如何生成控制台重定向标准的句柄的进程

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点击这里察看该文章的英文版: 190351
概要
本文介绍如何重定向输入和输出的子进程从标准输入句柄接收输入,或将输出发送到标准输出句柄。Win32 API 使应用程序可以生成与重定向标准的句柄的子控制台进程。此功能允许父进程发送和接收的输入和输出的子进程。

注意某些基于的控制台应用程序并为其输入/输出 (IO) 操作不使用标准的句柄。Win32 API 不支持这些进程的重定向。
更多信息
通过 STARTUPINFO 结构 CreateProcess() API 使您能够重定向标准的句柄的子基于控制台进程。如果 dwFlags 成员被设置为 STARTF_USESTDHANDLES,然后以下 STARTUPINFO 成员指定的子基于控制台进程标准控点:
   HANDLE hStdInput - Standard input handle of the child process.   HANDLE hStdOutput - Standard output handle of the child process.   HANDLE hStdError - Standard error handle of the child process.				
可以以任意一个管道句柄,文件的句柄来设置这些图柄或任何控点上,可以执行同步读取和写入通过 ReadFile() 和 WriteFile() API。控点必须是可继承,并且 CreateProcess() API 必须指定的可继承句柄的子进程继承通过 bInheritHandles 参数中指定为 TRUE。如果父进程只希望重定向一个或两个标准的句柄,指定为特定的句柄的 GetStdHandle() 会导致子创建标准的句柄,因为它通常不重定向。例如对于如果父进程只需要重定向标准输出和错误的子进程,然后 hStdInput 成员 STARTUPINFO 结构的填充,如下所示:
   hStdInput = GetStdHandle(STD_INPUT_HANDLE);				
重定向时,注意 子进程的此类 C 运行时函数用作 printf () 和 fprintf() 可以不良行为。C 运行时函数维护单独的 IO 缓冲区。重定向时, 可能不在每个 IO 调用后立即刷新这些缓冲区。如此一来从 getch() 调用 printf () 调用或输入的重定向管道输出不立即刷新,延迟,有时无限延迟发生。如果在子进程会 IO 缓冲区刷新到 C 运行时 IO 函数每次调用后,被避免此问题。只有子进程可以刷新其 C 运行时 IO 缓冲区。一个进程可以通过调用 fflush() 函数刷新其 C 运行时 IO 缓冲区。

