Add syslog APIs

[lambda-fairy]

The syslog interfaces are useful for writing daemons and such. It would be nice to have bindings to them.

[lambda-fairy]

I've published a preliminary set of bindings on my fork. There are a few issues with it so far:

• According to the Linux documentation, the ident argument to openlog() should have a static lifetime. I have modeled this using &'static CStr, which is correct but kind of fiddly.
• The interface of syslog() itself almost matches that of printf, except the former supports an extra code %m. I have no idea how to expose this safely. EDIT: printf supports this code as well.

Given these issues, I think we'd be better off just using a pure-Rust implementation instead.

[fiveop]

I have modeled this using &'static CStr, which is correct but kind of fiddly.

I think is the correct way to expose it safely.

The interface of syslog() itself almost matches that of printf, except the former supports an extra code %m. I have no idea how to expose this safely.

I have not encountered a good way of dealing with foreign functions with a variable number of arguments. When strings are involved, it only gets messier.

[lambda-fairy]

I have not encountered a good way of dealing with foreign functions with a variable number of arguments. When strings are involved, it only gets messier.

A syntax extension would work, but I think that would be overkill for this crate.

[tisonkun]

I think we'd be better off just using a pure-Rust implementation instead.

A binding is still helpful.

Today, I tried to write syslogs to macos, and encounter this issue python/cpython#91070, while directly call syslog(3) can work.

[tisonkun]

Or from the other perspective, how to implement syslog lib as in rust?

I made https://github.com/fast/fasyslog/ as a syslog client library. It works well for remote server and if the syslog daemon listens to a UNIX domain socket. But macos no longer works in either way so it's hard to make it work on macos.

[SteveLauC]

A binding is still helpful.

while directly call syslog(3) can work.

Considering that macOS bug, I agree it would be still helpful to bind them, if we can safely do so.

[tisonkun]

Ref -

• https://github.com/python/cpython/blob/v3.13.0/Modules/clinic/syslogmodule.c.h#L112
• https://github.com/python/cpython/blob/v3.13.0/Modules/syslogmodule.c
• https://docs.python.org/3/library/syslog.html

[tisonkun]

The interface of syslog() itself almost matches that of printf, except the former supports an extra code %m. I have no idea how to expose this safely. EDIT: printf supports this code as well.

I don't think we need to support the C formatter. Rust has its own format functions and we can also pass the formatted string without any other format signs.