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uefi

Verifying that EFI device path is valid

I want to check efi image path is valid, This is the code: 

 gBS->LocateHandleBuffer (
         ByProtocol,
         &gEfiSimpleFileSystemProtocolGuid,
         NULL,
         &NumberSimpleFileSystemHandles,
         &SimpleFileSystemHandles
         );
  for (Index = 0; Index < NumberSimpleFileSystemHandles; Index++) {
   TempImagePath = FileDevicePath (SimpleFileSystemHandles[Index], L"\\EFI\\BOOT\\boo.efi");
   if(IsDevicePathValid(TempImagePath,sizeof(EFI_DEVICE_PATH_PROTOCOL)) == TRUE){
          //OK
  }

This code always returns that the path is invalid, I think there is a problem in the second parameter of IsDevicePathValid.

What is the problem?

Thanks.

Solution

  • IsDevicePathValid returns false if the total length of the device path exceeds the value of the second parameter, MaxPath. Obviously it exceeds sizeof (EFI_DEVICE_PATH_PROTOCOL), which is 4. You should pass 0 for this parameter.