rr
quickjs-emscripten
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rr | quickjs-emscripten | |
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98 | 21 | |
8,556 | 1,087 | |
1.1% | - | |
9.6 | 9.4 | |
7 days ago | 5 days ago | |
C++ | TypeScript | |
GNU General Public License v3.0 or later | GNU General Public License v3.0 or later |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
rr
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So you think you want to write a deterministic hypervisor?
https://rr-project.org/ had the same problem. They use the retired conditional branch counter instead of instruction counter, and then instruction steeping until at the correct address.
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Is Something Bugging You?
That'll work great for your Distributed QSort Incorporated startup, where the only product is a sorting algorithm.
Formal software verification is very useful. But what can be usefully formalized is rather limited, and what can be formalized correctly in practice is even more limited. That means you need to restrict your scope to something sane and useful. As a result, in the real world running thousands of tests is practically useful. (Well, it depends on what those tests are; it's easy to write 1000s of tests that either test the same thing, or only test the things that will pass and not the things that would fail.) They are especially useful if running in a mode where the unexpected happens often, as it sounds like this system can do. (It's reminiscent of rr's chaos mode -- https://rr-project.org/ linking to https://robert.ocallahan.org/2016/02/introducing-rr-chaos-mo... )
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When "letting it crash" is not enough
The approach of check-pointing computation such that it is resumable and restartable sounds similar to a time-traveling debugger, like rr or WinDbg:
https://learn.microsoft.com/windows-hardware/drivers/debugge...
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When I got started I debugged using printf() today I debug with print()
https://rr-project.org
This is indeed a problem people have with debuggers, so some very smart people found a way to fix it.
...and you're not on Linux, because on Linux we have rr! https://rr-project.org/
(I still use print statements 99.99% of the time though)
- OpenBSD KDE Plasma Desktop
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Firefox 118
> I've heard Linux support was down to like one guy [...]
Linux support is down to you. It's down to all of us. Install rr (https://rr-project.org/) and capture a crash with it.
Then you can replay the crash, find out that it's actually crashing in your closed-source graphics driver, which will motivate you to switch to an open source driver and fix your issue.
Also, while you're at it, update your linux kernel and wayland. They've both had bugs that could manifest as random firefox crashes in the last several months.
- A Modern C Development Environment
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Raku: A Language for Gremlins
I imagine you are referring to https://rr-project.org/ ?
Had never heard of it, looks pretty amazing, I might actually enjoy debugging now!
quickjs-emscripten
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New QuickJS Release
Based on your comment below I think you figured out the difference - but if you're looking to execute JS, you can pick between ShadowRealm (where available, or using a polyfill) or my library quickjs-emscripten.
Pros of quickjs-emscripten over ShadowRealm:
- You can use quickjs today in any browser with WASM. ShadowRealm isn't available yet, and polyfills have had security issues in the past. See https://www.figma.com/blog/an-update-on-plugin-security/
- In ShadowRealm eval, untrusted code can consume arbitrary CPU cycles. With QuickJS, you can control the CPU time used during an `eval` using an [interrupt handler] that's called periodically during the eval.
- In ShadowRealm eval, untrusted code can allocate arbitrary amounts of memory. With QuickJS, you can control both the [stack size] and the [heap size] available inside the runtime.
- quickjs-emscripten can do interesting things with custom module loaders and facades that allow synchronous code inside the runtime to call async code on the host.
Pros of ShadowRealm over QuickJS:
- ShadowRealm will (presumably?) execute code using your native runtime, probably v8, JavaScriptCore, or SpiderMonkey. Quickjs is orders of magnitude slower than JIT'd javascript performance of v8 etc. It's also slower than v8/JSC's interpreters, although not by a huge amount. See [benchmarks] from 2019.
- You can easily call and pass values to ShadowRealm imported functions. Talking to quickjs-emscripten guest code requires a lot of fiddly and manual object building.
- Overall the quickjs(-emscripten) API is verbose, and requires manual memory management of references to values inside the quickjs runtime.
[interrupt handler]: https://github.com/justjake/quickjs-emscripten/blob/main/doc...
[stack size]: https://github.com/justjake/quickjs-emscripten/blob/main/doc...
[heap size]: https://github.com/justjake/quickjs-emscripten/blob/main/doc...
