Patch for mhical to support "BYDAY=-1SU"-type RRULEs.

Notes:

- Added dmlastday() function to dtime.c, to obtain last day of month.
  Minor modifications to other parts here to reuse code.

- Modified rrule_clock() in datetime.c to handle negative BYDAY
  correctly.

- Added a couple of tests.

- Mainly this is to scratch an itch since UK timezone history makes
  heavy use of BYDAY=-1SU-type RRULEs, and the resultant complaints
  are annoying.  I had a brief look at "properly" extending
  icalparse.y, but I kindof think any serious extension of mhical
  should really instead adopt libical?

diff --git a/sbr/datetime.c b/sbr/datetime.c
index 333f2dd..2955226 100644 (file)
--- a/sbr/datetime.c
+++ b/sbr/datetime.c
@@ -288,14 +288,15 @@ rrule_clock (const char *rrule, const char *starttime, const char *zone,
         int specific_day = 1; /* BYDAY integer (prefix) */
         char buf[32];
         int day;
+        int end_of_week;
 
         if ((cp = nmh_strcasestr (rrule, "BYDAY="))) {
             cp += 6;
             /* BYDAY integers must be ASCII. */
-            if (*cp == '+') { ++cp; } /* +n specific day; don't support '-' */
-            else if (*cp == '-') { goto fail; }
+            if (*cp == '+') { ++cp; } /* +n specific day */
+            else if (*cp == '-') { ++cp; specific_day = -1; }
 
-            if (isdigit ((unsigned char) *cp)) { specific_day = *cp++ - 0x30; }
+            if (isdigit ((unsigned char) *cp)) { specific_day *= *cp++ - 0x30; }
 
             if (! strncasecmp (cp, "SU", 2)) { wday = 0; }
             else if (! strncasecmp (cp, "MO", 2)) { wday = 1; }
@@ -309,12 +310,13 @@ rrule_clock (const char *rrule, const char *starttime, const char *zone,
             month = atoi (cp + 8);
         }
 
-        for (day = 1; day <= 7; ++day) {
+        end_of_week = specific_day > 0 ? 7 * specific_day :
+                dmlastday(year, month) + 7 * (1 + specific_day);
+        for (day = end_of_week - 6; day <= end_of_week; ++day) {
             /* E.g, 11-01-2014 02:00:00-0400 */
             snprintf (buf, sizeof buf, "%02d-%02d-%04u %.2s:%.2s:%.2s%s",
-                      month, day + 7 * (specific_day-1), year,
-                      starttime, starttime + 2, starttime + 4,
-                      zone ? zone : "0000");
+                      month, day, year, starttime, starttime + 2,
+                      starttime + 4, zone ? zone : "0000");
             if ((tws = dparsetime (buf))) {
                 if (! (tws->tw_flags & (TW_SEXP|TW_SIMP))) { set_dotw (tws); }
 
@@ -325,7 +327,7 @@ rrule_clock (const char *rrule, const char *starttime, const char *zone,
             }
         }
 
-        if (day <= 7) {
+        if (day <= end_of_week) {
             clock = tws->tw_clock;
         }
     }

diff --git a/sbr/dtime.c b/sbr/dtime.c
index 9a10026..0ed012b 100644 (file)
--- a/sbr/dtime.c
+++ b/sbr/dtime.c
@@ -20,11 +20,17 @@ extern long timezone;
    2,147,483,648 / 60 = 35,791,394 */
 #define DTZ_BUFFER_SIZE (sizeof "+3579139459")
 
+/*
+ * 1 if leap year, 0 otherwise.
+ */
+#define        isleapyear01(y) \
+       (((y) % 4) ? 0 : (((y) % 100) ? 1 : (((y) % 400) ? 0 : 1)))
+
 /*
  * The number of days in the year, accounting for leap years
  */
 #define        dysize(y)       \
-       (((y) % 4) ? 365 : (((y) % 100) ? 366 : (((y) % 400) ? 365 : 366)))
+       (365 + isleapyear01(y))
 
 char *tw_moty[] = {
     "Jan", "Feb", "Mar", "Apr",
@@ -45,8 +51,13 @@ char *tw_ldotw[] = {
     "Saturday",  NULL
 };
 
-static int dmsize[] = {
-    31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+static int dmsize[][12] = {
+    { /* Not a leap year */
+        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+    },
+    { /* Leap year: February = 29 */
+        31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+    }
 };
 
