win32 equivalent of system()

Hi All,

I'm a unix programmer and I'm trying to find the best way of running an external programm using win32 and getting it's exit status. So, what is the equivalent of using System()?

I've noticed that there is a _popen() function, but I don't need to communicate with the process - just call it and get the exit status.

Any ideas?

rotis23

CreateProcess()
WaitForSingleObject()
GetExitCodeProcess()
CloseHandle()

Search board or web for samples.

There's a System() function in Windows. It's not the best way of doing things, though.

Thanks for the pointer.

I'm having a couple problems with GetExitCodeProcess. My code:

Code:

---

if(CreateProcess(fullPath,args, 0, 0, false,
                CREATE_DEFAULT_ERROR_MODE, 0, 0, &siStartupInfo,
                        &piProcessInfo) != false)
        {
                /* A loop to watch the process. Dismissed with SecondsToWait set to 0 */
                GetExitCodeProcess(piProcessInfo.hProcess, &dwExitCode);

                while (dwExitCode == STILL_ACTIVE && SecondsToWait != 0)
                {
                        GetExitCodeProcess(piProcessInfo.hProcess, &dwExitCode);
                        Sleep(500);
                        iMyCounter += 500;

                        if (iMyCounter > (SecondsToWait * 1000))
                        {
                                dwExitCode = 0;
                        }
                }
        }
        else
        {
                iReturnVal = 2;
        }

---

I'm getting back error 127 (ERROR_PROC_NOT_FOUND) and the process is completing successfully.


I guess I should use waitforsingleobject?

rotis23

>> I'm getting back error 127 (ERROR_PROC_NOT_FOUND) <<

How? The code you posted does not contain a call to GetLastErrror(). Your code looks fine.

>> I guess I should use waitforsingleobject? <<

Yes. WaitForSingleObject is simpler and you don't have to worry about the child process returning STILL_ACTIVE.

Code:

---

if (CreateProcess(...))
{
    if (WAIT_OBJECT_0 == WaitForSingleObject(pi.hProcess, cSeconds * 1000))
    {
          // Process is finished
          GetExitCodeProcess(...);
    }
    else
    {
          // Timeout or error
    }

    CloseHandle(pi.hThread);
    CloseHandle(pi.hProcess);
}

---

Thanks

I've changed to use WaitForSingleObject but I'm still getting back error 127 (ERROR_PROC_NOT_FOUND) and the process is completing successfully.

Any ideas? Could it be the way I'm calling CreateProcess?

1 more question (I still have the problem above).

When running the above code froma service - how do I stop the command window popping up when the process is created?

To stop the window popping up use DETACHED_PROCESS as an argument to CreateProcess.

Google doesn't know about error 127 though.

I'm assuming the 127 is being returned by GetLastError()? When do you call GetLastError()? GetLastError() will only return a valid value immediately after an API call has failed. Is this a 16bit or DOS process you are launching?

Have a look at this thread:
http://groups.google.com/groups?thre...eld.com&rnum=2

Thanks for your help anonytmouse.

That thread doesn't really shed any light - I've done a good amount of googling.

I'm actaully calling pscp (Putty Secure Copy) to send a file via ssh to a unix box. I guess that 16bit?????

I call getlasterror directly after successfully calling getexitcodeprocess:

Code:

---

/* CreateProcess API initialization */
        STARTUPINFO siStartupInfo;
        PROCESS_INFORMATION piProcessInfo;
        memset(&siStartupInfo, 0, sizeof(siStartupInfo));
        memset(&piProcessInfo, 0, sizeof(piProcessInfo));
        siStartupInfo.cb = sizeof(siStartupInfo);
        siStartupInfo.dwFlags = STARTF_USESHOWWINDOW;
          siStartupInfo.wShowWindow = SW_HIDE;

if(CreateProcess(fullPath,args,NULL,NULL, false,
                CREATE_DEFAULT_ERROR_MODE, NULL, NULL, &siStartupInfo,
                        &piProcessInfo) != false)
        {

                if (WAIT_OBJECT_0 == WaitForSingleObject(piProcessInfo.hProcess,timeout * 1000))
                {
                        if(GetExitCodeProcess(piProcessInfo.hProcess, &dwExitCode))
                        {
                                printf("exited - %d - %d\n",dwExitCode,GetLastError());
                        }
                        else
                        {
                                dwExitCode = GetLastError();
                        }
                }
                else
                {
                        //timeout or error
                        dwExitCode = GetLastError();
                }

                CloseHandle(piProcessInfo.hProcess);
                CloseHandle(piProcessInfo.hThread);
        }
        else
        {
                dwExitCode = GetLastError();
        }

---

Quote:

---

Originally Posted by anonytmouse

GetLastError() will only return a valid value immediately after an API call has failed.

---

unless otherwise stated in MSDN.

Some API functions will call other API functions which may fail and use SetLastError(). However, the parent function may recover and return successfully. Why @err is 127 after GetExitCodeProcess() returns, I can't even guess.

Quote:

---

Originally Posted by rotis23

I'm actaully calling pscp (Putty Secure Copy) to send a file via ssh to a unix box. I guess that 16bit?????

---

32 :)

Ah - OK - I see - the function suceeded and therefore getlasterror doesn't mean anything.

I'm trying to find out why the return status of of getexitcodeprocess is 0 - even though the process suceeds in what it's doing (scp'ing a file).

hmmmmmmm

I guess this could be that pscp is not returning it's exit status correctly. I'll try and dig around more - thanks for all your help so far.

As far as process return values:

Code:

---

0  == EXIT_SUCCESS

!0 == EXIT_FAILURE

---

Same across windows and nix.

This lets you return a range of failure values.

The source for pscp is available online. If you look in SCP.c you will find at the bottom of the main() function:

Code:

---

    return (errs == 0 ? 0 : 1);

---

P.S If you've spent a couple of days trying to figure out this "error", please check below before you chuck your monitor out the window.

I think it ryhmes with clucking bell!

Sorry to waste your time anonytmouse - I guess we solved some other problems and clarified some issues along the way!

rotis23