Telling GNU readline to autoquote/autoescape file names like bash does

Question

I'm adding readline support for a program with an interactive shell.

I've found some great examples online like this one but I'm having trouble telling readline to automatically expand file names with \␣ when the file name has a whitespace.

The blog post mentioned above explains how to do that with custom completion. However I have a command of the type load filename, so for the second argument I'm letting readline do the default behaviour which is to complete file names by setting rl_attempted_completion_over to 0.

I'm also reading the api documentation and there are several functions and variables related to that topic, however I'm a little bit overwhelmed with that documentation, that's too much information to take it at once.

So simple example:

#include <readline/readline.h>

int main(void)
{
    rl_filename_quoting_desired = 1;
    rl_filename_quote_characters = " \t\n\"\\'`@$><=;|&{(";
    rl_filename_completion_desired = 1;
    rl_filename_quoting_desired = 1;
    // rl_completer_quote_characters = "\"";  see explanation below

    char *buffer = readline("> ");
    free(buffer);
    return 0;
}

So, if I run this

> fi<TAB>
file with spaces.txt  firefox_shaoran/
> fil<TAB>
> file with spaces.txt

But I want readline to exapnd like bash does, that means after > file<TAB> I want to get file\ with\ spaces.txt.

I've been playing around with the different variables provided by readline, but I cannot get the same result. In the documentation of rl_basic_word_break_characters it says that bash uses " \t\n\"\\'@$><=;|&{(". I tried setting rl_filename_completion_desired and rl_filename_quoting_desired to 1, but it doesn't work either.

What should I do in the simple example so that readline expands file names as bash does?

// edit:

After reading a little bit of the bash source code, I came across the bashline.c file and found a place where rl_filename_quote_characters and rl_completer_quote_characters are set. In my example I commented that line because without it, the behaviour didn't change. However if I uncomment the line, readline quotes file names with empty spaces, which is great. What I haven't found so far in the documentation is how to escape the completion instead of quoting it.

I also tried rl_completer_quote_characters = "\"";