Creates a new bare Git index object, without a repository to back
it. This index object is capable of storing SHA256 objects.
int git_index_open_ext(git_index **index_out, const char *index_path, const git_index_options *opts);
In
index_out
the pointer for the new index
const char *
In
index_path
the path to the index file in disk
In
opts
the options for opening the index, or NULL
