Only normalize OffsetDateTimes when they are normalizable

Possible fix for FasterXML#166. This commit adds a check before the OffsetDateTime adjustment of ADJUST_DATES_TO_CONTEXT_TIME_ZONE that ensures that the OffsetDateTime is normalizeable given a specific time zone offset. When it is not, normalization is skipped and the un-adjusted OffsetDateTime is returned.

Author: morth

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/deser/InstantDeserializer.java

@@ -29,11 +29,7 @@
 
 import java.io.IOException;
 import java.math.BigDecimal;
-import java.time.DateTimeException;
-import java.time.Instant;
-import java.time.OffsetDateTime;
-import java.time.ZoneId;
-import java.time.ZonedDateTime;
+import java.time.*;
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.Temporal;
 import java.time.temporal.TemporalAccessor;
@@ -69,7 +65,15 @@ public class InstantDeserializer<T extends Temporal>
             OffsetDateTime::from,
             a -> OffsetDateTime.ofInstant(Instant.ofEpochMilli(a.value), a.zoneId),
             a -> OffsetDateTime.ofInstant(Instant.ofEpochSecond(a.integer, a.fraction), a.zoneId),
-            (d, z) -> d.withOffsetSameInstant(z.getRules().getOffset(d.toLocalDateTime())),
+            (d, z) -> {
+                ZoneOffset o = z.getRules().getOffset(d.toLocalDateTime());
+                // Only adjust the OffsetDateTime when it is normalizable
+                if (isAdjustable(d, o)) {
+                    return d.withOffsetSameInstant(o);
+                } else {
+                    return d;
+                }
+            },
             true // yes, replace zero offset with Z
     );
 
@@ -320,6 +324,24 @@ private String replaceZeroOffsetAsZIfNecessary(String text)
         return text;
     }
 
+    /**
+     * Checks whether an {@link OffsetDateTime} is normalizable to a certain
+     * {@link ZoneOffset}. See [jackson-modules-java8#166].
+     *
+     * @param d The {@link OffsetDateTime} to normalize
+     * @param o The desired {@link ZoneOffset} of the normalization
+     * @return true, when the {@link OffsetDateTime} can be normalized to the
+     *         given {@link ZoneOffset}, false else
+     */
+    private static boolean isAdjustable(OffsetDateTime d, ZoneOffset o)
+    {
+        OffsetDateTime lowerBoundEx = OffsetDateTime.MIN
+                .plusHours(18).minusSeconds(o.getTotalSeconds()).minusNanos(1);
+        OffsetDateTime upperBoundEx = OffsetDateTime.MAX
+                .minusHours(18).minusSeconds(o.getTotalSeconds()).plusNanos(1);
+        return d.isAfter(lowerBoundEx) && d.isBefore(upperBoundEx);
+    }
+
     public static class FromIntegerArguments // since 2.8.3
     {
         public final long value;

datetime/src/test/java/com/fasterxml/jackson/datatype/jsr310/deser/OffsetDateTimeDeserTest.java

@@ -522,6 +522,79 @@ public void testRoundTripOfOffsetDateTimeAndJavaUtilDate() throws Exception
         assertEquals(givenInstant.atOffset(ZoneOffset.UTC), actual);
     }
 
+    /*
+     * Tests for the deserialization of OffsetDateTimes that cannot be
+     * normalized with ADJUST_DATES_TO_CONTEXT_TIME_ZONE enabled. The expected
+     * behaviour is that normalization is skipped for those OffsetDateTimes
+     * that cannot be normalized. See [jackson-modules-java8#166].
+     */
+
+    @Test
+    public void testDeserializationOfOffsetDateTimeMin() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MIN;
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertNotEquals("The time zone has been normalized.", ZoneOffset.UTC, value.getOffset());
+    }
+
+    @Test
+    public void testDeserializationOfUnadjustableOffsetDateTimeNearMin() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MIN.plusHours(18).minusNanos(1);
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertNotEquals("The time zone has been normalized.", ZoneOffset.UTC, value.getOffset());
+    }
+
+    @Test
+    public void testDeserializationOfAdjustableOffsetDateTimeNearMin() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MIN.plusHours(18);
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertEquals("The time zone is not correct.", ZoneOffset.UTC, value.getOffset());
+    }
+
+    @Test
+    public void testDeserializationOfOffsetDateTimeMax() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MAX;
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertNotEquals("The time zone has been normalized.", ZoneOffset.UTC, value.getOffset());
+    }
+
+    @Test
+    public void testDeserializationOfUnadjustableOffsetDateTimeNearMax() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MAX.minusHours(18).plusNanos(1);
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertNotEquals("The time zone has been normalized.", ZoneOffset.UTC, value.getOffset());
+    }
+
+    @Test
+    public void testDeserializationOfAdjustableOffsetDateTimeNearMax() throws Exception
+    {
+        OffsetDateTime date = OffsetDateTime.MAX.minusHours(18);
+        OffsetDateTime value = MAPPER.readerFor(OffsetDateTime.class)
+                .with(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE)
+                .readValue('"' + FORMATTER.format(date) + '"');
+        assertIsEqual(date, value);
+        assertEquals("The time zone is not correct.", ZoneOffset.UTC, value.getOffset());
+    }
+
     /*
     /**********************************************************
     /* Tests for empty string handling