73 lines
1.6 KiB
Rust
73 lines
1.6 KiB
Rust
// Copyright (c) 2015, edef <edef@edef.eu>
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// See the LICENSE file included in this distribution.
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//! This module provides stacks using the operating system's
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//! anonymous memory mapping facility, usually `mmap`.
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//! The stacks it provides come with a guard page, which is not included
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//! in the stack limit.
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extern crate std;
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use core::prelude::*;
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use self::std::io::Error as IoError;
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use stack;
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mod sys;
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#[allow(raw_pointer_derive)]
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#[derive(Debug)]
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pub struct Stack {
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ptr: *mut u8,
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len: usize
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}
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unsafe impl Send for Stack {}
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impl Stack {
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pub fn new(size: usize) -> Result<Stack, IoError> {
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let page_size = sys::page_size();
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// round the page size up,
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// using the fact that it is a power of two
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let len = (size + page_size - 1) & !(page_size - 1);
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let stack = unsafe {
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let ptr = try!(match sys::map_stack(size) {
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None => Err(IoError::last_os_error()),
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Some(ptr) => Ok(ptr)
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});
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Stack { ptr: ptr as *mut u8, len: len }
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};
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try!(unsafe {
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if sys::protect_stack(stack.ptr) { Ok(()) }
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else { Err(IoError::last_os_error()) }
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});
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Ok(stack)
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}
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}
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impl stack::Stack for Stack {
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fn top(&mut self) -> *mut u8 {
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unsafe {
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self.ptr.offset(self.len as isize)
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}
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}
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fn limit(&self) -> *const u8 {
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unsafe {
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self.ptr.offset(sys::page_size() as isize)
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}
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}
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}
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impl Drop for Stack {
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fn drop(&mut self) {
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unsafe {
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if !sys::unmap_stack(self.ptr, self.len) {
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panic!("munmap for stack {:p} of size {} failed: {}",
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self.ptr, self.len, IoError::last_os_error())
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}
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}
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}
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}
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