注意重定向特定的子进程的标准控点时,windows 95 和 Windows 98 将需要额外的步骤。

下面的示例将重定向标准输入、 输出和 CreateProcess 调用中指定的子进程的错误。本示例将重定向提供的控制台进程 (Child.c)。

示例代码

   /*++      Copyright (c) 1998  Microsoft Corporation      Module Name:         Redirect.c      Description:          This sample illustrates how to spawn a child console based          application with redirected standard handles.          The following import libraries are required:          user32.lib      Dave McPherson (davemm)   11-March-98   --*/    #include<windows.h>   #pragma comment(lib, "User32.lib")   void DisplayError(char *pszAPI);   void ReadAndHandleOutput(HANDLE hPipeRead);   void PrepAndLaunchRedirectedChild(HANDLE hChildStdOut,                                     HANDLE hChildStdIn,                                     HANDLE hChildStdErr);   DWORD WINAPI GetAndSendInputThread(LPVOID lpvThreadParam);   HANDLE hChildProcess = NULL;   HANDLE hStdIn = NULL; // Handle to parents std input.   BOOL bRunThread = TRUE;   void main ()   {      HANDLE hOutputReadTmp,hOutputRead,hOutputWrite;      HANDLE hInputWriteTmp,hInputRead,hInputWrite;      HANDLE hErrorWrite;      HANDLE hThread;      DWORD ThreadId;      SECURITY_ATTRIBUTES sa;      // Set up the security attributes struct.      sa.nLength= sizeof(SECURITY_ATTRIBUTES);      sa.lpSecurityDescriptor = NULL;      sa.bInheritHandle = TRUE;      // Create the child output pipe.      if (!CreatePipe(&hOutputReadTmp,&hOutputWrite,&sa,0))         DisplayError("CreatePipe");      // Create a duplicate of the output write handle for the std error      // write handle. This is necessary in case the child application      // closes one of its std output handles.      if (!DuplicateHandle(GetCurrentProcess(),hOutputWrite,                           GetCurrentProcess(),&hErrorWrite,0,                           TRUE,DUPLICATE_SAME_ACCESS))         DisplayError("DuplicateHandle");      // Create the child input pipe.      if (!CreatePipe(&hInputRead,&hInputWriteTmp,&sa,0))         DisplayError("CreatePipe");      // Create new output read handle and the input write handles. Set      // the Properties to FALSE. Otherwise, the child inherits the      // properties and, as a result, non-closeable handles to the pipes      // are created.      if (!DuplicateHandle(GetCurrentProcess(),hOutputReadTmp,                           GetCurrentProcess(),                           &hOutputRead, // Address of new handle.                           0,FALSE, // Make it uninheritable.                           DUPLICATE_SAME_ACCESS))         DisplayError("DupliateHandle");      if (!DuplicateHandle(GetCurrentProcess(),hInputWriteTmp,                           GetCurrentProcess(),                           &hInputWrite, // Address of new handle.                           0,FALSE, // Make it uninheritable.                           DUPLICATE_SAME_ACCESS))      DisplayError("DupliateHandle");      // Close inheritable copies of the handles you do not want to be      // inherited.      if (!CloseHandle(hOutputReadTmp)) DisplayError("CloseHandle");      if (!CloseHandle(hInputWriteTmp)) DisplayError("CloseHandle");      // Get std input handle so you can close it and force the ReadFile to      // fail when you want the input thread to exit.      if ( (hStdIn = GetStdHandle(STD_INPUT_HANDLE)) ==                                                INVALID_HANDLE_VALUE )         DisplayError("GetStdHandle");      PrepAndLaunchRedirectedChild(hOutputWrite,hInputRead,hErrorWrite);      // Close pipe handles (do not continue to modify the parent).      // You need to make sure that no handles to the write end of the      // output pipe are maintained in this process or else the pipe will      // not close when the child process exits and the ReadFile will hang.      if (!CloseHandle(hOutputWrite)) DisplayError("CloseHandle");      if (!CloseHandle(hInputRead )) DisplayError("CloseHandle");      if (!CloseHandle(hErrorWrite)) DisplayError("CloseHandle");      // Launch the thread that gets the input and sends it to the child.      hThread = CreateThread(NULL,0,GetAndSendInputThread,                              (LPVOID)hInputWrite,0,&ThreadId);      if (hThread == NULL) DisplayError("CreateThread");      // Read the child's output.      ReadAndHandleOutput(hOutputRead);      // Redirection is complete      // Force the read on the input to return by closing the stdin handle.      if (!CloseHandle(hStdIn)) DisplayError("CloseHandle");      // Tell the thread to exit and wait for thread to die.      bRunThread = FALSE;      if (WaitForSingleObject(hThread,INFINITE) == WAIT_FAILED)         DisplayError("WaitForSingleObject");      if (!CloseHandle(hOutputRead)) DisplayError("CloseHandle");      if (!CloseHandle(hInputWrite)) DisplayError("CloseHandle");   }   ///////////////////////////////////////////////////////////////////////    // PrepAndLaunchRedirectedChild   // Sets up STARTUPINFO structure, and launches redirected child.   ///////////////////////////////////////////////////////////////////////    void PrepAndLaunchRedirectedChild(HANDLE hChildStdOut,                                     HANDLE hChildStdIn,                                     HANDLE hChildStdErr)   {      PROCESS_INFORMATION pi;      STARTUPINFO si;      // Set up the start up info struct.      ZeroMemory(&si,sizeof(STARTUPINFO));      si.cb = sizeof(STARTUPINFO);      si.dwFlags = STARTF_USESTDHANDLES;      si.hStdOutput = hChildStdOut;      si.hStdInput  = hChildStdIn;      si.hStdError  = hChildStdErr;      // Use this if you want to hide the child:      //     si.wShowWindow = SW_HIDE;      // Note that dwFlags must include STARTF_USESHOWWINDOW if you want to      // use the wShowWindow flags.      // Launch the process that you want to redirect (in this case,      // Child.exe). Make sure Child.exe is in the same directory as      // redirect.c launch redirect from a command line to prevent location      // confusion.      if (!CreateProcess(NULL,"Child.EXE",NULL,NULL,TRUE,                         CREATE_NEW_CONSOLE,NULL,NULL,&si,&pi))         DisplayError("CreateProcess");      // Set global child process handle to cause threads to exit.      hChildProcess = pi.hProcess;      // Close any unnecessary handles.      if (!CloseHandle(pi.hThread)) DisplayError("CloseHandle");   }   ///////////////////////////////////////////////////////////////////////    // ReadAndHandleOutput   // Monitors handle for input. Exits when child exits or pipe breaks.   ///////////////////////////////////////////////////////////////////////    void ReadAndHandleOutput(HANDLE hPipeRead)   {      CHAR lpBuffer[256];      DWORD nBytesRead;      DWORD nCharsWritten;      while(TRUE)      {         if (!ReadFile(hPipeRead,lpBuffer,sizeof(lpBuffer),                                          &nBytesRead,NULL) || !nBytesRead)         {            if (GetLastError() == ERROR_BROKEN_PIPE)               break; // pipe done - normal exit path.            else               DisplayError("ReadFile"); // Something bad happened.         }         // Display the character read on the screen.         if (!WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE),lpBuffer,                           nBytesRead,&nCharsWritten,NULL))            DisplayError("WriteConsole");      }   }   ///////////////////////////////////////////////////////////////////////    // GetAndSendInputThread   // Thread procedure that monitors the console for input and sends input   // to the child process through the input pipe.   // This thread ends when the child application exits.   ///////////////////////////////////////////////////////////////////////    DWORD WINAPI GetAndSendInputThread(LPVOID lpvThreadParam)   {      CHAR read_buff[256];      DWORD nBytesRead,nBytesWrote;      HANDLE hPipeWrite = (HANDLE)lpvThreadParam;      // Get input from our console and send it to child through the pipe.      while (bRunThread)      {         if(!ReadConsole(hStdIn,read_buff,1,&nBytesRead,NULL))            DisplayError("ReadConsole");         read_buff[nBytesRead] = '\0'; // Follow input with a NULL.         if (!WriteFile(hPipeWrite,read_buff,nBytesRead,&nBytesWrote,NULL))         {            if (GetLastError() == ERROR_NO_DATA)               break; // Pipe was closed (normal exit path).            else            DisplayError("WriteFile");         }      }      return 1;   }   ///////////////////////////////////////////////////////////////////////    // DisplayError   // Displays the error number and corresponding message.   ///////////////////////////////////////////////////////////////////////    void DisplayError(char *pszAPI)   {       LPVOID lpvMessageBuffer;       CHAR szPrintBuffer[512];       DWORD nCharsWritten;       FormatMessage(                FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM,                NULL, GetLastError(),                MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),                (LPTSTR)&lpvMessageBuffer, 0, NULL);       wsprintf(szPrintBuffer,         "ERROR: API    = %s.\n   error code = %d.\n   message    = %s.\n",                pszAPI, GetLastError(), (char *)lpvMessageBuffer);       WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE),szPrintBuffer,                     lstrlen(szPrintBuffer),&nCharsWritten,NULL);       LocalFree(lpvMessageBuffer);       ExitProcess(GetLastError());   }   //////////////////////////////////////////////////////////////////////    // child.c   // Echoes all input to stdout. This will be redirected by the redirect   // sample. Compile and build child.c as a Win32 Console application and   // put it in the same directory as the redirect sample.   //    #include<windows.h>   #include<stdio.h>   #include<string.h>   void main ()   {      FILE*    fp;      CHAR     szInput[1024];      // Open the console. By doing this, you can send output directly to      // the console that will not be redirected.      fp = fopen("CON", "w");      if (!fp) {         printf("Error opening child console - perhaps there is none.\n");         fflush(NULL);      }      else      {      // Write a message direct to the console (will not be redirected).         fprintf(fp,"This data is being printed directly to the\n");         fprintf(fp,"console and will not be redirected.\n\n");         fprintf(fp,"Since the standard input and output have been\n");         fprintf(fp,"redirected data sent to and from those handles\n");         fprintf(fp,"will be redirected.\n\n");         fprintf(fp,"To send data to the std input of this process.\n");         fprintf(fp,"Click on the console window of the parent process\n");         fprintf(fp,"(redirect), and enter data from it's console\n\n");         fprintf(fp,"To exit this process send the string 'exit' to\n");         fprintf(fp,"it's standard input\n");         fflush(fp);      }      ZeroMemory(szInput,1024);      while (TRUE)      {         gets(szInput);         printf("Child echoing [%s]\n",szInput);         fflush(NULL);  // Must flush output buffers or else redirection                        // will be problematic.         if (!_stricmp(szInput,"Exit") )            break;         ZeroMemory(szInput,strlen(szInput) );      }   }
参考
MSDN 库 SDK 文档: CreateProcess() ; STARTUPINFO 结构

继承在 Win32 平台 SDK 中的示例:
   \MSSDK\samples\winbase\ipc\inherit				
继承重定向的重定向 stdhandles

警告:本文已自动翻译

属性

文章 ID:190351 - 上次审阅时间:11/21/2006 15:28:50 - 修订版本: 7.1

Microsoft Win32 Application Programming Interface

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