getdate.y

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

	      if (value != value1)
		return '?';

	      /* Accumulate fraction, to ns precision.  */
	      p++;
	      ns = *p++ - '0';
	      for (digits = 2; digits <= LOG10_BILLION; digits++)
		{
		  ns *= 10;
		  if (ISDIGIT (*p))
		    ns += *p++ - '0';
		}

	      /* Skip excess digits, truncating toward -Infinity.  */
	      if (sign < 0)
		for (; ISDIGIT (*p); p++)
		  if (*p != '0')
		    {
		      ns++;
		      break;
		    }
	      while (ISDIGIT (*p))
		p++;

	      /* Adjust to the timespec convention, which is that
		 tv_nsec is always a positive offset even if tv_sec is
		 negative.  */
	      if (sign < 0 && ns)
		{
		  s--;
		  if (! (s < 0))
		    return '?';
		  ns = BILLION - ns;
		}

	      lvalp->timespec.tv_sec = s;
	      lvalp->timespec.tv_nsec = ns;
	      pc->input = p;
	      return sign ? tSDECIMAL_NUMBER : tUDECIMAL_NUMBER;
	    }
	  else
	    {
	      lvalp->textintval.negative = sign < 0;
	      if (sign < 0)
		{
		  lvalp->textintval.value = - value;
		  if (0 < lvalp->textintval.value)
		    return '?';
		}
	      else
		{
		  lvalp->textintval.value = value;
		  if (lvalp->textintval.value < 0)
		    return '?';
		}
	      lvalp->textintval.digits = p - pc->input;
	      pc->input = p;
	      return sign ? tSNUMBER : tUNUMBER;
	    }
	}

      if (isalpha (c))
	{
	  char buff[20];
	  char *p = buff;
	  table const *tp;

	  do
	    {
	      if (p < buff + sizeof buff - 1)
		*p++ = c;
	      c = *++pc->input;
	    }
	  while (isalpha (c) || c == '.');

	  *p = '\0';
	  tp = lookup_word (pc, buff);
	  if (! tp)
	    return '?';
	  lvalp->intval = tp->value;
	  return tp->type;
	}

      if (c != '(')
	return *pc->input++;
      count = 0;
      do
	{
	  c = *pc->input++;
	  if (c == '\0')
	    return c;
	  if (c == '(')
	    count++;
	  else if (c == ')')
	    count--;
	}
      while (count != 0);
    }
}

/* Do nothing if the parser reports an error.  */
static int
yyerror (parser_control const *pc ATTRIBUTE_UNUSED,
	 char const *s ATTRIBUTE_UNUSED)
{
  return 0;
}

/* If *TM0 is the old and *TM1 is the new value of a struct tm after
   passing it to mktime, return true if it's OK that mktime returned T.
   It's not OK if *TM0 has out-of-range members.  */

static bool
mktime_ok (struct tm const *tm0, struct tm const *tm1, time_t t)
{
  if (t == (time_t) -1)
    {
      /* Guard against falsely reporting an error when parsing a time
	 stamp that happens to equal (time_t) -1, on a host that
	 supports such a time stamp.  */
      tm1 = localtime (&t);
      if (!tm1)
	return false;
    }

  return ! ((tm0->tm_sec ^ tm1->tm_sec)
	    | (tm0->tm_min ^ tm1->tm_min)
	    | (tm0->tm_hour ^ tm1->tm_hour)
	    | (tm0->tm_mday ^ tm1->tm_mday)
	    | (tm0->tm_mon ^ tm1->tm_mon)
	    | (tm0->tm_year ^ tm1->tm_year));
}

/* A reasonable upper bound for the size of ordinary TZ strings.
   Use heap allocation if TZ's length exceeds this.  */
enum { TZBUFSIZE = 100 };

/* Return a copy of TZ, stored in TZBUF if it fits, and heap-allocated
   otherwise.  */
static char *
get_tz (char tzbuf[TZBUFSIZE])
{
  char *tz = getenv ("TZ");
  if (tz)
    {
      size_t tzsize = strlen (tz) + 1;
      tz = (tzsize <= TZBUFSIZE
	    ? memcpy (tzbuf, tz, tzsize)
	    : xmemdup (tz, tzsize));
    }
  return tz;
}

