rust-hl-modules fails with file operations?

[robitex]

Hi,
I'm starting to experiment your fantastic library, especially to create lib for Lua.
One uses the rust-image lib: it's ok if the code don't access to the file system otherwise the process crashed (with the same error reported below).
Another experiment is an attempt with rust-tabular... but fails.
So I began to think that I/O is the problem and I write this example: saving a text file from Lua perfectly functional in "only Rust" code.

#![feature(phase)]

#[phase(plugin)]
extern crate lua_mod = "rust-hl-lua-modules";

#[export_lua_module]
pub mod save {// <-- must be the name of the Lua module
    use std::io::File;
    fn savefile() {
        let p = Path::new("a-file.txt");
        let mut file = match File::create(&p) {
            Ok(f) => f,
            Err(e) => fail!("file error: {}", e),
        };
        file.write(b"content");
    }

    #[lua_module_init]
    fn init() {
        println!("module initialized!")
    }
}

Then I compile it with Cargo with this config:

[package]

name = "save"
version = "0.1.0"
authors = [ "my.username@my.email.com" ]

[[lib]]

name = "save" # the name of the executable to generate
crate_type = ["dylib"]

[dependencies.rust-hl-lua-modules]

git = "https://github.com/tomaka/rust-hl-lua"

In a terminal session the behaviour of the library is this:

roberto@roberto-desktop:~/Scrivania/test-save/test$ lua
Lua 5.2.3  Copyright (C) 1994-2013 Lua.org, PUC-Rio
> s = require "save"
module initialized!
> s.savefile()

You've met with a terrible fate, haven't you?

fatal runtime error: Could not unwind stack, error = 5
Istruzione non consentita (core dump creato)

Can you help me?
Is a question of local library installed on my system?
Thank you very much.
My dev platform is an Ubuntu 14.04 with ultimate version of Rust (0.12.0-pre-nightly 25741603f), Cargo and github library.

[tomaka]

Thanks for reporting this.

This is because of the way the rust I/O works.
There are two issues here:

• I/O functions don't work because the runtime is not initialized
• fail! will leave the Rust function while unwinding and will crash

[tomaka]

Can't fix properly before rust-lang/rust#1793 is fixed

Using libc should work however.

[tomaka]

Partially fixed. All of the Rust std should be usable now.

However:

• A failure will likely trigger a crash instead of a Lua error (but should this really be fixed? if fail! crashes the program it's for a good reason)
• You can't use return something from within an exported function (I didn't think about this while writing the fix, I'll have to rewrite some parts of the implementation)
• I'm not a 100% sure that this is error-proof because of the Rust issue linked above.
• This fix may make things a bit slower, but it's probably almost not measurable.

[robitex]

I can confirm that now the test program works but the function savefile() appears blocked after the file creation. In another test I obtain this error at compile time:

error: mismatched types: expected `()` but found `int`

due to what you say at the second point in the precedent list.
Thank you again.
R.

[tomaka]

Fixed thanks to rust-lang/rust#19654

[robitex]

Uh. Great. Great job!

[robitex]

Hi,
after adding some semicolon on macro definition and macro call in "rust_table.rs", "functions_write.rs", "tuples.rs" and "values.rs", and modified the crate declaration in mylib.rs example program (no more equals sign), I receive an error on #[export_lua_module]:

src/mylib.rs:7:1: 7:21 error: obsolete syntax: `proc` expression
src/mylib.rs:7 #[export_lua_module]
               ^~~~~~~~~~~~~~~~~~~~
note: use a `move ||` expression instead
error: aborting due to previous error
Could not compile `mylib`.

This is the code of mylib.rs:

#![crate_type = "dylib"]
#![feature(phase)]

#[phase(plugin)]
extern crate "rust-hl-lua-modules" as lua;

#[export_lua_module]
pub mod mylib {// <-- must be the name of the Lua module
    // factorial function
    fn fact(n: int) -> int {
        let mut f = 1;
        for i in range(1, n+1) {
            f *= i;
        }
        return f;
    }

    #[lua_module_init]
    fn init() {
        println!("Ok. Module mylib initialized!")
    }
}

I think this is due to something to change in "rust-hl-lua-modules.rs" after the recent Rust breaking-change update but I'm not so expert to understand your code, too advanced for my knowledge...
I wish to help you... maybe with the documentation.
Thanks a lot.
R.