[benchmarks]: https://bellard.org/quickjs/bench.html
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Extism Makes WebAssembly Easy
The thing I want to achieve with WebAssembly is still proving a lot harder than I had anticipated.
I want to be able to take strings of untrusted code provided by users and execute them in a safe sandbox.
I have all sorts of things I want this for - think custom templates for a web application, custom workflow automation scripts (Zapier-style), running transformations against JSON data.
When you're dealing with untrusted code you need a really robust sandbox. WebAssembly really should be that sandbox.
I'd like to support Python, JavaScript and maybe other languages too. I want to take a user-provided string of code in one of those languages and execute that in a sandbox with a strict limit on both memory usage and time taken (so I can't be crashed by a "while True" loop). If memory or time limit are exceeded, I want to get an exception which I can catch and return an error message to the user.
I've been exploring options for this for quite a while now. The furthest I've got was running Pyodide inside of Deno: https://til.simonwillison.net/deno/pyodide-sandbox
Surprisingly I've not found a good pattern for running a JavaScript interpreter in a WASM sandbox yet. https://github.com/justjake/quickjs-emscripten looks promising but I've not found the right recipe to call it from server-side Python or Deno yet.
Can Extism help with this? I'm confident I'm not the only person who's looking for a solution here!
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Node on Web. Use Nodejs freely in your browser with Linux infrastructure.
"Safely execute untrusted Javascript in your Javascript, and execute synchronous code that uses async functions" quickjs-emscripten, NPM
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Sandboxing JavaScript Code
This maybe, as a start?
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Hacker News top posts: Nov 20, 2022
QuickJS Running in WebAssembly\ (17 comments)
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QuickJS Running in WebAssembly
The library was inspired by Figma’s blog posts about their plug-in system: https://github.com/justjake/quickjs-emscripten#background
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Show HN: Run unsafe user generated JavaScript in the browser
If you need to call into user-generated Javascript synchronously or have greater control over the sandbox environment, you can use WebAssembly to run a Javascript interpreter: https://github.com/justjake/quickjs-emscripten#quickjs-emscr...
QuickJS in WebAssembly is much slower than your browser's native Javascript runtime, but possibly faster than async calls using postMessage. As an added bonus, it can make async functions in the host appear to be synchronous inside the sandbox using asyncify: https://emscripten.org/docs/porting/asyncify.html.
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Why Would Anyone Need JavaScript Generator Functions?
You can use One Weird Trick with generator functions to make your code "generic" over synchronicity. I use this technique to avoid needing to implement both sync and async versions of some functions in my quickjs-emscripten library.
The great part about this technique as a library author is that unlike choosing to use a Promise return type, this technique is invisible in my public API. I can write a function like `export function coolAlgorithm(getData: (request: I) => O | Promise): R | Promise`, and we get automatic performance improvement if the user's function happens to return synchronously, without mystery generator stuff showing up in the function signature.
Helper to make a function that can be either sync or async: https://github.com/justjake/quickjs-emscripten/blob/ff211447...
Uses: https://cs.github.com/justjake/quickjs-emscripten?q=yield*+l...
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Why Am I Excited About WebAssembly?
This seems like a pretty nice, recently enabled way of getting a sandboxed js environment: QuickJS compiled to WASM: https://github.com/justjake/quickjs-emscripten.
What are some alternatives?
wasmtime - A fast and secure runtime for WebAssembly
wasmer - 🚀 The leading Wasm Runtime supporting WASIX, WASI and Emscripten
wizer - The WebAssembly Pre-Initializer
CodeLLDB - A native debugger extension for VSCode based on LLDB
gef - GEF (GDB Enhanced Features) - a modern experience for GDB with advanced debugging capabilities for exploit devs & reverse engineers on Linux
rrweb - record and replay the web
Module Linker - browse modules by clicking directly on "import" statements on GitHub
nbdev - Create delightful software with Jupyter Notebooks
clog-cli - Generate beautiful changelogs from your Git commit history
rustfmt - Format Rust code
Clippy - A bunch of lints to catch common mistakes and improve your Rust code. Book: https://doc.rust-lang.org/clippy/
iPlug2 - C++ Audio Plug-in Framework for desktop, mobile and web