1 files changed, 39 insertions, 35 deletions

diff --git a/src/timezone/zic.c b/src/timezone/zic.c
index ae61264364c..4613919afe4 100644
--- a/src/timezone/zic.c
+++ b/src/timezone/zic.c
@@ -167,9 +167,11 @@ PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1};
    QTBUG-53071 <https://bugreports.qt.io/browse/QTBUG-53071>.  This
    workaround will no longer be needed when Qt 5.6.1 and earlier are
    obsolete, say in the year 2021.  */
+#ifndef WORK_AROUND_QTBUG_53071
 enum
 {
 WORK_AROUND_QTBUG_53071 = true};
+#endif
 
 static int	charcnt;
 static bool errors;
@@ -1912,12 +1914,6 @@ atcomp(const void *avp, const void *bvp)
 	return (a < b) ? -1 : (a > b);
 }
 
-static bool
-is32(const zic_t x)
-{
-	return x == ((zic_t) ((int32) x));
-}
-
 static void
 swaptypes(int i, int j)
 {
@@ -1971,7 +1967,12 @@ writezone(const char *const name, const char *const string, char version,
 	zic_t		one = 1;
 	zic_t		y2038_boundary = one << 31;
 	ptrdiff_t	nats = timecnt + WORK_AROUND_QTBUG_53071;
-	zic_t	   *ats = emalloc(size_product(nats, sizeof *ats + 1));
+
+	/*
+	 * Allocate the ATS and TYPES arrays via a single malloc, as this is a bit
+	 * faster.
+	 */
+	zic_t	   *ats = emalloc(MAXALIGN(size_product(nats, sizeof *ats + 1)));
 	void	   *typesptr = ats + nats;
 	unsigned char *types = typesptr;
 
@@ -2030,20 +2031,6 @@ writezone(const char *const name, const char *const string, char version,
 	}
 
 	/*
-	 * Work around QTBUG-53071 for timestamps less than y2038_boundary - 1, by
-	 * inserting a no-op transition at time y2038_boundary - 1. This works
-	 * only for timestamps before the boundary, which should be good enough in
-	 * practice as QTBUG-53071 should be long-dead by 2038.
-	 */
-	if (WORK_AROUND_QTBUG_53071 && timecnt != 0
-		&& ats[timecnt - 1] < y2038_boundary - 1 && strchr(string, '<'))
-	{
-		ats[timecnt] = y2038_boundary - 1;
-		types[timecnt] = types[timecnt - 1];
-		timecnt++;
-	}
-
-	/*
 	 * Correct for leap seconds.
 	 */
 	for (i = 0; i < timecnt; ++i)
@@ -2058,31 +2045,47 @@ writezone(const char *const name, const char *const string, char version,
 	}
 
 	/*
+	 * Work around QTBUG-53071 for timestamps less than y2038_boundary - 1, by
+	 * inserting a no-op transition at time y2038_boundary - 1. This works
+	 * only for timestamps before the boundary, which should be good enough in
+	 * practice as QTBUG-53071 should be long-dead by 2038.  Do this after
+	 * correcting for leap seconds, as the idea is to insert a transition just
+	 * before 32-bit pg_time_t rolls around, and this occurs at a slightly
+	 * different moment if transitions are leap-second corrected.
+	 */
+	if (WORK_AROUND_QTBUG_53071 && timecnt != 0
+		&& ats[timecnt - 1] < y2038_boundary - 1 && strchr(string, '<'))
+	{
+		ats[timecnt] = y2038_boundary - 1;
+		types[timecnt] = types[timecnt - 1];
+		timecnt++;
+	}
+
+	/*
 	 * Figure out 32-bit-limited starts and counts.
 	 */
 	timecnt32 = timecnt;
 	timei32 = 0;
 	leapcnt32 = leapcnt;
 	leapi32 = 0;
-	while (timecnt32 > 0 && !is32(ats[timecnt32 - 1]))
+	while (0 < timecnt32 && PG_INT32_MAX < ats[timecnt32 - 1])
 		--timecnt32;
-	while (timecnt32 > 0 && !is32(ats[timei32]))
+	while (1 < timecnt32 && ats[timei32] < PG_INT32_MIN
+		   && ats[timei32 + 1] <= PG_INT32_MIN)
 	{
+		/*
+		 * Discard too-low transitions, except keep any last too-low
+		 * transition if no transition is exactly at PG_INT32_MIN. The kept
+		 * transition will be output as an PG_INT32_MIN "transition"
+		 * appropriate for buggy 32-bit clients that do not use time type 0
+		 * for timestamps before the first transition; see below.
+		 */
 		--timecnt32;
 		++timei32;
 	}
-
-	/*
-	 * Output an INT32_MIN "transition" if appropriate; see below.
-	 */
-	if (timei32 > 0 && ats[timei32] > PG_INT32_MIN)
-	{
-		--timei32;
-		++timecnt32;
-	}
-	while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
+	while (0 < leapcnt32 && PG_INT32_MAX < trans[leapcnt32 - 1])
 		--leapcnt32;
-	while (leapcnt32 > 0 && !is32(trans[leapi32]))
+	while (0 < leapcnt32 && trans[leapi32] < PG_INT32_MIN)
 	{
 		--leapcnt32;
 		++leapi32;
@@ -2315,7 +2318,8 @@ writezone(const char *const name, const char *const string, char version,
 			if (pass == 1)
 
 				/*
-				 * Output an INT32_MIN "transition" if appropriate; see above.
+				 * Output an PG_INT32_MIN "transition" if appropriate; see
+				 * above.
 				 */
 				puttzcode(((ats[i] < PG_INT32_MIN) ?
 						   PG_INT32_MIN : ats[i]), fp);