std::string getCanonicalEfiDevicePath(const CFDataRef& data) {
std::string path;
// Iterate through the EFI_DEVICE_PATH_PROTOCOL stacked structs.
auto bytes = CFDataGetBytePtr((CFDataRef)data);
size_t length = CFDataGetLength((CFDataRef)data);
size_t search_offset = 0;
while ((search_offset + sizeof(EFI_DEVICE_PATH_PROTOCOL)) < length) {
auto node = (const EFI_DEVICE_PATH_PROTOCOL*)(bytes + search_offset);
if (EfiIsDevicePathEnd(node)) {
// End of the EFI device path stacked structs.
break;
}
if (EfiDevicePathNodeLength(node) + search_offset > length) {
// Malformed EFI device header.
break;
}
// Only support paths and hard drive partitions.
if (EfiDevicePathType(node) == MEDIA_DEVICE_PATH) {
if (node->SubType == MEDIA_FILEPATH_DP) {
for (int i = 0; i < EfiDevicePathNodeLength(node); i += 2) {
// Strip UTF16 characters to UTF8.
path += (((char*)(node)) + sizeof(EFI_DEVICE_PATH_PROTOCOL))[i];
}
} else if (node->SubType == MEDIA_HARDDRIVE_DP) {
// Extract the device UUID to later join with block devices.
auto uuid = ((const HARDDRIVE_DEVICE_PATH*)node)->Signature;
boost::uuids::uuid hdd_signature = {{
uuid[3], uuid[2], uuid[1], uuid[0],
uuid[5], uuid[4],
uuid[7], uuid[6],
uuid[8], uuid[9],
uuid[10], uuid[11], uuid[12], uuid[13], uuid[14], uuid[15],
}};
path += boost::to_upper_copy(boost::uuids::to_string(hdd_signature));
}
}
search_offset += EfiDevicePathNodeLength(node);
}
return path;
}
//
// get partition handle by number
//
EFI_HANDLE DevPathGetPartitionHandleByNumber(EFI_DEVICE_PATH_PROTOCOL* referencePath, UINT32 number)
{
UINTN nodeCount = DevPathGetNodeCount(referencePath);
if(!nodeCount)
return nullptr;
UINTN count = 0;
EFI_HANDLE* handleArray = nullptr;
if(EFI_ERROR(EfiBootServices->LocateHandleBuffer(ByProtocol, &EfiBlockIoProtocolGuid, nullptr, &count, &handleArray)))
return nullptr;
EFI_HANDLE retValue = nullptr;
for(UINTN i = 0; i < count; i ++)
{
EFI_HANDLE theHandle = handleArray[i];
if(!theHandle)
continue;
EFI_DEVICE_PATH_PROTOCOL* devicePath = DevPathGetDevicePathProtocol(theHandle);
if(!devicePath)
continue;
if(DevPathGetNodeCount(devicePath) != nodeCount)
continue;
EFI_DEVICE_PATH_PROTOCOL* pathA = referencePath;
EFI_DEVICE_PATH_PROTOCOL* pathB = devicePath;
BOOLEAN checkResult = TRUE;
for(UINTN i = 0; i < nodeCount && !EfiIsDevicePathEnd(pathA) && !EfiIsDevicePathEnd(pathB); i ++)
{
if(EfiDevicePathNodeLength(pathA) != EfiDevicePathNodeLength(pathB))
{
checkResult = FALSE;
break;
}
#if 0
if(pathA->Type == MESSAGING_DEVICE_PATH && pathA->SubType == MSG_VENDOR_DP && !memcmp(pathA + 1, &EfiDevicePathMessagingSASGuid, sizeof(EFI_GUID)))
{
SAS_DEVICE_PATH* sasA = _CR(pathA, SAS_DEVICE_PATH, Header);
SAS_DEVICE_PATH* sasB = _CR(pathB, SAS_DEVICE_PATH, Header);
if(sasA->SasAddress != sasB->SasAddress || sasA->Lun != sasB->Lun || sasA->RelativeTargetPort != sasB->RelativeTargetPort)
{
checkResult = FALSE;
break;
}
}
#endif
if(memcmp(pathA, pathB, EfiDevicePathNodeLength(pathA)))
{
checkResult = FALSE;
break;
}
}
if(!checkResult)
continue;
if(DevPathGetPartitionNumber(devicePath) != number)
continue;
retValue = theHandle;
break;
}
MmFreePool(handleArray);
return retValue;
}
