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);
}
_______________________________________________
svn-src-stable-10@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-stable-10
To unsubscribe, send any mail to "svn-src-stable-10-unsubscr...@freebsd.org"
