text: /*
  ** $Id: loslib.c,v 1.19.1.3 2008/01/18 16:38:18 roberto Exp $
  ** Standard Operating System library
  ** See Copyright Notice in lua.h
  */
  
  
  #include <errno.h>
  #include <locale.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  
  #define loslib_c
  #define LUA_LIB
  
  #include "lua.h"
  
  #include "lauxlib.h"
  #include "lualib.h"
  
  
  static int os_pushresult (lua_State *L, int i, const char *filename) {
    int en = errno;  /* calls to Lua API may change this value */
    if (i) {
      lua_pushboolean(L, 1);
      return 1;
    }
    else {
      lua_pushnil(L);
      lua_pushfstring(L, "%s: %s", filename, strerror(en));
      lua_pushinteger(L, en);
      return 3;
    }
  }
  
  
  static int os_execute (lua_State *L) {
    lua_pushinteger(L, system(luaL_optstring(L, 1, NULL)));
    return 1;
  }
  
  
  static int os_remove (lua_State *L) {
    const char *filename = luaL_checkstring(L, 1);
    return os_pushresult(L, remove(filename) == 0, filename);
  }
  
  
  static int os_rename (lua_State *L) {
    const char *fromname = luaL_checkstring(L, 1);
    const char *toname = luaL_checkstring(L, 2);
    return os_pushresult(L, rename(fromname, toname) == 0, fromname);
  }
  
  
  static int os_tmpname (lua_State *L) {
    char buff[LUA_TMPNAMBUFSIZE];
    int err;
    lua_tmpnam(buff, err);
    if (err)
      return luaL_error(L, "unable to generate a unique filename");
    lua_pushstring(L, buff);
    return 1;
  }
  
  
  static int os_getenv (lua_State *L) {
    lua_pushstring(L, getenv(luaL_checkstring(L, 1)));  /* if NULL push nil */
    return 1;
  }
  
  
  static int os_clock (lua_State *L) {
    lua_pushnumber(L, ((lua_Number)clock())/(lua_Number)CLOCKS_PER_SEC);
    return 1;
  }
  
  
  /*
  ** {======================================================
  ** Time/Date operations
  ** { year=%Y, month=%m, day=%d, hour=%H, min=%M, sec=%S,
  **   wday=%w+1, yday=%j, isdst=? }
  ** =======================================================
  */
  
  static void setfield (lua_State *L, const char *key, int value) {
    lua_pushinteger(L, value);
    lua_setfield(L, -2, key);
  }
  
  static void setboolfield (lua_State *L, const char *key, int value) {
    if (value < 0)  /* undefined? */
      return;  /* does not set field */
    lua_pushboolean(L, value);
    lua_setfield(L, -2, key);
  }
  
  static int getboolfield (lua_State *L, const char *key) {
    int res;
    lua_getfield(L, -1, key);
    res = lua_isnil(L, -1) ? -1 : lua_toboolean(L, -1);
    lua_pop(L, 1);
    return res;
  }
  
  
  static int getfield (lua_State *L, const char *key, int d) {
    int res;
    lua_getfield(L, -1, key);
    if (lua_isnumber(L, -1))
      res = (int)lua_tointeger(L, -1);
    else {
      if (d < 0)
        return luaL_error(L, "field " LUA_QS " missing in date table", key);
      res = d;
    }
    lua_pop(L, 1);
    return res;
  }
  
