// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![allow(dead_code)]

use core::prelude::*;

use cmp;
use ffi::CString;
use io;
use libc::consts::os::posix01::PTHREAD_STACK_MIN;
use libc;
use mem;
use ptr;
use sys::os;
use thunk::Thunk;
use time::Duration;

use sys_common::stack::RED_ZONE;
use sys_common::thread::*;

pub type rust_thread = libc::pthread_t;

#[cfg(all(not(target_os = "linux"),
          not(target_os = "macos"),
          not(target_os = "bitrig"),
          not(target_os = "openbsd")))]
pub mod guard {
    pub unsafe fn current() -> usize { 0 }
    pub unsafe fn main() -> usize { 0 }
    pub unsafe fn init() {}
}


#[cfg(any(target_os = "linux",
          target_os = "macos",
          target_os = "bitrig",
          target_os = "openbsd"))]
#[allow(unused_imports)]
pub mod guard {
    use libc::{self, pthread_t};
    use libc::funcs::posix88::mman::mmap;
    use libc::consts::os::posix88::{PROT_NONE,
                                    MAP_PRIVATE,
                                    MAP_ANON,
                                    MAP_FAILED,
                                    MAP_FIXED};
    use mem;
    use ptr;
    use super::{pthread_self, pthread_attr_destroy};
    use sys::os;

    // These are initialized in init() and only read from after
    static mut GUARD_PAGE: usize = 0;

    #[cfg(any(target_os = "macos",
              target_os = "bitrig",
              target_os = "openbsd"))]
    unsafe fn get_stack_start() -> *mut libc::c_void {
        current() as *mut libc::c_void
    }

    #[cfg(any(target_os = "linux", target_os = "android"))]
    unsafe fn get_stack_start() -> *mut libc::c_void {
        let mut attr: libc::pthread_attr_t = mem::zeroed();
        assert_eq!(pthread_getattr_np(pthread_self(), &mut attr), 0);
        let mut stackaddr = ptr::null_mut();
        let mut stacksize = 0;
        assert_eq!(pthread_attr_getstack(&attr, &mut stackaddr, &mut stacksize), 0);
        assert_eq!(pthread_attr_destroy(&mut attr), 0);
        stackaddr
    }

    pub unsafe fn init() {
        let psize = os::page_size();
        let mut stackaddr = get_stack_start();

        // Ensure stackaddr is page aligned! A parent process might
        // have reset RLIMIT_STACK to be non-page aligned. The
        // pthread_attr_getstack() reports the usable stack area
        // stackaddr < stackaddr + stacksize, so if stackaddr is not
        // page-aligned, calculate the fix such that stackaddr <
        // new_page_aligned_stackaddr < stackaddr + stacksize
        let remainder = (stackaddr as usize) % psize;
        if remainder != 0 {
            stackaddr = ((stackaddr as usize) + psize - remainder)
                as *mut libc::c_void;
        }

        // Rellocate the last page of the stack.
        // This ensures SIGBUS will be raised on
        // stack overflow.
        let result = mmap(stackaddr,
                          psize as libc::size_t,
                          PROT_NONE,
                          MAP_PRIVATE | MAP_ANON | MAP_FIXED,
                          -1,
                          0);

        if result != stackaddr || result == MAP_FAILED {
            panic!("failed to allocate a guard page");
        }

        let offset = if cfg!(target_os = "linux") {2} else {1};

        GUARD_PAGE = stackaddr as usize + offset * psize;
    }

    pub unsafe fn main() -> usize {
        GUARD_PAGE
    }

    #[cfg(target_os = "macos")]
    pub unsafe fn current() -> usize {
        extern {
            fn pthread_get_stackaddr_np(thread: pthread_t) -> *mut libc::c_void;
            fn pthread_get_stacksize_np(thread: pthread_t) -> libc::size_t;
        }
        (pthread_get_stackaddr_np(pthread_self()) as libc::size_t -
         pthread_get_stacksize_np(pthread_self())) as usize
    }

