Re: multiple unsequenced modifications

[Bruno H. <br...@cl...>]

Hi Sam,

> I get this:
> --8<---------------cut here---------------start------------->8---
> modules/rawsock/rawsock.c:893:48: warning: multiple unsequenced
>   modifications to 'STACK' [-Wunsequenced]
> --8<---------------cut here---------------end--------------->8---
> 
> because of
> 
> --8<---------------cut here---------------start------------->8---
>   struct addrinfo hints = {addrinfo_flags(),
>                            check_socket_domain(popSTACK()),
>                            check_socket_type(popSTACK()),
>                            get_socket_protocol(popSTACK()),
>                            0,NULL,NULL,NULL};
> --8<---------------cut here---------------end--------------->8---

GCC told you about one problem with this code.

The other problem is that the code assumes a certain order of
the members of 'struct addrinfo'. Which is not guaranteed by POSIX: [1] says
   "The <netdb.h> header shall define the addrinfo structure, which
    shall include at least the following members:"

> The only honest way to avoid the issue is
> 
> --8<---------------cut here---------------start------------->8---
>   struct addrinfo hints = {0,0,0,0,0,NULL,NULL,NULL};
>   hints.ai_flags = addrinfo_flags();
>   hints.ai_family = check_socket_domain(popSTACK());
>   hints.ai_socktype = check_socket_type(popSTACK());
>   hints.ai_protocol = get_socket_protocol(popSTACK());
> --8<---------------cut here---------------end--------------->8---

This is better, but it too suffers from the second problem.

How about this?

  struct addrinfo hints;
  memset(&hints,0,sizeof(hints));
  hints.ai_flags = addrinfo_flags();
  hints.ai_family = check_socket_domain(popSTACK());
  hints.ai_socktype = check_socket_type(popSTACK());
  hints.ai_protocol = get_socket_protocol(popSTACK());

> It is worth bothering with?

Definitely!

Bruno

[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html