Hello,

I'm trying to execute a console program from a graphic (MFC)
application (under Win 95, with VC5), without showing its console, and
pick up its standard output (or error) in a CString
variable. I think ShellExecute (or ShellExecuteEx)
doesn't allow to get program's stdout. So I tryed to
do it with CreateProcess redirecting standard handles.

If someone has a similar experiance or knows how to do
the thing properly, please help. I would really apreciate
any help.

Here is my code which doesn't work all the time. I'm not
sure about some parameters (I marked this lines of the
code with ****).

BOOL MyExecCommandWithOutput(CString& strList, LPTSTR lpCommandLine ,
LPVOID lpEnv)
/*
   strList: receives the stdout or stderr
   lpCommandLine: pointer to the command line
   lpEnv: pointer to the new environment
*/
{

        DWORD dwExitCode;
        HANDLE hChildStdoutRd , hChildStdoutWr;
        HANDLE hChildStderrRd , hChildStderrWr;

        SECURITY_ATTRIBUTES saAttr;
        PROCESS_INFORMATION piProcInfo;
        STARTUPINFO siStartInfo;

        // Set up members of SECURITY_ATTRIBUTES structure.
        ZeroMemory( &saAttr, sizeof(SECURITY_ATTRIBUTES) );
        saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);

        // **** I'm not sure about this
        saAttr.bInheritHandle = TRUE;

        if (! CreatePipe(&hChildStdoutRd, &hChildStdoutWr, &saAttr, PIPEBUF))
                MyErrorExit("Stdout pipe creation failed\n");

        if (! CreatePipe(&hChildStderrRd, &hChildStderrWr, &saAttr, PIPEBUF))
                MyErrorExit("Stdout pipe creation failed\n");

        // Set up members of STARTUPINFO structure.
        ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );
        siStartInfo.cb = sizeof(STARTUPINFO);
        siStartInfo.lpReserved = NULL;
        siStartInfo.lpReserved2 = NULL;
        siStartInfo.cbReserved2 = 0;
        siStartInfo.lpDesktop = NULL;

        // Use created pipes as stdout and stderr
        siStartInfo.dwFlags = STARTF_USESTDHANDLES;
        siStartInfo.hStdOutput = hChildStdoutWr;  
        siStartInfo.hStdError = hChildStderrWr;

        // Don't show program's console
        // **** I'm not sure about this
        DWORD dwFlag =  DETACHED_PROCESS;

        // Create the child process.
        BOOL bl;
        bl = CreateProcess(NULL,
                lpCommandLine, // command line
                NULL,          // process security attributes
                NULL,          // primary thread security attributes
                TRUE,          // handles are inherited **** I'm not sure about this
                dwFlag,        // creation flags
                lpEnv,         // environment
                NULL,          // use parent's current directory
                &siStartInfo,  // STARTUPINFO pointer
                &piProcInfo);  // receives PROCESS_INFORMATION

        if (!bl)
        MyErrorExit("Create process failed");

        if (!GetExitCodeProcess(piProcInfo.hProcess, &dwExitCode))
                MyErrorExit("GetExitCodeProcess failed.\n");

        // Close the write end of the pipe before reading from the
    // read end of the pipe.
    if (! CloseHandle(hChildStdoutWr) ||
                ! CloseHandle(hChildStderrWr) )
        MyErrorExit("Closing handle failed");

        // Get the results
        if (dwExitCode != 1) {
                // Program exited with code 0.
                // Read the stdout.
                MyReadFile2Str(strList , hChildStdoutRd);
                if (! CloseHandle(hChildStdoutRd) ||
                        ! CloseHandle(hChildStderrRd) )
                        MyErrorExit("Closing handle failed");
                return TRUE;
        }
        else {
                // Program exited with nonzero code.
                // Read the stderr.
                MyReadFile2Str(strList , hChildStderrRd);
                if (! CloseHandle(hChildStdoutRd) ||
                        ! CloseHandle(hChildStderrRd) )
                        MyErrorExit("Closing handle failed");
                return FALSE;
        }

VOID MyReadFile2Str(CString& str , HANDLE hRead)
/*
   str: receives the results
   hRead: handle to the file to read from
*/
{
        str.Empty();
    DWORD dwRead;
        CHAR chBuf[BUFSIZE+1];

    // Read output from hRead handle, and write it in the chBuf array.
        BOOL br;
    for (;;) {
                br = ReadFile(hRead, chBuf, BUFSIZE, &dwRead, NULL);
                if (!br || dwRead == 0)
                        break;

                strlist += CString(chBuf, dwRead);
        }
        return;

___________________________________________________________
Vartan Akopian
University of Southern California
Department of Mathematics
1042 W. 36th Place, DRB 155
Los Angeles, CA 90089-1113

Look at MSDN article # Q126628
"How to Spawn a Console App and Refdirect Standard Handles".

 ReadFile(hRead, chBuf, BUFSIZE, &dwRead, NULL);

Try the following code. It worked for me at least. Hope it will
help you also.

