//! Get system identification

use crate::{Errno, Result};

use libc::c_char;

use std::ffi::OsStr;

use std::mem;

use std::os::unix::ffi::OsStrExt;

/// Describes the running system.  Return type of [`uname`].

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]

#[repr(transparent)]

pub struct UtsName(libc::utsname);

impl UtsName {

    /// Name of the operating system implementation.

    pub fn sysname(&self) -> &OsStr {

        cast_and_trim(&self.0.sysname)

    }

    /// Network name of this machine.

    pub fn nodename(&self) -> &OsStr {

        cast_and_trim(&self.0.nodename)

    }

    /// Release level of the operating system.

    pub fn release(&self) -> &OsStr {

        cast_and_trim(&self.0.release)

    }

    /// Version level of the operating system.

    pub fn version(&self) -> &OsStr {

        cast_and_trim(&self.0.version)

    }

    /// Machine hardware platform.

    pub fn machine(&self) -> &OsStr {

        cast_and_trim(&self.0.machine)

    }

    /// NIS or YP domain name of this machine.

    #[cfg(linux_android)]

    pub fn domainname(&self) -> &OsStr {

        cast_and_trim(&self.0.domainname)

    }

}

/// Get system identification

pub fn uname() -> Result<UtsName> {

    unsafe {

        let mut ret = mem::MaybeUninit::zeroed();

        Errno::result(libc::uname(ret.as_mut_ptr()))?;

        Ok(UtsName(ret.assume_init()))

    }

}

fn cast_and_trim(slice: &[c_char]) -> &OsStr {

    let length = slice

        .iter()

        .position(|&byte| byte == 0)

        .unwrap_or(slice.len());

    let bytes =

        unsafe { std::slice::from_raw_parts(slice.as_ptr().cast(), length) };

    OsStr::from_bytes(bytes)

}