Re: [PATCH 02/10] builtin/fast-import: fix segfault with unsafe SHA1

Patrick Steinhardt [off-list ref] writes:

I think the ideal state would be if the hashing function used was stored
as part of `struct git_hash_ctx`. So the flow basically becomes for
example:

    struct git_hash_ctx ctx;
    struct object_id oid;

    git_hash_sha1_init(&ctx);
    git_hash_update(&ctx, data);
    git_hash_final_oid(&oid, &ctx);

Note how the intermediate calls don't need to know which hash function
you used to initialize the `struct git_hash_ctx` -- the structure itself
should remember what it has been initilized with and do the right thing.

Yup, that sounds perfect.