创建进程并等待其退出

た入场券 2022-08-10 08:54 256阅读 0赞

在命令行里，你敲完一个命令后，一般是这个命令执行完毕后你才获得控制台。在360的软件管家里面也有这种效果（软件升级时）。如果你要实现这种效果，一般就需要创建进程并等待其退出的函数。这个函数实现的关键是CreateProcessW和WaitForSingleObject两个函数，网上也有这样的代码。下面是一个叫做[Eraser][]的开源工程里面的一段代码，这个里面也有一些其他有用的代码，大家可以参考参考：

[http://eraser.heidi.ie/trac/browser/trunk/eraser6/Installer/Bootstrapper/Bootstrapper.cpp?rev=1278][http_eraser.heidi.ie_trac_browser_trunk_eraser6_Installer_Bootstrapper_Bootstrapper.cpp_rev_1278]

int CreateProcessAndWait(const std::wstring& commandLine, const std::wstring& appName) \{ //Get a mutable version of the command line wchar\_t\* cmdLine = new wchar\_t\[commandLine.length() + 1\]; wcscpy\_s(cmdLine, commandLine.length() + 1, commandLine.c\_str()); //Launch the process STARTUPINFOW startupInfo; PROCESS\_INFORMATION pInfo; ::ZeroMemory(&startupInfo, sizeof(startupInfo)); ::ZeroMemory(&pInfo, sizeof(pInfo)); if (!CreateProcessW(NULL, cmdLine, NULL, NULL, false, 0, NULL, NULL, &startupInfo, &pInfo)) \{ delete\[\] cmdLine; throw L"Error while executing " + appName + L": " + GetErrorMessage(GetLastError()); \} delete\[\] cmdLine; //Ok the process was created, wait for it to terminate. DWORD lastWait = 0; while ((lastWait = WaitForSingleObject(pInfo.hProcess, 50)) == WAIT\_TIMEOUT) Application::Get().Yield(); if (lastWait == WAIT\_ABANDONED) throw std::wstring(L"The condition waiting on the termination of the .NET installer was abandoned."); //Get the exit code DWORD exitCode = 0; if (!GetExitCodeProcess(pInfo.hProcess, &exitCode)) throw GetErrorMessage(GetLastError()); //Clean up CloseHandle(pInfo.hProcess); CloseHandle(pInfo.hThread); //Return the exit code. return exitCode; \}

下面是chrome里面创建进程并获取输出的代码：

bool GetAppOutput(const CommandLine& cl, std::string\* output) \{ HANDLE out\_read = NULL; HANDLE out\_write = NULL; SECURITY\_ATTRIBUTES sa\_attr; // Set the bInheritHandle flag so pipe handles are inherited. sa\_attr.nLength = sizeof(SECURITY\_ATTRIBUTES); sa\_attr.bInheritHandle = TRUE; sa\_attr.lpSecurityDescriptor = NULL; // Create the pipe for the child process's STDOUT. if (!CreatePipe(&out\_read, &out\_write, &sa\_attr, 0)) \{ NOTREACHED() << "Failed to create pipe"; return false; \} // Ensure we don't leak the handles. win::ScopedHandle scoped\_out\_read(out\_read); win::ScopedHandle scoped\_out\_write(out\_write); // Ensure the read handle to the pipe for STDOUT is not inherited. if (!SetHandleInformation(out\_read, HANDLE\_FLAG\_INHERIT, 0)) \{ NOTREACHED() << "Failed to disabled pipe inheritance"; return false; \} // Now create the child process PROCESS\_INFORMATION proc\_info = \{ 0 \}; STARTUPINFO start\_info = \{ 0 \}; start\_info.cb = sizeof(STARTUPINFO); start\_info.hStdOutput = out\_write; // Keep the normal stdin and stderr. start\_info.hStdInput = GetStdHandle(STD\_INPUT\_HANDLE); start\_info.hStdError = GetStdHandle(STD\_ERROR\_HANDLE); start\_info.dwFlags |= STARTF\_USESTDHANDLES; // Create the child process. if (!CreateProcess(NULL, const\_cast<wchar\_t\*>(cl.command\_line\_string().c\_str()), NULL, NULL, TRUE, // Handles are inherited. 0, NULL, NULL, &start\_info, &proc\_info)) \{ NOTREACHED() << "Failed to start process"; return false; \} // We don't need the thread handle, close it now. CloseHandle(proc\_info.hThread); // Close our writing end of pipe now. Otherwise later read would not be able // to detect end of child's output. scoped\_out\_write.Close(); // Read output from the child process's pipe for STDOUT const int kBufferSize = 1024; char buffer\[kBufferSize\]; for (;;) \{ DWORD bytes\_read = 0; BOOL success = ReadFile(out\_read, buffer, kBufferSize, &bytes\_read, NULL); if (!success || bytes\_read == 0) break; output->append(buffer, bytes\_read); \} // Let's wait for the process to finish. WaitForSingleObject(proc\_info.hProcess, INFINITE); CloseHandle(proc\_info.hProcess); return true; \}

[Eraser]: http://sourceforge.net/projects/eraser/
[http_eraser.heidi.ie_trac_browser_trunk_eraser6_Installer_Bootstrapper_Bootstrapper.cpp_rev_1278]: http://eraser.heidi.ie/trac/browser/trunk/eraser6/Installer/Bootstrapper/Bootstrapper.cpp?rev=1278