I/O channel read/write functions can operate on any area of memory, regardless of the content their represent. Do not restrict to array of char, use the void* type, which is also the type of the underlying iovec::iov_base field. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> [DB: also adapt test-crypto-tlssession.c func signatures] Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>