  /* os.date ([format [, time]]) */
  static int os_date (lua_State *L) {
    const char *s = luaL_optstring(L, 1, "%c");
    time_t t = luaL_opt(L, (time_t)luaL_checknumber, 2, time(NULL));
    struct tm *stm;
    if (*s == '!') {  /* UTC? */
      stm = gmtime(&t);	/* 返回格林威治时区的时间 */
      s++;  /* skip `!' */
    }
    else
      stm = localtime(&t);
    if (stm == NULL)  /* invalid date? */
      lua_pushnil(L);
    else if (strcmp(s, "*t") == 0) {
      lua_createtable(L, 0, 9);  /* 9 = number of fields */
      setfield(L, "sec", stm->tm_sec);
      setfield(L, "min", stm->tm_min);
      setfield(L, "hour", stm->tm_hour);
      setfield(L, "day", stm->tm_mday);
      setfield(L, "month", stm->tm_mon+1);
      setfield(L, "year", stm->tm_year+1900);
      setfield(L, "wday", stm->tm_wday+1);
      setfield(L, "yday", stm->tm_yday+1);
      setboolfield(L, "isdst", stm->tm_isdst);
    }
    else {
      char cc[3];
      luaL_Buffer b;
      cc[0] = '%'; cc[2] = '\0';
      luaL_buffinit(L, &b);
      for (; *s; s++) {
        if (*s != '%' || *(s + 1) == '\0')  /* no conversion specifier? */
          luaL_addchar(&b, *s);
        else {
          size_t reslen;
          char buff[200];  /* should be big enough for any conversion result */
          cc[1] = *(++s);
          reslen = strftime(buff, sizeof(buff), cc, stm);
          luaL_addlstring(&b, buff, reslen);
        }
      }
      luaL_pushresult(&b);
    }
    return 1;
  }
  
  /* os.time ([table]) 传入nil则返回当前的UNIX时间戳，反之指定时间(本地)的UNIXhi时间戳 */
  static int os_time (lua_State *L) {
    time_t t;
    if (lua_isnoneornil(L, 1))  /* called without args? */
      t = time(NULL);  /* get current time */
    else {
      struct tm ts;
      luaL_checktype(L, 1, LUA_TTABLE);
      lua_settop(L, 1);  /* make sure table is at the top */
      ts.tm_sec = getfield(L, "sec", 0);
      ts.tm_min = getfield(L, "min", 0);
      ts.tm_hour = getfield(L, "hour", 12);
      ts.tm_mday = getfield(L, "day", -1);
      ts.tm_mon = getfield(L, "month", -1) - 1;
      ts.tm_year = getfield(L, "year", -1) - 1900;
      ts.tm_isdst = getboolfield(L, "isdst");
      t = mktime(&ts);	/* 将ts当作本地时区的时间 " */
    }
    if (t == (time_t)(-1))
      lua_pushnil(L);
    else
      lua_pushnumber(L, (lua_Number)t);
    return 1;
  }
  
  
  static int os_difftime (lua_State *L) {
    lua_pushnumber(L, difftime((time_t)(luaL_checknumber(L, 1)),
                               (time_t)(luaL_optnumber(L, 2, 0))));
    return 1;
  }
  
  /* }====================================================== */
  
  //os.setlocale (locale [, category])
  static int os_setlocale (lua_State *L) {
    static const int cat[] = {LC_ALL, LC_COLLATE, LC_CTYPE, LC_MONETARY,
                        LC_NUMERIC, LC_TIME};
    static const char *const catnames[] = {"all", "collate", "ctype", "monetary",
       "numeric", "time", NULL};
    const char *l = luaL_optstring(L, 1, NULL);
    int op = luaL_checkoption(L, 2, "all", catnames);
    lua_pushstring(L, setlocale(cat[op], l));
    return 1;
  }
  
  
  static int os_exit (lua_State *L) {
    exit(luaL_optint(L, 1, EXIT_SUCCESS));
  }
  
  static const luaL_Reg syslib[] = {
    {"clock",     os_clock},
    {"date",      os_date},
    {"difftime",  os_difftime},
    {"execute",   os_execute},
    {"exit",      os_exit},
    {"getenv",    os_getenv},
    {"remove",    os_remove},
    {"rename",    os_rename},
    {"setlocale", os_setlocale},
    {"time",      os_time},
    {"tmpname",   os_tmpname},
    {NULL, NULL}
  };
  
  /* }====================================================== */
  
  
  
  LUALIB_API int luaopen_os (lua_State *L) {
    luaL_register(L, LUA_OSLIBNAME, syslib);
    return 1;
  }
  
  