Date: Tue, 10 Aug 2010 12:01:03 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: des@des.no Cc: src-committers@FreeBSD.org, jilles@stack.nl, svn-src-all@FreeBSD.org, olli@fromme.com, olli@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r211023 - head/usr.sbin/syslogd Message-ID: <20100810.120103.69891821625677670.imp@bsdimp.com> In-Reply-To: <86sk2m1hsj.fsf@ds4.des.no> References: <201008101623.o7AGNs7I042679@haluter.fromme.com> <20100810.110642.335141733495090585.imp@bsdimp.com> <86sk2m1hsj.fsf@ds4.des.no>
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In message: <86sk2m1hsj.fsf@ds4.des.no> Dag-Erling Sm=F8rgrav <des@des.no> writes: : "M. Warner Losh" <imp@bsdimp.com> writes: : > /* : > * Macros to cast a struct sockaddr, or parts thereof. : > * On architectures with strict alignment requirements, the compile= r : > * can bogusly warn about alignment problems since its static analy= sis : > * is insufficient for it to know that with the APIs used, there : > * really is no alignment issue. : > */ : = : That's a bit harsh on the compiler, don't you think? It never pays t= o : hurt the compiler's feelings :) /* * Macros to cast a struct sockaddr, or parts thereof. struct * sockaddr's alginment is loose to later be cast to a sockaddr_in or * sockaddr_in6. On architectures with strict alignment requirements, * this leads to compiler warnings because the compiler doesn't know * the ABI guarantees proper alignment. */ But this leads me to think that the right fix might be: /* * Structure used by kernel to store most * addresses. */ struct sockaddr { unsigned char sa_len; /* total length */ sa_family_t sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ } __aligned(4); since that's what the ABI defines.... : > : @@ -2410,8 +2419,8 @@ : > : } : > : reject =3D 0; : > : for (j =3D 0; j < 16; j +=3D 4) { : > : - if ((*(u_int32_t *)&sin6->sin6_addr.s6_addr[j] & *(u_int32_= t *)&m6p->sin6_addr.s6_addr[j]) : > : - !=3D *(u_int32_t *)&a6p->sin6_addr.s6_addr[j]) { : > : + if ((UINT32_CAST(sin6->sin6_addr.s6_addr[j]) & UINT32_CAST(= m6p->sin6_addr.s6_addr[j])) : > : + !=3D UINT32_CAST(a6p->sin6_addr.s6_addr[j])) { : > : ++reject; : > : break; : > : } : > : = : > : = : > : > Why 16 and 4 here? What's so magical about them? : = : 4 =3D bytes in a uint32_t, 16 =3D bytes in an ipv6 address. Isn't that better served by 'sizeof(uint32_t)' and 'sizeof(ipv6_addr_t)'? Warner
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