1 files changed, 117 insertions, 0 deletions
diff --git a/grub-core/lib/datetime.c b/grub-core/lib/datetime.c
new file mode 100644
index 0000000..9120128
--- /dev/null
+++ b/grub-core/lib/datetime.c
@@ -0,0 +1,117 @@
+/* datetime.c - Module for common datetime function.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *
+ *  GRUB 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/datetime.h>
+#include <grub/i18n.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+
+static const char *const grub_weekday_names[] =
+{
+  N_("Sunday"),
+  N_("Monday"),
+  N_("Tuesday"),
+  N_("Wednesday"),
+  N_("Thursday"),
+  N_("Friday"),
+  N_("Saturday"),
+};
+
+int
+grub_get_weekday (struct grub_datetime *datetime)
+{
+  unsigned a, y, m;
+
+  if (datetime->month <= 2)
+    a = 1;
+  else
+    a = 0;
+  y = datetime->year - a;
+  m = datetime->month + 12 * a - 2;
+
+  return (datetime->day + y + y / 4 - y / 100 + y / 400 + (31 * m / 12)) % 7;
+}
+
+const char *
+grub_get_weekday_name (struct grub_datetime *datetime)
+{
+  return _ (grub_weekday_names[grub_get_weekday (datetime)]);
+}
+
+#define SECPERMIN 60
+#define SECPERHOUR (60*SECPERMIN)
+#define SECPERDAY (24*SECPERHOUR)
+#define DAYSPERYEAR 365
+#define DAYSPER4YEARS (4*DAYSPERYEAR+1)
+
+
+void
+grub_unixtime2datetime (grub_int64_t nix, struct grub_datetime *datetime)
+{
+  int i;
+  grub_uint8_t months[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+  /* In the period of validity of unixtime all years divisible by 4
+     are bissextile*/
+  /* Convenience: let's have 3 consecutive non-bissextile years
+     at the beginning of the counting date. So count from 1901. */
+  int days_epoch;
+  /* Number of days since 1st Januar, 1901.  */
+  unsigned days;
+  /* Seconds into current day.  */
+  unsigned secs_in_day;
+
+  /* Transform C divisions and modulos to mathematical ones */
+  if (nix < 0)
+    /*
+     * The result of division here shouldn't be larger than GRUB_INT_MAX.
+     * So, it's safe to store the result back in an int.
+     */
+    days_epoch = -(grub_divmod64 (((grub_int64_t) (SECPERDAY) - nix - 1), SECPERDAY, NULL));
+  else
+    days_epoch = grub_divmod64 (nix, SECPERDAY, NULL);
+
+  secs_in_day = nix - days_epoch * SECPERDAY;
+  days = days_epoch + 69 * DAYSPERYEAR + 17;
+
+  datetime->year = 1901 + 4 * (days / DAYSPER4YEARS);
+  days %= DAYSPER4YEARS;
+  /* On 31st December of bissextile years 365 days from the beginning
+     of the year elapsed but year isn't finished yet */
+  if (days / DAYSPERYEAR == 4)
+    {
+      datetime->year += 3;
+      days -= 3*DAYSPERYEAR;
+    }
+  else
+    {
+      datetime->year += days / DAYSPERYEAR;
+      days %= DAYSPERYEAR;
+    }
+  for (i = 0; i < 12
+	 && days >= (i==1 && datetime->year % 4 == 0
+		      ? 29 : months[i]); i++)
+    days -= (i==1 && datetime->year % 4 == 0
+			    ? 29 : months[i]);
+  datetime->month = i + 1;
+  datetime->day = 1 + days;
+  datetime->hour = (secs_in_day / SECPERHOUR);
+  secs_in_day %= SECPERHOUR;
+  datetime->minute = secs_in_day / SECPERMIN;
+  datetime->second = secs_in_day % SECPERMIN;
+}