如何等待ShellExecute运行？

Question

我已经设法在VC++中使用ShellExecute来启动一个文档。现在，我希望运行一个接收一些参数的命令行工具，并在后台运行(作为隐藏，而不是最小化)，并让它阻塞我的程序流，这样我就可以等待它完成。如何修改以下命令行：

ShellExecute(NULL,"open",FULL_PATH_TO_CMD_LINE_TOOL,ARGUMENTS,NULL,SW_HIDE);

问题是，我有一个工具可以将html转换成pdf，我希望一旦这个工具完成，也就是pdf准备好了，就可以有另一个ShellExecute来查看它。

Answer 1

有一个CodeProject article展示了如何使用ShellExecuteEx而不是ShellExecute

SHELLEXECUTEINFO ShExecInfo = {0};
ShExecInfo.cbSize = sizeof(SHELLEXECUTEINFO);
ShExecInfo.fMask = SEE_MASK_NOCLOSEPROCESS;
ShExecInfo.hwnd = NULL;
ShExecInfo.lpVerb = NULL;
ShExecInfo.lpFile = "c:\\MyProgram.exe";        
ShExecInfo.lpParameters = "";   
ShExecInfo.lpDirectory = NULL;
ShExecInfo.nShow = SW_SHOW;
ShExecInfo.hInstApp = NULL; 
ShellExecuteEx(&ShExecInfo);
WaitForSingleObject(ShExecInfo.hProcess, INFINITE);
CloseHandle(ShExecInfo.hProcess);

关键点是标志SEE_MASK_NOCLOSEPROCESS，也就是as MSDN says

用于指示hProcess成员接收进程句柄。此句柄通常用于允许应用程序找出使用ShellExecuteEx创建的进程何时终止

另外，请注意：

调用应用程序负责在不再需要该句柄时将其关闭。

Answer 2

您也可以使用CreateProcess代替ShellExecute/ShellExecuteEx。该函数包含一个cmd.exe包装器选项，返回退出代码，并返回标准输出。(包含的内容可能并不完美)。

注意:在我的使用中，我知道必须有标准输出结果，但是PeekedNamePipe函数并不总是在第一次尝试时返回字节计数，因此出现了循环。也许，有人可以解决这个问题，并发布一个修订？另外，也许应该生成一个单独返回stderr的替代版本？

#include <stdio.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <Shellapi.h>


/*
Note: 
    The exitCode for a "Cmd Process" is not the exitCode
    for a sub process launched from it!  That can be retrieved
    via the errorlevel variable in the command line like so:
    set errorlevel=&[launch command]&echo.&echo exitCode=%errorlevel%&echo.
    The stdOut vector will then contain the exitCode on a seperate line
*/
BOOL executeCommandLine( const CStringW &command,
                         DWORD &exitCode,
                         const BOOL asCmdProcess=FALSE,
                         std::vector<CStringW> *stdOutLines=NULL )
{
    // Init return values
    BOOL bSuccess = FALSE;
    exitCode = 0;
    if( stdOutLines ) stdOutLines->clear();

    // Optionally prepend cmd.exe to command line to execute
    CStringW cmdLine( (asCmdProcess ? L"cmd.exe /C " : L"" ) +
                      command );

    // Create a pipe for the redirection of the STDOUT 
    // of a child process. 
    HANDLE g_hChildStd_OUT_Rd = NULL;
    HANDLE g_hChildStd_OUT_Wr = NULL;
    SECURITY_ATTRIBUTES saAttr; 
    saAttr.nLength = sizeof(SECURITY_ATTRIBUTES); 
    saAttr.bInheritHandle = TRUE; 
    saAttr.lpSecurityDescriptor = NULL; 
    bSuccess = CreatePipe( &g_hChildStd_OUT_Rd, 
                           &g_hChildStd_OUT_Wr, &saAttr, 0);
    if( !bSuccess ) return bSuccess;         
    bSuccess = SetHandleInformation( g_hChildStd_OUT_Rd, 
                                     HANDLE_FLAG_INHERIT, 0 );
    if( !bSuccess ) return bSuccess;         

    // Setup the child process to use the STDOUT redirection
    PROCESS_INFORMATION piProcInfo; 
    STARTUPINFO siStartInfo;    
    ZeroMemory( &piProcInfo, sizeof(PROCESS_INFORMATION) );
    ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );
    siStartInfo.cb = sizeof(STARTUPINFO); 
    siStartInfo.hStdError = g_hChildStd_OUT_Wr;
    siStartInfo.hStdOutput = g_hChildStd_OUT_Wr;
    siStartInfo.dwFlags |= STARTF_USESTDHANDLES;

    // Execute a synchronous child process & get exit code
    bSuccess = CreateProcess( NULL, 
      cmdLine.GetBuffer(),  // 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( !bSuccess ) return bSuccess;         
    WaitForSingleObject( piProcInfo.hProcess, (DWORD)(-1L) );
    GetExitCodeProcess( piProcInfo.hProcess, &exitCode );   
    CloseHandle( piProcInfo.hProcess );
    CloseHandle( piProcInfo.hThread );

    // Return if the caller is not requesting the stdout results
    if( !stdOutLines ) return TRUE;

    // Read the data written to the pipe
    DWORD bytesInPipe = 0;
    while( bytesInPipe==0 ){
        bSuccess = PeekNamedPipe( g_hChildStd_OUT_Rd, NULL, 0, NULL, 
                                  &bytesInPipe, NULL );
        if( !bSuccess ) return bSuccess;
    }
    if( bytesInPipe == 0 ) return TRUE; 
    DWORD dwRead; 
    CHAR *pipeContents = new CHAR[ bytesInPipe ];    
    bSuccess = ReadFile( g_hChildStd_OUT_Rd, pipeContents, 
                         bytesInPipe, &dwRead, NULL);
    if( !bSuccess || dwRead == 0 ) return FALSE; 

    // Split the data into lines and add them to the return vector
    std::stringstream stream( pipeContents );
    std::string str;
    while( getline( stream, str ) ) 
        stdOutLines->push_back( CStringW( str.c_str() ) );

    return TRUE;
}

Answer 3

如果使用COM，则使用ShellExecuteEx有时不起作用，因此必须考虑以下备注。

由于ShellExecuteEx可以将执行委托给使用组件对象模型( COM )激活的外壳程序扩展(数据源、上下文菜单处理程序、谓词实现)，因此应在调用ShellExecuteEx之前初始化COM。某些Shell扩展需要COM单线程单元(STA)类型。在这种情况下，COM应该按如下所示进行初始化：

CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE)

在某些情况下，ShellExecuteEx不使用这些类型的外壳扩展之一，并且这些实例根本不需要初始化COM。尽管如此，在使用此函数之前始终初始化COM是一种好的做法。

更多来自MSDN这里https://docs.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-shellexecuteexa