Google Summer of Code 2021

strace was taking part in the GSoC 2021 as a mentor organization.

About strace project

strace is a diagnostic, debugging and instructional userspace tracer for Linux. It is used to monitor and tamper with interactions between processes and the Linux kernel, which include system calls, signal deliveries, and changes of process state. The operation of strace is made possible by the kernel feature known as ptrace.

strace is one of the longest running open source projects and had been started even before Linux was started.

strace is an important tool for debugging and tracing deployed on all Linux distributions with a small community of active contributors.

While strace is a small project, the strace tool is essential for many developers, system administrators and open source projects. Its maintainers and contributors are experienced developers.

The project organization is simple: the community discusses proposed patches and a few core maintainers eventually accept or reject contributions. All contributions are submitted as git patches to the mailing list, which is the single point of communication, in a mode very similar to the ways of the Linux kernel.

strace release cycle is currently synchronized with the release cycle of the Linux kernel.

Note that we are pretty laid back and cool compared to larger and professional projects like the Linux kernel but our standards are high and the people involved in strace are die hard system coders often contributing to or maintaining major C libraries such as Glibc, Glib or Bionic, contributing to the Linux Kernel and other major free and open source projects.

So we expect that you would be making the efforts to learn our mailing list and patch ways and ask good questions and do your home work for a most productive and efficient participation.

What to do as a prospective student

We want engage with students that are interested in system programming and want to help making strace a better tool. We hope to gain you as a new long term contributor and that you will contribute interesting and new features.

You need to grok C and have an interest in system programming and debugging. The codebase is not huge but the domain is not simple and requires a meticulous attention to many details.

All the communication is going through a single mailing list: https://lists.strace.io/mailman/listinfo/strace-devel

Subscribe to the list, introduce yourself and start the discussion!

Please prefix your email subjects with GSOC. 

Please be kind enough to follow these simple guidelines when posting to the list:

1. only send text emails. No HTML
2. do not top post
3. use and abuse the mailing list archive to see how proper discussions are handled
4. be patient, a reply may need a week to come by
5. use git tools to create and submit patches to the list
6. apply to your code the same code style and indentation used overall in strace

Thank you!

— https://lists.strace.io/pipermail/strace-devel/2016-March/004704.html

After introducing yourself on the list, you can join our IRC channel, #strace @ oftc. Introducing yourself only on IRC is not enough; the mailing list is the primary means of communication.

Check our list of projects ideas below or submit new ideas to the list for consideration.

It is required that students who want to apply to the strace project for the GSoC 2021 complete a relatively small code-related "microproject" as part of their application. Please refer to our guidelines and suggestions for MicroProjects for more information. Completing a microproject is not only an important way for us to get experience with applicants, but it will also help applicants become familiar with strace's development and submission process.

General proposal requirements

You will need to submit your official proposal via https://summerofcode.withgoogle.com and plain text is the way to go.

Please subscribe to the strace-devel mailing list and post your proposal there too.

We expect your application to be in the range of 1000 words. Anything less than that will probably not contain enough information for us to determine whether you are the right person for the job. Your proposal should contain at least the following information, plus anything you think is relevant:

Beyond your proposal you need obviously to be familiar with C and Git (or willing to learn these two super quick).

List of project ideas for students

Comprehensive test suite

Suggested by: Eugene Syromyatnikov, Dmitry V. Levin

The test suite we have today is far from covering all branches of all parsers yet. According to Codecov, current test coverage is just under 90%, but it tells very little about the actual coverage of various corner cases (checks for type sizes, signedness, handling of pointers to invalid memory, etc).

The goal of this project is to improve the test suite to a level that makes strace more reliable.

On the one hand, it would be educational for any student who is interested in syscall internals because writing syscall parsers and tests for them is the second best way to find out how syscalls work.

On the other hand, a comprehensive test suite is a prerequisite for any major change in strace source code. This test suite project does not have to be a work from scratch, there are already existing tests (e.g. strace/tests, ltp/testcases/kernel/syscalls, and sandbox/tests) that could be used as a starting point.

Support for BTF and other BPF decoding improvements

Suggested by: Eugene Syromyatnikov

Add support for using BTF for printing eBPF map elements. If BPF assembly dumping patch[1][2] will be merged, this also can be used in the disassembly output, similarly to the way bpftool does this.

Implement a syscall parser / parser test generator

Suggested by: Elvira Khabirova

Some of the syscall parsers (especially much of the ioctl parsers) look like they could be automatically generated, if a machine-readable description was provided. Same goes for a lot of the tests.

Syzkaller is using a certain format for syscall descriptions, and has some of them described. See https://github.com/google/syzkaller/tree/master/sys/linux

This project consists of two parts.

  1. Either create your own syscall description format, or use the one syzkaller is using. The latter is preferrable, since it would be nice to have an universal database one day that many projects could use. But if the format syzkaller is using is not suitable for some reason, it's fine.
  2. Create a parser generator. It could be just an ioctl generator, to begin with. The wider the range of parsers that could be generated, the better. Alternatively, you could generate tests for some of the already existing parsers.

See also: https://www.linuxplumbersconf.org/event/2/contributions/78/attachments/63/74/lpc_2018-what_could_be_done_in_the_kernel_to_make_strace_happy.pdf, pages 16-19

Implement the features requested on Github

Suggested by: Elvira Khabirova

There are several issues present on the github issues page. A couple of them could be enough for a 175-hour long project, depending on the size of the changes required. You'll have to try and estimate how many hours you'll need for each task that you pick. Adding own enhancement ideas to the plan is fine. See also: FeatureRequests

There is an assortment of small enhancements that can be picked from that list, for example:

- Separate the test running system from the build system to make it possible to run pre-built tests on embedded devices (without gcc or even make); also #151

- Related to syscall statistics: #47 #48, also #156

- Naming the output file: #54 #153

- Enhance -e inject= condition specification #86 #104 #173, also #125

- Fork/thread-following-related #141 #175

- Autostop conditions: #139. Also, we need an ability to split logs during runtime into files of X bytes or less (imagine vfat file size limitations).

- Adding new ioctls is a never-ending resource of possible enhancements: #28 #29 #30 etc.

Support for alternative tracing backends

Suggested by: Eugene Syromyatnikov

For GSoC 2021, the fate of this project idea is undecided, since the this year students will only have 175 hours to complete a project.

Add support for providing various backends for strace.

There is one backend already in development (gdbserver), but it's still not finished:

There is also an idea that uprobes/kprobes/ftrace/perf can be utilized for tracing syscalls as a more modern way of tracing processes, which makes the possible support for various tracing backend more useful.

Improving documentation of the internal APIs

Suggested by: Eugene Syromyatnikov

For GSoC 2021, the fate of this project idea is undecided, since the program rules urge not to include documentation-only projects.

Over the years, strace's internal APIs, that are used for various purposes (like printing various entities), have been grown significantly, to the point it leads to duplication of the code (for example, printing of hexadecimal strings used to be duplicated now in v4l2.c, btrfs.c and util.c for quite some time). The other issue with the vast internal API (which is usually the result of long history of handling various issues with various architectures and version of the Linux kernel) is that it's not self-evident how things should be done properly. It's believed that documenting current APIs could lower the learning curve and increase overall quality of the code. Some things that could be done here include, but are not limited to:

Other ideas

We are also open to any suggestions not listed on this page.

Some existing ideas are present on a separate page. Note, however, that they may be not adequately sized for a GSoC project or require specific qualifications.

GoogleSummerOfCode2021 (last edited 2023-02-13 15:51:21 by DmitryLevin)