libasm-smasher is a tester for the 42 network's project called libasm.

Many tests are performed to ensure that functions work properly and that the assembly code respects the most fundamental aspects of the System V AMD64 ABI calling convention.

This tester will not work on MacOS, you need to have an operating system running on the linux kernel.

You can simply perform a docker run command and it will automatically fetch the aurelienbrabant/libasm-smasher image from DockerHub:

docker run -t -v/path/to/libasm:/libasm aurelienbrabant/libasm-smasher

NOTE: to bind your libasm to the docker container, you must use an absolute path. Assuming that your libasm is in your home directory, it would look like that: -v$HOME/libasm:/libasm.

To fit defense requirements, the container is using the ubuntu 18.04 as of today, so pulling the image can take some time, be patient.

If you don't have an internet connection or just want to build the image directly, follow these steps:

1. Build the image

docker build -t abrabant/libasm-smasher .

2. Run a container based on the built image

docker run -t -v /path/to/libasm:/libasm abrabant/libasm-smasher

You need to bind your libasm repository to /libasm in the docker container for the tester to work.

• A GNU/Linux based operating system (tested on Gentoo and Xubuntu 18.04, but it should work on any distribution).
• The clang C compiler
• The nasm ASM compiler
• The make build utility

You can copy paste the following command, assuming that you're at the root of your libasm's repository:

git clone https://github.com/aurelien-brabant/libasm-smasher && make test -C libasm-smasher 

If you want to specify another path for your libasm, feel free to make the smasher using the make LIBASM_PATH=path/to/your/libasm syntax. It will override the default value of the Makefile's variable LIBASM_PATH.

Note: your code is supposed to be compiled using clang-9. If you're compiling using gcc with a shell alias to clang, this will not work and use the real gcc instead. A convenient way to circumvent that is to use the docker image which ships with the perfect test environment and aliases.

• Complete test modules for mandatory part (ft_write, ft_read, ft_strcpy, ft_strdup, ft_strcmp, ft_strlen).
• The tester checks if callee saved registers are well restored (except rbp), as specified by the calling convention.
• Comprehensive logging of errors (error messages and/or diff files for some tests with large outputs such as read tests).

Note: Bonus part is not covered yet, but I'm currently working on it when I've time.

Segfault when running the tester

Then your code is probably faulty. However, my code is obviously not perfect at all, so feel free to open an issue if you can't figure out why the segfault happens on your system. I also accept pull requests as long as they fix / add something useful to the project.

Infinite loop

Same thing than above, your code is probably faulty.

What does the unpreserved register error means

It means that your code does not respect the System V AMD64 ABI calling convention, which is definitely BAD. This is not a warning, that's an error. It can cause several and unexpected errors after your ASM routines have been called. Some reading about the calling convention described above will tell you why it is bad, and how to deal with it.