stuck 0.1.3

Multi-threading scheduled task facility building on cooperative stackful coroutine
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

use std::alloc;

use super::page_size;

/// StackSize specifies desired stack size for new task.
///
/// It defaults to `8` times page size or [libc::MINSIGSTKSZ] depending on which one is bigger.
#[derive(Copy, Clone, Default, Debug)]
pub struct StackSize {
    size: isize,
}

impl StackSize {
    fn align_to_page_size(size: usize) -> usize {
        let mask = page_size::get() - 1;
        (size + mask) & !mask
    }

    fn aligned_page_size(&self) -> usize {
        let size = match self.size {
            0 => 8 * page_size::get(),
            1.. => 8 * page_size::get() + Self::align_to_page_size(self.size as usize),
            _ => Self::align_to_page_size((-self.size) as usize),
        };
        size.max(libc::MINSIGSTKSZ)
    }

    /// Specifies extra stack size in addition to default.
    pub fn with_extra_size(size: usize) -> StackSize {
        assert!(size <= isize::MAX as usize);
        StackSize { size: size as isize }
    }

    /// Specifies desired stack size.
    pub fn with_size(size: usize) -> StackSize {
        assert!(size <= isize::MAX as usize, "stack size is too large");
        StackSize { size: -(size.max(1) as isize) }
    }
}

pub(crate) struct Stack {
    base: *mut u8,
    size: libc::size_t,
}

impl Stack {
    pub fn base(&self) -> *mut u8 {
        self.base
    }

    pub fn size(&self) -> usize {
        self.size as usize
    }

    pub fn alloc(size: StackSize) -> Stack {
        let page_size = page_size::get();
        let stack_size = size.aligned_page_size();
        let alloc_size = stack_size + 2 * page_size;
        let layout = unsafe { alloc::Layout::from_size_align_unchecked(alloc_size, page_size) };
        let stack_low = unsafe { alloc::alloc(layout) };
        let stack_base = unsafe { stack_low.add(page_size) };
        let stack_high = unsafe { stack_base.add(stack_size) };
        unsafe { libc::mprotect(stack_low as *mut libc::c_void, page_size, libc::PROT_NONE) };
        unsafe { libc::mprotect(stack_high as *mut libc::c_void, page_size, libc::PROT_NONE) };
        Stack { base: stack_base, size: stack_size }
    }
}

impl Drop for Stack {
    fn drop(&mut self) {
        if self.base.is_null() {
            return;
        }
        let page_size = page_size::get();
        let alloc_size = self.size + 2 * page_size;
        let low = unsafe { self.base.sub(page_size) };
        let high = unsafe { self.base.add(self.size) };
        let prot = libc::PROT_READ | libc::PROT_WRITE;
        unsafe { libc::mprotect(low as *mut libc::c_void, page_size, prot) };
        unsafe { libc::mprotect(high as *mut libc::c_void, page_size, prot) };
        let layout = unsafe { alloc::Layout::from_size_align_unchecked(alloc_size, page_size) };
        unsafe { alloc::dealloc(low, layout) };
    }
}

#[cfg(test)]
mod tests {
    use std::mem;

    use super::*;

    fn read_stack(stack: &Stack) {
        let _ = *unsafe { stack.base().as_ref().unwrap() };
        let _ = *unsafe { stack.base().add(stack.size() - 1).as_ref().unwrap() };
    }

    fn write_stack(stack: &Stack) {
        *unsafe { stack.base().as_mut().unwrap() } = 0x11;
        *unsafe { stack.base().add(stack.size() - 1).as_mut().unwrap() } = 0x11;
    }

    #[test]
    fn stack_zeroed() {
        let _stack: Stack = unsafe { mem::zeroed() };
    }

    #[test]
    fn stack_default() {
        let stack = Stack::alloc(StackSize::default());
        assert!(stack.size() / page_size::get() > 0);
        assert_eq!(stack.size() % page_size::get(), 0);

        read_stack(&stack);
        write_stack(&stack);
    }

    #[test]
    fn stack_custom() {
        let stack = Stack::alloc(StackSize::with_size(20));
        assert!(stack.size() / page_size::get() > 0);
        assert_eq!(stack.size() % page_size::get(), 0);

        read_stack(&stack);
        write_stack(&stack);
    }

    #[test]
    fn stack_extra_size() {
        let stack = Stack::alloc(StackSize::with_extra_size(20));
        assert!(stack.size() / page_size::get() > 0);
        assert_eq!(stack.size() % page_size::get(), 0);

        read_stack(&stack);
        write_stack(&stack);
    }
}