5ac8fb035e surjectionproof: make sure that n_used_pubkeys > 0 in generate (Jonas Nick)
Pull request description:
ACKs for top commit:
apoelstra:
utACK 5ac8fb035e
Tree-SHA512: 915f7181e69e2c4e1f830d6c2620a2d9b0af4d2ae8a63709b489b01ed9e13ccfeeaedebd4680cf2d927cd473a6ae88602cf29e2fdd116cb597fba6c0ab77720d
If the proof was generated with surjectionproof_initialize (as mandated by the
API docs), then n_used_pubkeys can never be 0. Without this commit, compilers
will (rightfully) warn that borromean_s[ring_input_index] is not initialized in
surjectionproof_generate. Therefore, this commit makes sure that n_used_pubkeys
is greater than 0 which ensures that the array is initialized at
ring_input_index.
The comments with 'XXX' was intended to indicate that the listed
concerns was subject to review and change, but the code with these
comments was merged straight away. This commit replaces comments
with more complete text describing the issues.
This also signifies that the commit that this code was introduced in is
not anymore 'work in progress'.
