C++ Logo

std-proposals

Advanced search

Re: [std-proposals] constexpr support in std::filesystem API

From: Marcin Jaczewski <marcinjaczewski86_at_[hidden]>
Date: Tue, 12 Mar 2024 15:40:05 +0100
wt., 12 mar 2024 o 15:15 Sebastian Wittmeier via Std-Proposals
<std-proposals_at_[hidden]> napisał(a):
>
> To be fair:
>
>
>
> How much different is it in power from a C23 #embed?
>
>
>
> Both feature that certain files, the ones which the implementation allows, can be fully (binarily) read at compile time.
>
>
>
> Differences:
>
> - the filepath can be created at runtime -> better hiding of the file read read; C23 probably supports macros for the filepath?
>
> - the contents can be processed by constexpr functions -> probably the same can be achieved by mixing C23 with C++ constexpr
>
> - the files could be read several times -> Denial of Service build; a long build can probably be achieved by other ways
>

Probaby biggest problem is `pwd`, `#embed` or `#include` work
relative to the current header,
and the filesystem API does not have any of this information.
If we use path of `.cpp` file then we can easy make ODR violations as same
header code could try get some file "x.text" and diffrent
compilation units could get diffrent files outputting wrong code like:
```
struct Foo
{
    char bar[getFileSize("x.txt")];
}
```

>
>
>
> -----Urspr├╝ngliche Nachricht-----
> Von: Tiago Freire via Std-Proposals <std-proposals_at_[hidden]>
> Gesendet: Di 12.03.2024 15:06
> Betreff: Re: [std-proposals] constexpr support in std::filesystem API
> An: Andrei Grosu <andrei_dg_at_[hidden]>; std-proposals_at_[hidden]; Jonathan Wakely <cxx_at_[hidden]>;
> CC: Tiago Freire <tmiguelf_at_[hidden]>;
> > That is a straw man argument.
> > If you had amazon.com as your home it should not have passed code review and merge request, along with whatever security audit tooling your build system should run anyways.
>
> Its not a strawman. A standard is not just for you, it is for everyone. Including people who do open-source projects, and whose working environment isn't as closely monitored as you may think.
> Even in your closed environment I can think of extremely easy ways to hide malicious constexpr payload to take over your entire company and you wouldn't even notice in a PR.
> And that's just 5 minutes thinking about the problem, imagine what a motivated malicious actor with enough time and resources could achieve.
>
> And why would I want to do this to begin with?
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals

Received on 2024-03-12 14:40:18