[CM] Weirdness with s7_load_c_string_with_environment, xxd fun

[Christos Vagias]

Hi Bil,

Was able to create a demo where this bug occurs
The readme.org contains the instructions for building this, and some notes

See attached file

On Fri, 9 Jul 2021 at 02:34, Christos Vagias <chris.actondev at gmail.com> wrote:
>
> Hi Bil,
>
> I'm getting some weird behavior with s7_load_c_string_with_environment.
> I don't have a working example atm, it's late and just wanted to report this :)
>
> Some description of what I'm doing:
>
> calling s7_eval_c_string("(load \"main.scm\")");
> and I have the load function replaced:
>
> s7_define_function(sc, "load", load_with_resources, 1, 1, false,
>                      "(load file (let (rootlet)))\n\
> Tries to load \"file\" as an embedded resource first, and if it fails
> it fallbacks to s7's load function");
>
> And load_with_resources will either load a file from the memory (from
> an included file produced with xxd -i) or try to actually load it from
> the filesystem.
>
> s7_pointer load_with_resources(s7_scheme *sc, s7_pointer args) {
>   s7_pointer sc_file = s7_car(args);
>   const char *file = s7_string(s7_car(args));
>   s7_pointer env = s7_nil(sc);
>   args = s7_cdr(args);
>   if (args != s7_nil(sc))
>     env = s7_car(args);
>
>   Resource r = get_resource(sc, file);
>   if (!r.data) {
>     printf("Failed to load %s as embedded resource, trying normal
> load\n", file);
>     s7_pointer res = s7_load_with_environment(sc, file, env);
>     // res might be null, should be careful to not return this
>     // since this is an s7 binding
>     if (!res) {
>       return (s7_error(
>           sc, s7_make_symbol(sc, "error"),
>           s7_list(sc, 2, s7_make_string(sc, "load: can't open ~S"), sc_file)));
>     }
>     return res;
>   }
>
>   return s7_load_c_string_with_environment(sc, (char *)r.data, r.size,
>                                            env);
> }
>
> And from the main.scm file, I'm loading other files:
>
> (catch #t (lambda ()
>                  (load "some-scheme-file.scm" some-env))
>                (lambda (tag info) <print error> ))
>
> And here is where I'm getting an error:
>         unbound-variable
>         unbound variable (symbol "\x94;\x10;")
>
> When not replacing the "load" function (so that means loading the
> files from the actual filesystem) all goes well. But, when loading the
> files via the s7_load_c_string_with_environment
> this error occurs.
>
> If this is not helpful at all, I'll try to make some isolated demo
> that demonstrates the problem.
>
> Another note, s7_load_with_environment returns NULL if something goes
> wrong, so returning
> its result from an s7_function can lead to crashes. I know this is
> documented but still seemed a bit weird for a behavior.
>
> Best,
> Christos
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