text: /*
  ** $Id: loslib.c,v 1.54 2014/12/26 14:46:07 roberto Exp $
  ** Standard Operating System library
  ** See Copyright Notice in lua.h
  */
  
  #define loslib_c
  #define LUA_LIB
  
  #include "lprefix.h"
  
  
  #include <errno.h>
  #include <locale.h>
  #include "c_stdlib.h"
  #include "c_string.h"
  #include <time.h>
  
  #include "lua.h"
  
  #include "lauxlib.h"
  #include "lualib.h"
  
  
  #if !defined(LUA_STRFTIMEOPTIONS)	/* { */
  /*
  ** list of valid conversion specifiers for the 'strftime' function
  */
  
  #if defined(LUA_USE_C89)
  #define LUA_STRFTIMEOPTIONS	{ "aAbBcdHIjmMpSUwWxXyYz%", "" }
  #else  /* C99 specification */
  #define LUA_STRFTIMEOPTIONS \
  	{ "aAbBcCdDeFgGhHIjmMnprRStTuUVwWxXyYzZ%", "", \
  	  "E", "cCxXyY",  \
  	  "O", "deHImMSuUVwWy" }
  #endif
  
  #endif					/* } */
  
  
  
  #if !defined(l_time_t)		/* { */
  /*
  ** type to represent time_t in Lua
  */
  #define l_timet			lua_Integer
  #define l_pushtime(L,t)		lua_pushinteger(L,(lua_Integer)(t))
  #define l_checktime(L,a)	((time_t)luaL_checkinteger(L,a))
  
  #endif				/* } */
  
  
  
  #if !defined(lua_tmpnam)	/* { */
  /*
  ** By default, Lua uses tmpnam except when POSIX is available, where it
  ** uses mkstemp.
  */
  
  #if defined(LUA_USE_POSIX)	/* { */
  
  #include <unistd.h>
  
  #define LUA_TMPNAMBUFSIZE	32
  
  #if !defined(LUA_TMPNAMTEMPLATE)
  #define LUA_TMPNAMTEMPLATE	"/tmp/lua_XXXXXX"
  #endif
  
  #define lua_tmpnam(b,e) { \
          c_strcpy(b, LUA_TMPNAMTEMPLATE); \
          e = mkstemp(b); \
          if (e != -1) close(e); \
          e = (e == -1); }
  
  #else				/* }{ */
  
  /* ISO C definitions */
  #define LUA_TMPNAMBUFSIZE	L_tmpnam
  #define lua_tmpnam(b,e)		{ e = (tmpnam(b) == NULL); }
  
  #endif				/* } */
  
  #endif				/* } */
  
  
  
  #if !defined(l_gmtime)		/* { */
  /*
  ** By default, Lua uses gmtime/localtime, except when POSIX is available,
  ** where it uses gmtime_r/localtime_r
  */
  
  #if defined(LUA_USE_POSIX)	/* { */
  
  #define l_gmtime(t,r)		gmtime_r(t,r)
  #define l_localtime(t,r)	localtime_r(t,r)
  
  #else				/* }{ */
  
  /* ISO C definitions */
  #define l_gmtime(t,r)		((void)(r)->tm_sec, gmtime(t))
  #define l_localtime(t,r)  	((void)(r)->tm_sec, localtime(t))
  
  #endif				/* } */
  
  #endif				/* } */
  
  
  
  static int os_execute (lua_State *L) {
    const char *cmd = luaL_optstring(L, 1, NULL);
    int stat = system(cmd);
    if (cmd != NULL)
      return luaL_execresult(L, stat);
    else {
      lua_pushboolean(L, stat);  /* true if there is a shell */
      return 1;
    }
  }
  
  
  static int os_remove (lua_State *L) {
    const char *filename = luaL_checkstring(L, 1);
    return luaL_fileresult(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 luaL_fileresult(L, rename(fromname, toname) == 0, NULL);
  }
  
  
  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;
    res = (lua_getfield(L, -1, key) == LUA_TNIL) ? -1 : lua_toboolean(L, -1);
    lua_pop(L, 1);
    return res;
  }
  
  
  static int getfield (lua_State *L, const char *key, int d) {
    int res, isnum;
    lua_getfield(L, -1, key);
    res = (int)lua_tointegerx(L, -1, &isnum);
    if (!isnum) {
      if (d < 0)
        return luaL_error(L, "field '%s' missing in date table", key);
      res = d;
    }
    lua_pop(L, 1);
    return res;
  }
  
  
  static const char *checkoption (lua_State *L, const char *conv, char *buff) {
    static const char *const options[] = LUA_STRFTIMEOPTIONS;
    unsigned int i;
    for (i = 0; i < sizeof(options)/sizeof(options[0]); i += 2) {
      if (*conv != '\0' && c_strchr(options[i], *conv) != NULL) {
        buff[1] = *conv;
        if (*options[i + 1] == '\0') {  /* one-char conversion specifier? */
          buff[2] = '\0';  /* end buffer */
          return conv + 1;
        }
        else if (*(conv + 1) != '\0' &&
                 c_strchr(options[i + 1], *(conv + 1)) != NULL) {
          buff[2] = *(conv + 1);  /* valid two-char conversion specifier */
          buff[3] = '\0';  /* end buffer */
          return conv + 2;
        }
      }
    }
    luaL_argerror(L, 1,
      lua_pushfstring(L, "invalid conversion specifier '%%%s'", conv));
    return conv;  /* to avoid warnings */
  }
  
  
  static int os_date (lua_State *L) {
    const char *s = luaL_optstring(L, 1, "%c");
    time_t t = luaL_opt(L, l_checktime, 2, time(NULL));
    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? */
      lua_pushnil(L);
    else if (c_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[4];
      luaL_Buffer b;
      cc[0] = '%';
      luaL_buffinit(L, &b);
      while (*s) {
        if (*s != '%')  /* no conversion specifier? */
          luaL_addchar(&b, *s++);
        else {
          size_t reslen;
          char buff[200];  /* should be big enough for any conversion result */
          s = checkoption(L, s + 1, cc);
          reslen = strftime(buff, sizeof(buff), cc, stm);
          luaL_addlstring(&b, buff, reslen);
        }
      }
      luaL_pushresult(&b);
    }
    return 1;
  }
  
  
  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);
    }
    if (t != (time_t)(l_timet)t)
      luaL_error(L, "time result cannot be represented in this Lua instalation");
    else if (t == (time_t)(-1))
      lua_pushnil(L);
    else
      l_pushtime(L, t);
    return 1;
  }
  
  
  static int os_difftime (lua_State *L) {
    double res = difftime((l_checktime(L, 1)), (l_checktime(L, 2)));
    lua_pushnumber(L, (lua_Number)res);
    return 1;
  }
  
  /* }====================================================== */
  
  
  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) {
    int status;
    if (lua_isboolean(L, 1))
      status = (lua_toboolean(L, 1) ? EXIT_SUCCESS : EXIT_FAILURE);
    else
      status = (int)luaL_optinteger(L, 1, EXIT_SUCCESS);
    if (lua_toboolean(L, 2))
      lua_close(L);
    if (L) exit(status);  /* 'if' to avoid warnings for unreachable 'return' */
    return 0;
  }
  
  
  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}
  };
  
  /* }====================================================== */
  
  
  
  LUAMOD_API int luaopen_os (lua_State *L) {
    luaL_newlib(L, syslib);
    return 1;
  }
  
  