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    <ol> <li>This method implemented as unmanaged function internally. You can download <a href="http://www.microsoft.com/download/en/details.aspx?id=4917" rel="nofollow">Shared Source Common Language</a> and take a look at that method implementation.</li> </ol> <p>Here the code that I found in safechandle.cpp file:</p> <pre><code>FCIMPL2(void, SafeHandle::DangerousAddRef, SafeHandle* refThisUNSAFE, CLR_BOOL *pfSuccess) { CONTRACTL { THROWS; MODE_COOPERATIVE; DISABLED(GC_TRIGGERS); SO_TOLERANT; } CONTRACTL_END; SAFEHANDLEREF sh(refThisUNSAFE); HELPER_METHOD_FRAME_BEGIN_1(sh); if (pfSuccess == NULL) COMPlusThrow(kNullReferenceException); sh-&gt;AddRef(); *pfSuccess = TRUE; HELPER_METHOD_FRAME_END(); } FCIMPLEND </code></pre> <p>But I'm not sure is it usefull or not.</p> <hr> <p>And now about second question.</p> <p>During marshalling from managed code to native code object marshallel converts any <code>SafeHandle</code> to <code>IntPtr</code> by calling <code>DangerousGetHandle</code> method.</p> <p>During unmarshalling from native code to managed code there is opposed conversion: any <code>IntPtr</code> returns as <code>SafeHandle</code>.</p> <p>When you're calling any unmanaged code that takes <code>DWORD</code> or <code>PVOID</code> we could pass <code>SafeHandle</code> or one of its descendants.</p> <p>For example if we have a couple of external functions in our umanaged DLL:</p> <pre><code>PVOID CreateCustomHandle(); void ReleaseCustomHandle(PVOID handle); </code></pre> <p>We could call them in following way:</p> <pre><code>[DllImport("kernel32")] public static extern MySafeHandle CreateCustomHandle(); [DLLImport("kernel32")] public static extern void ReleaseCustomHandle(MySafeHandle handle); </code></pre> <p>Where <code>MySafeHandle</code> is subclass of <code>SafeHandle</code> class that knows how to deal with that particular resource.</p>
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    1. COThanks You helped me. What about the second question?
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    2. CODuring Safehandle to IntPtr conversion, how he knows which method should be invoked to actually obtain the underlying handle? (why it is: DangerousGetHandle) And How does he knowh which method to use to create SafeHandle from IntPtr? or maybe it happens through the reflection. It is looking for a suitable method returning the expected variable type?
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    3. COThis marshaller actually not call DangerousGetHandle, at least I can't find direct call for that method. You can take a look at marshaler.h yourself (and to additional files as well, like cgenx86.cpp) but there are a lot of low level stuff that very hard to read and understand. But any way, we can thing about it in following way: SafeHande is implicitly convertible to and from IntPtr by some internal CLR stuff. So anytime you have IntPtr in native code you should use SafeHandle or one of it descendants.
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