rollback previous commit if the current one fails

Hi,
i need to emulate oracle's savepoint behaviour inside of the plpgsql
function.

This function is able to insert all the rows that weren't caught on the
exception, but i need also to rollback the insert that happens before the
exception.

So let's say the exception is thrown when j=3 so i need also to rollback
j=2.
Any idea how to approach it?

DROP TABLE IF EXISTS test;
CREATE TABLE test
(
id INT
);

CREATE OR REPLACE PROCEDURE test()
AS
$$
DECLARE
j INT;
BEGIN

FOR j IN 0..6
LOOP
BEGIN
INSERT INTO test VALUES (1 / j);
EXCEPTION
WHEN OTHERS THEN
END;
END LOOP;
END;
$$ LANGUAGE plpgsql;

CALL test();
TABLE test;

--
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