    #[cfg(any(target_os = "openbsd", target_os = "bitrig"))]
    pub unsafe fn current() -> usize {
        #[repr(C)]
        struct stack_t {
            ss_sp: *mut libc::c_void,
            ss_size: libc::size_t,
            ss_flags: libc::c_int,
        }
        extern {
            fn pthread_main_np() -> libc::c_uint;
            fn pthread_stackseg_np(thread: pthread_t,
                                   sinfo: *mut stack_t) -> libc::c_uint;
        }

        let mut current_stack: stack_t = mem::zeroed();
        assert_eq!(pthread_stackseg_np(pthread_self(), &mut current_stack), 0);

        let extra = if cfg!(target_os = "bitrig") {3} else {1} * os::page_size();
        if pthread_main_np() == 1 {
            // main thread
            current_stack.ss_sp as usize - current_stack.ss_size as usize + extra
        } else {
            // new thread
            current_stack.ss_sp as usize - current_stack.ss_size as usize
        }
    }

    #[cfg(any(target_os = "linux", target_os = "android"))]
    pub unsafe fn current() -> usize {
        let mut attr: libc::pthread_attr_t = mem::zeroed();
        assert_eq!(pthread_getattr_np(pthread_self(), &mut attr), 0);
        let mut guardsize = 0;
        assert_eq!(pthread_attr_getguardsize(&attr, &mut guardsize), 0);
        if guardsize == 0 {
            panic!("there is no guard page");
        }
        let mut stackaddr = ptr::null_mut();
        let mut size = 0;
        assert_eq!(pthread_attr_getstack(&attr, &mut stackaddr, &mut size), 0);
        assert_eq!(pthread_attr_destroy(&mut attr), 0);

        stackaddr as usize + guardsize as usize
    }

    #[cfg(any(target_os = "linux", target_os = "android"))]
    extern {
        fn pthread_getattr_np(native: libc::pthread_t,
                              attr: *mut libc::pthread_attr_t) -> libc::c_int;
        fn pthread_attr_getguardsize(attr: *const libc::pthread_attr_t,
                                     guardsize: *mut libc::size_t) -> libc::c_int;
        fn pthread_attr_getstack(attr: *const libc::pthread_attr_t,
                                 stackaddr: *mut *mut libc::c_void,
                                 stacksize: *mut libc::size_t) -> libc::c_int;
    }
}

pub unsafe fn create(stack: usize, p: Thunk) -> io::Result<rust_thread> {
    let p = box p;
    let mut native: libc::pthread_t = mem::zeroed();
    let mut attr: libc::pthread_attr_t = mem::zeroed();
    assert_eq!(pthread_attr_init(&mut attr), 0);

    // Reserve room for the red zone, the runtime's stack of last resort.
    let stack_size = cmp::max(stack, RED_ZONE + min_stack_size(&attr) as usize);
    match pthread_attr_setstacksize(&mut attr, stack_size as libc::size_t) {
        0 => {}
        n => {
            assert_eq!(n, libc::EINVAL);
            // EINVAL means |stack_size| is either too small or not a
            // multiple of the system page size.  Because it's definitely
            // >= PTHREAD_STACK_MIN, it must be an alignment issue.
            // Round up to the nearest page and try again.
            let page_size = os::page_size();
            let stack_size = (stack_size + page_size - 1) &
                             (-(page_size as isize - 1) as usize - 1);
            assert_eq!(pthread_attr_setstacksize(&mut attr,
                                                 stack_size as libc::size_t), 0);
        }
    };

    let ret = pthread_create(&mut native, &attr, thread_start,
                             &*p as *const _ as *mut _);
    assert_eq!(pthread_attr_destroy(&mut attr), 0);

    return if ret != 0 {
        Err(io::Error::from_os_error(ret))
    } else {
        mem::forget(p); // ownership passed to pthread_create
        Ok(native)
    };

    #[no_stack_check]
    extern fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
        start_thread(main);
        0 as *mut _
    }
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub unsafe fn set_name(name: &str) {
    // pthread_setname_np() since glibc 2.12
    // availability autodetected via weak linkage
    type F = unsafe extern fn(libc::pthread_t, *const libc::c_char)
                              -> libc::c_int;
    extern {
        #[linkage = "extern_weak"]
        static pthread_setname_np: *const ();
    }
    if !pthread_setname_np.is_null() {
        let cname = CString::new(name).unwrap();
        mem::transmute::<*const (), F>(pthread_setname_np)(pthread_self(),
                                                           cname.as_ptr());
    }
}

#[cfg(any(target_os = "freebsd",
          target_os = "dragonfly",
          target_os = "bitrig",
          target_os = "openbsd"))]
pub unsafe fn set_name(name: &str) {
    extern {
        fn pthread_set_name_np(tid: libc::pthread_t, name: *const libc::c_char);
    }
    let cname = CString::new(name).unwrap();
    pthread_set_name_np(pthread_self(), cname.as_ptr());
}

