Open a diff from %G blame without opening the commit? (File for current blame?)

[idbrii]

Currently, to open a commit from a blame I take advantage of how <CR> opens a :Gdiffsplit when the cursor is on the 'diff --git' line of a commit view. Mapping in ~/.vim/after/ftplugin/fugitiveblame.vim with:

nmap <buffer> dd <CR>?^diff<CR><CR>

However, is it possible to skip opening the commit? Sometimes our commits are huge and slow to open (binary files and bad merges, I can't prevent it). If I could :Gedit sha:file and then :Gdiff sha~, then that should work. But I don't know how to get file because the fugitiveblame file is a temp file.

Even worse, I actually always use :%G blame to skip the scrollbind and just view the blame contents so there isn't another window with the file.

Is there some way to get the filename for the current blame buffer?

[JoaoNevez]

git blame -L 42,42 path/to/file

[idbrii]

That opens a blame for a single line of the file but how do I jump from that to a split diff that introduced that line?