Function svn_stream_printf 

pub unsafe extern "C" fn svn_stream_printf(
    stream: *mut svn_stream_t,
    pool: *mut apr_pool_t,
    fmt: *const c_char,
    ...
) -> *mut svn_error_t

Write to @a stream using a printf-style @a fmt specifier, passed through apr_psprintf() using memory from @a pool.