 
@@ -313,6 +324,16 @@ dtimezone(int offset, int flags)
 }
 
 
+/*
+ * Last day of month (1-12) in given year.
+ */
+
+int
+dmlastday(int year, int mon)
+{
+    return dmsize[isleapyear01 (year)][mon - 1];
+}
+
 /*
  * Convert nmh time structure for local "broken-down"
  * time to calendar time (clock value).  This routine
@@ -323,7 +344,7 @@ dtimezone(int offset, int flags)
 time_t
 dmktime (struct tws *tw)
 {
-    int i, sec, min, hour, mday, mon, year;
+    int i, sec, min, hour, mday, mon, year, *msize;
     time_t result;
 
     if (tw->tw_clock != 0)
@@ -347,10 +368,9 @@ dmktime (struct tws *tw)
 
     for (i = 1970; i < year; i++)
        result += dysize (i);
-    if (dysize (year) == 366 && mon >= 3)
-       result++;
+    msize = dmsize[isleapyear01 (year)];
     while (--mon)
-       result += dmsize[mon - 1];
+       result += msize[mon - 1];
     result += mday - 1;
     result *= 24; /* Days to hours. */
     result += hour;

diff --git a/sbr/dtime.h b/sbr/dtime.h
index 8accd9e..24216d4 100644 (file)
--- a/sbr/dtime.h
+++ b/sbr/dtime.h
@@ -16,6 +16,7 @@ char *dtimenow(int);
 char *dtime(time_t *, int);
 char *dasctime(struct tws *, int);
 char *dtimezone(int, int);
+int dmlastday(int, int);
 time_t dmktime(struct tws *);
 void set_dotw(struct tws *);
 int twsort(struct tws *, struct tws *);

diff --git a/test/mhical/test-mhical b/test/mhical/test-mhical
index 3ebc35f..d017a54 100755 (executable)
--- a/test/mhical/test-mhical
+++ b/test/mhical/test-mhical
@@ -30,6 +30,92 @@ actual="$MH_TEST_DIR/test-mhical$$.actual"
 actual_err="$MH_TEST_DIR/test-mhical$$.actual_err"
 
 
+# check timezone boundary at transition from daylight saving time, -2SU
+start_test "timezone boundary at transition from daylight saving time, -2SU"
+# Specifically looking at "second last Sunday of the month" type transitions.
+cat >"$expected" <<'EOF'
+Summary: BST to GMT
+At: Sat, 22 Oct 1994 23:33 +0000
+To: Sun, 23 Oct 1994 07:34
+EOF
+
+cat >"$MH_TEST_DIR/test1.ics" <<'EOF'
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:test-mhical
+BEGIN:VTIMEZONE
+TZID:London
+BEGIN:STANDARD
+TZNAME:GMT
+DTSTART:19931018T020000
+TZOFFSETFROM:+0100
+TZOFFSETTO:+0000
+RRULE:FREQ=YEARLY;BYDAY=-2SU;BYMONTH=10
+END:STANDARD
+BEGIN:DAYLIGHT
+TZNAME:BST
+DTSTART:19810329T010000
+TZOFFSETFROM:+0000
+TZOFFSETTO:+0100
+RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
+END:DAYLIGHT
+END:VTIMEZONE
+BEGIN:VEVENT
+DTSTAMP:19941002T115852Z
+DTSTART;TZID=London:19941022T233300
+DTEND;TZID=London:19941023T073400
+Summary: BST to GMT
+END:VEVENT
+END:VCALENDAR
+EOF
+
+TZ=GMT mhical <"$MH_TEST_DIR/test1.ics" >"$MH_TEST_DIR/test1.txt"
+check "$expected" "$MH_TEST_DIR/test1.txt"
+
+
+# check timezone boundary at transition to daylight saving time, -1SU
+start_test "timezone boundary at transition to daylight saving time, -1SU"
+# Specifically looking at "last Sunday of the month" type transitions.
+cat >"$expected" <<'EOF'
+Summary: GMT to BST
+At: Sat, 27 Mar 1982 23:31 +0000
+To: Sun, 28 Mar 1982 07:32
+EOF
+
+cat >"$MH_TEST_DIR/test1.ics" <<'EOF'
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:test-mhical
+BEGIN:VTIMEZONE
+TZID:London
+BEGIN:STANDARD
+TZNAME:GMT
+DTSTART:19781025T030000
+TZOFFSETFROM:+0100
+TZOFFSETTO:+0000
+RRULE:FREQ=YEARLY;UNTIL=19811025T010000Z;BYDAY=-1SU;BYMONTH=10
+END:STANDARD
+BEGIN:DAYLIGHT
+TZNAME:BST
+DTSTART:19810329T010000
+TZOFFSETFROM:+0000
+TZOFFSETTO:+0100
+RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
+END:DAYLIGHT
+END:VTIMEZONE
+BEGIN:VEVENT
+DTSTAMP:19820302T115852Z
+DTSTART;TZID=London:19820327T233100
+DTEND;TZID=London:19820328T073200
+Summary: GMT to BST
+END:VEVENT
+END:VCALENDAR
+EOF
+
+TZ=GMT mhical <"$MH_TEST_DIR/test1.ics" >"$MH_TEST_DIR/test1.txt"
+check "$expected" "$MH_TEST_DIR/test1.txt"
+
+
 # check -help
 start_test "-help"
 cat >"$expected" <<EOF