5 ms·

What would be the right way to do it? A plain old Python C extension?

by saghul 5y ago

masklinn 5y ago
Or using API-mode cffi which basically does that for you, though it’s still not quite safe you can combine `cdef` and `set_source` to re-export exactly what you’re looking for. `set_source` will basically create an intermediate module under your control. Sadly AFAIK you always need a `cdef` which defines the binding between Python and C, I don’t think you can tell cffi to get this information from a real header file. But by providing a custom source you can more easily ensure the `cdef` and the function for it match correctly, with `set_source` bridging to the real underlying functions. One drawback of using API-level CFFI is it requires a C compiler (and probably all sorts of dev packages / headers), whereas ABI-level use doesn’t.
AndyMcConachie 5y ago
I would check to make sure I was running on an OpenBSD system first before anything else. You could use sys.platform() https://docs.python.org/3/library/sys.html#sys.platform https://docs.python.org/3/library/sys.html#sys.platform
- codetrotter 5y ago
  > I would check to make sure I was running on an OpenBSD system first before anything else. But SerenityOS has pledge and unveil too. https://awesomekling.github.io/pledge-and-unveil-in-SerenityOS/ https://awesomekling.github.io/pledge-and-unveil-in-Serenity... Dunno if Python runs on SerenityOS or not yet tho
- jodrellblank 5y ago
  Not wanting to tie it to OpenBSD only was the reason he chose feature sniffing. From the article: > "Systems other than OpenBSD may support these functions, now or in the future, and it would be nice to automatically make use of them when available. This means no checking for OpenBSD specifically but instead feature sniffing for their presence."
  - AndyMcConachie 5y ago
    That's a good point. But I would still include a check for OS's that I know support it. This means it wouldn't work on OS's without first explicitly allowing it. I view this as a feature and not a bug. There's a good chance there are other things to consider when a new OS adds pledge or unveil, and this gives the developer a chance to test support on the new OS before anyone uses it. Basically, I disagree with the article that you want to implement this in Python in a completely OS agnostic manner.
  - mleonhard 5y ago
    Make "failed to find `pledge` function' a hard error on OSes known to have it.

What would be the right way to do it? A plain old Python C extension?

by saghul 5y ago

What would be the right way to do it? A plain old Python C extension?

Or using API-mode cffi which basically does that for you, though it’s still not quite safe you can combine `cdef` and `set_source` to re-export exactly what you’re looking for. `set_source` will basically create an intermediate module under your control. Sadly AFAIK you always need a `cdef` which defines the binding between Python and C, I don’t think you can tell cffi to get this information from a real header file. But by providing a custom source you can more easily ensure the `cdef` and the function for it match correctly, with `set_source` bridging to the real underlying functions. One drawback of using API-level CFFI is it requires a C compiler (and probably all sorts of dev packages / headers), whereas ABI-level use doesn’t.

AndyMcConachie 5y ago

I would check to make sure I was running on an OpenBSD system first before anything else. You could use sys.platform() https://docs.python.org/3/library/sys.html#sys.platform https://docs.python.org/3/library/sys.html#sys.platform

codetrotter 5y ago
> I would check to make sure I was running on an OpenBSD system first before anything else. But SerenityOS has pledge and unveil too. https://awesomekling.github.io/pledge-and-unveil-in-SerenityOS/ https://awesomekling.github.io/pledge-and-unveil-in-Serenity... Dunno if Python runs on SerenityOS or not yet tho
jodrellblank 5y ago
Not wanting to tie it to OpenBSD only was the reason he chose feature sniffing. From the article: > "Systems other than OpenBSD may support these functions, now or in the future, and it would be nice to automatically make use of them when available. This means no checking for OpenBSD specifically but instead feature sniffing for their presence."
- AndyMcConachie 5y ago
  That's a good point. But I would still include a check for OS's that I know support it. This means it wouldn't work on OS's without first explicitly allowing it. I view this as a feature and not a bug. There's a good chance there are other things to consider when a new OS adds pledge or unveil, and this gives the developer a chance to test support on the new OS before anyone uses it. Basically, I disagree with the article that you want to implement this in Python in a completely OS agnostic manner.
- mleonhard 5y ago
  Make "failed to find `pledge` function' a hard error on OSes known to have it.