fam: Add a unit test for the vfio_irq_set wrapper

Compare the FAM wrapper generated set with a vec_with_array one.

Signed-off-by: Samuel Ortiz <[email protected]>

Author: Samuel Ortiz

Cargo.toml

@@ -15,3 +15,6 @@ fam-wrappers = ["vmm-sys-util"]
 
 [dependencies]
 vmm-sys-util = { version = ">=0.2.0", optional = true }
+
+[dev-dependencies]
+byteorder = ">=1.2.1"

src/fam_wrappers.rs

@@ -19,3 +19,95 @@ generate_fam_struct_impl!(vfio_irq_set, u8, data, u32, count, MSIX_MAX_VECTORS);
 /// elements, this type is implemented using
 /// [FamStructWrapper](../vmm_sys_util/fam/struct.FamStructWrapper.html).
 pub type IrqSet = FamStructWrapper<vfio_irq_set>;
+
+#[cfg(test)]
+mod tests {
+    extern crate byteorder;
+
+    use super::*;
+    use byteorder::{ByteOrder, LittleEndian};
+    use std::mem;
+
+    fn vec_with_size_in_bytes<T: Default>(size_in_bytes: usize) -> Vec<T> {
+        let rounded_size = (size_in_bytes + mem::size_of::<T>() - 1) / mem::size_of::<T>();
+        let mut v = Vec::with_capacity(rounded_size);
+        for _ in 0..rounded_size {
+            v.push(T::default())
+        }
+        v
+    }
+
+    fn vec_with_array_field<T: Default, F>(count: usize) -> Vec<T> {
+        let element_space = count * mem::size_of::<F>();
+        let vec_size_bytes = mem::size_of::<T>() + element_space;
+        vec_with_size_in_bytes(vec_size_bytes)
+    }
+
+    // Opinionated PartialEq implementation for vfio_irq_set.
+    impl PartialEq for vfio_irq_set {
+        fn eq(&self, other: &Self) -> bool {
+            if self.argsz != other.argsz
+                || self.flags != other.flags
+                || self.index != other.index
+                || self.start != other.start
+                || self.count != other.count
+            {
+                return false;
+            }
+            true
+        }
+    }
+
+    #[test]
+    fn irqset_fam_test() {
+        let event_fds: Vec<u32> = vec![0, 1, 2, 3, 4, 5];
+
+        // Build a FAM wrapper for this vfio_irq_set.
+        let mut irq_set_wrapper = IrqSet::new(event_fds.len() * mem::size_of::<u32>());
+        let mut irq_set_fam = irq_set_wrapper.as_mut_fam_struct();
+
+        let fds_fam = irq_set_fam.as_mut_slice();
+        for (index, event_fd) in event_fds.iter().enumerate() {
+            let fds_offset = index * mem::size_of::<u32>();
+            let fd = &mut fds_fam[fds_offset..fds_offset + mem::size_of::<u32>()];
+            LittleEndian::write_u32(fd, *event_fd);
+        }
+
+        irq_set_fam.argsz = mem::size_of::<vfio_irq_set>() as u32
+            + (event_fds.len() * mem::size_of::<u32>()) as u32;
+        irq_set_fam.flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
+        irq_set_fam.index = 1;
+        irq_set_fam.start = 0;
+        irq_set_fam.count = event_fds.len() as u32;
+
+        // Build the same vfio_irq_set structure with the vec_with_array routines
+        let mut irq_set_vec = vec_with_array_field::<vfio_irq_set, u32>(event_fds.len());
+        irq_set_vec[0].argsz = mem::size_of::<vfio_irq_set>() as u32
+            + (event_fds.len() * mem::size_of::<u32>()) as u32;
+        irq_set_vec[0].flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
+        irq_set_vec[0].index = 1;
+        irq_set_vec[0].start = 0;
+        irq_set_vec[0].count = event_fds.len() as u32;
+
+        let fds_vec = unsafe {
+            irq_set_vec[0]
+                .data
+                .as_mut_slice(event_fds.len() * mem::size_of::<u32>())
+        };
+        for (index, event_fd) in event_fds.iter().enumerate() {
+            let fds_offset = index * mem::size_of::<u32>();
+            let fd = &mut fds_vec[fds_offset..fds_offset + mem::size_of::<u32>()];
+            LittleEndian::write_u32(fd, *event_fd);
+        }
+
+        // Both sets should be identical.
+        assert_eq!(
+            irq_set_vec
+                .iter()
+                .zip(irq_set_wrapper.into_raw().iter())
+                .filter(|&(a, b)| a == b)
+                .count(),
+            irq_set_vec.len()
+        );
+    }
+}