Different behavior using CreateProcess vs. launching directly...

[MrViggy]

Hey all,

This is interesting. I have two MFC based apps, one dialog based, one MDI based. The dialog based app has the ability to launch the MDI app, using CreateProcess:

   PROCESS_INFORMATION procInfo;
        STARTUPINFO startInfo;
        memset (&startInfo, 0, sizeof(STARTUPINFO));
        startInfo.cb = sizeof(STARTUPINFO);
        ::CreateProcess(
            NULL,                                               // name of executable module
            commandLine.GetBuffer(commandLine.GetLength()+1),   // command line string
            NULL,                                               // SD
            NULL,                                               // SD
            FALSE,                                              // handle inheritance option
            DETACHED_PROCESS,                                   // creation flags
            NULL,                                               // new environment block
            NULL,                                               // current directory name
            &startInfo,                                               // startup information
            &procInfo                                                // process information
            );
        commandLine.ReleaseBuffer();
		::CloseHandle(procInfo.hThread);
		::CloseHandle(procInfo.hProcess);

Where 'commandLine' is:

"d:\Projects\FR\debugbin\AppName" ""D:\Projects\FR\test\001148940"

In re-reading the docs, I guess I don't need the "DETACHED_PROCESS" flag, as this is not a console app.

Anyhow, if I launch the app this way, I get all sorts or weirdness when printing in the second (MDI) app. First, my clients are saying that no matter what, a maximum of 3 pages is printed. Whether they specify a range, or try to print the whole document.

I just recompiled both apps to use MFC statically (CRT statically, too), and they are now getting an error when printing ("Improper Argument") when printing. I do get an assertion in the CView class:

In CView::DoPreparePrinting:
ENSURE(pInfo->m_strPageDesc.LoadString(AFX_IDS_PREVIEWPAGEDESC));

I can reproduce the issues they are seeing; however, I cannot reproduce *any* of this if I run the MDI app standalone!!! Everything works great!

My guess is that this is some result of the fact that the MDI app is a child process of the dialog app. Is there a trick to doing something like this?

Thanks!!!

Viggy

[Arjay]

My guess is that this is some result of the fact that the MDI app is a child process of the dialog app.

Windows doesn't really have the concept of a child process. I would remove the DETACH_PROCESS flag and set the lpCurrentDirectory to the location where the new exe is located.

[MrViggy]

Hmm, interesting. I bluffed! Well, okay, maybe not exactly. I do see this strange behavior when I run standalone. All I did was change to statically link the MFC and CRT libraries.

Viggy