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ffi/target/release/build/mlua-sys-6a99a2ae50f12319/out/luajit-build/build/src/lj_str.c  view on Meta::CPAN

#if LUAJIT_SECURITY_STRHASH
      uintptr_t u;
      if (LJ_LIKELY(!s->hashalg)) {  /* String hashed with primary hash. */
	hash &= newmask;
	u = gcrefu(newtab[hash]);
	if (LJ_UNLIKELY(u & 1)) {  /* Switch string to secondary hash. */
	  s->hash = hash = hash_dense(g->str.seed, s->hash, strdata(s), s->len);
	  s->hashalg = 1;
	  hash &= newmask;
	  u = gcrefu(newtab[hash]);
	}
      } else {  /* String hashed with secondary hash. */
	MSize shash = hash_sparse(g->str.seed, strdata(s), s->len);
	u = gcrefu(newtab[shash & newmask]);
	if (u & 1) {
	  hash &= newmask;
	  u = gcrefu(newtab[hash]);
	} else {  /* Revert string back to primary hash. */
	  s->hash = shash;
	  s->hashalg = 0;
	  hash = (shash & newmask);
	}
      }
      /* NOBARRIER: The string table is a GC root. */
      setgcrefp(o->gch.nextgc, (u & ~(uintptr_t)1));
      setgcrefp(newtab[hash], ((uintptr_t)o | (u & 1)));
#else
      hash &= newmask;
      /* NOBARRIER: The string table is a GC root. */
      setgcrefr(o->gch.nextgc, newtab[hash]);
      setgcref(newtab[hash], o);
#endif
      o = next;
    }
  }

  /* Free old table and replace with new table. */
  lj_str_freetab(g);
  g->str.tab = newtab;
  g->str.mask = newmask;
}

#if LUAJIT_SECURITY_STRHASH
/* Rehash and rechain all strings in a chain. */
static LJ_NOINLINE GCstr *lj_str_rehash_chain(lua_State *L, StrHash hashc,
					      const char *str, MSize len)
{
  global_State *g = G(L);
  int ow = g->gc.state == GCSsweepstring ? otherwhite(g) : 0;  /* Sweeping? */
  GCRef *strtab = g->str.tab;
  MSize strmask = g->str.mask;
  GCobj *o = gcref(strtab[hashc & strmask]);
  setgcrefp(strtab[hashc & strmask], (void *)((uintptr_t)1));
  g->str.second = 1;
  while (o) {
    uintptr_t u;
    GCobj *next = gcnext(o);
    GCstr *s = gco2str(o);
    StrHash hash;
    if (ow) {  /* Must sweep while rechaining. */
      if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) {  /* String alive? */
	lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
		   "sweep of undead string");
	makewhite(g, o);
      } else {  /* Free dead string. */
	lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
		   "sweep of unlive string");
	lj_str_free(g, s);
	o = next;
	continue;
      }
    }
    hash = s->hash;
    if (!s->hashalg) {  /* Rehash with secondary hash. */
      hash = hash_dense(g->str.seed, hash, strdata(s), s->len);
      s->hash = hash;
      s->hashalg = 1;
    }
    /* Rechain. */
    hash &= strmask;
    u = gcrefu(strtab[hash]);
    setgcrefp(o->gch.nextgc, (u & ~(uintptr_t)1));
    setgcrefp(strtab[hash], ((uintptr_t)o | (u & 1)));
    o = next;
  }
  /* Try to insert the pending string again. */
  return lj_str_new(L, str, len);
}
#endif

/* Reseed String ID from PRNG after random interval < 2^bits. */
#if LUAJIT_SECURITY_STRID == 1
#define STRID_RESEED_INTERVAL	8
#elif LUAJIT_SECURITY_STRID == 2
#define STRID_RESEED_INTERVAL	4
#elif LUAJIT_SECURITY_STRID >= 3
#define STRID_RESEED_INTERVAL	0
#endif

/* Allocate a new string and add to string interning table. */
static GCstr *lj_str_alloc(lua_State *L, const char *str, MSize len,
			   StrHash hash, int hashalg)
{
  GCstr *s = lj_mem_newt(L, lj_str_size(len), GCstr);
  global_State *g = G(L);
  uintptr_t u;
  newwhite(g, s);
  s->gct = ~LJ_TSTR;
  s->len = len;
  s->hash = hash;
#ifndef STRID_RESEED_INTERVAL
  s->sid = g->str.id++;
#elif STRID_RESEED_INTERVAL
  if (!g->str.idreseed--) {
    uint64_t r = lj_prng_u64(&g->prng);
    g->str.id = (StrID)r;
    g->str.idreseed = (uint8_t)(r >> (64 - STRID_RESEED_INTERVAL));
  }
  s->sid = g->str.id++;
#else
  s->sid = (StrID)lj_prng_u64(&g->prng);