support opening a connection with custom flags

This introduces the use of the options pattern with the new `ConnectorWithOpts`
function. The opt `WithOpenFlags` allows specifying custom flags to use when
opening connections. When left unspecified, we use the same
`sqliteh.OpenFlagsDefault` as before.

Updates tailscale/corp#36592

Signed-off-by: Percy Wegmann <percy@tailscale.com>

Author: oxtoacart

sqlite.go

@@ -116,19 +116,15 @@ type drv struct{}
 
 func (drv) Open(name string) (driver.Conn, error) { panic("deprecated, unused") }
 func (drv) OpenConnector(name string) (driver.Connector, error) {
-	return &connector{name: name}, nil
+	return &connector{name: name, openFlags: sqliteh.OpenFlagsDefault}, nil
 }
 
 // Connector returns a [driver.Connector] for the given connection
 // parameters.
 //
 // The tracer may be nil.
 func Connector(sqliteURI string, connInitFunc ConnInitFunc, tracer sqliteh.Tracer) driver.Connector {
-	return &connector{
-		name:         sqliteURI,
-		tracer:       tracer,
-		connInitFunc: connInitFunc,
-	}
+	return ConnectorWithOpts(sqliteURI, connInitFunc, WithTracer(tracer))
 }
 
 // ConnectorWithLogger returns a [driver.Connector] for the given connection
@@ -137,11 +133,48 @@ func Connector(sqliteURI string, connInitFunc ConnInitFunc, tracer sqliteh.Trace
 //
 // The tracer may also be nil.
 func ConnectorWithLogger(sqliteURI string, connInitFunc ConnInitFunc, tracer sqliteh.Tracer, makeLogger func() ConnLogger) driver.Connector {
-	return &connector{
+	return ConnectorWithOpts(sqliteURI, connInitFunc, WithTracer(tracer), WithConnLogger(makeLogger))
+}
+
+// ConnectorWithOpts returns a [driver.Connector] for the given connection parameters, optionally
+// configured with one or more [ConnectorOpt]s.
+func ConnectorWithOpts(sqliteURI string, connInitFunc ConnInitFunc, opts ...ConnectorOpt) driver.Connector {
+	p := &connector{
 		name:         sqliteURI,
-		tracer:       tracer,
-		makeLogger:   makeLogger,
 		connInitFunc: connInitFunc,
+		openFlags:    sqliteh.OpenFlagsDefault, // default flags unless [WithOpenFlags] option is used
+	}
+	for _, opt := range opts {
+		opt(p)
+	}
+	return p
+}
+
+// ConnectorOpt is an option to [ConnectorWithOpts].
+type ConnectorOpt func(p *connector)
+
+// WithTracer returns a [ConnectorOpt] that configures the [driver.Connector]
+// to enable tracing on new connections using the given [sqliteh.Tracer].
+func WithTracer(tracer sqliteh.Tracer) ConnectorOpt {
+	return func(p *connector) {
+		p.tracer = tracer
+	}
+}
+
+// WithConnLogger returns a [ConnectorOpt] that configures the [driver.Connector]
+// to use a [ConnLogger] returned by the provided makeLogger when opening new
+// connections.
+func WithConnLogger(makeLogger func() ConnLogger) ConnectorOpt {
+	return func(p *connector) {
+		p.makeLogger = makeLogger
+	}
+}
+
+// WithOpenFlags returns a [ConnectorOpt] that configures the [driver.Connector]
+// to use the given [sqliteh.OpenFlags] when opening new connections.
+func WithOpenFlags(openFlags sqliteh.OpenFlags) ConnectorOpt {
+	return func(p *connector) {
+		p.openFlags = openFlags
 	}
 }
 
@@ -150,11 +183,15 @@ type connector struct {
 	tracer       sqliteh.Tracer    // or nil
 	makeLogger   func() ConnLogger // or nil
 	connInitFunc ConnInitFunc
+	openFlags    sqliteh.OpenFlags
 }
 
+// Driver implements [driver.Connector.Driver].
 func (p *connector) Driver() driver.Driver { return drv{} }
+
+// Connect implements [driver.Connector.Connect]
 func (p *connector) Connect(ctx context.Context) (driver.Conn, error) {
-	db, err := Open(p.name, sqliteh.OpenFlagsDefault, "")
+	db, err := Open(p.name, p.openFlags, "")
 	if err != nil {
 		if ec, ok := err.(sqliteh.ErrCode); ok {
 			e := &Error{