/* Parse a date/time string, storing the resulting time value into *RESULT.
   The string itself is pointed to by P.  Return true if successful.
   P can be an incomplete or relative time specification; if so, use
   *NOW as the basis for the returned time.  */
bool
get_date (struct timespec *result, char const *p, struct timespec const *now)
{
  time_t Start;
  long int Start_ns;
  struct tm const *tmp;
  struct tm tm;
  struct tm tm0;
  parser_control pc;
  struct timespec gettime_buffer;
  unsigned char c;
  bool tz_was_altered = false;
  char *tz0 = NULL;
  char tz0buf[TZBUFSIZE];
  bool ok = true;

  if (! now)
    {
      gettime (&gettime_buffer);
      now = &gettime_buffer;
    }

  Start = now->tv_sec;
  Start_ns = now->tv_nsec;

  tmp = localtime (&now->tv_sec);
  if (! tmp)
    return false;

  while (c = *p, isspace (c))
    p++;

  if (strncmp (p, "TZ=\"", 4) == 0)
    {
      char const *tzbase = p + 4;
      size_t tzsize = 1;
      char const *s;

      for (s = tzbase; *s; s++, tzsize++)
	if (*s == '\\')
	  {
	    s++;
	    if (! (*s == '\\' || *s == '"'))
	      break;
	  }
	else if (*s == '"')
	  {
	    char *z;
	    char *tz1;
	    char tz1buf[TZBUFSIZE];
	    bool large_tz = TZBUFSIZE < tzsize;
	    bool setenv_ok;
	    tz0 = get_tz (tz0buf);
	    z = tz1 = large_tz ? xmalloc (tzsize) : tz1buf;
	    for (s = tzbase; *s != '"'; s++)
	      *z++ = *(s += *s == '\\');
	    *z = '\0';
	    setenv_ok = setenv ("TZ", tz1, 1) == 0;
	    if (large_tz)
	      free (tz1);
	    if (!setenv_ok)
	      goto fail;
	    tz_was_altered = true;
	    p = s + 1;
	  }
    }

  /* As documented, be careful to treat the empty string just like
     a date string of "0".  Without this, an empty string would be
     declared invalid when parsed during a DST transition.  */
  if (*p == '\0')
    p = "0";

  pc.input = p;
  pc.year.value = tmp->tm_year;
  pc.year.value += TM_YEAR_BASE;
  pc.year.digits = 0;
  pc.month = tmp->tm_mon + 1;
  pc.day = tmp->tm_mday;
  pc.hour = tmp->tm_hour;
  pc.minutes = tmp->tm_min;
  pc.seconds.tv_sec = tmp->tm_sec;
  pc.seconds.tv_nsec = Start_ns;
  tm.tm_isdst = tmp->tm_isdst;

  pc.meridian = MER24;
  pc.rel = RELATIVE_TIME_0;
  pc.timespec_seen = false;
  pc.rels_seen = false;
  pc.dates_seen = 0;
  pc.days_seen = 0;
  pc.times_seen = 0;
  pc.local_zones_seen = 0;
  pc.dsts_seen = 0;
  pc.zones_seen = 0;

#if HAVE_STRUCT_TM_TM_ZONE
  pc.local_time_zone_table[0].name = tmp->tm_zone;
  pc.local_time_zone_table[0].type = tLOCAL_ZONE;
  pc.local_time_zone_table[0].value = tmp->tm_isdst;
  pc.local_time_zone_table[1].name = NULL;

  /* Probe the names used in the next three calendar quarters, looking
     for a tm_isdst different from the one we already have.  */
  {
    int quarter;
    for (quarter = 1; quarter <= 3; quarter++)
      {
	time_t probe = Start + quarter * (90 * 24 * 60 * 60);
	struct tm const *probe_tm = localtime (&probe);
	if (probe_tm && probe_tm->tm_zone
	    && probe_tm->tm_isdst != pc.local_time_zone_table[0].value)
	  {
	      {
		pc.local_time_zone_table[1].name = probe_tm->tm_zone;
		pc.local_time_zone_table[1].type = tLOCAL_ZONE;
		pc.local_time_zone_table[1].value = probe_tm->tm_isdst;
		pc.local_time_zone_table[2].name = NULL;
	      }
	    break;
	  }
      }
  }
#else
#if HAVE_TZNAME
  {
# if !HAVE_DECL_TZNAME
    extern char *tzname[];
# endif
    int i;
    for (i = 0; i < 2; i++)
      {
	pc.local_time_zone_table[i].name = tzname[i];
	pc.local_time_zone_table[i].type = tLOCAL_ZONE;
	pc.local_time_zone_table[i].value = i;
      }
    pc.local_time_zone_table[i].name = NULL;
  }
#else
  pc.local_time_zone_table[0].name = NULL;
#endif
#endif

