std/backtrace/src/symbolize/gimli/
stash.rs

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1#![allow(clippy::all)]
2// only used on Linux right now, so allow dead code elsewhere
3#![cfg_attr(not(target_os = "linux"), allow(dead_code))]
4
5use super::Mmap;
6use alloc::vec;
7use alloc::vec::Vec;
8use core::cell::UnsafeCell;
9
10/// A simple arena allocator for byte buffers.
11pub struct Stash {
12    buffers: UnsafeCell<Vec<Vec<u8>>>,
13    mmaps: UnsafeCell<Vec<Mmap>>,
14}
15
16impl Stash {
17    pub fn new() -> Stash {
18        Stash {
19            buffers: UnsafeCell::new(Vec::new()),
20            mmaps: UnsafeCell::new(Vec::new()),
21        }
22    }
23
24    /// Allocates a buffer of the specified size and returns a mutable reference
25    /// to it.
26    pub fn allocate(&self, size: usize) -> &mut [u8] {
27        // SAFETY: this is the only function that ever constructs a mutable
28        // reference to `self.buffers`.
29        let buffers = unsafe { &mut *self.buffers.get() };
30        let i = buffers.len();
31        buffers.push(vec![0; size]);
32        // SAFETY: we never remove elements from `self.buffers`, so a reference
33        // to the data inside any buffer will live as long as `self` does.
34        &mut buffers[i]
35    }
36
37    /// Stores a `Mmap` for the lifetime of this `Stash`, returning a pointer
38    /// which is scoped to just this lifetime.
39    pub fn cache_mmap(&self, map: Mmap) -> &[u8] {
40        // SAFETY: this is the only location for a mutable pointer to
41        // `mmaps`, and this structure isn't threadsafe to shared across
42        // threads either. We also never remove elements from `self.mmaps`,
43        // so a reference to the data inside the map will live as long as
44        // `self` does.
45        unsafe {
46            let mmaps = &mut *self.mmaps.get();
47            mmaps.push(map);
48            mmaps.last().unwrap()
49        }
50    }
51}
std/backtrace/src/symbolize/gimli/stash.rs

std/backtrace/src/symbolize/gimli/
stash.rs
