Function luaL_prepbuffsize

depends/lua/src/lauxlib.c:505–525

** returns a pointer to a free area with at least 'sz' bytes */

** returns a pointer to a free area with at least 'sz' bytes
*/
LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
  lua_State *L = B->L;
  if (B->size - B->n < sz) {  /* not enough space? */
    char *newbuff;
    size_t newsize = B->size * 2;  /* double buffer size */
    if (newsize - B->n < sz)  /* not big enough? */
      newsize = B->n + sz;
    if (newsize < B->n || newsize - B->n < sz)
      luaL_error(L, "buffer too large");
    /* create larger buffer */
    if (buffonstack(B))
      newbuff = (char *)resizebox(L, -1, newsize);
    else {  /* no buffer yet */
      newbuff = (char *)newbox(L, newsize);
      memcpy(newbuff, B->b, B->n * sizeof(char));  /* copy original content */
    }
    B->b = newbuff;
    B->size = newsize;
  }
  return &B->b[B->n];
}


LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {