IDXGIResource1::CreateSharedHandle method

Creates a handle to a shared resource. You can then use the returned handle with multiple Direct3D devices.

Syntax


HRESULT CreateSharedHandle(
  [in]   const SECURITY_ATTRIBUTES *pAttributes,
  [in]   DWORD dwAccess,
  [in]   LPCWSTR lpName,
  [out]  HANDLE *pHandle
);

Parameters

pAttributes [in]

A pointer to a SECURITY_ATTRIBUTES structure that contains two separate but related data members: an optional security descriptor, and a Boolean value that determines whether child processes can inherit the returned handle.

Set this parameter to NULL if you want child processes that the application might create to not inherit the handle returned by CreateSharedHandle, and if you want the resource that is associated with the returned handle to get a default security descriptor.

The lpSecurityDescriptor member of the structure specifies a SECURITY_DESCRIPTOR for the resource. Set this member to NULL if you want the runtime to assign a default security descriptor to the resource that is associated with the returned handle. The ACLs in the default security descriptor for the resource come from the primary or impersonation token of the creator. For more info, see Synchronization Object Security and Access Rights.

dwAccess [in]

The requested access rights to the resource. In addition to the generic access rights, DXGI defines the following values:

  • DXGI_SHARED_RESOURCE_READ ( 0x80000000L ) - specifies read access to the resource.
  • DXGI_SHARED_RESOURCE_WRITE ( 1 ) - specifies write access to the resource.

You can combine these values by using a bitwise OR operation.

lpName [in]

The name of the resource to share. The name is limited to MAX_PATH characters. Name comparison is case sensitive. You will need the resource name if you call the ID3D11Device1::OpenSharedResourceByName method to access the shared resource by name. If you instead call the ID3D11Device1::OpenSharedResource1 method to access the shared resource by handle, set this parameter to NULL.

If lpName matches the name of an existing resource, CreateSharedHandle fails with DXGI_ERROR_NAME_ALREADY_EXISTS. This occurs because these objects share the same namespace.

The name can have a "Global\" or "Local\" prefix to explicitly create the object in the global or session namespace. The remainder of the name can contain any character except the backslash character (\). For more information, see Kernel Object Namespaces. Fast user switching is implemented using Terminal Services sessions. Kernel object names must follow the guidelines outlined for Terminal Services so that applications can support multiple users.

The object can be created in a private namespace. For more information, see Object Namespaces.

pHandle [out]

A pointer to a variable that receives the NT HANDLE value to the resource to share. You can use this handle in calls to access the resource.

Return value

Returns S_OK if successful; otherwise, returns one of the following values:

  • DXGI_ERROR_INVALID_CALL if one of the parameters is invalid.
  • DXGI_ERROR_NAME_ALREADY_EXISTS if the supplied name of the resource to share is already associated with another resource.
  • E_ACCESSDENIED if the object is being created in a protected namespace.
  • E_OUTOFMEMORY if sufficient memory is not available to create the handle.
  • Possibly other error codes that are described in the DXGI_ERROR topic.

Platform Update for Windows 7:  On Windows 7 or Windows Server 2008 R2 with the Platform Update for Windows 7 installed, CreateSharedHandle fails with E_NOTIMPL. For more info about the Platform Update for Windows 7, see Platform Update for Windows 7.

Remarks

CreateSharedHandle only returns the NT handle when you created the resource as shared and specified that it uses NT handles (that is, you set the D3D11_RESOURCE_MISC_SHARED_NTHANDLE and D3D11_RESOURCE_MISC_SHARED_KEYEDMUTEX flags). If you created the resource as shared and specified that it uses NT handles, you must use CreateSharedHandle to get a handle for sharing. In this situation, you can't use the IDXGIResource::GetSharedHandle method because it will fail.

You can pass the handle that CreateSharedHandle returns in a call to the ID3D11Device1::OpenSharedResource1 method to give a device access to a shared resource that you created on a different device.

Because the handle that CreateSharedHandle returns is an NT handle, you can use the handle with CloseHandle, DuplicateHandle, and so on. You can call CreateSharedHandle only once for a shared resource; later calls fail. If you need more handles to the same shared resource, call DuplicateHandle. When you no longer need the shared resource handle, call CloseHandle to close the handle, in order to avoid memory leaks.

If you pass a name for the resource to lpName when you call CreateSharedHandle to share the resource, you can subsequently pass this name in a call to the ID3D11Device1::OpenSharedResourceByName method to give another device access to the shared resource. If you use a named resource, a malicious user can use this named resource before you do and prevent your app from starting. To prevent this situation, create a randomly named resource and store the name so that it can only be obtained by an authorized user. Alternatively, you can use a file for this purpose. To limit your app to one instance per user, create a locked file in the user's profile directory.

If you created the resource as shared and did not specify that it uses NT handles, you cannot use CreateSharedHandle to get a handle for sharing because CreateSharedHandle will fail.

Windows Phone 8: This API is supported.

Examples

ID3D11Texture2D* pTexture2D;
ID3D11Device* pDevice;

pDevice->CreateTexture2D(…, &pTexture2D); // Create the texture as shared with NT HANDLEs.

HANDLE handle;
IDXGIResource1* pResource;
pTexture2D->QueryInterface(__uuidof(IDXGIResource1), (void**) &pResource);
pResource->CreateSharedHandle(NULL, 
         DXGI_SHARED_REOUSRCE_READ | DXGI_SHARED_RESOURCE_WRITE, 
         NULL,
         &handle);

// Pass the handle to another process to share the resource.

Requirements

Minimum supported client

Windows 8 and Platform Update for Windows 7 [desktop apps | Windows Store apps]

Minimum supported server

Windows Server 2012 and Platform Update for Windows Server 2008 R2 [desktop apps | Windows Store apps]

Header

DXGI1_2.h

Library

Dxgi.lib

See also

IDXGIResource1

 

 

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