  if (pc.local_time_zone_table[0].name && pc.local_time_zone_table[1].name
      && ! strcmp (pc.local_time_zone_table[0].name,
		   pc.local_time_zone_table[1].name))
    {
      /* This locale uses the same abbrevation for standard and
	 daylight times.  So if we see that abbreviation, we don't
	 know whether it's daylight time.  */
      pc.local_time_zone_table[0].value = -1;
      pc.local_time_zone_table[1].name = NULL;
    }

  if (yyparse (&pc) != 0)
    goto fail;

  if (pc.timespec_seen)
    *result = pc.seconds;
  else
    {
      if (1 < (pc.times_seen | pc.dates_seen | pc.days_seen | pc.dsts_seen
	       | (pc.local_zones_seen + pc.zones_seen)))
	goto fail;

      tm.tm_year = to_year (pc.year) - TM_YEAR_BASE;
      tm.tm_mon = pc.month - 1;
      tm.tm_mday = pc.day;
      if (pc.times_seen || (pc.rels_seen && ! pc.dates_seen && ! pc.days_seen))
	{
	  tm.tm_hour = to_hour (pc.hour, pc.meridian);
	  if (tm.tm_hour < 0)
	    goto fail;
	  tm.tm_min = pc.minutes;
	  tm.tm_sec = pc.seconds.tv_sec;
	}
      else
	{
	  tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
	  pc.seconds.tv_nsec = 0;
	}

      /* Let mktime deduce tm_isdst if we have an absolute time stamp.  */
      if (pc.dates_seen | pc.days_seen | pc.times_seen)
	tm.tm_isdst = -1;

      /* But if the input explicitly specifies local time with or without
	 DST, give mktime that information.  */
      if (pc.local_zones_seen)
	tm.tm_isdst = pc.local_isdst;

      tm0 = tm;

      Start = mktime (&tm);

      if (! mktime_ok (&tm0, &tm, Start))
	{
	  if (! pc.zones_seen)
	    goto fail;
	  else
	    {
	      /* Guard against falsely reporting errors near the time_t
		 boundaries when parsing times in other time zones.  For
		 example, suppose the input string "1969-12-31 23:00:00 -0100",
		 the current time zone is 8 hours ahead of UTC, and the min
		 time_t value is 1970-01-01 00:00:00 UTC.  Then the min
		 localtime value is 1970-01-01 08:00:00, and mktime will
		 therefore fail on 1969-12-31 23:00:00.  To work around the
		 problem, set the time zone to 1 hour behind UTC temporarily
		 by setting TZ="XXX1:00" and try mktime again.  */

	      long int time_zone = pc.time_zone;
	      long int abs_time_zone = time_zone < 0 ? - time_zone : time_zone;
	      long int abs_time_zone_hour = abs_time_zone / 60;
	      int abs_time_zone_min = abs_time_zone % 60;
	      char tz1buf[sizeof "XXX+0:00"
			  + sizeof pc.time_zone * CHAR_BIT / 3];
	      if (!tz_was_altered)
		tz0 = get_tz (tz0buf);
	      sprintf (tz1buf, "XXX%s%ld:%02d", "-" + (time_zone < 0),
		       abs_time_zone_hour, abs_time_zone_min);
	      if (setenv ("TZ", tz1buf, 1) != 0)
		goto fail;
	      tz_was_altered = true;
	      tm = tm0;
	      Start = mktime (&tm);
	      if (! mktime_ok (&tm0, &tm, Start))
		goto fail;
	    }
	}

      if (pc.days_seen && ! pc.dates_seen)
	{
	  tm.tm_mday += ((pc.day_number - tm.tm_wday + 7) % 7
			 + 7 * (pc.day_ordinal - (0 < pc.day_ordinal)));
	  tm.tm_isdst = -1;
	  Start = mktime (&tm);
	  if (Start == (time_t) -1)
	    goto fail;
	}

      if (pc.zones_seen)
	{
	  long int delta = pc.time_zone * 60;
	  time_t t1;
#ifdef HAVE_TM_GMTOFF
	  delta -= tm.tm_gmtoff;
#else
	  time_t t = Start;
	  struct tm const *gmt = gmtime (&t);
	  if (! gmt)
	    goto fail;
	  delta -= tm_diff (&tm, gmt);
#endif
	  t1 = Start - delta;
	  if ((Start < t1) != (delta < 0))
	    goto fail;	/* time_t overflow */
	  Start = t1;
	}

