1 files changed, 56 insertions, 17 deletions

diff --git a/src/timezone/localtime.c b/src/timezone/localtime.c
index ae9c2d23e63..6e0fa10066c 100644
--- a/src/timezone/localtime.c
+++ b/src/timezone/localtime.c
@@ -17,8 +17,9 @@
 #include <fcntl.h>
 
 #include "datatype/timestamp.h"
-#include "private.h"
 #include "pgtz.h"
+
+#include "private.h"
 #include "tzfile.h"
 
 
@@ -414,10 +415,10 @@ tzloadbody(char const * name, char *canonname, struct state * sp, bool doextend,
 		{
 			/*
 			 * Attempt to reuse existing abbreviations. Without this,
-			 * America/Anchorage would stop working after 2037 when
-			 * TZ_MAX_CHARS is 50, as sp->charcnt equals 42 (for LMT CAT CAWT
-			 * CAPT AHST AHDT YST AKDT AKST) and ts->charcnt equals 10 (for
-			 * AKST AKDT).  Reusing means sp->charcnt can stay 42 in this
+			 * America/Anchorage would be right on the edge after 2037 when
+			 * TZ_MAX_CHARS is 50, as sp->charcnt equals 40 (for LMT AST AWT
+			 * APT AHST AHDT YST AKDT AKST) and ts->charcnt equals 10 (for
+			 * AKST AKDT).  Reusing means sp->charcnt can stay 40 in this
 			 * example.
 			 */
 			int			gotabbr = 0;
@@ -451,6 +452,17 @@ tzloadbody(char const * name, char *canonname, struct state * sp, bool doextend,
 			if (gotabbr == 2)
 			{
 				sp->charcnt = charcnt;
+
+				/*
+				 * Ignore any trailing, no-op transitions generated by zic as
+				 * they don't help here and can run afoul of bugs in zic 2016j
+				 * or earlier.
+				 */
+				while (1 < sp->timecnt
+					   && (sp->types[sp->timecnt - 1]
+						   == sp->types[sp->timecnt - 2]))
+					sp->timecnt--;
+
 				for (i = 0; i < ts->timecnt; i++)
 					if (sp->ats[sp->timecnt - 1] < ts->ats[i])
 						break;
@@ -974,6 +986,8 @@ tzparse(const char *name, struct state * sp, bool lastditch)
 			int			yearlim;
 			int			timecnt;
 			pg_time_t	janfirst;
+			int32		janoffset = 0;
+			int			yearbeg;
 
 			++name;
 			if ((name = getrule(name, &start)) == NULL)
@@ -994,8 +1008,23 @@ tzparse(const char *name, struct state * sp, bool lastditch)
 			sp->defaulttype = 0;
 			timecnt = 0;
 			janfirst = 0;
-			yearlim = EPOCH_YEAR + YEARSPERREPEAT;
-			for (year = EPOCH_YEAR; year < yearlim; year++)
+			yearbeg = EPOCH_YEAR;
+
+			do
+			{
+				int32		yearsecs
+				= year_lengths[isleap(yearbeg - 1)] * SECSPERDAY;
+
+				yearbeg--;
+				if (increment_overflow_time(&janfirst, -yearsecs))
+				{
+					janoffset = -yearsecs;
+					break;
+				}
+			} while (EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg);
+
+			yearlim = yearbeg + YEARSPERREPEAT + 1;
+			for (year = yearbeg; year < yearlim; year++)
 			{
 				int32
 							starttime = transtime(year, &start, stdoffset),
@@ -1020,24 +1049,34 @@ tzparse(const char *name, struct state * sp, bool lastditch)
 				{
 					if (TZ_MAX_TIMES - 2 < timecnt)
 						break;
-					yearlim = year + YEARSPERREPEAT + 1;
 					sp->ats[timecnt] = janfirst;
-					if (increment_overflow_time
-						(&sp->ats[timecnt], starttime))
-						break;
-					sp->types[timecnt++] = reversed;
+					if (!increment_overflow_time
+						(&sp->ats[timecnt],
+						 janoffset + starttime))
+						sp->types[timecnt++] = reversed;
+					else if (janoffset)
+						sp->defaulttype = reversed;
 					sp->ats[timecnt] = janfirst;
-					if (increment_overflow_time
-						(&sp->ats[timecnt], endtime))
-						break;
-					sp->types[timecnt++] = !reversed;
+					if (!increment_overflow_time
+						(&sp->ats[timecnt],
+						 janoffset + endtime))
+					{
+						sp->types[timecnt++] = !reversed;
+						yearlim = year + YEARSPERREPEAT + 1;
+					}
+					else if (janoffset)
+						sp->defaulttype = !reversed;
 				}
-				if (increment_overflow_time(&janfirst, yearsecs))
+				if (increment_overflow_time
+					(&janfirst, janoffset + yearsecs))
 					break;
+				janoffset = 0;
 			}
 			sp->timecnt = timecnt;
 			if (!timecnt)
 				sp->typecnt = 1;	/* Perpetual DST.  */
+			else if (YEARSPERREPEAT < year - yearbeg)
+				sp->goback = sp->goahead = true;
 		}
 		else
 		{