Luaゲーム開発チュートリアル - タイムゾーンの問題

-- Beijing time
local serverTime = 1536722753 -- 2018/09/12 11:25

function getTimeZone()
 local now = os.time()
 return os.difftime(now, os.time(os.date(""! *t", now)))
end

-- 8 hours * 3600 seconds = 28800 seconds
local timeZone = getTimeZone()/ 3600

print("timeZone : " . timeZone)



local timeInterval = os.time(os.date(""! *t", serverTime)) + timeZone * 3600 + (os.date("*t", time).isdst and -1 or 0) * 3600

local timeTable = os.date("*t", timeInterval)

--[[
for k, v in pairs(timeTable) do
 print(k ... ":" . tostring(v))
end
]]

print(timeTable.year ... "/" ... timeTable.month ... "/" ... timeTable.day ... " " ... timeTable.hour ... ":" ... timeTable.min ... ":" ... timeTable.sec)

static int os_date (lua_State *L) {
 size_t slen;
 const char *s = luaL_optlstring(L, 1, "%c", &slen);
 time_t t = luaL_opt(L, l_checktime, 2, time(NULL));
 const char *se = s + slen; /* 's' end */
 struct tm tmr, *stm;
 if (*s == '!') { /* UTC? */
 stm = l_gmtime(&t, &tmr);
 s++; /* skip '!' */
 }
 else
 stm = l_localtime(&t, &tmr);
 if (stm == NULL) /* invalid date?
 luaL_error(L, "time result cannot be represented in this installation");
 if (strcmp(s, "*t") == 0) {
 lua_createtable(L, 0, 9); /* 9 = number of fields */
 setallfields(L, stm);
 }
 else {
 char cc[4]; /* buffer for individual conversion specifiers */
 luaL_Buffer b;
 cc[0] = '%';
 luaL_buffinit(L, &b);
 while (s < se) {
  if (*s ! = '%') /* not a conversion specifier? */
  luaL_addchar(&b, *s++);
  else {
  size_t reslen;
  char *buff = luaL_prepbuffsize(&b, SIZETIMEFMT);
  s++; /* skip '%' */
  s = checkoption(L, s, se - s, cc + 1); /* copy specifier to 'cc' */
  reslen = strftime(buff, SIZETIMEFMT, cc, stm);
  luaL_addsize(&b, reslen);
  }
 }
 luaL_pushresult(&b);
 }
 return 1;
}

#define l_gmtime(t,r) gmtime_r(t,r)