ioctl/framesizes: add v4l2_frmsizeenum accessor

Add an accessor for v4l2_frmsizeenum anonymous union members, avoiding having to write the union name and safely returning the appropiate member of the union that is used. Signed-off-by: Albert Esteve <aesteve@redhat.com>
lu-zero · Sep 26, 2023 · 532c316 · 532c316
1 parent 883dba7
commit 532c316
Showing 1 changed file with 34 additions and 0 deletions.
diff --git a/lib/src/ioctl/framesizes.rs b/lib/src/ioctl/framesizes.rs
@@ -13,6 +13,40 @@ impl FrameSize for bindings::v4l2_frmsizeenum {
     }
 }
 
+/// A wrapper for the 'v4l2_frmsizeenum' union member types
+#[derive(Debug)]
+pub enum FrmSizeTypes<'a> {
+    Discrete(&'a bindings::v4l2_frmsize_discrete),
+    StepWise(&'a bindings::v4l2_frmsize_stepwise),
+}
+
+impl bindings::v4l2_frmsizeenum {
+    /// Safely access the size member of the struct based on the
+    /// returned index.
+    pub fn size(&self) -> Option<FrmSizeTypes> {
+        match self.index {
+            // SAFETY: the member of the union that gets used by the driver
+            // is determined by the index
+            bindings::v4l2_frmsizetypes_V4L2_FRMSIZE_TYPE_DISCRETE => {
+                Some(FrmSizeTypes::Discrete(unsafe {
+                    &self.__bindgen_anon_1.discrete
+                }))
+            }
+
+            // SAFETY: the member of the union that gets used by the driver
+            // is determined by the index
+            bindings::v4l2_frmsizetypes_V4L2_FRMSIZE_TYPE_CONTINUOUS
+            | bindings::v4l2_frmsizetypes_V4L2_FRMSIZE_TYPE_STEPWISE => {
+                Some(FrmSizeTypes::StepWise(unsafe {
+                    &self.__bindgen_anon_1.stepwise
+                }))
+            }
+
+            _ => None,
+        }
+    }
+}
+
 #[doc(hidden)]
 mod ioctl {
     use crate::bindings::v4l2_frmsizeenum;