builder-module: Change the default wrap-mode policy of meson

By default network access inside the build sandbox is
disabled, however meson defaults into trying to initialize
fallbacks and attempt to download them, returning a
potentially misleading error message.

Setting wrap-mode to nodownload will instruct meson to
not try to use the network to fetch any resources and
only the pre-existing checkouts will be taken into account.
This matches both the default network permission and the
design of flatpak-builder for bundling and staging all
the sources ahead of time.

Side effect is that it makes it slightly harder for
projects to use the network access at build time, is
they also have to edit their meson setup arguments
to change the wrap-mode.

Author: alatiera

src/builder-module.c

@@ -1780,6 +1780,22 @@ builder_module_build_helper (BuilderModule  *self,
 	{
 	  /* Meson's setup command is now meson setup */
           g_ptr_array_add (configure_args_arr, g_strdup ("setup"));
+          /*
+          * By default network access inside the build sandbox is disabled,
+          * however meson defaults into trying to initialize fallbacks and attempt to
+          * download them, returning a potentially misleading error message.
+          *
+          * Setting wrap-mode to nodownload will instruct meson to not try to use the
+          * network to fetch any resources and only the pre-existing checkouts will be
+          * taken into account. This matches both the default network permission
+          * and the design of flatpak-builder for bundling and staging all the sources
+          * ahead of time.
+          *
+          * Side effect is that it makes it slightly harder for projects to use the
+          * network access at build time, is they also have to edit their meson setup
+          * arguments to change the wrap-mode.
+          */
+          g_ptr_array_add (configure_args_arr, g_strdup ("--wrap-mode=nodownload"));
 	}
 
       if (cmake || cmake_ninja)