cwexec (kwset_t kwset, char const *text, size_t len, struct kwsmatch *kwsmatch)
{
  struct trie * const *next;
  struct trie const *trie;
  struct trie const *accept;
  char const *beg, *lim, *mch, *lmch;
  unsigned char c;
  unsigned char const *delta;
  int d;
  char const *end, *qlim;
  struct tree const *tree;
  char const *trans;

#ifdef lint
  accept = NULL;
#endif

  /* Initialize register copies and look for easy ways out. */
  if (len < kwset->mind)
    return -1;
  next = kwset->next;
  delta = kwset->delta;
  trans = kwset->trans;
  lim = text + len;
  end = text;
  if ((d = kwset->mind) != 0)
    mch = NULL;
  else
    {
      mch = text, accept = kwset->trie;
      goto match;
    }

  if (len >= 4 * kwset->mind)
    qlim = lim - 4 * kwset->mind;
  else
    qlim = NULL;

  while (lim - end >= d)
    {
      if (qlim && end <= qlim)
        {
          end += d - 1;
          while ((d = delta[c = *end]) && end < qlim)
            {
              end += d;
              end += delta[U(*end)];
              end += delta[U(*end)];
            }
          ++end;
        }
      else
        d = delta[c = (end += d)[-1]];
      if (d)
        continue;
      beg = end - 1;
      trie = next[c];
      if (trie->accepting)
        {
          mch = beg;
          accept = trie;
        }
      d = trie->shift;
      while (beg > text)
        {
          unsigned char uc = *--beg;
          c = trans ? trans[uc] : uc;
          tree = trie->links;
          while (tree && c != tree->label)
            if (c < tree->label)
              tree = tree->llink;
            else
              tree = tree->rlink;
          if (tree)
            {
              trie = tree->trie;
              if (trie->accepting)
                {
                  mch = beg;
                  accept = trie;
                }
            }
          else
            break;
          d = trie->shift;
        }
      if (mch)
        goto match;
    }
  return -1;

 match:
  /* Given a known match, find the longest possible match anchored
     at or before its starting point.  This is nearly a verbatim
     copy of the preceding main search loops. */
  if (lim - mch > kwset->maxd)
    lim = mch + kwset->maxd;
  lmch = 0;
  d = 1;
  while (lim - end >= d)
    {
      if ((d = delta[c = (end += d)[-1]]) != 0)
        continue;
      beg = end - 1;
      if (!(trie = next[c]))
        {
          d = 1;
          continue;
        }
      if (trie->accepting && beg <= mch)
        {
          lmch = beg;
          accept = trie;
        }
      d = trie->shift;
      while (beg > text)
        {
          unsigned char uc = *--beg;
          c = trans ? trans[uc] : uc;
          tree = trie->links;
          while (tree && c != tree->label)
            if (c < tree->label)
              tree = tree->llink;
            else
              tree = tree->rlink;
          if (tree)
            {
              trie = tree->trie;
              if (trie->accepting && beg <= mch)
                {
                  lmch = beg;
                  accept = trie;
                }
            }
          else
            break;
          d = trie->shift;
        }
      if (lmch)
        {
          mch = lmch;
          goto match;
        }
      if (!d)
        d = 1;
    }

  kwsmatch->index = accept->accepting / 2;
  kwsmatch->offset[0] = mch - text;
  kwsmatch->size[0] = accept->depth;

  return mch - text;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.