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rr – record and replay debugger for C/C++

rr-project.org

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Re: rr – record and replay debugger for C/C++

#21

Post by detaro »

johnwatson11218 wrote: post #17
tarruda wrote: post #9

Earlier quoted context omitted.

I don't understand the "rewrite X/Y/Z in Rust" trend that has been going for a few years. I'm not familiar with Rust, but I'm almost sure it has a good C interoperability. If a certain piece of software is working well, what is the benefit of rewriting it in Rust?

Recently the federal government issued a security advisory encouraging all new development to be done in Rust. I'm not sure the extent of which agencies this was meant to cover but it struck me as very unrealistic having just done years of java development for a state agency. https://www.nextgov.com/cybersecurity/2024/02/white-house-ur...

It doesn't say that, no. Even in the title it says "memory-safe languages", which of course includes Java.

Rust is "only" mentioned in the context of a C / C++ replacement, which tends to be a different area.

Re: rr – record and replay debugger for C/C++

#22

Post by borodi »

dzaima wrote: post #15
borodi wrote: post #10

Earlier quoted context omitted.

Chaos mode is an option when invoking rr that can expose some concurrency issues. Basically it switches which thread is executing a bunch to try and simulate multiple cores executing. It has found some race conditions for me but it’s of course limited

Unfortunately that only works for large-scale races, and not, say, one instruction interleaving with another one on another thread without proper synchronization. -fsanitize=thread probably works for that though (and of course you could then combine said sanitizer with rr to some effect probably).

I havent tried Tsan with rr but msan and asan work quite well with it (it’s quite slow when doing this) but seeing the sanitizer trigger then following back what caused it to trigger is very useful.

Re: rr – record and replay debugger for C/C++

#23

Post by laserbeam »

Is it truly only for C/C++?

My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code).

Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones? Obviously, I wouldn't expect it to work for python, js, c# and other languages with managed memory.

Re: rr – record and replay debugger for C/C++

#24

Post by fragmede »

laserbeam wrote: post #23

Is it truly only for C/C++? My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code). Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones?…

for js, there's http://replay.io

Re: rr – record and replay debugger for C/C++

#26

Post by leni536 »

laserbeam wrote: post #23

Is it truly only for C/C++? My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code). Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones?…

Interestingly gdb (and in turn rr) has some limited support for debugging python. At least you can get a python backtrace, but I didn't have success in setting pyhton breakpoints.

Re: rr – record and replay debugger for C/C++

#27

Post by dzaima »

laserbeam wrote: post #23

Is it truly only for C/C++? My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code). Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones?…

rr uses gdb as the actual debugger part, so anything that works in gdb will work in rr. (you won't get rr running on windows though, as it is very much linux-specific, having to wrap all of its syscalls. The linux symbol info thing is DWARF)

Re: rr – record and replay debugger for C/C++

#28

Post by db48x »

laserbeam wrote: post #23

Is it truly only for C/C++? My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code). Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones?…

Yes, it can generally debug any language that compiles to a binary with proper debug information.

Re: rr – record and replay debugger for C/C++

#29

Post by leni536 »

tdullien wrote: post #11
nsjolj wrote: post #3

[flagged]

I've used it for years for vulnerability development (when you need to debug why a particular exploitation run went wrong etc.). It is indeed marvelous for many situations; except for concurrency bugs ;)

It is sometimes useful with concurreny bugs, especially when used in "chaos" mode. Altough it probably masks some classes of concurrency bugs. I wonder if rr + TSAN works.

Re: rr – record and replay debugger for C/C++

#30

Post by laserbeam »

leni536 wrote: post #26
laserbeam wrote: post #23

Is it truly only for C/C++? My limited understanding says a debugger needs: a list of symbols (.pdb files on windows, can't remember what they are on linux), understanding of syscalls and a few other similar things. I thought they don't care too much what generated the binaries they are debugging (obviously as long as it's native code). Doesn't rr work with other languages like rust, zig, odin, nim, and similar ones?…

Interestingly gdb (and in turn rr) has some limited support for debugging python. At least you can get a python backtrace, but I didn't have success in setting pyhton breakpoints.

Yeah, 'cause you're technically debugging the python interpreter. I've had some success with tracing tools designed for C/C++ for a python project. Was not easy to set up and will obviously include frames from the interpreter.

Tho, it feels wrong to expect a tool designed for native binaries to work well with python in this context. And that's ok. It feels lucky when it works as much as it does.

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