pub unsafe extern "C" fn libssh2_userauth_publickey_frommemory(
    sess: *mut LIBSSH2_SESSION,
    username: *const c_char,
    username_len: size_t,
    publickeydata: *const c_char,
    publickeydata_len: size_t,
    privatekeydata: *const c_char,
    privatekeydata_len: size_t,
    passphrase: *const c_char
) -> c_int