Merge "Test empty VirtIO block device."
diff --git a/vmbase/example/src/pci.rs b/vmbase/example/src/pci.rs
index 384a9c1..6abe66e 100644
--- a/vmbase/example/src/pci.rs
+++ b/vmbase/example/src/pci.rs
@@ -25,7 +25,7 @@
         pci::{bus::PciRoot, virtio_device_type, PciTransport},
         DeviceType, Transport,
     },
-    BufferDirection, Hal, PhysAddr, PAGE_SIZE,
+    BufferDirection, Error, Hal, PhysAddr, PAGE_SIZE,
 };
 
 /// The standard sector size of a VirtIO block device, in bytes.
@@ -36,6 +36,7 @@
 
 pub fn check_pci(pci_root: &mut PciRoot) {
     let mut checked_virtio_device_count = 0;
+    let mut block_device_count = 0;
     for (device_function, info) in pci_root.enumerate_bus(0) {
         let (status, command) = pci_root.get_status_command(device_function);
         info!("Found {} at {}, status {:?} command {:?}", info, device_function, status, command);
@@ -47,24 +48,31 @@
                 transport.device_type(),
                 transport.read_device_features(),
             );
-            if check_virtio_device(transport, virtio_type) {
-                checked_virtio_device_count += 1;
+            match virtio_type {
+                DeviceType::Block => {
+                    check_virtio_block_device(transport, block_device_count);
+                    block_device_count += 1;
+                    checked_virtio_device_count += 1;
+                }
+                DeviceType::Console => {
+                    check_virtio_console_device(transport);
+                    checked_virtio_device_count += 1;
+                }
+                _ => {}
             }
         }
     }
 
-    assert_eq!(checked_virtio_device_count, 4);
+    assert_eq!(checked_virtio_device_count, 5);
+    assert_eq!(block_device_count, 2);
 }
 
-/// Checks the given VirtIO device, if we know how to.
-///
-/// Returns true if the device was checked, or false if it was ignored.
-fn check_virtio_device(transport: impl Transport, device_type: DeviceType) -> bool {
-    match device_type {
-        DeviceType::Block => {
-            let mut blk =
-                VirtIOBlk::<HalImpl, _>::new(transport).expect("failed to create blk driver");
-            info!("Found {} KiB block device.", blk.capacity() * SECTOR_SIZE_BYTES as u64 / 1024);
+/// Checks the given VirtIO block device.
+fn check_virtio_block_device(transport: impl Transport, index: usize) {
+    let mut blk = VirtIOBlk::<HalImpl, _>::new(transport).expect("failed to create blk driver");
+    info!("Found {} KiB block device.", blk.capacity() * SECTOR_SIZE_BYTES as u64 / 1024);
+    match index {
+        0 => {
             assert_eq!(blk.capacity(), EXPECTED_SECTOR_COUNT as u64);
             let mut data = [0; SECTOR_SIZE_BYTES * EXPECTED_SECTOR_COUNT];
             for i in 0..EXPECTED_SECTOR_COUNT {
@@ -75,22 +83,27 @@
                 assert_eq!(chunk, &(i as u32).to_le_bytes());
             }
             info!("Read expected data from block device.");
-            true
         }
-        DeviceType::Console => {
-            let mut console = VirtIOConsole::<HalImpl, _>::new(transport)
-                .expect("Failed to create VirtIO console driver");
-            info!("Found console device: {:?}", console.info());
-            for &c in b"Hello VirtIO console\n" {
-                console.send(c).expect("Failed to send character to VirtIO console device");
-            }
-            info!("Wrote to VirtIO console.");
-            true
+        1 => {
+            assert_eq!(blk.capacity(), 0);
+            let mut data = [0; SECTOR_SIZE_BYTES];
+            assert_eq!(blk.read_block(0, &mut data), Err(Error::IoError));
         }
-        _ => false,
+        _ => panic!("Unexpected VirtIO block device index {}.", index),
     }
 }
 
+/// Checks the given VirtIO console device.
+fn check_virtio_console_device(transport: impl Transport) {
+    let mut console = VirtIOConsole::<HalImpl, _>::new(transport)
+        .expect("Failed to create VirtIO console driver");
+    info!("Found console device: {:?}", console.info());
+    for &c in b"Hello VirtIO console\n" {
+        console.send(c).expect("Failed to send character to VirtIO console device");
+    }
+    info!("Wrote to VirtIO console.");
+}
+
 /// Gets the memory region in which BARs are allocated.
 pub fn get_bar_region(pci_info: &PciInfo) -> MemoryRegion {
     MemoryRegion::new(pci_info.bar_range.start as usize, pci_info.bar_range.end as usize)
diff --git a/vmbase/example/tests/test.rs b/vmbase/example/tests/test.rs
index 9088f1a..085a620 100644
--- a/vmbase/example/tests/test.rs
+++ b/vmbase/example/tests/test.rs
@@ -35,6 +35,8 @@
 const VMBASE_EXAMPLE_PATH: &str =
     "/data/local/tmp/vmbase_example.integration_test/arm64/vmbase_example.bin";
 const TEST_DISK_IMAGE_PATH: &str = "/data/local/tmp/vmbase_example.integration_test/test_disk.img";
+const EMPTY_DISK_IMAGE_PATH: &str =
+    "/data/local/tmp/vmbase_example.integration_test/empty_disk.img";
 
 /// Runs the vmbase_example VM as an unprotected VM via VirtualizationService.
 #[test]
@@ -76,13 +78,25 @@
     let test_image = ParcelFileDescriptor::new(test_image);
     let disk_image = DiskImage { image: Some(test_image), writable: false, partitions: vec![] };
 
+    // Make file for empty test disk image.
+    let empty_image = File::options()
+        .create(true)
+        .read(true)
+        .write(true)
+        .truncate(true)
+        .open(EMPTY_DISK_IMAGE_PATH)
+        .with_context(|| format!("Failed to open empty disk image {}", EMPTY_DISK_IMAGE_PATH))?;
+    let empty_image = ParcelFileDescriptor::new(empty_image);
+    let empty_disk_image =
+        DiskImage { image: Some(empty_image), writable: false, partitions: vec![] };
+
     let config = VirtualMachineConfig::RawConfig(VirtualMachineRawConfig {
         name: String::from("VmBaseTest"),
         kernel: None,
         initrd: None,
         params: None,
         bootloader: Some(bootloader),
-        disks: vec![disk_image],
+        disks: vec![disk_image, empty_disk_image],
         protectedVm: false,
         memoryMib: 300,
         cpuTopology: CpuTopology::ONE_CPU,