initial import

1 files changed, 506 insertions, 0 deletions

diff --git a/time/mktime.c b/time/mktime.c
new file mode 100644
index 0000000000..f86496a941
--- /dev/null
+++ b/time/mktime.c
@@ -0,0 +1,506 @@
+/* Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc.
+   Contributed by Noel Cragg (noel@cs.oberlin.edu), with fixes by
+   Michael E. Calwas (calwas@ttd.teradyne.com) and
+   Wade Hampton (tasi029@tmn.com).
+
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+/* Define this to have a standalone program to test this implementation of
+   mktime.  */
+/* #define DEBUG */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/types.h>		/* Some systems define `time_t' here.  */
+#include <time.h>
+
+
+#ifndef __isleap
+/* Nonzero if YEAR is a leap year (every 4 years,
+   except every 100th isn't, and every 400th is).  */
+#define	__isleap(year)	\
+  ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
+#endif
+
+#ifndef __P
+#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
+#define __P(args) args
+#else
+#define __P(args) ()
+#endif  /* GCC.  */
+#endif  /* Not __P.  */
+
+/* How many days are in each month.  */
+const unsigned short int __mon_lengths[2][12] =
+  {
+    /* Normal years.  */
+    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+    /* Leap years.  */
+    { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+  };
+
+
+static int times_through_search; /* This library routine should never
+				    hang -- make sure we always return
+				    when we're searching for a value */
+
+
+#ifdef DEBUG
+
+#include <stdio.h>
+#include <ctype.h>
+
+int debugging_enabled = 0;
+
+/* Print the values in a `struct tm'. */
+static void
+printtm (it)
+     struct tm *it;
+{
+  printf ("%02d/%02d/%04d %02d:%02d:%02d (%s) yday:%03d dst:%d gmtoffset:%ld",
+	  it->tm_mon + 1,
+	  it->tm_mday,
+	  it->tm_year + 1900,
+	  it->tm_hour,
+	  it->tm_min,
+	  it->tm_sec,
+	  it->tm_zone,
+	  it->tm_yday,
+	  it->tm_isdst,
+	  it->tm_gmtoff);
+}
+#endif
+
+
+static time_t
+dist_tm (t1, t2)
+     struct tm *t1;
+     struct tm *t2;
+{
+  time_t distance = 0;
+  unsigned long int v1, v2;
+  int diff_flag = 0;
+
+  v1 = v2 = 0;
+
+#define doit(x, secs)                                                         \
+  v1 += t1->x * secs;                                                         \
+  v2 += t2->x * secs;                                                         \
+  if (!diff_flag)                                                             \
+    {                                                                         \
+      if (t1->x < t2->x)                                                      \
+	diff_flag = -1;                                                       \
+      else if (t1->x > t2->x)                                                 \
+	diff_flag = 1;                                                        \
+    }
+  
+  doit (tm_year, 31536000);	/* Okay, not all years have 365 days. */
+  doit (tm_mon, 2592000);	/* Okay, not all months have 30 days. */
+  doit (tm_mday, 86400);
+  doit (tm_hour, 3600);
+  doit (tm_min, 60);
+  doit (tm_sec, 1);
+  
+#undef doit
+  
+  /* We should also make sure that the sign of DISTANCE is correct -- if
+     DIFF_FLAG is positive, the distance should be positive and vice versa. */
+  
+  distance = (v1 > v2) ? (v1 - v2) : (v2 - v1);
+  if (diff_flag < 0)
+    distance = -distance;
+
+  if (times_through_search > 20) /* Arbitrary # of calls, but makes sure we
+				    never hang if there's a problem with
+				    this algorithm.  */
+    {
+      distance = diff_flag;
+    }
+
+  /* We need this DIFF_FLAG business because it is forseeable that the
+     distance may be zero when, in actuality, the two structures are