#[cfg(any(target_os = "macos", target_os = "ios"))]
pub unsafe fn set_name(name: &str) {
    extern {
        fn pthread_setname_np(name: *const libc::c_char) -> libc::c_int;
    }
    let cname = CString::new(name).unwrap();
    pthread_setname_np(cname.as_ptr());
}

pub unsafe fn join(native: rust_thread) {
    assert_eq!(pthread_join(native, ptr::null_mut()), 0);
}

pub unsafe fn detach(native: rust_thread) {
    assert_eq!(pthread_detach(native), 0);
}

pub unsafe fn yield_now() {
    assert_eq!(sched_yield(), 0);
}

pub fn sleep(dur: Duration) {
    unsafe {
        if dur < Duration::zero() {
            return yield_now()
        }
        let seconds = dur.num_seconds();
        let ns = dur - Duration::seconds(seconds);
        let mut ts = libc::timespec {
            tv_sec: seconds as libc::time_t,
            tv_nsec: ns.num_nanoseconds().unwrap() as libc::c_long,
        };
        // If we're awoken with a signal then the return value will be -1 and
        // nanosleep will fill in `ts` with the remaining time.
        while dosleep(&mut ts) == -1 {
            assert_eq!(os::errno(), libc::EINTR);
        }
    }

    #[cfg(target_os = "linux")]
    unsafe fn dosleep(ts: *mut libc::timespec) -> libc::c_int {
        extern {
            fn clock_nanosleep(clock_id: libc::c_int, flags: libc::c_int,
                               request: *const libc::timespec,
                               remain: *mut libc::timespec) -> libc::c_int;
        }
        clock_nanosleep(libc::CLOCK_MONOTONIC, 0, ts, ts)
    }
    #[cfg(not(target_os = "linux"))]
    unsafe fn dosleep(ts: *mut libc::timespec) -> libc::c_int {
        libc::nanosleep(ts, ts)
    }
}

// glibc >= 2.15 has a __pthread_get_minstack() function that returns
// PTHREAD_STACK_MIN plus however many bytes are needed for thread-local
// storage.  We need that information to avoid blowing up when a small stack
// is created in an application with big thread-local storage requirements.
// See #6233 for rationale and details.
//
// Link weakly to the symbol for compatibility with older versions of glibc.
// Assumes that we've been dynamically linked to libpthread but that is
// currently always the case.  Note that you need to check that the symbol
// is non-null before calling it!
#[cfg(target_os = "linux")]
fn min_stack_size(attr: *const libc::pthread_attr_t) -> libc::size_t {
    type F = unsafe extern "C" fn(*const libc::pthread_attr_t) -> libc::size_t;
    extern {
        #[linkage = "extern_weak"]
        static __pthread_get_minstack: *const ();
    }
    if __pthread_get_minstack.is_null() {
        PTHREAD_STACK_MIN
    } else {
        unsafe { mem::transmute::<*const (), F>(__pthread_get_minstack)(attr) }
    }
}

// __pthread_get_minstack() is marked as weak but extern_weak linkage is
// not supported on OS X, hence this kludge...
#[cfg(not(target_os = "linux"))]
fn min_stack_size(_: *const libc::pthread_attr_t) -> libc::size_t {
    PTHREAD_STACK_MIN
}

extern {
    fn pthread_self() -> libc::pthread_t;
    fn pthread_create(native: *mut libc::pthread_t,
                      attr: *const libc::pthread_attr_t,
                      f: extern fn(*mut libc::c_void) -> *mut libc::c_void,
                      value: *mut libc::c_void) -> libc::c_int;
    fn pthread_join(native: libc::pthread_t,
                    value: *mut *mut libc::c_void) -> libc::c_int;
    fn pthread_attr_init(attr: *mut libc::pthread_attr_t) -> libc::c_int;
    fn pthread_attr_destroy(attr: *mut libc::pthread_attr_t) -> libc::c_int;
    fn pthread_attr_setstacksize(attr: *mut libc::pthread_attr_t,
                                 stack_size: libc::size_t) -> libc::c_int;
    fn pthread_attr_setdetachstate(attr: *mut libc::pthread_attr_t,
                                   state: libc::c_int) -> libc::c_int;
    fn pthread_detach(thread: libc::pthread_t) -> libc::c_int;
    fn sched_yield() -> libc::c_int;
}