vis-lua: introduce pre-save hook

The first argument is the file object while the second argument denotes
the full path to which it will be written. Path might be `nil` if the
file is going to be written to stdout.

The Lua function is expected to return a boolean value indicating whether
the write operation should proceed or be aborted.

1 files changed, 1 insertions, 0 deletions

diff --git a/main.c b/main.c
index 5b2a9bb..c558ced 100644
--- a/main.c
+++ b/main.c
@@ -2203,6 +2203,7 @@ int main(int argc, char *argv[]) {
 		.vis_start = vis_lua_start,
 		.vis_quit = vis_lua_quit,
 		.file_open = vis_lua_file_open,
+		.file_save_pre = vis_lua_file_save_pre,
 		.file_save_post = vis_lua_file_save_post,
 		.file_close = vis_lua_file_close,
 		.win_open = vis_lua_win_open,