Date: Sat, 3 Sep 2016 01:08:52 +0000 (UTC) From: "Andrey A. Chernov" <ache@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r305316 - stable/10/lib/libc/net Message-ID: <201609030108.u8318q1b093612@repo.freebsd.org>
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Author: ache Date: Sat Sep 3 01:08:52 2016 New Revision: 305316 URL: https://svnweb.freebsd.org/changeset/base/305316 Log: MFC r305133 Apply the same qsort() usage fix as in r304911 getaddrinfo.c qsort() can't be stabilized with just return(-1) alone. Modified: stable/10/lib/libc/net/name6.c Directory Properties: stable/10/ (props changed) Modified: stable/10/lib/libc/net/name6.c ============================================================================== --- stable/10/lib/libc/net/name6.c Sat Sep 3 00:50:18 2016 (r305315) +++ stable/10/lib/libc/net/name6.c Sat Sep 3 01:08:52 2016 (r305316) @@ -186,6 +186,7 @@ struct hp_order { #define aio_sa aio_un.aiou_sa int aio_matchlen; char *aio_h_addr; + int aio_initial_sequence; }; static struct hostent *_hpcopy(struct hostent *, int *); @@ -711,6 +712,7 @@ _hpreorder(struct hostent *hp) aio[i].aio_dstscope = gai_addr2scopetype(sa); aio[i].aio_dstpolicy = match_addrselectpolicy(sa, &policyhead); set_source(&aio[i], &policyhead); + aio[i].aio_initial_sequence = i; } /* perform sorting. */ @@ -1045,6 +1047,23 @@ comp_dst(const void *arg1, const void *a } /* Rule 10: Otherwise, leave the order unchanged. */ + + /* + * Note that qsort is unstable; so, we can't return zero and + * expect the order to be unchanged. + * That also means we can't depend on the current position of + * dst2 being after dst1. We must enforce the initial order + * with an explicit compare on the original position. + * The qsort specification requires that "When the same objects + * (consisting of width bytes, irrespective of their current + * positions in the array) are passed more than once to the + * comparison function, the results shall be consistent with one + * another." + * In other words, If A < B, then we must also return B > A. + */ + if (dst2->aio_initial_sequence < dst1->aio_initial_sequence) + return(1); + return(-1); }
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