+     different.  This is usually the case when the dates are 366 days apart
+     and one of the years is a leap year.  */
+
+  if (distance == 0 && diff_flag)
+    distance = 86400 * diff_flag;
+
+  return distance;
+}
+      
+
+/* MKTIME converts the values in a struct tm to a time_t.  The values
+   in tm_wday and tm_yday are ignored; other values can be put outside
+   of legal ranges since they will be normalized.  This routine takes
+   care of that normalization. */
+
+void
+do_normalization (tmptr)
+     struct tm *tmptr;
+{
+
+#define normalize(foo,x,y,bar); \
+  while (tmptr->foo < x) \
+    { \
+      tmptr->bar--; \
+      tmptr->foo = (y - (x - tmptr->foo) + 1); \
+    } \
+  while (tmptr->foo > y) \
+    { \
+      tmptr->foo = (x + (tmptr->foo - y) - 1); \
+      tmptr->bar++; \
+    }
+  
+  normalize (tm_sec, 0, 59, tm_min);
+  normalize (tm_min, 0, 59, tm_hour);
+  normalize (tm_hour, 0, 23, tm_mday);
+  
+  /* Do the month first, so day range can be found. */
+  normalize (tm_mon, 0, 11, tm_year);
+
+  /* Since the day range modifies the month, we should be careful how
+     we reference the array of month lengths -- it is possible that
+     the month will go negative, hence the modulo...
+
+     Also, tm_year is the year - 1900, so we have to 1900 to have it
+     work correctly. */
+
+  normalize (tm_mday, 1,
+	     __mon_lengths[__isleap (tmptr->tm_year + 1900)]
+                          [((tmptr->tm_mon < 0)
+			    ? (12 + (tmptr->tm_mon % 12))
+			    : (tmptr->tm_mon % 12)) ],
+	     tm_mon);
+
+  /* Do the month again, because the day may have pushed it out of range. */
+  normalize (tm_mon, 0, 11, tm_year);
+
+  /* Do the day again, because the month may have changed the range. */
+  normalize (tm_mday, 1,
+	     __mon_lengths[__isleap (tmptr->tm_year + 1900)]
+	                  [((tmptr->tm_mon < 0)
+			    ? (12 + (tmptr->tm_mon % 12))
+			    : (tmptr->tm_mon % 12)) ],
+	     tm_mon);
+  
+#ifdef DEBUG
+  if (debugging_enabled)
+    {
+      printf ("   After normalizing:\n     ");
+      printtm (tmptr);
+      putchar ('\n');
+    }
+#endif
+
+}
+
+
+/* Here's where the work gets done. */
+
+#define BAD_STRUCT_TM ((time_t) -1)
+
+time_t
+_mktime_internal (timeptr, producer)
+     struct tm *timeptr;
+     struct tm *(*producer) __P ((const time_t *));
+{
+  struct tm our_tm;		/* our working space */
+  struct tm *me = &our_tm;	/* a pointer to the above */
+  time_t result;		/* the value we return */
+
+  *me = *timeptr;		/* copy the struct tm that was passed
+				   in by the caller */
+
+
+  /***************************/
+  /* Normalize the structure */
+  /***************************/
+
+  /* This routine assumes that the value of TM_ISDST is -1, 0, or 1.
+     If the user didn't pass it in that way, fix it. */
+
+  if (me->tm_isdst > 0)
+    me->tm_isdst = 1;
+  else if (me->tm_isdst < 0)
+    me->tm_isdst = -1;
+
+  do_normalization (me);
+
+  /* Get out of here if it's not possible to represent this struct.
+     If any of the values in the normalized struct tm are negative,
+     our algorithms won't work.  Luckily, we only need to check the
+     year at this point; normalization guarantees that all values will
+     be in correct ranges EXCEPT the year. */
+
+  if (me->tm_year < 0)
+    return BAD_STRUCT_TM;
+
+  /*************************************************/
+  /* Find the appropriate time_t for the structure */
+  /*************************************************/
+
+  /* Modified b-search -- make intelligent guesses as to where the
+     time might lie along the timeline, assuming that our target time
+     lies a linear distance (w/o considering time jumps of a
+     particular region).
