sgx_tstd/src/sys/time.rs

// Copyright (C) 2017-2018 Baidu, Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
//  * Neither the name of Baidu, Inc., nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use sgx_trts::libc;
use core::cmp::Ordering;
use core::hash::{Hash, Hasher};
use time::Duration;

pub use self::inner::{Instant, SystemTime, UNIX_EPOCH};
use core::convert::TryInto;

const NSEC_PER_SEC: u64 = 1_000_000_000;

#[derive(Copy, Clone)]
struct Timespec {
    t: libc::timespec,
}

impl Timespec {
    fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
        if self >= other {
            Ok(if self.t.tv_nsec >= other.t.tv_nsec {
                Duration::new((self.t.tv_sec - other.t.tv_sec) as u64,
                              (self.t.tv_nsec - other.t.tv_nsec) as u32)
            } else {
                Duration::new((self.t.tv_sec - 1 - other.t.tv_sec) as u64,
                              self.t.tv_nsec as u32 + (NSEC_PER_SEC as u32) -
                              other.t.tv_nsec as u32)
            })
        } else {
            match other.sub_timespec(self) {
                Ok(d) => Err(d),
                Err(d) => Ok(d),
            }
        }
    }

    fn add_duration(&self, other: &Duration) -> Timespec {
        let mut secs = other
            .as_secs()
            .try_into() // <- target type would be `sgx_trts::libc::time_t`
            .ok()
            .and_then(|secs| self.t.tv_sec.checked_add(secs))
            .expect("overflow when adding duration to time");

        // Nano calculations can't overflow because nanos are <1B which fit
        // in a u32.
        let mut nsec = other.subsec_nanos() + self.t.tv_nsec as u32;
        if nsec >= NSEC_PER_SEC as u32 {
            nsec -= NSEC_PER_SEC as u32;
            secs = secs.checked_add(1).expect("overflow when adding \
                                               duration to time");
        }
        Timespec {
            t: libc::timespec {
                tv_sec: secs,
                tv_nsec: nsec as libc::c_long,
            },
        }
    }

    fn sub_duration(&self, other: &Duration) -> Timespec {
        let mut secs = other
            .as_secs()
            .try_into() // <- target type would be `sgx_trts::libc::time_t`
            .ok()
            .and_then(|secs| self.t.tv_sec.checked_sub(secs))
            .expect("overflow when subtracting duration from time");

        // Similar to above, nanos can't overflow.
        let mut nsec = self.t.tv_nsec as i32 - other.subsec_nanos() as i32;
        if nsec < 0 {
            nsec += NSEC_PER_SEC as i32;
            secs = secs.checked_sub(1).expect("overflow when subtracting \
                                               duration from time");
        }
        Timespec {
            t: libc::timespec {
                tv_sec: secs,
                tv_nsec: nsec as libc::c_long,
            },
        }
    }
}

impl PartialEq for Timespec {
    fn eq(&self, other: &Timespec) -> bool {
        self.t.tv_sec == other.t.tv_sec && self.t.tv_nsec == other.t.tv_nsec
    }
}

impl Eq for Timespec {}

impl PartialOrd for Timespec {
    fn partial_cmp(&self, other: &Timespec) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Timespec {
    fn cmp(&self, other: &Timespec) -> Ordering {
        let me = (self.t.tv_sec, self.t.tv_nsec);
        let other = (other.t.tv_sec, other.t.tv_nsec);
        me.cmp(&other)
    }
}

impl Hash for Timespec {
    fn hash<H : Hasher>(&self, state: &mut H) {
        self.t.tv_sec.hash(state);
        self.t.tv_nsec.hash(state);
    }
}

mod inner {
    use sgx_types::sgx_status_t;
    use sgx_trts::libc::{self, c_int};
    use core::fmt;
    use sys::cvt;
    use io;
    use time::Duration;

    use super::Timespec;

    #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
    pub struct Instant {
        t: Timespec,
    }

    #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
    pub struct SystemTime {
        t: Timespec,
    }

    pub const UNIX_EPOCH: SystemTime = SystemTime {
        t: Timespec {
            t: libc::timespec {
                tv_sec: 0,
                tv_nsec: 0,
            },
        },
    };

    impl Instant {
        pub fn now() -> Instant {
            Instant { t: now(libc::CLOCK_MONOTONIC) }
        }

        pub fn sub_instant(&self, other: &Instant) -> Duration {
            self.t.sub_timespec(&other.t).unwrap_or_else(|_| {
                panic!("other was less than the current instant")
            })
        }

        pub fn add_duration(&self, other: &Duration) -> Instant {
            Instant { t: self.t.add_duration(other) }
        }

        pub fn sub_duration(&self, other: &Duration) -> Instant {
            Instant { t: self.t.sub_duration(other) }
        }
    }

    impl fmt::Debug for Instant {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            f.debug_struct("Instant")
             .field("tv_sec", &self.t.t.tv_sec)
             .field("tv_nsec", &self.t.t.tv_nsec)
             .finish()
        }
    }

    impl SystemTime {
        pub fn now() -> SystemTime {
            SystemTime { t: now(libc::CLOCK_REALTIME) }
        }

        pub fn sub_time(&self, other: &SystemTime)
                        -> Result<Duration, Duration> {
            self.t.sub_timespec(&other.t)
        }

        pub fn add_duration(&self, other: &Duration) -> SystemTime {
            SystemTime { t: self.t.add_duration(other) }
        }

        pub fn sub_duration(&self, other: &Duration) -> SystemTime {
            SystemTime { t: self.t.sub_duration(other) }
        }
    }

    impl From<libc::timespec> for SystemTime {
        fn from(t: libc::timespec) -> SystemTime {
            SystemTime { t: Timespec { t: t } }
        }
    }

    impl fmt::Debug for SystemTime {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            f.debug_struct("SystemTime")
             .field("tv_sec", &self.t.t.tv_sec)
             .field("tv_nsec", &self.t.t.tv_nsec)
             .finish()
        }
    }

    fn now(clock: libc::clockid_t) -> Timespec {
        let mut t = Timespec {
            t: libc::timespec {
                tv_sec: 0,
                tv_nsec: 0,
            }
        };
        cvt(unsafe {
            clock_gettime(clock, &mut t.t)
        }).unwrap();
        t
    }

    extern "C" {
        pub fn u_clock_gettime_ocall(result: * mut c_int,
                                     errno: * mut c_int,
                                     clk_id: libc::clockid_t, 
                                     tp: * mut libc::timespec) -> sgx_status_t;
    }
    
    unsafe fn clock_gettime(clk_id: libc::clockid_t, tp: &mut libc::timespec) -> c_int {

        let mut result: c_int = 0;
        let mut error: c_int = 0;
        let status = u_clock_gettime_ocall(&mut result as * mut c_int, 
                                           &mut error as * mut c_int,
                                           clk_id, 
                                           tp as * mut libc::timespec);
    
        if status == sgx_status_t::SGX_SUCCESS {
            if result == -1 {
                io::set_errno(error);
            }
        } else {
            io::set_errno(libc::ESGX);
            result = -1;
        }
        result
    }
}