From 169f128eb478e24f6e706486dd5dd2019f223619 Mon Sep 17 00:00:00 2001
From: Sharang Gupta <sharang@sharanggupta.dev>
Date: Wed, 28 Oct 2026 23:48:45 +0000
Subject: [PATCH] Fix encoding of negative fractional TIME values

Duration.getSeconds() is floored, so borrowing a second for the
fraction wrote second = -1 whenever the floored value was a whole
minute, and MySQL stored -59.5 seconds as zero.

Signed-off-by: Sharang Gupta <sharang@sharanggupta.dev>
Assisted-by: Anthropic Claude (claude-opus-5-5)
---
 .../impl/datatype/DataTypeCodec.java           | 18 ++++++------------
 .../data/DateTimeBinaryCodecTest.java          |  5 +++++
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java b/vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java
index d153e4cd5..543e3f4db 100644
--- a/vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java
+++ b/vertx-mysql-client/src/main/java/io/vertx/mysqlclient/impl/datatype/DataTypeCodec.java
@@ -387,17 +387,17 @@ private static void binaryEncodeTime(LocalTime value, ByteBuf buffer) {
   }
 
   private static void binaryEncodeTime(Duration value, ByteBuf buffer) {
-    long secondsOfDuration = value.getSeconds();
-    int nanosOfDuration = value.getNano();
-    if (secondsOfDuration == 0 && nanosOfDuration == 0) {
+    if (value.isZero()) {
       buffer.writeByte(0);
       return;
     }
     byte isNegative = 0;
-    if (secondsOfDuration < 0) {
+    if (value.isNegative()) {
       isNegative = 1;
-      secondsOfDuration = -secondsOfDuration;
+      value = value.negated();
     }
+    long secondsOfDuration = value.getSeconds();
+    int nanosOfDuration = value.getNano();
 
     int days = (int) (secondsOfDuration / 86400);
     int secondsOfADay = (int) (secondsOfDuration % 86400);
@@ -415,13 +415,7 @@ private static void binaryEncodeTime(Duration value, ByteBuf buffer) {
       return;
     }
 
-    int microSecond;
-    if (isNegative == 1 && nanosOfDuration > 0) {
-      second = second - 1;
-      microSecond = (1000_000_000 - nanosOfDuration) / 1000;
-    } else {
-      microSecond = nanosOfDuration / 1000;
-    }
+    int microSecond = nanosOfDuration / 1000;
 
     buffer.writeByte(12);
     buffer.writeByte(isNegative);
diff --git a/vertx-mysql-client/src/test/java/io/vertx/tests/mysqlclient/data/DateTimeBinaryCodecTest.java b/vertx-mysql-client/src/test/java/io/vertx/tests/mysqlclient/data/DateTimeBinaryCodecTest.java
index 0d17f3bc2..9f01927ef 100644
--- a/vertx-mysql-client/src/test/java/io/vertx/tests/mysqlclient/data/DateTimeBinaryCodecTest.java
+++ b/vertx-mysql-client/src/test/java/io/vertx/tests/mysqlclient/data/DateTimeBinaryCodecTest.java
@@ -82,6 +82,11 @@ public void testEncodeFractionalSecondsPart(TestContext ctx) {
     testEncodeTime(ctx, Duration.ofHours(11).plusMinutes(12).plusNanos(123456000), Duration.ofHours(11).plusMinutes(12).plusNanos(123456000));
   }
 
+  @Test
+  public void testEncodeNegativeFractionalSecondsPart(TestContext ctx) {
+    testEncodeTime(ctx, Duration.ofSeconds(-59).minusMillis(500), Duration.ofSeconds(-59).minusMillis(500));
+  }
+
   @Test
   public void testEncodeTimeFromLocalTimeWithFractionalSecondsPart(TestContext ctx) {
     testEncodeTime(ctx, LocalTime.of(11, 12, 0, 123456000), Duration.ofHours(11).plusMinutes(12).plusNanos(123456000), LocalTime.of(11, 12, 0, 123456000));