atomic: Fix potential race

... as any unguarded access to non-const members of the same
shared_ptr instance require the use of `atomic_load` and
`atomic_store`.

(cherry picked from commit bda3dabe37fdde648f90ce5aa4b20d7336570cf0)

2 files changed, 7 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 319f0577..9e9d1166 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ Bug fixes on top of release `1.2.4`.
 - `just-mr` now reports the name of the build tool correctly, even
   if not called `just`.
 - Taintedness of "configure" targets is now propagated correctly.
+- Missing atomic primitives added to the source code.
 
 ## Release `1.2.4` (2023-12-19)
 
diff --git a/src/utils/cpp/atomic.hpp b/src/utils/cpp/atomic.hpp
index fbba8b92..bc2a7865 100644
--- a/src/utils/cpp/atomic.hpp
+++ b/src/utils/cpp/atomic.hpp
@@ -106,16 +106,18 @@ class atomic_shared_ptr {
     auto operator=(atomic_shared_ptr&& other) -> atomic_shared_ptr& = delete;
     auto operator=(ptr_t desired) -> ptr_t {  // NOLINT
         std::shared_lock lock(mutex_);
-        value_ = desired;
+        std::atomic_store(&value_, desired);
         return desired;
     }
-    operator ptr_t() const { value_; }  // NOLINT
+    operator ptr_t() const { return std::atomic_load(&value_); }  // NOLINT
 
     void store(ptr_t desired) {
         std::shared_lock lock(mutex_);
-        value_ = std::move(desired);
+        std::atomic_store(&value_, std::move(desired));
+    }
+    [[nodiscard]] auto load() const -> ptr_t {
+        return std::atomic_load(&value_);
     }
-    [[nodiscard]] auto load() const -> ptr_t { return value_; }
 
     void notify_one() { cv_.notify_one(); }
     void notify_all() { cv_.notify_all(); }