We were premature if bumping this because some of our builds are still
on older glibs. Just copy the compat handler for now and we can remove
it later.

Fixes: ee293103b0 (plugins: update lockstep to use g_memdup2)
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2161
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240729144414.830369-14-alex.bennee@linaro.org>

diff --git a/contrib/plugins/lockstep.c b/contrib/plugins/lockstep.c
index 6a7e9bbb39..62981d4e09 100644
--- a/contrib/plugins/lockstep.c
+++ b/contrib/plugins/lockstep.c
@@ -101,6 +101,31 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
     plugin_cleanup(id);
 }
 
+/*
+ * g_memdup has been deprecated in Glib since 2.68 and
+ * will complain about it if you try to use it. However until
+ * glib_req_ver for QEMU is bumped we make a copy of the glib-compat
+ * handler.
+ */
+static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size)
+{
+#if GLIB_CHECK_VERSION(2, 68, 0)
+    return g_memdup2(mem, byte_size);
+#else
+    gpointer new_mem;
+
+    if (mem && byte_size != 0) {
+        new_mem = g_malloc(byte_size);
+        memcpy(new_mem, mem, byte_size);
+    } else {
+        new_mem = NULL;
+    }
+
+    return new_mem;
+#endif
+}
+#define g_memdup2(m, s) g_memdup2_qemu(m, s)
+
 static void report_divergance(ExecState *us, ExecState *them)
 {
     DivergeState divrec = { log, 0 };
-- 
2.39.2