find-buffer-visiting

find-buffer-visiting is a compiled Lisp function in `files.el'.

(find-buffer-visiting FILENAME &optional PREDICATE)

Return the buffer visiting file FILENAME (a string).
This is like `get-file-buffer', except that it checks for any buffer
visiting the same file, possibly under a different name.
If PREDICATE is non-nil, only buffers satisfying it are eligible,
and others are ignored.
If there is no such live buffer, return nil.