........................................................................
SECURITY_ATTRIBUTES lsa;
STARTUPINFO         si;
PROCESS_INFORMATION pi;
LPPROCESS_INFORMATION lppi=π

HANDLE hReadPipe, hWritePipe;

CWaitCursor WaitCursor;
lsa.nLength=sizeof(SECURITY_ATTRIBUTES);
lsa.lpSecurityDescriptor=NULL;
lsa.bInheritHandle=TRUE;

if (!CreatePipe(&hReadPipe,&hWritePipe,&lsa,0)) // create the pipe for
output
{
    AfxMessageBox("Couldnt create Pipe\n");
    return;

memset(&si,0,sizeof(STARTUPINFO));
si.cb=sizeof(STARTUPINFO);

//important part - making SW_HIDE we prevent console to open up

si.dwFlags=STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
si.wShowWindow = SW_HIDE;
si.hStdOutput=hWritePipe;

if (!CreateProcess(NULL,
                  "test.exe",
                  NULL,
                  NULL,
                  TRUE,
                  0,
                  NULL,
                  NULL,
                  &si,
                  &pi))
{
     AfxMessageBox("Couldnt Create Process\r\n");
     return;

DWORD cchReadBuffer;  // number of bytes read or to be written
CString sText;
TCHAR ph[5000];

//lets read our output, while being able to catch the moment of program
//shutdown

for (;;){
    cchReadBuffer = 0;
     if(!PeekNamedPipe(hReadPipe,            // ReadFile is blocking call so we should first
         ph,1,&cchReadBuffer,NULL,NULL))   // check if we have something to read
         break;
     if(cchReadBuffer){                 // yes we do, so read it and print out to the edit ctrl
         if (!ReadFile(hReadPipe,
               ph,
               4096,
              &cchReadBuffer,  // number of bytes actually read
               NULL))
                break;
          ph[cchReadBuffer] = 0;

         YourEdit.GetWindowText(sText);
        sText += ph;
        YourEdit.SetWindowText(sText);
        YourEdit.UpdateWindow();

   }
    else     // no we don't have anything in the buffer
          //maybe the program exited
          if(WaitForSingleObject(pi.hProcess,0) == WAIT_OBJECT_0)
               break;        // so we should exit either
          Sleep(500);
        // continue otherwise
     }

CloseHandle(hReadPipe);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
CloseHandle(hWritePipe);

--
Dima Shamroni
Abirnet Ltd., MEMCO Software Company

---
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[Snip]

I've been trying to do this for some time now, but your example is the
only one that has ever worked the way I want.

Thanks,

--Matt

Thanks very much for your code. It worked very well. And especially it
solved one of the major problems I had: ReadFile() was blocking.
Again Thanks.

Vartan

Try the following code. It worked for me at least. Hope it will
help you also.

........................................................................
SECURITY_ATTRIBUTES lsa;
STARTUPINFO         si;
PROCESS_INFORMATION pi;
LPPROCESS_INFORMATION lppi=π

HANDLE hReadPipe, hWritePipe;

CWaitCursor WaitCursor;
lsa.nLength=sizeof(SECURITY_ATTRIBUTES);
lsa.lpSecurityDescriptor=NULL;
lsa.bInheritHandle=TRUE;

if (!CreatePipe(&hReadPipe,&hWritePipe,&lsa,0)) // create the pipe for
output
{
    AfxMessageBox("Couldnt create Pipe\n");
    return;

memset(&si,0,sizeof(STARTUPINFO));
si.cb=sizeof(STARTUPINFO);

//important part - making SW_HIDE we prevent console to open up

si.dwFlags=STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
si.wShowWindow = SW_HIDE;
si.hStdOutput=hWritePipe;

if (!CreateProcess(NULL,
                  "test.exe",
                  NULL,
                  NULL,
                  TRUE,
                  0,
                  NULL,
                  NULL,
                  &si,
                  &pi))
{
     AfxMessageBox("Couldnt Create Process\r\n");
     return;

DWORD cchReadBuffer;  // number of bytes read or to be written
CString sText;
TCHAR ph[5000];

//lets read our output, while being able to catch the moment of program
//shutdown

for (;;){
    cchReadBuffer = 0;
     if(!PeekNamedPipe(hReadPipe,            // ReadFile is blocking
call so we should first
         ph,1,&cchReadBuffer,NULL,NULL))   // check if we have something
to read
         break;
     if(cchReadBuffer){                 // yes we do, so read it and
print out to the edit ctrl
         if (!ReadFile(hReadPipe,
               ph,
               4096,
              &cchReadBuffer,  // number of bytes actually read
               NULL))
                break;
          ph[cchReadBuffer] = 0;

         YourEdit.GetWindowText(sText);
        sText += ph;
        YourEdit.SetWindowText(sText);
        YourEdit.UpdateWindow();

   }
    else     // no we don't have anything in the buffer
          //maybe the program exited
          if(WaitForSingleObject(pi.hProcess,0) == WAIT_OBJECT_0)
               break;        // so we should exit either
          Sleep(500);
        // continue otherwise
     }

CloseHandle(hReadPipe);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
CloseHandle(hWritePipe);

___________________________________________________________
Vartan Akopian
University of Southern California
Department of Mathematics
1042 W. 36th Place, DRB 155
Los Angeles, CA 90089-1113