starry-kernel 0.5.10

use ax_errno::{AxError, AxResult};
use ax_hal::time::TimeValue;
use ax_task::current;
use linux_raw_sys::general::{__kernel_old_timeval, RLIM_NLIMITS, rlimit64, rusage};
use starry_process::Pid;
use starry_vm::{VmMutPtr, VmPtr};

use crate::{
    task::{AsThread, Thread, get_process_data, get_task},
    time::TimeValueLike,
};

pub fn sys_prlimit64(
    pid: Pid,
    resource: u32,
    new_limit: *const rlimit64,
    old_limit: *mut rlimit64,
) -> AxResult<isize> {
    if resource >= RLIM_NLIMITS {
        return Err(AxError::InvalidInput);
    }

    let proc_data = get_process_data(pid)?;
    if let Some(old_limit) = old_limit.nullable() {
        let limit = &proc_data.rlim.read()[resource];
        old_limit.vm_write(rlimit64 {
            rlim_cur: limit.current,
            rlim_max: limit.max,
        })?;
    }

    if let Some(new_limit) = new_limit.nullable() {
        // FIXME: AnyBitPattern
        let new_limit = unsafe { new_limit.vm_read_uninit()?.assume_init() };
        if new_limit.rlim_cur > new_limit.rlim_max {
            return Err(AxError::InvalidInput);
        }

        let limit = &mut proc_data.rlim.write()[resource];
        // TODO: when a capability system is added, check CAP_SYS_RESOURCE
        // before allowing new_limit.rlim_max > limit.max (return EPERM).
        limit.max = new_limit.rlim_max;
        limit.current = new_limit.rlim_cur;
    }

    Ok(0)
}

#[derive(Default)]
struct Rusage {
    utime: TimeValue,
    stime: TimeValue,
}

impl Rusage {
    fn from_thread(thread: &Thread) -> Self {
        let (utime, stime) = thread.time.borrow().output();
        Self { utime, stime }
    }

    fn collate(mut self, other: Rusage) -> Self {
        self.utime += other.utime;
        self.stime += other.stime;
        self
    }
}

impl From<Rusage> for rusage {
    fn from(value: Rusage) -> Self {
        // FIXME: Zeroable
        let mut usage: rusage = unsafe { core::mem::zeroed() };
        usage.ru_utime = __kernel_old_timeval::from_time_value(value.utime);
        usage.ru_stime = __kernel_old_timeval::from_time_value(value.stime);
        usage
    }
}

pub fn sys_getrusage(who: i32, usage: *mut rusage) -> AxResult<isize> {
    const RUSAGE_SELF: i32 = linux_raw_sys::general::RUSAGE_SELF as i32;
    const RUSAGE_CHILDREN: i32 = linux_raw_sys::general::RUSAGE_CHILDREN;
    const RUSAGE_THREAD: i32 = linux_raw_sys::general::RUSAGE_THREAD as i32;

    let curr = current();
    let thr = curr.as_thread();

    let result = match who {
        RUSAGE_SELF => {
            thr.proc_data
                .proc
                .threads()
                .into_iter()
                .fold(Rusage::default(), |acc, tid| {
                    if let Ok(task) = get_task(tid) {
                        acc.collate(Rusage::from_thread(task.as_thread()))
                    } else {
                        acc
                    }
                })
        }
        RUSAGE_CHILDREN => {
            thr.proc_data
                .proc
                .threads()
                .into_iter()
                .fold(Rusage::default(), |acc, child| {
                    if let Ok(task) = get_task(child)
                        && !curr.ptr_eq(&task)
                    {
                        acc.collate(Rusage::from_thread(task.as_thread()))
                    } else {
                        acc
                    }
                })
        }
        RUSAGE_THREAD => Rusage::from_thread(thr),
        _ => return Err(AxError::InvalidInput),
    };
    usage.vm_write(result.into())?;

    Ok(0)
}