From 1d8534aa4dff5d140a7d2b6a94ef88d838311494 Mon Sep 17 00:00:00 2001
From: Philip O'Toole <philip.otoole@yahoo.com>
Date: Tue, 6 Sep 2022 10:02:38 -0400
Subject: [PATCH] Add Serialize and Deserialize support

---
 sqlite3.go      |  44 ++++++++++++++++++++
 sqlite3_test.go | 105 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 149 insertions(+)

diff --git a/sqlite3.go b/sqlite3.go
index 5ac95709..cef691e8 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -905,6 +905,50 @@ func (c *SQLiteConn) begin(ctx context.Context) (driver.Tx, error) {
 	return &SQLiteTx{c}, nil
 }
 
+// Serialize returns a byte slice that is a serialization of the database.
+// If the database fails to serialize, a nil slice will be returned.
+//
+// See https://www.sqlite.org/c3ref/serialize.html
+func (c *SQLiteConn) Serialize(schema string) []byte {
+	if schema == "" {
+		schema = "main"
+	}
+	var zSchema *C.char
+	zSchema = C.CString(schema)
+	defer C.free(unsafe.Pointer(zSchema))
+
+	var sz C.sqlite3_int64
+	ptr := C.sqlite3_serialize(c.db, zSchema, &sz, 0)
+	if ptr == nil {
+		return nil
+	}
+	defer C.sqlite3_free(unsafe.Pointer(ptr))
+	return C.GoBytes(unsafe.Pointer(ptr), C.int(sz))
+}
+
+// Deserialize causes the connection to disconnect from the current database
+// and then re-open as an in-memory database based on the contents of the
+// byte slice. If deserelization fails, error will contain the return code
+// of the underlying SQLite API call.
+//
+// See https://www.sqlite.org/c3ref/deserialize.html
+func (c *SQLiteConn) Deserialize(b []byte, schema string) error {
+	if schema == "" {
+		schema = "main"
+	}
+	var zSchema *C.char
+	zSchema = C.CString(schema)
+	defer C.free(unsafe.Pointer(zSchema))
+
+	rc := C.sqlite3_deserialize(c.db, zSchema,
+		(*C.uint8_t)(unsafe.Pointer(&b[0])),
+		C.sqlite3_int64(len(b)), C.sqlite3_int64(len(b)), 0)
+	if rc != 0 {
+		return fmt.Errorf("deserialize failed with return %v", rc)
+	}
+	return nil
+}
+
 // Open database and return a new connection.
 //
 // A pragma can take either zero or one argument.
diff --git a/sqlite3_test.go b/sqlite3_test.go
index 878ec495..e5660c58 100644
--- a/sqlite3_test.go
+++ b/sqlite3_test.go
@@ -888,6 +888,111 @@ func TestTransaction(t *testing.T) {
 	}
 }
 
+func TestSerialize(t *testing.T) {
+	d := SQLiteDriver{}
+
+	srcConn, err := d.Open(":memory:")
+	if err != nil {
+		t.Fatal("failed to get database connection:", err)
+	}
+	defer srcConn.Close()
+	sqlite3conn := srcConn.(*SQLiteConn)
+
+	_, err = sqlite3conn.Exec(`CREATE TABLE foo (name string)`, nil)
+	if err != nil {
+		t.Fatal("failed to create table:", err)
+	}
+	_, err = sqlite3conn.Exec(`INSERT INTO foo(name) VALUES("alice")`, nil)
+	if err != nil {
+		t.Fatal("failed to insert record:", err)
+	}
+
+	// Serialize the database to a file
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
+	if err := ioutil.WriteFile(tempFilename, sqlite3conn.Serialize(""), 0644); err != nil {
+		t.Fatalf("failed to write serialized database to disk")
+	}
+
+	// Open the SQLite3 file, and test that contents are as expected.
+	db, err := sql.Open("sqlite3", tempFilename)
+	if err != nil {
+		t.Fatal("failed to open database:", err)
+	}
+	defer db.Close()
+
+	rows, err := db.Query(`SELECT * FROM foo`)
+	if err != nil {
+		t.Fatal("failed to query database:", err)
+	}
+	defer rows.Close()
+
+	rows.Next()
+
+	var name string
+	rows.Scan(&name)
+	if exp, got := name, "alice"; exp != got {
+		t.Errorf("Expected %s for fetched result, but got %s:", exp, got)
+	}
+}
+
+func TestDeserialize(t *testing.T) {
+	var sqlite3conn *SQLiteConn
+	d := SQLiteDriver{}
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
+
+	// Create source database on disk.
+	conn, err := d.Open(tempFilename)
+	if err != nil {
+		t.Fatal("failed to open on-disk database:", err)
+	}
+	defer conn.Close()
+	sqlite3conn = conn.(*SQLiteConn)
+	_, err = sqlite3conn.Exec(`CREATE TABLE foo (name string)`, nil)
+	if err != nil {
+		t.Fatal("failed to create table:", err)
+	}
+	_, err = sqlite3conn.Exec(`INSERT INTO foo(name) VALUES("alice")`, nil)
+	if err != nil {
+		t.Fatal("failed to insert record:", err)
+	}
+	conn.Close()
+
+	// Read database file bytes from disk.
+	b, err := ioutil.ReadFile(tempFilename)
+	if err != nil {
+		t.Fatal("failed to read database file on disk", err)
+	}
+
+	// Deserialize file contents into memory.
+	conn, err = d.Open(":memory:")
+	if err != nil {
+		t.Fatal("failed to open in-memory database:", err)
+	}
+	sqlite3conn = conn.(*SQLiteConn)
+	defer conn.Close()
+	if err := sqlite3conn.Deserialize(b, ""); err != nil {
+		t.Fatal("failed to deserialize database", err)
+	}
+
+	// Check database contents are as expected.
+	rows, err := sqlite3conn.Query(`SELECT * FROM foo`, nil)
+	if err != nil {
+		t.Fatal("failed to query database:", err)
+	}
+	if len(rows.Columns()) != 1 {
+		t.Fatal("incorrect number of columns returned:", len(rows.Columns()))
+	}
+	values := make([]driver.Value, 1)
+	rows.Next(values)
+	if v, ok := values[0].(string); !ok {
+		t.Fatalf("wrong type for value: %T", v)
+	} else if v != "alice" {
+		t.Fatal("wrong value returned", v)
+	}
+}
+
 func TestWAL(t *testing.T) {
 	tempFilename := TempFilename(t)
 	defer os.Remove(tempFilename)