1 files changed, 52 insertions, 0 deletions
diff --git a/vendor/backtrace/src/symbolize/gimli/stash.rs b/vendor/backtrace/src/symbolize/gimli/stash.rs
new file mode 100644
index 000000000..3adfc598a
--- /dev/null
+++ b/vendor/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<Vec<Vec<u8>>>,
+    mmap_aux: UnsafeCell<Option<Mmap>>,
+}
+
+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()
+        }
+    }
+}