XiZi's Blog

这里记录一个用CreatePipe的坑

1. 问题来源：在Windows上编译了一个cgit, 加了source-filter，代码高亮（使用highlight处理）之后，死活不显示代码。发现是execvp的问题，开始想好好弄，后来放弃了，反正只加个代码高亮，直接dirtry的解决方案算了。所以就参照微软的官方<Creating a Child Process with Redirected Input and Output>, 进行highlight进程的创建。测试小文件可以正常高亮，大文件就会卡住。

2.问题所在和解决方案：经过各种查找，定位到了WriteFile给子线程的Stdin pipe时发生了阻塞。查了查，发现CreatePipes时，有buffersize的设置，增大buffersize, 问题得到了解决。

 

贴出Dirty的核心代码吧：

  1.  

    #define _WIN32_WINNT 0x0600
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winnt.h>
#include <winternl.h>
#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <process.h>
 
typedef struct ProcessPrepare_Info
{
    PROCESS_INFORMATION child_pi;
    HANDLE IN_Rd;
    HANDLE IN_Wr;
    HANDLE OUT_Rd;
    HANDLE OUT_Wr;  
} PPInfo;
 
#define BUFSIZE 4096 
#define PIPE_BUFSIZE 1024*1024*1024

  2.  

    PPInfo prepare_highlight(const char* filename)
{
	SECURITY_ATTRIBUTES saAttr;
	char file_ext[1024];
	char *fext;
	PPInfo ppinfo;
	
	PROCESS_INFORMATION child_pi;
	
	HANDLE g_hChildStd_IN_Rd = NULL;
	HANDLE g_hChildStd_IN_Wr = NULL;
	HANDLE g_hChildStd_OUT_Rd = NULL;
	HANDLE g_hChildStd_OUT_Wr = NULL;

	
	fext = get_filename_ext(filename);
	if (!fext)
		strcpy(file_ext,"txt");
	else
		strcpy(file_ext,fext);
	
	if (strstr(filename,"Makefile") == filename)
		strcpy(file_ext,"mk");
	

	// printf("\n->Start of parent execution.\n");

	// Set the bInheritHandle flag so pipe handles are inherited. 

	saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
	saAttr.bInheritHandle = TRUE;
	saAttr.lpSecurityDescriptor = NULL;

	// Create a pipe for the child process's STDOUT. 

	if (!CreatePipe(&g_hChildStd_OUT_Rd, &g_hChildStd_OUT_Wr, &saAttr, PIPE_BUFSIZE))
		debug_log(TEXT("StdoutRd CreatePipe"));

	// Ensure the read handle to the pipe for STDOUT is not inherited.

	if (!SetHandleInformation(g_hChildStd_OUT_Rd, HANDLE_FLAG_INHERIT, 0))
		debug_log(TEXT("Stdout SetHandleInformation"));

	// Create a pipe for the child process's STDIN. 

	if (!CreatePipe(&g_hChildStd_IN_Rd, &g_hChildStd_IN_Wr, &saAttr, PIPE_BUFSIZE))
		debug_log(TEXT("Stdin CreatePipe"));

	// Ensure the write handle to the pipe for STDIN is not inherited. 

	if (!SetHandleInformation(g_hChildStd_IN_Wr, HANDLE_FLAG_INHERIT, 0))
		debug_log(TEXT("Stdin SetHandleInformation"));

	// Create the child process. 

	child_pi = CreateChildProcess(file_ext,g_hChildStd_OUT_Wr,g_hChildStd_IN_Rd);
	
	debug_log("Create highlight process finished.\n");
	
	ppinfo.child_pi = child_pi;
	ppinfo.IN_Rd = g_hChildStd_IN_Rd;
	ppinfo.IN_Wr = g_hChildStd_IN_Wr;
	ppinfo.OUT_Rd = g_hChildStd_OUT_Rd;
	ppinfo.OUT_Wr = g_hChildStd_OUT_Wr;
	
	return ppinfo;
}

     

  3.  

    void wait_highlight(PPInfo ppinfo)
{
	//WaitForSingleObject(ppinfo.child_pi.hProcess, INFINITE);
	WaitForSingleObject(ppinfo.child_pi.hProcess, 10000);
	
	if (!CloseHandle(ppinfo.OUT_Wr))
		debug_log(TEXT("Child StdOutWr CloseHandle"));

	// Read from pipe that is the standard output for child process. 

	//printf("\n->Contents of child process STDOUT:\n\n", argv[1]);
	ReadFromPipe(ppinfo.OUT_Rd);

	//printf("\n->End of parent execution.\n");

	// The remaining open handles are cleaned up when this process terminates. 
	// To avoid resource leaks in a larger application, close handles explicitly. 
}

     

  4.  

