Check for the year span 1902-2037

Reintroduce year check for systems with a 32-bit time_t type. Remove the
lower limit (1902) for systems with a 64-bit time_t. This limits
movements in the calendar (for 32-bit systems) and in no way ensures
constistency of data.

Commit a12833e (Handle dates past January 19th, 2038, 2015-01-19)
removed the upper limit (2037) on dates but left the lower limit (1902).
It did not ensure the support of the target system.

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

3 files changed, 34 insertions, 15 deletions

diff --git a/src/calcurse.h b/src/calcurse.h
index ca55e1f..f4f0e6c 100644
--- a/src/calcurse.h
+++ b/src/calcurse.h
@@ -304,10 +304,15 @@ enum datefmt {
 /* Day heading default format. */
 #define DAY_HEADING_DEFAULT "%B %-d, %Y"
 
+/*
+ * Calcurse representation of the date of a day in the calendar.
+ * When time_t is a 32-bit signed integer, the year range is 1902 - 2037.
+ */
+#define YEAR1902_2037 (sizeof(time_t) == 4)
 struct date {
-	unsigned dd;
-	unsigned mm;
-	unsigned yyyy;
+	unsigned dd;		/* day: 1 - 31 */
+	unsigned mm;		/* month: 1 - 12 */
+	unsigned yyyy;		/* year AD */
 };
 
 #define ISLEAP(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
diff --git a/src/ui-calendar.c b/src/ui-calendar.c
index 93115da..07d82f3 100644
--- a/src/ui-calendar.c
+++ b/src/ui-calendar.c
@@ -713,18 +713,30 @@ void ui_calendar_move(enum move move, int count)
 		ret = 1;
 		/* NOTREACHED */
 	}
-
-	if (ret == 0) {
+	if (ret == 1 || (YEAR1902_2037 && t.tm_year < 2)
+		     || (YEAR1902_2037 && t.tm_year > 137)) {
+		char *out, *msg = _("The move failed (%d/%d/%d, ret=%d)."), ch;
+		asprintf(&out, msg, t.tm_mday, t.tm_mon + 1, t.tm_year + 1900, ret);
+		do {
+			status_mesg(out, _("Press [ENTER] to continue"));
+			ch = keys_wgetch(win[KEY].p);
+		} while (ch != '\n');
+		mem_free(out);
+		wins_update(FLAG_STA);
 		if (t.tm_year < 2) {
 			t.tm_mday = 1;
 			t.tm_mon = 0;
 			t.tm_year = 2;
 		}
-
-		slctd_day.dd = t.tm_mday;
-		slctd_day.mm = t.tm_mon + 1;
-		slctd_day.yyyy = t.tm_year + 1900;
+		if (t.tm_year > 137) {
+			t.tm_mday = 31;
+			t.tm_mon = 11;
+			t.tm_year = 137;
+		}
 	}
+	slctd_day.dd = t.tm_mday;
+	slctd_day.mm = t.tm_mon + 1;
+	slctd_day.yyyy = t.tm_year + 1900;
 }
 
 /* Returns the beginning of current year as a long. */
diff --git a/src/utils.c b/src/utils.c
index f3739ea..c046ad5 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -481,7 +481,7 @@ void date_sec2date_fmt(long sec, const char *fmt, char *datef)
 }
 
 /*
- * Used to change date by adding a certain amount of days or weeks.
+ * Used to change date by adding a certain amount of days or months.
  * Returns 0 on success, 1 otherwise.
  */
 int date_change(struct tm *date, int delta_month, int delta_day)
@@ -501,7 +501,7 @@ int date_change(struct tm *date, int delta_month, int delta_day)
 }
 
 /*
- * Used to change date by adding a certain amount of days or weeks.
+ * Used to change date by adding a certain amount of days or months.
  */
 long date_sec_change(long date, int delta_month, int delta_day)
 {
@@ -540,7 +540,7 @@ long update_time_in_date(long date, unsigned hr, unsigned mn)
 }
 
 /*
- * Returns the date in seconds from year 1900.
+ * Returns the date in seconds from year 1970.
  * If no date is entered, current date is chosen.
  */
 time_t get_sec_date(struct date date)
@@ -617,7 +617,7 @@ item_in_popup(const char *a_start, const char *a_end, const char *msg,
 	delwin(popup_win);
 }
 
-/* Returns the beginning of current day in seconds from 1900. */
+/* Returns the beginning of current day in seconds from 1970. */
 time_t get_today(void)
 {
 	struct tm lt;
@@ -749,11 +749,13 @@ static void get_weekday_ymd(int *year, int *month, int *day, int weekday)
 }
 
 /*
- * Check if a date is valid.
+ * Check if a calcurse date is valid.
  */
 int check_date(unsigned year, unsigned month, unsigned day)
 {
-	return (year >= 1902 && month >= 1 && month <= 12 && day >= 1 &&
+	return ((YEAR1902_2037 ? year >= 1902 && year <= 2037 : 1) &&
+		month >= 1 && month <= 12 &&
+		day >= 1 &&
 		day <= days[month - 1] + (month == 2 && ISLEAP(year)) ? 1 : 0);
 }