From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- library/backtrace/src/symbolize/gimli/stash.rs | 52 ++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 library/backtrace/src/symbolize/gimli/stash.rs (limited to 'library/backtrace/src/symbolize/gimli/stash.rs') diff --git a/library/backtrace/src/symbolize/gimli/stash.rs b/library/backtrace/src/symbolize/gimli/stash.rs new file mode 100644 index 000000000..3adfc598a --- /dev/null +++ b/library/backtrace/src/symbolize/gimli/stash.rs @@ -0,0 +1,52 @@ +// only used on Linux right now, so allow dead code elsewhere +#![cfg_attr(not(target_os = "linux"), allow(dead_code))] + +use super::Mmap; +use alloc::vec; +use alloc::vec::Vec; +use core::cell::UnsafeCell; + +/// A simple arena allocator for byte buffers. +pub struct Stash { + buffers: UnsafeCell>>, + mmap_aux: UnsafeCell>, +} + +impl Stash { + pub fn new() -> Stash { + Stash { + buffers: UnsafeCell::new(Vec::new()), + mmap_aux: UnsafeCell::new(None), + } + } + + /// Allocates a buffer of the specified size and returns a mutable reference + /// to it. + pub fn allocate(&self, size: usize) -> &mut [u8] { + // SAFETY: this is the only function that ever constructs a mutable + // reference to `self.buffers`. + let buffers = unsafe { &mut *self.buffers.get() }; + let i = buffers.len(); + buffers.push(vec![0; size]); + // SAFETY: we never remove elements from `self.buffers`, so a reference + // to the data inside any buffer will live as long as `self` does. + &mut buffers[i] + } + + /// Stores a `Mmap` for the lifetime of this `Stash`, returning a pointer + /// which is scoped to just this lifetime. + pub fn set_mmap_aux(&self, map: Mmap) -> &[u8] { + // SAFETY: this is the only location for a mutable pointer to + // `mmap_aux`, and this structure isn't threadsafe to shared across + // threads either. This also is careful to store at most one `mmap_aux` + // since overwriting a previous one would invalidate the previous + // pointer. Given that though we can safely return a pointer to our + // interior-owned contents. + unsafe { + let mmap_aux = &mut *self.mmap_aux.get(); + assert!(mmap_aux.is_none()); + *mmap_aux = Some(map); + mmap_aux.as_ref().unwrap() + } + } +} -- cgit v1.2.3