Remove uses of Option::unwrap_unchecked as a safety precaution (#2310)

vulkano/src/buffer/subbuffer.rs

@@ -129,11 +129,9 @@ impl<T: ?Sized> Subbuffer<T> {
     /// [`MappingState::slice`]: crate::memory::MappingState::slice
     pub fn mapped_slice(&self) -> Result<NonNull<[u8]>, HostAccessError> {
         match self.buffer().memory() {
-            BufferMemory::Normal(a) => {
-                let opt = a.mapped_slice(self.range());
-
+            BufferMemory::Normal(allocation) => {
                 // SAFETY: `self.range()` is in bounds of the allocation.
-                unsafe { opt.unwrap_unchecked() }
+                unsafe { allocation.mapped_slice_unchecked(self.range()) }
             }
             BufferMemory::Sparse => unreachable!(),
         }
@@ -510,7 +508,7 @@ impl<T> Subbuffer<[T]> {
 
     #[cfg_attr(not(feature = "document_unchecked"), doc(hidden))]
     pub unsafe fn slice_unchecked(mut self, range: impl RangeBounds<DeviceSize>) -> Subbuffer<[T]> {
-        let Range { start, end } = memory::range(range, ..self.len()).unwrap_unchecked();
+        let Range { start, end } = memory::range_unchecked(range, ..self.len());
 
         self.offset += start * size_of::<T>() as DeviceSize;
         self.size = (end - start) * size_of::<T>() as DeviceSize;

vulkano/src/memory/allocator/suballocator.rs

@@ -157,6 +157,23 @@ impl MemoryAlloc {
         Some(res)
     }
 
+    #[cfg_attr(not(feature = "document_unchecked"), doc(hidden))]
+    #[inline]
+    pub unsafe fn mapped_slice_unchecked(
+        &self,
+        range: impl RangeBounds<DeviceSize>,
+    ) -> Result<NonNull<[u8]>, HostAccessError> {
+        let mut range = memory::range_unchecked(range, ..self.size());
+        range.start += self.offset();
+        range.end += self.offset();
+
+        if let Some(state) = self.device_memory().mapping_state() {
+            state.slice(range).ok_or(HostAccessError::OutOfMappedRange)
+        } else {
+            Err(HostAccessError::NotHostMapped)
+        }
+    }
+
     pub(crate) fn atom_size(&self) -> Option<DeviceAlignment> {
         self.atom_size
     }

vulkano/src/memory/mod.rs

@@ -590,3 +590,27 @@ pub(crate) fn range(
 
     (start <= end && end <= len).then_some(Range { start, end })
 }
+
+/// Converts a `RangeBounds` into a `Range` without doing any bounds checking.
+pub(crate) fn range_unchecked(
+    range: impl RangeBounds<DeviceSize>,
+    bounds: RangeTo<DeviceSize>,
+) -> Range<DeviceSize> {
+    let len = bounds.end;
+
+    let start = match range.start_bound() {
+        Bound::Included(&start) => start,
+        Bound::Excluded(start) => start + 1,
+        Bound::Unbounded => 0,
+    };
+
+    let end = match range.end_bound() {
+        Bound::Included(end) => end + 1,
+        Bound::Excluded(&end) => end,
+        Bound::Unbounded => len,
+    };
+
+    debug_assert!(start <= end && end <= len);
+
+    Range { start, end }
+}