Re: [PATCH v6 4/5] builtin/stash: provide a way to export stashes to a ref

> +static int check_stash_topology(struct repository *r, struct commit *stash)
> +{
> +	struct commit *p1, *p2, *p3 = NULL;
> +
> +	/* stash must have two or three parents */
> +	if (!stash->parents || !stash->parents->next ||
> +			(stash->parents->next->next && stash->parents->next->next->next))
> +		return -1;
> +	p1 = stash->parents->item;
> +	p2 = stash->parents->next->item;
> +	if (stash->parents->next->next)
> +		p3 = stash->parents->next->next->item;
> +	if (repo_parse_commit(r, p1) || repo_parse_commit(r, p2) ||
> +			(p3 && repo_parse_commit(r, p3)))
> +		return -1;
> +	/* p2 must have a single parent, p3 must have no parents */
> +	if (!p2->parents || p2->parents->next || (p3 && p3->parents))
> +		return -1;
> +	if (repo_parse_commit(r, p2->parents->item))
> +		return -1;
> +	/* p2^1 must equal p1 */
> +	if (!oideq(&p1->object.oid, &p2->parents->item->object.oid))
> +		return -1;
> +
> +	return 0;
> +}

> +	this = lookup_commit_reference(r, oid);
> +	buffer = repo_get_commit_buffer(r, this, &bufsize);
> +	orig_author = find_commit_header(buffer, "author", &author_len);
> +	orig_committer = find_commit_header(buffer, "committer", &committer_len);
> +
> +	if (!orig_author || !orig_committer) {
> +		ret = error(_("cannot parse commit %s"), oid_to_hex(oid));
> +		goto out;
> +	}
> +
> +	if (split_ident_line(&id, orig_author, author_len) < 0 ||
> +	    split_ident_line(&id, orig_committer, committer_len) < 0) {
> +		ret = error(_("invalid author or committer for %s"), oid_to_hex(oid));
> +		goto out;
> +	}
> +
> +	p = strstr(buffer, "\n\n");
> +	strbuf_addstr(&msg, "git stash: ");
> +
> +	if (p)
> +		strbuf_add(&msg, p + 2, bufsize - (p + 2 - buffer));
> +	strbuf_complete_line(&msg);
> +
> +	author = xmemdupz(orig_author, author_len);
> +	committer = xmemdupz(orig_committer, committer_len);
> +
> +	if (commit_tree_extended(msg.buf, msg.len,
> +				 r->hash_algo->empty_tree, parents,
> +				 out, author, committer,
> +				 NULL, NULL)) {
> +		ret = error(_("could not write commit"));
> +		goto out;
> +	}
> +out:
> +	strbuf_release(&msg);
> +	repo_unuse_commit_buffer(r, this, buffer);
> +	free_commit_list(parents);
> +	free(author);
> +	free(committer);
> +	return ret;
> +}

> +	if (argc) {
> +		/*
> +		 * Find each specified stash, and load data into the array.
> +		 */
> +		for (i = 0; i < argc; i++) {
> +			struct object_id oid;
> +			struct commit *stash;
> +
> +			if (parse_stash_revision(&revision, argv[i], 1) ||
> +			    get_oid_with_context(r, revision.buf,
> +						 GET_OID_QUIETLY | GET_OID_GENTLY,
> +						 &oid, &unused)) {
> +				res = error(_("unable to find stash entry %s"), argv[i]);
> +				goto out;
> +			}
> +
> +			stash = lookup_commit_reference(r, &oid);
> +			if (!stash || check_stash_topology(r, stash)) {
> +				res = error(_("%s does not look like a stash commit"),
> +						revision.buf);
> +				goto out;
> +			}
> +			oid_array_append(&items, &oid);
> +		}
> +	} else {
> +		/*
> +		 * Walk the reflog, finding each stash entry, and load data into the
> +		 * array.
> +		 */
> +		struct complete_reflogs *crl = read_complete_reflog("refs/stash");
> +		for (i = 0; i < crl->nr; i++) {
> +			/*
> +			 * Iterate from the latest item in the reflog to the
> +			 * earliest.  crl->items starts from the earliest first.
> +			 */
> +			struct reflog_info *item = crl->items + (crl->nr - i - 1);
> +			struct commit *stash;
> +
> +			stash = lookup_commit_reference(r, &item->noid);
> +			if (!stash || check_stash_topology(r, stash)) {
> +				res = error(_("%s does not look like a stash commit"),
> +						revision.buf);
> +				goto out;
> +			}
> +			oid_array_append(&items, &item->noid);
> +		}
> +		free_complete_reflog(crl);
> +	}