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Language: Enterprise
Expertise: Advanced

Apr 24, 2001

Whenever a handle is passed to another thread, use the DuplicateHandle API to create a duplicate handle to the same object and pass this duplicated handle to the thread. That way, Thread A can use the original handle and Thread B can use the duplicated handle without worrying about each other.

The following code will create a duplicate handle dupHandle for hHandle. When both handles are closed, the object is destroyed.

 
HANDLE hHandle = CreateFile(...); //used by Thread A

HANDLE dupHandle; //used by thread B

DulplicateHandle(GetCurrentProcess(),hHandle, GetCurrentProcess(),
&dupHandle, 0, FALSE, DUPLICATE_SAME_ACCESS);