C / C++ / MFC

Re: Shell Executing From VC++

7-Mar-06 23:58

A Demo[^]

Nibu thomas
Software Developer

Malli_S8-Mar-06 0:25

Malli_S

8-Mar-06 0:25

Thanks Thomas !
It Worked ! I was under impression that CreateProcess()also behave like ShellExecute(), and would give same problem!

-Malli...!

Re: Shell Executing From VC++

David Crow8-Mar-06 2:26

8-Mar-06 2:26

Malli_S wrote:
I've tried with waitforsingleobject() using handle returned by ShellExecute(). That didn't work.

You'll need to use ShellExecuteEx() instead.

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

Process hirarchy

Aqueel7-Mar-06 23:40

7-Mar-06 23:40

Hello
Does Windows support process hirarchy. That is we can create a process from parent process using CreateProcess(...). Can we create another process from the newly created child process? I have read somewhere that Windows does not support process hirarchy.

Here is a reference code from MSDN.

#include <windows.h><br />
#include <stdio.h><br />
<br />
void main( VOID )<br />
{<br />
    TCHAR szCmdline[]=TEXT("MyChildProcess");<br />
    STARTUPINFO si;<br />
    PROCESS_INFORMATION pi;<br />
<br />
    ZeroMemory( &si, sizeof(si) );<br />
    si.cb = sizeof(si);<br />
    ZeroMemory( &pi, sizeof(pi) );<br />
<br />
    // Start the child process. <br />
    if( !CreateProcess( NULL,   // No module name (use command line)<br />
        szCmdline,      // Command line<br />
        NULL,           // Process handle not inheritable<br />
        NULL,           // Thread handle not inheritable<br />
        FALSE,          // Set handle inheritance to FALSE<br />
        0,              // No creation flags<br />
        NULL,           // Use parent's environment block<br />
        NULL,           // Use parent's starting directory <br />
        &si,            // Pointer to STARTUPINFO structure<br />
        &pi )           // Pointer to PROCESS_INFORMATION structure<br />
    ) <br />
    {<br />
        printf( "CreateProcess failed (%d).\n", GetLastError() );<br />
        return;<br />
    }<br />
<br />
    // Wait until child process exits.<br />
    WaitForSingleObject( pi.hProcess, INFINITE );<br />
<br />
    // Close process and thread handles. <br />
    CloseHandle( pi.hProcess );<br />
    CloseHandle( pi.hThread );<br />
}

In above code, a child process has been created. I want to ask can we create nested child process using newly created process in above example.
Thank you.

We Believe in Excellence

Nibu babu thomas8-Mar-06 0:36

8-Mar-06 0:36

Windows processes do not share a hierarchical relationship. The creating process receives the process handle and ID of the process it created so a hierarchical relationship can be maintained/simulated if the application requires it to do so. However, the operating system treats all processes as belonging to the same generation.

Processes in windows (by default) inherit the security settings of the creating process.

Nibu thomas
Software Developer

Aqueel8-Mar-06 1:06

8-Mar-06 1:06

OK. In the example given in previous message, infomation about new process (lets say it ProcessA)has been stored in PROCESS_INFORMATION. How can i create a new process that is child process of ProcessA?
Thank You.

We Believe in Excellence

Nibu babu thomas8-Mar-06 1:15

8-Mar-06 1:15

Aqueel wrote:
OK. In the example given in previous message, infomation about new process (lets say it ProcessA)has been stored in PROCESS_INFORMATION. How can i create a new process that is child process of ProcessA?

No you cannot create a child process of another process. Of course you can maintain a process hierarchy in your application.

Nibu thomas
Software Developer

Aqueel8-Mar-06 1:21

8-Mar-06 1:21

Thank you Nibu.
If i can not create that process then what is meant by maintainig hirarchy. Are you meant by single level hirarchy.

We Believe in Excellence

Nibu babu thomas8-Mar-06 1:28

8-Mar-06 1:28

Aqueel wrote:
If i can not create that process then what is meant by maintainig hirarchy. Are you meant by single level hirarchy.

No. As said in my first reply you can simulate a hierarchical behavior in your application. But it make no difference to the OS.

Nibu thomas
Software Developer

Aqueel8-Mar-06 1:34

8-Mar-06 1:34

Sorry Nibu. It seems i am not getting it. As you said that we can simulate hirarical behavior. I want to ask that how can i do that?
Thank you.

We Believe in Excellence

Nibu babu thomas8-Mar-06 1:37

8-Mar-06 1:37

Aqueel wrote:
Sorry Nibu. It seems i am not getting it. As you said that we can simulate hirarical behavior. I want to ask that how can i do that?
Thank you.

Maintain a hierarchical structure of the processes that you create in your application. Now you have to decide which one is a parent process and which one is a child process.

Nibu thomas
Software Developer

[OT]

toxcct8-Mar-06 1:53

toxcct

8-Mar-06 1:53

can't you click the [Reply] link on the guy's response you want to give feedback instead of replying to yourself ?! Hmmm | :|

Re: [OT]

David Crow8-Mar-06 2:29

8-Mar-06 2:29

I guess that would create some sort of thread hierarchy. Wink | ;)

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

Re: [OT]

Eytukan8-Mar-06 2:50

Eytukan

8-Mar-06 2:50

timing!! 5

VuNic

Aqueel8-Mar-06 1:47

8-Mar-06 1:47

Thank you Nibu. I got it. Can you please tell me its reason i mean why does windows not support process hirarchy.
Thank you again

We Believe in Excellence

jhwurmbach8-Mar-06 2:48

jhwurmbach

8-Mar-06 2:48

Aqueel wrote:
Can you please tell me its reason i mean why does windows not support process hirarchy

Deliberate design decision.
Why sould one have primary processes and processes of second, third... order?
In Unixoid systems this decision was made to allow some simulation of threads. Threads on Unix( Linux) are only now gaining momentum (NPTL).

In Windows, threads where there right from the start (of real, NT-type Windows, not graphical DOS-Extenders).
So there was simply no need for a logically not justified hierarchy among them.

"We trained hard, but it seemed that every time we were beginning to form up into teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by reorganising: and a wonderful method it can be for creating the illusion of progress, while producing confusion, inefficiency and demoralisation."

-- Caius Petronius, Roman Consul, 66 A.D.

David Crow8-Mar-06 2:32

8-Mar-06 2:32

Aqueel wrote:
Can we create another process from the newly created child process?

Of course. CreateProcess() can be used as many times as needed. Process A can start process B, which can start process C, which can start process D, etc.

"Let us be thankful for the fools. But for them the rest of us could not succeed." - Mark Twain

"There is no death, only a change of worlds." - Native American Proverb

Aqueel8-Mar-06 2:45

8-Mar-06 2:45

Hello Mr. David,
I used CreateProcess to create a child process called processA. Now i want to create child process of processA. How can i do that?
Thank you.

We Believe in Excellence

jhwurmbach8-Mar-06 2:52

jhwurmbach

8-Mar-06 2:52

Aqueel wrote:
Now i want to create child process of processA. How can i do that

You have ProcessB call CreateProcess.
But these (then) three processes do not share a inherent hierarchical relationship.
They are independent processes of the system.
With inter-process-communication you can send messages about creation of another child-process to the creator so that you can maintain somthing like a graph.
But you have to do that yourself.

David Crow8-Mar-06 2:53