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Fix the broken "avoid unaligned data" fix. The problem is that the builtin

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gcc memcpy "knows" about types that are supposed to be actually already
aligned and triggers alignment errors doing the memcpy itself.
"Fix" this by changing it to a bcopy().  In this case, we had:
  struct timeval *tp;
  struct timeval tv1;
  memcpy(&tv1,tp,sizeof(tv1));
.. and since gcc *knows* that a pointer to a timeval is longword aligned
and that tv1 is longword aligned, then it can use an inline that assumes
alignment.  The following works too:
  cp = (char *)tp;
  memcpy(&tv1,cp,sizeof(tv1));
Simply casting (char *)tp  for the memcpy doesn't work. :-(
This affected different 64 bit platforms in different ways and depends
a lot on gcc as well.  I've seen this on alpha and ia64 at least, although
alpha isn't doing it right now.
This commit is contained in:
Peter Wemm 2002-08-10 03:00:55 +00:00
parent fd35706acb
commit 11bad678c6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=101623
1 changed files with 2 additions and 2 deletions
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4
sbin/ping/ping.c
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@ -841,8 +841,8 @@ pr_pack(buf, cc, from, tv)
#else
tp = (struct timeval *)icp->icmp_data;
#endif
/* Avoid unaligned data: */
memcpy(&tv1,tp,sizeof(tv1));
/* Avoid unaligned data (cannot use memcpy) */
bcopy(tp, &tv1, sizeof(tv1));
tvsub(tv, &tv1);
triptime = ((double)tv->tv_sec) * 1000.0 +
((double)tv->tv_usec) / 1000.0;