extensions/khr: Add ExternalSemaphoreFd safe wrapper (#395)

* extensions/khr: Add ExternalSemaphoreFd safe wrapper

Implement the two small import and export and functions, part of the
VK_KHR_external_semaphore_fd extension.

* device: Pass ImageSubresource by immutable reference

It is only used as pointer by the native function, and should not (need
to) be moved.

ash/src/device.rs

@@ -1902,15 +1902,11 @@ pub trait DeviceV1_0 {
     unsafe fn get_image_subresource_layout(
         &self,
         image: vk::Image,
-        subresource: vk::ImageSubresource,
+        subresource: &vk::ImageSubresource,
     ) -> vk::SubresourceLayout {
         let mut layout = mem::zeroed();
-        self.fp_v1_0().get_image_subresource_layout(
-            self.handle(),
-            image,
-            &subresource,
-            &mut layout,
-        );
+        self.fp_v1_0()
+            .get_image_subresource_layout(self.handle(), image, subresource, &mut layout);
         layout
     }
 

ash/src/extensions/khr/external_semaphore_fd.rs

@@ -0,0 +1,54 @@
+use crate::prelude::*;
+use crate::version::{DeviceV1_0, InstanceV1_0};
+use crate::vk;
+use std::ffi::CStr;
+use std::mem;
+
+#[derive(Clone)]
+pub struct ExternalSemaphoreFd {
+    handle: vk::Device,
+    external_semaphore_fd_fn: vk::KhrExternalSemaphoreFdFn,
+}
+
+impl ExternalSemaphoreFd {
+    pub fn new<I: InstanceV1_0, D: DeviceV1_0>(instance: &I, device: &D) -> Self {
+        let external_semaphore_fd_fn = vk::KhrExternalSemaphoreFdFn::load(|name| unsafe {
+            mem::transmute(instance.get_device_proc_addr(device.handle(), name.as_ptr()))
+        });
+        Self {
+            handle: device.handle(),
+            external_semaphore_fd_fn,
+        }
+    }
+
+    pub fn name() -> &'static CStr {
+        vk::KhrExternalSemaphoreFdFn::name()
+    }
+
+    #[doc = "<https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/vkImportSemaphoreFdKHR.html>"]
+    pub unsafe fn import_semaphore_fd(
+        &self,
+        import_info: &vk::ImportSemaphoreFdInfoKHR,
+    ) -> VkResult<()> {
+        self.external_semaphore_fd_fn
+            .import_semaphore_fd_khr(self.handle, import_info)
+            .result()
+    }
+
+    #[doc = "<https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/vkGetSemaphoreFdKHR.html>"]
+    pub unsafe fn get_semaphore_fd(&self, get_info: &vk::SemaphoreGetFdInfoKHR) -> VkResult<i32> {
+        let mut fd = -1;
+
+        self.external_semaphore_fd_fn
+            .get_semaphore_fd_khr(self.handle, get_info, &mut fd)
+            .result_with_success(fd)
+    }
+
+    pub fn fp(&self) -> &vk::KhrExternalSemaphoreFdFn {
+        &self.external_semaphore_fd_fn
+    }
+
+    pub fn device(&self) -> vk::Device {
+        self.handle
+    }
+}

ash/src/extensions/khr/mod.rs

@@ -6,6 +6,7 @@ pub use self::display::Display;
 pub use self::display_swapchain::DisplaySwapchain;
 pub use self::draw_indirect_count::DrawIndirectCount;
 pub use self::external_memory_fd::ExternalMemoryFd;
+pub use self::external_semaphore_fd::ExternalSemaphoreFd;
 pub use self::get_memory_requirements2::GetMemoryRequirements2;
 pub use self::maintenance1::Maintenance1;
 pub use self::maintenance3::Maintenance3;
@@ -28,6 +29,7 @@ mod display;
 mod display_swapchain;
 mod draw_indirect_count;
 mod external_memory_fd;
+mod external_semaphore_fd;
 mod get_memory_requirements2;
 mod maintenance1;
 mod maintenance3;