    DWORD WriteBufToPipe(HANDLE wHandle,const char* buf, DWORD bufsize)

// Read from a file and write its contents to the pipe for the child's STDIN.
// Stop when there is no more data. 
{
	int i, dwRead;
	DWORD dwWritten;
	CHAR chBuf[BUFSIZE+1];
	BOOL bSuccess = FALSE;
	
	chBuf[BUFSIZE] = 0;
#if false	
	
	bSuccess = WriteFile(wHandle, buf, bufsize, &dwWritten, NULL);
	
#else
	i=0;
	for (;;)
	{
		//bSuccess = ReadFile(g_hInputFile, chBuf, BUFSIZE, &dwRead, NULL);
		//if (!bSuccess || dwRead == 0) break;
		dwRead = (bufsize - BUFSIZE*i);
		if ( dwRead <= 0) break;
		dwRead = min(dwRead+1,BUFSIZE);
		memcpy(chBuf,&(buf[BUFSIZE*i]),dwRead);
		debug_log("Write %d bytes of chbuf %s to handle\n",dwRead,chBuf);
		bSuccess = WriteFile(wHandle, chBuf, dwRead, &dwWritten, NULL);
		debug_log("Write buf %d time,bSuccess=%d\n",i,bSuccess);
		if (!bSuccess) break;
		FlushFileBuffers(wHandle);
		debug_log("Flush write handle.\n");
		i=i+1;
	}
#endif
	
	debug_log("Write buf finished\n");

	// Close the pipe handle so the child process stops reading. 

	if (!CloseHandle(wHandle))
		debug_log(TEXT("StdInWr CloseHandle"));
	
	return dwWritten;
}

     

  5.  

    PROCESS_INFORMATION CreateChildProcess(const char* file_ext,HANDLE hOutput, HANDLE hInput)
// Create a child process that uses the previously created pipes for STDIN and STDOUT.
{
	TCHAR szCmdline[1024] = TEXT("D:\\Data\\WebRoot\\cgit\\highlight-3.39-x64\\highlight.exe --force --inline-css -f -I -O xhtml -S ");
	PROCESS_INFORMATION piProcInfo;
	STARTUPINFO siStartInfo;
	BOOL bSuccess = FALSE;
	
	//Append file extension
	strcat(szCmdline,file_ext);
	
	debug_log("%s\n",szCmdline);

	// Set up members of the PROCESS_INFORMATION structure. 

	ZeroMemory(&piProcInfo, sizeof(PROCESS_INFORMATION));

	// Set up members of the STARTUPINFO structure. 
	// This structure specifies the STDIN and STDOUT handles for redirection.

	ZeroMemory(&siStartInfo, sizeof(STARTUPINFO));
	siStartInfo.cb = sizeof(STARTUPINFO);
	siStartInfo.hStdError = hOutput;//g_hChildStd_OUT_Wr;
	siStartInfo.hStdOutput = hOutput;//g_hChildStd_OUT_Wr;
	siStartInfo.hStdInput = hInput;//g_hChildStd_IN_Rd;
	siStartInfo.dwFlags |= STARTF_USESTDHANDLES;

	// Create the child process. 

	bSuccess = CreateProcess(TEXT("D:\\Data\\WebRoot\\cgit\\highlight-3.39-x64\\highlight.exe"),
		szCmdline,     // command line 
		NULL,          // process security attributes 
		NULL,          // primary thread security attributes 
		TRUE,          // handles are inherited 
		0,             // creation flags 
		NULL,          // use parent's environment 
		NULL,          // use parent's current directory 
		&siStartInfo,  // STARTUPINFO pointer 
		&piProcInfo);  // receives PROCESS_INFORMATION 

	// If an error occurs, exit the application. 
	if (!bSuccess)
		debug_log(TEXT("CreateProcess Failed."));
	else
	{
		// Close handles to the child process and its primary thread.
		// Some applications might keep these handles to monitor the status
		// of the child process, for example. 

		CloseHandle(piProcInfo.hProcess);
		CloseHandle(piProcInfo.hThread);
	}
	return piProcInfo;
}

     

  6.  

    const char *get_filename_ext(const char *filename) {
    const char *dot = strrchr(filename, '.');
    if(!dot || dot == filename) return NULL;
    return dot + 1;
}

     

  7. Test Main Code

    int test_process2(const char* filename,const char* buf, DWORD bufsize)
{
	PPInfo cIn;
	
	int i, dwRead;
	DWORD dwWritten;
	CHAR chBuf[BUFSIZE+1];
	BOOL bSuccess = FALSE;
	
	chBuf[BUFSIZE] = 0;
	
	debug_log("test_process2 start.\n");
	
	cIn=prepare_highlight(filename);
	
	//WriteToPipe(cIn.IN_Wr,g_hInputFile);
	i=0;
	for (;;)
	{
		//bSuccess = ReadFile(g_hInputFile, chBuf, BUFSIZE, &dwRead, NULL);
		//if (!bSuccess || dwRead == 0) break;
		dwRead = (bufsize - BUFSIZE*i);
		if ( dwRead <= 0) break;
		dwRead = min(dwRead+1,BUFSIZE);
		memcpy(chBuf,&(buf[BUFSIZE*i]),dwRead);
		debug_log("Write %d bytes of chbuf %s to handle\n",dwRead,chBuf);
		bSuccess = WriteFile(cIn.IN_Wr, chBuf, dwRead, &dwWritten, NULL);
		debug_log("Write buf %d time\n",i);
		if (!bSuccess) break;
		i=i+1;
	}
	
	debug_log("Write buf finished\n");

	// Close the pipe handle so the child process stops reading. 

	if (!CloseHandle(cIn.IN_Wr))
		debug_log(TEXT("StdInWr CloseHandle"));
	
	wait_highlight(cIn);
	
	debug_log("test_process2 finished.\n");
	
	return 0;
}

     

PS:

 

 这里在顺便提一下，如何在Windows下编译cgit, 下载并安装git-sdk，然后在打开的shell里面make即可。之后拷贝到Apache相关目录并设置即可。

未分类 windows highlight cgit pipe hang pipe block pipe Comments(972) 2017年7月29日 17:46




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