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Apply the same qsort() usage fix as in r304911 getaddrinfo.c

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qsort() can't be stabilized with just return(-1) alone.

MFC after:      3 days
This commit is contained in:
Andrey A. Chernov 2016-08-31 15:47:58 +00:00
parent 32286efee1
commit af98aa6e21
1 changed files with 19 additions and 0 deletions
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19
lib/libc/net/name6.c
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@ -185,6 +185,7 @@ 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 *arg2)
}
/* 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);
}