Add an extra example extension

flake.nix

@@ -58,6 +58,9 @@
           "$CC" -c subext.c
           "$AR" rcs libsubext.a subext.o
 
+          "$CC" -c multext.c
+          "$AR" rcs libmultext.a multext.o
+
           runHook postBuild
         '';
 
@@ -83,6 +86,10 @@
             library = "${sqlite-example-exts-static}/lib/libsubext.a";
             init = "sqlite3_subext_init";
           }
+          {
+            library = "${sqlite-example-exts-static}/lib/libmultext.a";
+            init = "sqlite3_multext_init";
+          }
         ];
       };
     in {

sqlite-example-exts/multext.c

@@ -0,0 +1,38 @@
+#include <sqlite3ext.h>
+
+SQLITE_EXTENSION_INIT1
+
+static void mult_func(
+    sqlite3_context *ctx,
+    int argc,
+    sqlite3_value **argv
+) {
+    if (argc != 2) {
+        sqlite3_result_null(ctx);
+        return;
+    }
+
+    int a = sqlite3_value_int(argv[0]);
+    int b = sqlite3_value_int(argv[1]);
+
+    sqlite3_result_int(ctx, a * b);
+}
+
+int sqlite3_multext_init(
+    sqlite3 *db,
+    char **pzErrMsg,
+    const sqlite3_api_routines *pApi
+) {
+    SQLITE_EXTENSION_INIT2(pApi);
+
+    return sqlite3_create_function(
+        db,
+        "mymult",
+        2,
+        SQLITE_UTF8 | SQLITE_DETERMINISTIC,
+        0,
+        mult_func,
+        0,
+        0
+    );
+}