From 3f7118f07725ca6c085b00aea3054d1d6814c0aa Mon Sep 17 00:00:00 2001
From: Martijn Smidt <martijn@squeezely.tech>
Date: Mon, 12 Jul 2021 16:27:05 +0200
Subject: [PATCH 1/2] Fixes mediumint unsigned overflowing inside uint32 #299

---
 dml_events.go |  5 ++++-
 uint24.go     | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 uint24.go

diff --git a/dml_events.go b/dml_events.go
index 9935da66..55653489 100644
--- a/dml_events.go
+++ b/dml_events.go
@@ -292,7 +292,7 @@ func NewBinlogDMLEvents(table *TableSchema, ev *replication.BinlogEvent, pos, re
 			)
 		}
 		for i, col := range table.Columns {
-			if col.IsUnsigned {
+			if col.IsUnsigned && col.Type != schema.TYPE_MEDIUM_INT {
 				switch v := row[i].(type) {
 				case int64:
 					row[i] = uint64(v)
@@ -305,6 +305,9 @@ func NewBinlogDMLEvents(table *TableSchema, ev *replication.BinlogEvent, pos, re
 				case int:
 					row[i] = uint(v)
 				}
+			} else if col.IsUnsigned && col.Type == schema.TYPE_MEDIUM_INT {
+				val := row[i].(int32)
+				row[i] = NewUint24(val).Uint32()
 			}
 		}
 	}
diff --git a/uint24.go b/uint24.go
new file mode 100644
index 00000000..fac9c15e
--- /dev/null
+++ b/uint24.go
@@ -0,0 +1,27 @@
+// with the courtesy of this github file: https://github.com/Cryptkeeper/go-fseq/blob/v0.2.6/pkg/uint24/uint24.go
+// used to convert a int32 to uint24 (mediumint)
+package ghostferry
+
+const MaxUint24 = 1<<24 - 1
+
+func NewUint24(val int32) *Uint24 {
+	var u = new(Uint24)
+	u.Set(val)
+	return u
+}
+
+type Uint24 [3]uint8
+
+func (u *Uint24) Set(val int32) {
+	// panic since this is closer to how a compiler/runtime would treat an overflow compared to err returns
+	if val > MaxUint24 {
+		panic("cannot set Uint24 larger than uint24.MaxUint24")
+	}
+	(*u)[0] = uint8(val & 0xFF)
+	(*u)[1] = uint8((val >> 8) & 0xFF)
+	(*u)[2] = uint8((val >> 16) & 0xFF)
+}
+
+func (u Uint24) Uint32() uint32 {
+	return uint32(u[0]) | uint32(u[1])<<8 | uint32(u[2])<<16
+}
\ No newline at end of file

From b1d405a6fa79072bb3c587bfdccef4557909eb8b Mon Sep 17 00:00:00 2001
From: Martijn Smidt <martijn@squeezely.tech>
Date: Mon, 12 Jul 2021 17:15:55 +0200
Subject: [PATCH 2/2] also accept null/nil values

---
 dml_events.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/dml_events.go b/dml_events.go
index 55653489..f5a6172a 100644
--- a/dml_events.go
+++ b/dml_events.go
@@ -306,8 +306,10 @@ func NewBinlogDMLEvents(table *TableSchema, ev *replication.BinlogEvent, pos, re
 					row[i] = uint(v)
 				}
 			} else if col.IsUnsigned && col.Type == schema.TYPE_MEDIUM_INT {
-				val := row[i].(int32)
-				row[i] = NewUint24(val).Uint32()
+				if row[i] != nil {
+					val := row[i].(int32)
+					row[i] = NewUint24(val).Uint32()
+				}
 			}
 		}
 	}