From: Claudio Jeker <cjeker@diehard.n-r-g.com>
Subject: Re: Cruft: drop htonl() etc. from libc
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: tech@openbsd.org
Date: Fri, 12 Apr 2024 09:13:55 +0200

On Fri, Apr 12, 2024 at 01:21:41AM +0200, Christian Weisgerber wrote:
> Userland code compiled in a normal fashion picks up the htonl(),
> htons(), ntohl(), ntohs() inline functions from endian.h.
> 
> The implementations in libc are effectively unused.  We can drop
> the MD functions.  I chose to keep the MI functions on the off
> chance that something looks for the symbols in libc or plays games
> with "#undef htonl", but I changed them so they now also pick up
> the implementation from endian.h.
> 
> This passed a release build on amd64.
> 
> No symbol changes.  aarch64 and arm have this:
> /usr/lib/libc.so.99.0 --> obj/libc.so.99.0
> Dynamic export changes:
> strengthened:
>         htonl
>         htons
>         ntohl
>         ntohs
> 
> Comments?  OK?

See below


> blob - 0d05bac78a1c9ad61f7a7418022914c6704adfb4
> blob + a9b2c86f5ca31081bf66ca627122a96570846b2b
> --- lib/libc/net/ntohl.c
> +++ lib/libc/net/ntohl.c
> @@ -1,6 +1,5 @@
>  /*	$OpenBSD: ntohl.c,v 1.7 2014/07/21 01:51:10 guenther Exp $ */
>  /*
> - * Written by J.T. Conklin <jtc@netbsd.org>.
>   * Public domain.
>   */
>  
> @@ -12,10 +11,5 @@
>  u_int32_t
>  ntohl(u_int32_t x)
>  {
> -#if BYTE_ORDER == LITTLE_ENDIAN
> -	u_char *s = (u_char *)&x;
> -	return (u_int32_t)(s[0] << 24 | s[1] << 16 | s[2] << 8 | s[3]);
> -#else
> -	return x;
> -#endif
> +	return __htobe32(x);
>  }
> blob - b5ea361f8304c322f46bc564e0e74a9a135d69c4
> blob + 8a39f68a0ae5960d8ea4cbc046d157210985bad2
> --- lib/libc/net/ntohs.c
> +++ lib/libc/net/ntohs.c
> @@ -1,6 +1,5 @@
>  /*	$OpenBSD: ntohs.c,v 1.9 2014/07/21 01:51:10 guenther Exp $ */
>  /*
> - * Written by J.T. Conklin <jtc@netbsd.org>.
>   * Public domain.
>   */
>  
> @@ -12,10 +11,5 @@
>  u_int16_t
>  ntohs(u_int16_t x)
>  {
> -#if BYTE_ORDER == LITTLE_ENDIAN
> -	u_char *s = (u_char *) &x;
> -	return (u_int16_t)(s[0] << 8 | s[1]);
> -#else
> -	return x;
> -#endif
> +	return __htobe16(x);

This looks the wrong way around. ntohs() is be16toh(). Same for ntohl
above. While it does not matter for our cases I think we should use the
right conversions here.

-- 
:wq Claudio