（由句柄m_hSelfWrite写入，m_hCmdRead在子进程读出）这意味着子进程将从此管道读取数据。
  2. **si.hStdOutput**：设置为子进程的写入句柄 m_hCmdWrite（由句柄m_hCmdWrite写入，由m_hSelfRead在父进程读出),这意味着子进程将把输出数据写入此管道。