+
+     Assume that time does not fluctuate at all along the timeline --
+     e.g., assume that a day will always take 86400 seconds, etc. --
+     and come up with a hypothetical value for the time_t
+     representation of the struct tm TARGET, in relation to the guess
+     variable -- it should be pretty close!
+
+     After testing this, the maximum number of iterations that I had
+     on any number that I tried was 3!  Not bad.
+
+     The reason this is not a subroutine is that we will modify some
+     fields in the struct tm (yday and mday).  I've never felt good
+     about side-effects when writing structured code... */
+
+  {
+    struct tm *guess_tm;
+    time_t guess = 0;
+    time_t distance = 0;
+    time_t last_distance = 0;
+
+    times_through_search = 0;
+
+    do
+      {
+	guess += distance;
+
+	times_through_search++;     
+      
+	guess_tm = (*producer) (&guess);
+      
+#ifdef DEBUG
+	if (debugging_enabled)
+	  {
+	    printf ("   Guessing time_t == %d\n     ", (int) guess);
+	    printtm (guess_tm);
+	    putchar ('\n');
+	  }
+#endif
+      
+	/* How far is our guess from the desired struct tm? */
+	distance = dist_tm (me, guess_tm);
+      
+	/* Handle periods of time where a period of time is skipped.
+	   For example, 2:15 3 April 1994 does not exist, because DST
+	   is in effect.  The distance function will alternately
+	   return values of 3600 and -3600, because it doesn't know
+	   that the requested time doesn't exist.  In these situations
+	   (even if the skip is not exactly an hour) the distances
+	   returned will be the same, but alternating in sign.  We
+	   want the later time, so check to see that the distance is
+	   oscillating and we've chosen the correct of the two
+	   possibilities.
+
+	   Useful: 3 Apr 94 765356300, 30 Oct 94 783496000 */
+
+	if ((distance == -last_distance) && (distance < last_distance))
+	  {
+	    /* If the caller specified that the DST flag was off, it's
+               not possible to represent this time. */
+	    if (me->tm_isdst == 0)
+	      {
+#ifdef DEBUG
+	    printf ("   Distance is oscillating -- dst flag nixes struct!\n");
+#endif
+		return BAD_STRUCT_TM;
+	      }
+
+#ifdef DEBUG
+	    printf ("   Distance is oscillating -- chose the later time.\n");
+#endif
+	    distance = 0;
+	  }
+
+	if ((distance == 0) && (me->tm_isdst != -1)
+	    && (me->tm_isdst != guess_tm->tm_isdst))
+	  {
+	    /* If we're in this code, we've got the right time but the
+               wrong daylight savings flag.  We need to move away from
+               the time that we have and approach the other time from
+               the other direction.  That is, if I've requested the
+               non-DST version of a time and I get the DST version
+               instead, I want to put us forward in time and search
+               backwards to get the other time.  I checked all of the
+               configuration files for the tz package -- no entry
+               saves more than two hours, so I think we'll be safe by
+               moving 24 hours in one direction.  IF THE AMOUNT OF
+               TIME SAVED IN THE CONFIGURATION FILES CHANGES, THIS
+               VALUE MAY NEED TO BE ADJUSTED.  Luckily, we can never
