* Heikki Linnakangas (heikki.linnakan...@iki.fi) wrote:
> This patch alleviates that in two ways. First, instead of storing pointers
> in the hash table, store 16-bit indexes into the hist_entries array. That
> slashes the size of the hash table to 1/2 or 1/4 of the original, depending
> on the pointer width. Secondly, adjust the size of the hash table based on
> input size. For very small inputs, you don't need a large hash table to
> avoid collisions.

  The coverity scanner has a bit of an issue with this patch which, at
  least on first blush, looks like a valid concern.
  While the change in pg_lzcompress.c:pglz_find_match() to loop on:
  while (hent != INVALID_ENTRY_PTR)
          const char *ip = input;
          const char *hp = hent->pos;

  looks good, and INVALID_ENTRY_PTR is the address of the first entry in
  the array (and can't be NULL), towards the end of the loop we do:

  hent = hent->next;
  if (hent)

  Should we really be checking for 'hent != INVALID_ENTRY_PTR' here?  If
  not, and hent really can end up as NULL, then we're going to segfault
  on the next loop due to the unchecked 'hent->pos' early in the loop.
  If hent can never be NULL, then we probably don't need this check at



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