Initial revision

1 files changed, 146 insertions, 0 deletions

diff --git a/date.c b/date.c
new file mode 100644
index 00000000..9cd20897
--- /dev/null
+++ b/date.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 1996-8 Michael R. Elkins <me@cs.hmc.edu>
+ * 
+ *     This program is free software; you can redistribute it and/or modify
+ *     it under the terms of the GNU General Public License as published by
+ *     the Free Software Foundation; either version 2 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program 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 General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program; if not, write to the Free Software
+ *     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */ 
+
+#include "mutt.h"
+
+/* returns the seconds west of UTC given `g' and its corresponding gmtime()
+   representation */
+static time_t mutt_compute_tz (time_t g, struct tm *utc)
+{
+  struct tm *lt = localtime (&g);
+  time_t t;
+
+  t = (((utc->tm_hour - lt->tm_hour) * 60) + (utc->tm_min - lt->tm_min)) * 60;
+  switch (utc->tm_yday - lt->tm_yday)
+  {
+    case 0:
+      break;
+
+    case 1:
+    case -364:
+    case -365:
+      t += 24 * 60 * 60;
+      break;
+
+    case -1:
+    case 364:
+    case 365:
+      t -= 24 * 60 * 60;
+      break;
+
+    default:
+      mutt_error ("Please report this program error in the function mutt_mktime.");
+  }
+
+  return t;
+}
+
+time_t mutt_local_tz (void)
+{
+  struct tm *ptm;
+  struct tm utc;
+  time_t now;
+
+  now = time (NULL);
+  ptm = gmtime (&now);
+  /* need to make a copy because gmtime/localtime return a pointer to
+     static memory (grr!) */
+  memcpy (&utc, ptm, sizeof (utc));
+  return (mutt_compute_tz (now, &utc));
+}
+
+/* converts struct tm to time_t, but does not take the local timezone into
+   account unless ``local'' is nonzero */
+time_t mutt_mktime (struct tm *t, int local)
+{
+  time_t g;
+
+  static int AccumDaysPerMonth[12] = {
+    0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
+  };
+
+  /* Compute the number of days since January 1 in the same year */
+  g = AccumDaysPerMonth [t->tm_mon % 12];
+
+  /* The leap years are 1972 and every 4. year until 2096,
+   * but this algoritm will fail after year 2099 */
+  g += t->tm_mday;
+  if ((t->tm_year % 4) || t->tm_mon < 2)
+    g--;
+  t->tm_yday = g;
+
+  /* Compute the number of days since January 1, 1970 */
+  g += (t->tm_year - 70) * 365;
+  g += (t->tm_year - 69) / 4;
+
+  /* Compute the number of hours */
+  g *= 24;
+  g += t->tm_hour;
+
+  /* Compute the number of minutes */
+  g *= 60;
+  g += t->tm_min;
+
+  /* Compute the number of seconds */
+  g *= 60;
+  g += t->tm_sec;
+
+  if (local)
+    g += mutt_compute_tz (g, t);
+
+  return (g);
+}
+
+void mutt_normalize_time (struct tm *tm)
+{
+  static char DaysPerMonth[12] = {
+    31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+  };
+
+  while (tm->tm_sec < 0)
+  {
+    tm->tm_sec += 60;
+    tm->tm_min--;
+  }
+  while (tm->tm_min < 0)
+  {
+    tm->tm_min += 60;
+    tm->tm_hour--;
+  }
+  while (tm->tm_hour < 0)
+  {
+    tm->tm_hour += 24;
+    tm->tm_mday--;
+  }
+  while (tm->tm_mon < 0)
+  {
+    tm->tm_mon += 12;
+    tm->tm_year--;
+  }
+  while (tm->tm_mday < 0)
+  {
+    if (tm->tm_mon)
+      tm->tm_mon--;
+    else
+    {
+      tm->tm_mon = 11;
+      tm->tm_year--;
+    }
+    tm->tm_mday += DaysPerMonth[tm->tm_mon];
+  }
+}