17.5 Adding Driver Image Handles

The example below shows an internal worker function that adds a driver image handle to the ordered list of driver image handles in the private context data structure. This function is used by the bus driver to register image handles associated with UEFI Drivers discovered on child devices (i.e. when the PCI bus driver discovered UEFI Drivers stored in PCI option ROMs). As each UEFI driver is loaded, this internal worker function is called to add the image handle of the UEFI driver to the Bus Specific Driver Override Protocol. The order that the image handles are registered with AbcAddDriver() is the order in which they are returned from GetDriver().

If there is not enough room in the image handle array, an array with 10 additional handles is allocated. The contents of the old array are transferred to the new array and the old array is freed. The EDK II library MemoryAllocationLib provides the ReallocatePool() function, simplifying the implementations of UEFI Drivers required to manage dynamic memory. Lacking enough memory to allocate the new array, the EFI_OUT_OF_RESOURCES is returned. Once there is enough room to store the new image handle, the image handle is added to the end of the array and EFI_SUCCESS is returned.

Example 168-Adding Driver Image Handles

#include <Uefi.h>
#include <Librray/MemoryAllocationLib.h>

EFI_STATUS EFIAPI
AbcAddDriver (
  IN ABC_PRIVATE_DATA  *Private,
  IN EFI_HANDLE        DriverImageHandle
  )
{
  EFI_HANDLE           *NewBuffer;

  if (Private->NumberOfHandles >= Private->HandleBufferSize) {
    NewBuffer = ReallocatePool (
                  Private->HandleBufferSize * sizeof (EFI_HANDLE),
                  (Private->HandleBufferSize + 10) * sizeof (EFI_HANDLE),
                  Private->HandleBuffer
                  );
    if (NewBuffer == NULL) {
      return EFI_OUT_OF_RESOURCES;
    }
    Private->HandleBufferSize += 10;
    Private->HandleBuffer = NewBuffer;
  }
  Private->HandleBuffer[Private->NumberOfHandles] = DriverImageHandle;
  Private->NumberOfHandles++;
  return EFI_SUCCESS;
}