Merge pull request #247 from rtbo/fix_246

dereferencing through `copy_nonoverlapping`
rust-x-bindings · Dec 4, 2023 · c5411cd · c5411cd
2 parents d2314cd + 1e8c33d
commit c5411cd
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Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/build/cg/struct.rs b/build/cg/struct.rs
@@ -1622,7 +1622,10 @@ impl CodeGen {
                         "            let ptr = self.wire_ptr().add(offset) as *const {};",
                         q_rs_typ
                     )?;
-                    writeln!(out, "            let val = *ptr as u32;")?;
+                    writeln!(
+                        out,
+                        "            let val = base::value_from_ptr(ptr) as u32;"
+                    )?;
                     writeln!(
                         out,
                         "            std::mem::transmute::<u32, {}>(val)",
@@ -1711,7 +1714,7 @@ impl CodeGen {
                         cg::ind(3),
                         q_rs_typ
                     )?;
-                    writeln!(out, "            *ptr")?;
+                    writeln!(out, "{}base::value_from_ptr(ptr)", cg::ind(3),)?;
                     writeln!(out, "        }}")?;
                     writeln!(out, "    }}")?;
                 }

diff --git a/src/base.rs b/src/base.rs
@@ -1750,6 +1750,17 @@ pub(crate) fn align_pad(base: usize, align: usize) -> usize {
     (-base & (align - 1)) as usize
 }
 
+/// Get a value from a pointer, using ptr::copy_nonoverlapping to avoid alignment issues
+///
+/// # Safety
+/// The pointer must point to a valid `T` value
+#[inline]
+pub(crate) unsafe fn value_from_ptr<T>(ptr: *const T) -> T {
+    let mut val = mem::MaybeUninit::<T>::uninit();
+    ptr::copy_nonoverlapping(ptr, val.as_mut_ptr(), 1);
+    val.assume_init()
+}
+
 #[test]
 fn test_align_pad() {
     // align 1