From 2b2cb6fefd35355b6ce4db3d46ca04949e4fad4e Mon Sep 17 00:00:00 2001
From: grovesNL <josh@joshgroves.com>
Date: Mon, 9 Apr 2018 23:23:58 -0600
Subject: [PATCH] Return VK_INCOMPLETE for partial physical device enumeration

---
 libportability-gfx/src/impls.rs | 16 ++++++++++++----
 libportability-gfx/src/lib.rs   |  2 +-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/libportability-gfx/src/impls.rs b/libportability-gfx/src/impls.rs
index 1ef1cd6..1f23f17 100644
--- a/libportability-gfx/src/impls.rs
+++ b/libportability-gfx/src/impls.rs
@@ -69,18 +69,26 @@ pub extern "C" fn gfxEnumeratePhysicalDevices(
     pPhysicalDeviceCount: *mut u32,
     pPhysicalDevices: *mut VkPhysicalDevice,
 ) -> VkResult {
+    let num_adapters = instance.adapters.len();
+
     // If NULL, number of devices is returned.
     if pPhysicalDevices.is_null() {
-        unsafe { *pPhysicalDeviceCount = instance.adapters.len() as _ };
+        unsafe { *pPhysicalDeviceCount = num_adapters as _ };
         return VkResult::VK_SUCCESS;
     }
 
     let output = unsafe { slice::from_raw_parts_mut(pPhysicalDevices, *pPhysicalDeviceCount as _) };
-    let count = cmp::min(instance.adapters.len(), output.len());
+    let num_output = output.len();
+    let (code, count) = if num_output < num_adapters {
+        (VkResult::VK_INCOMPLETE, num_output)
+    } else {
+        (VkResult::VK_SUCCESS, num_adapters)
+    };
+    
     output.copy_from_slice(&instance.adapters[..count]);
-
     unsafe { *pPhysicalDeviceCount = count as _ };
-    VkResult::VK_SUCCESS
+
+    code
 }
 
 #[inline]
diff --git a/libportability-gfx/src/lib.rs b/libportability-gfx/src/lib.rs
index 5acbad7..669a1b6 100644
--- a/libportability-gfx/src/lib.rs
+++ b/libportability-gfx/src/lib.rs
@@ -25,7 +25,7 @@ mod impls;
 use back::Backend as B;
 use handle::{DispatchHandle, Handle};
 
-use std::{cmp, slice};
+use std::{slice};
 use std::collections::HashMap;
 
 pub use impls::*;