      /* Add relative date.  */
      if (pc.rel.year | pc.rel.month | pc.rel.day)
	{
	  int year = tm.tm_year + pc.rel.year;
	  int month = tm.tm_mon + pc.rel.month;
	  int day = tm.tm_mday + pc.rel.day;
	  if (((year < tm.tm_year) ^ (pc.rel.year < 0))
	      | ((month < tm.tm_mon) ^ (pc.rel.month < 0))
	      | ((day < tm.tm_mday) ^ (pc.rel.day < 0)))
	    goto fail;
	  tm.tm_year = year;
	  tm.tm_mon = month;
	  tm.tm_mday = day;
	  tm.tm_hour = tm0.tm_hour;
	  tm.tm_min = tm0.tm_min;
	  tm.tm_sec = tm0.tm_sec;
	  tm.tm_isdst = tm0.tm_isdst;
	  Start = mktime (&tm);
	  if (Start == (time_t) -1)
	    goto fail;
	}

      /* Add relative hours, minutes, and seconds.  On hosts that support
	 leap seconds, ignore the possibility of leap seconds; e.g.,
	 "+ 10 minutes" adds 600 seconds, even if one of them is a
	 leap second.  Typically this is not what the user wants, but it's
	 too hard to do it the other way, because the time zone indicator
	 must be applied before relative times, and if mktime is applied
	 again the time zone will be lost.  */
      {
	long int sum_ns = pc.seconds.tv_nsec + pc.rel.ns;
	long int normalized_ns = (sum_ns % BILLION + BILLION) % BILLION;
	time_t t0 = Start;
	long int d1 = 60 * 60 * pc.rel.hour;
	time_t t1 = t0 + d1;
	long int d2 = 60 * pc.rel.minutes;
	time_t t2 = t1 + d2;
	long int d3 = pc.rel.seconds;
	time_t t3 = t2 + d3;
	long int d4 = (sum_ns - normalized_ns) / BILLION;
	time_t t4 = t3 + d4;

	if ((d1 / (60 * 60) ^ pc.rel.hour)
	    | (d2 / 60 ^ pc.rel.minutes)
	    | ((t1 < t0) ^ (d1 < 0))
	    | ((t2 < t1) ^ (d2 < 0))
	    | ((t3 < t2) ^ (d3 < 0))
	    | ((t4 < t3) ^ (d4 < 0)))
	  goto fail;

	result->tv_sec = t4;
	result->tv_nsec = normalized_ns;
      }
    }

  goto done;

 fail:
  ok = false;
 done:
  if (tz_was_altered)
    ok &= (tz0 ? setenv ("TZ", tz0, 1) : unsetenv ("TZ")) == 0;
  if (tz0 != tz0buf)
    free (tz0);
  return ok;
}

#if TEST

int
main (int ac, char **av)
{
  char buff[BUFSIZ];

  printf ("Enter date, or blank line to exit.\n\t> ");
  fflush (stdout);

  buff[BUFSIZ - 1] = '\0';
  while (fgets (buff, BUFSIZ - 1, stdin) && buff[0])
    {
      struct timespec d;
      struct tm const *tm;
      if (! get_date (&d, buff, NULL))
	printf ("Bad format - couldn't convert.\n");
      else if (! (tm = localtime (&d.tv_sec)))
	{
	  long int sec = d.tv_sec;
	  printf ("localtime (%ld) failed\n", sec);
	}
      else
	{
	  int ns = d.tv_nsec;
	  printf ("%04ld-%02d-%02d %02d:%02d:%02d.%09d\n",
		  tm->tm_year + 1900L, tm->tm_mon + 1, tm->tm_mday,
		  tm->tm_hour, tm->tm_min, tm->tm_sec, ns);
	}
      printf ("\t> ");
      fflush (stdout);
    }
  return 0;
}
#endif /* TEST */