fix(libbitcoinkernel-sys): make btck_LogCallback and btck_WriteBytes non-nullable #204
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btck_logging_connection_create marks this arg NONNULL; a null callback is UB in C.
btck_transaction_to_bytes, btck_script_pubkey_to_bytes and btck_block_to_bytes mark this arg NONNULL; a null write is UB in C.
alexanderwiederin
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Summary
Both types are marked
BITCOINKERNEL_ARG_NONNULLin the C Header at every call site, but were bound asOption<unsafe extern "C" fn(...)letting callers pass None, which lowers to a null pointer and is UB in C.This PR drops the
Optionwrapper so null is representable at the type level.Changes
btck_LogCallback: bareunsafe extern "C" fn(...). Updatedbtck_logging_connection_createcall site to passlog_callback::<T>instead ofSome(log_callback::<T>).btck_WriteBytes: same treatment. Used as the nonnullwriterarg inbtck_transaction_to_bytes,btck_script_pubkey_to_bytes,btck_block_to_bytes. Thec_serializehelper and its call sites already pass the callback unwrapped, so no further changes needed.Why
Neither type ever had a valid "null" use case.