Forward reader options to maxminddb

Allow geoip2.Open and OpenBytes to accept variadic reader options and pass them through to the underlying maxminddb helpers. Extend the deprecated FromBytes helper to support the same options and document the change in the changelog.

Author: oschwald

CHANGELOG.md

@@ -1,6 +1,8 @@
 # 2.0.0 -
 
 - Updated dependency on `github.com/oschwald/maxminddb-golang/v2` to `v2.0.0`.
+- Allow `Open` and `OpenBytes` to forward reader options to `maxminddb-golang`,
+  enabling advanced reader configuration.
 
 # 2.0.0-beta.4 - 2025-08-23
 

reader.go

@@ -104,9 +104,10 @@ func (e UnknownDatabaseTypeError) Error() string {
 
 // Open takes a string path to a file and returns a Reader struct or an error.
 // The database file is opened using a memory map. Use the Close method on the
-// Reader object to return the resources to the system.
-func Open(file string) (*Reader, error) {
-	reader, err := maxminddb.Open(file)
+// Reader object to return the resources to the system. Any reader options
+// provided are passed directly to maxminddb.Open.
+func Open(file string, options ...maxminddb.ReaderOption) (*Reader, error) {
+	reader, err := maxminddb.Open(file, options...)
 	if err != nil {
 		return nil, err
 	}
@@ -117,9 +118,10 @@ func Open(file string) (*Reader, error) {
 // OpenBytes takes a byte slice corresponding to a GeoIP2/GeoLite2 database
 // file and returns a Reader struct or an error. Note that the byte slice is
 // used directly; any modification of it after opening the database will result
-// in errors while reading from the database.
-func OpenBytes(bytes []byte) (*Reader, error) {
-	reader, err := maxminddb.OpenBytes(bytes)
+// in errors while reading from the database. Any reader options provided are
+// passed directly to maxminddb.OpenBytes.
+func OpenBytes(bytes []byte, options ...maxminddb.ReaderOption) (*Reader, error) {
+	reader, err := maxminddb.OpenBytes(bytes, options...)
 	if err != nil {
 		return nil, err
 	}
@@ -134,8 +136,8 @@ func OpenBytes(bytes []byte) (*Reader, error) {
 //
 // Deprecated: Use OpenBytes instead. FromBytes will be removed in a future
 // version.
-func FromBytes(bytes []byte) (*Reader, error) {
-	return OpenBytes(bytes)
+func FromBytes(bytes []byte, options ...maxminddb.ReaderOption) (*Reader, error) {
+	return OpenBytes(bytes, options...)
 }
 
 func getDBType(reader *maxminddb.Reader) (databaseType, error) {