+               have more than one level of overlaps, or this would
+               never work. */
+
+#define SKIP_VALUE 86400
+
+	    if (guess_tm->tm_isdst == 0)
+	      /* we got the later one, but want the earlier one */
+	      distance = -SKIP_VALUE;
+	    else
+	      distance = SKIP_VALUE;
+	    
+#ifdef DEBUG
+	    printf ("   Got the right time, wrong DST value -- adjusting\n");
+#endif
+	  }
+
+	last_distance = distance;
+
+      } while (distance != 0);
+
+    /* Check to see that the dst flag matches */
+
+    if (me->tm_isdst != -1)
+      {
+	if (me->tm_isdst != guess_tm->tm_isdst)
+	  {
+#ifdef DEBUG
+	    printf ("   DST flag doesn't match!  FIXME?\n");
+#endif
+	    return BAD_STRUCT_TM;
+	  }
+      }
+
+    result = guess;		/* Success! */
+
+    /* On successful completion, the values of tm_wday and tm_yday
+       have to be set appropriately. */
+    
+    /* me->tm_yday = guess_tm->tm_yday; 
+       me->tm_mday = guess_tm->tm_mday; */
+
+    *me = *guess_tm;
+  }
+
+  /* Update the caller's version of the structure */
+
+  *timeptr = *me;
+
+  return result;
+}
+
+time_t
+#ifdef DEBUG			/* make it work even if the system's
+				   libc has it's own mktime routine */
+my_mktime (timeptr)
+#else
+mktime (timeptr)
+#endif
+     struct tm *timeptr;
+{
+  return _mktime_internal (timeptr, localtime);
+}
+
+#ifdef weak_alias
+weak_alias (mktime, timelocal)
+#endif
+
+#ifdef DEBUG
+void
+main (argc, argv)
+     int argc;
+     char *argv[];
+{
+  int time;
+  int result_time;
+  struct tm *tmptr;
+  
+  if (argc == 1)
+    {
+      long q;
+      
+      printf ("starting long test...\n");
+
+      for (q = 10000000; q < 1000000000; q += 599)
+	{
+	  struct tm *tm = localtime ((time_t *) &q);
+	  if ((q % 10000) == 0) { printf ("%ld\n", q); fflush (stdout); }
+	  if (q != my_mktime (tm))
+	    { printf ("failed for %ld\n", q); fflush (stdout); }
+	}
+      
+      printf ("test finished\n");
+
+      exit (0);
+    }
+  
+  if (argc != 2)
+    {
+      printf ("wrong # of args\n");
+      exit (0);
+    }
+  
+  debugging_enabled = 1;	/* We want to see the info */
+
+  ++argv;
+  time = atoi (*argv);
+  
+  tmptr = localtime ((time_t *) &time);
+  printf ("Localtime tells us that a time_t of %d represents\n     ", time);
+  printtm (tmptr);
+  putchar ('\n');
+
+  printf ("   Given localtime's return val, mktime returns %d which is\n     ",
+	  (int) my_mktime (tmptr));
+  printtm (tmptr);
+  putchar ('\n');
+
+#if 0
+  tmptr->tm_sec -= 20;
+  tmptr->tm_min -= 20;
+  tmptr->tm_hour -= 20;
+  tmptr->tm_mday -= 20;
+  tmptr->tm_mon -= 20;
+  tmptr->tm_year -= 20;
+  tmptr->tm_gmtoff -= 20000;	/* This has no effect! */
+  tmptr->tm_zone = NULL;	/* Nor does this! */
+  tmptr->tm_isdst = -1;
+#endif
+  
+  tmptr->tm_hour += 1;
+  tmptr->tm_isdst = -1;
+
+  printf ("\n\nchanged ranges: ");
+  printtm (tmptr);
+  putchar ('\n');
+
+  result_time = my_mktime (tmptr);
+  printf ("\nmktime: %d\n", result_time);
+
+  tmptr->tm_isdst = 0;
+
+  printf ("\n\nchanged ranges: ");
+  printtm (tmptr);
+  putchar ('\n');
+
+  result_time = my_mktime (tmptr);
+  printf ("\nmktime: %d\n", result_time);
+}
+#endif /* DEBUG */
+
+
+/*
+Local Variables:
+compile-command: "gcc -g mktime.c -o mktime -DDEBUG"
+End:
+*/