text: /*
  ** $Id: loslib.c $
  ** Standard Operating System library
  ** See Copyright Notice in lua.h
  */
  
  #define loslib_c
  #define LUA_LIB
  
  #include "lprefix.h"
  
  
  #include <locale.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  
  #include "lua.h"
  
  #include "lauxlib.h"
  #include "lualib.h"
  
  
  /*
  ** {==================================================================
  ** List of valid conversion specifiers for the 'strftime' function;
  ** options are grouped by length; group of length 2 start with '||'.
  ** ===================================================================
  */
  #if !defined(LUA_STRFTIMEOPTIONS)	/* { */
  
  /* options for ANSI C 89 (only 1-char options) */
  #define L_STRFTIMEC89		"aAbBcdHIjmMpSUwWxXyYZ%"
  
  /* options for ISO C 99 and POSIX */
  #define L_STRFTIMEC99 "aAbBcCdDeFgGhHIjmMnprRStTuUVwWxXyYzZ%" \
      "||" "EcECExEXEyEY" "OdOeOHOIOmOMOSOuOUOVOwOWOy"  /* two-char options */
  
  /* options for Windows */
  #define L_STRFTIMEWIN "aAbBcdHIjmMpSUwWxXyYzZ%" \
      "||" "#c#x#d#H#I#j#m#M#S#U#w#W#y#Y"  /* two-char options */
  
  #if defined(LUA_USE_WINDOWS)
  #define LUA_STRFTIMEOPTIONS	L_STRFTIMEWIN
  #elif defined(LUA_USE_C89)
  #define LUA_STRFTIMEOPTIONS	L_STRFTIMEC89
  #else  /* C99 specification */
  #define LUA_STRFTIMEOPTIONS	L_STRFTIMEC99
  #endif
  
  #endif					/* } */
  /* }================================================================== */
  
  
  /*
  ** {==================================================================
  ** Configuration for time-related stuff
  ** ===================================================================
  */
  
  /*
  ** type to represent time_t in Lua
  */
  #if !defined(LUA_NUMTIME)	/* { */
  
  #define l_timet			lua_Integer
  #define l_pushtime(L,t)		lua_pushinteger(L,(lua_Integer)(t))
  #define l_gettime(L,arg)	luaL_checkinteger(L, arg)
  
  #else				/* }{ */
  
  #define l_timet			lua_Number
  #define l_pushtime(L,t)		lua_pushnumber(L,(lua_Number)(t))
  #define l_gettime(L,arg)	luaL_checknumber(L, arg)
  
  #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				/* } */
  
  /* }================================================================== */
  
  
  /*
  ** {==================================================================
  ** Configuration for 'tmpnam':
  ** By default, Lua uses tmpnam except when POSIX is available, where
  ** it uses mkstemp.
  ** ===================================================================
  */
  #if !defined(lua_tmpnam)	/* { */
  
  #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) { \
          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				/* } */
  /* }================================================================== */
  
  
  
  
  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=? }
  ** =======================================================
  */
  
  /*
  ** About the overflow check: an overflow cannot occurr when time
  ** is represented by a lua_Integer, because either lua_Integer is
  ** large enough to represent all int fields or it is not large enough
  ** to represent a time that cause a field to overflow.  However, if
  ** times are represented as doubles and lua_Integer is int, then the
  ** time 0x1.e1853b0d184f6p+55 would cause an overflow when adding 1900
  ** to compute the year.
  */
  static void setfield (lua_State *L, const char *key, int value, int delta) {
    #if (defined(LUA_NUMTIME) && LUA_MAXINTEGER <= INT_MAX)
      if (value > LUA_MAXINTEGER - delta)
        luaL_error(L, "field '%s' is out-of-bound", key);
    #endif
    lua_pushinteger(L, (lua_Integer)value + delta);
    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);
  }
  
  
  /*
  ** Set all fields from structure 'tm' in the table on top of the stack
  */
  static void setallfields (lua_State *L, struct tm *stm) {
    setfield(L, "year", stm->tm_year, 1900);
    setfield(L, "month", stm->tm_mon, 1);
    setfield(L, "day", stm->tm_mday, 0);
    setfield(L, "hour", stm->tm_hour, 0);
    setfield(L, "min", stm->tm_min, 0);
    setfield(L, "sec", stm->tm_sec, 0);
    setfield(L, "yday", stm->tm_yday, 1);
    setfield(L, "wday", stm->tm_wday, 1);
    setboolfield(L, "isdst", stm->tm_isdst);
  }
  
  
  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 delta) {
    int isnum;
    int t = lua_getfield(L, -1, key);  /* get field and its type */
    lua_Integer res = lua_tointegerx(L, -1, &isnum);
    if (!isnum) {  /* field is not an integer? */
      if (t != LUA_TNIL)  /* some other value? */
        return luaL_error(L, "field '%s' is not an integer", key);
      else if (d < 0)  /* absent field; no default? */
        return luaL_error(L, "field '%s' missing in date table", key);
      res = d;
    }
    else {
      /* unsigned avoids overflow when lua_Integer has 32 bits */
      if (!(res >= 0 ? (lua_Unsigned)res <= (lua_Unsigned)INT_MAX + delta
                     : (lua_Integer)INT_MIN + delta <= res))
        return luaL_error(L, "field '%s' is out-of-bound", key);
      res -= delta;
    }
    lua_pop(L, 1);
    return (int)res;
  }
  
  
  static const char *checkoption (lua_State *L, const char *conv,
                                  ptrdiff_t convlen, char *buff) {
    const char *option = LUA_STRFTIMEOPTIONS;
    int oplen = 1;  /* length of options being checked */
    for (; *option != '\0' && oplen <= convlen; option += oplen) {
      if (*option == '|')  /* next block? */
        oplen++;  /* will check options with next length (+1) */
      else if (memcmp(conv, option, oplen) == 0) {  /* match? */
        memcpy(buff, conv, oplen);  /* copy valid option to buffer */
        buff[oplen] = '\0';
        return conv + oplen;  /* return next item */
      }
    }
    luaL_argerror(L, 1,
      lua_pushfstring(L, "invalid conversion specifier '%%%s'", conv));
    return conv;  /* to avoid warnings */
  }
  
  
  static time_t l_checktime (lua_State *L, int arg) {
    l_timet t = l_gettime(L, arg);
    luaL_argcheck(L, (time_t)t == t, arg, "time out-of-bounds");
    return (time_t)t;
  }
  
  
  /* maximum size for an individual 'strftime' item */
  #define SIZETIMEFMT	250
  
  
  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? */
      return luaL_error(L,
                   "date 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;
  }
  
  
  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_year = getfield(L, "year", -1, 1900);
      ts.tm_mon = getfield(L, "month", -1, 1);
      ts.tm_mday = getfield(L, "day", -1, 0);
      ts.tm_hour = getfield(L, "hour", 12, 0);
      ts.tm_min = getfield(L, "min", 0, 0);
      ts.tm_sec = getfield(L, "sec", 0, 0);
      ts.tm_isdst = getboolfield(L, "isdst");
      t = mktime(&ts);
      setallfields(L, &ts);  /* update fields with normalized values */
    }
    if (t != (time_t)(l_timet)t || t == (time_t)(-1))
      return luaL_error(L,
                    "time result cannot be represented in this installation");
    l_pushtime(L, t);
    return 1;
  }
  
  
  static int os_difftime (lua_State *L) {
    time_t t1 = l_checktime(L, 1);
    time_t t2 = l_checktime(L, 2);
    lua_pushnumber(L, (lua_Number)difftime(t1, t2));
    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;
  }
  
  