DuplicateHandle (), use in the first or second process?

Question

Windows API DuplicateHandle () http://msdn.microsoft.com/en-us/library/ms724251(VS.85).aspx Requires duplication of the Object and a handle to both the source process and the other process in which you want to use the duplicated descriptor.

I assume that if I have two UNSPECIFIED processes, could I call DuplicateHandle () in one of them while I had available descriptors available?

My question is using Pipe to communicate between two processes to achieve this using an event.

In the first process, I CreateEvent (). Now I want to use WaitForSingleObject () in the second process.

If I try to duplicate the descriptor in the first process, will I need to first send the second descriptor of the process to the first process through the channel, duplicate the descriptor, and then send the descriptor to the second process?

Alternatively, I could start by sending the first process descriptor and the event descriptor to the second process and simply duplicate it there.

Is there a reason I should choose one after another?

To add wrinkle, the event descriptor is inherited from the parent process, which is actually called the first process (which is a CGI application). If this event descriptor was created using HANDLE_DO_NOT_DUPLICATE (something like this), can I actually use DuplicateHandle () to duplicate it for the second process?

Answer:

, NAMED , , DUPLICATE , , , , DuplicateHandle().

IPC. , DuplicateHandle() , .

        hProcPseudo  = GetCurrentProcess() 

    //Then call either:
        lpRealHandle = OpenProcess( PROCESS_DUP_HANDLE, 0, hProcPseudo ) 
//This fails with GetLastError= 87 - The parameter is incorrect ???
// same thing with PROCESS_ALL_ACCESS ??


    //OR
        lRet = DuplicateHandle( hProcPseudo, hProcPseudo, hProcPseudo, lpRealHandle, DUPLICATE_SAME_ACCESS, 0, 0 )

    //then I can Duplicate my Event Handle in the first thread with:
        lRet = DuplicateHandle( hLocalProcess, hEvent, lpRealHandle, hDupEvent, DUPLICATE_SAME_ACCESS, 0, 0)

DuplicateHandle(), ,

hProcPseudo = 4294967295

hProcess = 152

. ( ) Duplicate handle:

DuplicateHandle( hFirstProcess, hEvent, hSecondProc, hDupEvent, DUPLICATE_SAME_ACCESS, 0, 0)

, :

DuplicateHandle hPipeFCGI GetLastError = 6 - .

( hFirstProcess) , hSecondProc !??

.

Answer 1

named pipe mailslots IPC, . , wait.

DuplicateHandle , .

Answer 2

, . , .

CreateEvent API, , OpenEvent API, .

, (OpenMutex) (OpenSemaphore).

Answer 3

• -, . GetCurrentProcessId()
• , HANDLE : hProcess = OpenProcess(PROCESS_DUP_HANDLE, FALSE, dwProcessId);
• , REAL- - : DuplicateHandle(GetCurrentProcess(), hEvent, hProcess, &hDupEvent, 0, FALSE, DUPLICATE_SAME_ACCESS);
• , OpenProcess ( , , ...). , BOTH : , .

Answer 4

. OpenProcess . - ...

HANDLE hProcess = OpenProcess (PROCESS_DUP_HANDLE, FALSE, GetCurrentProcessId());