From 36a78a23b6159064d4fdf7038f5149fd533f8252 Mon Sep 17 00:00:00 2001
From: Johan Andersson <repi@repi.se>
Date: Wed, 8 May 2019 15:36:24 +0200
Subject: [PATCH] Fix Windows crash on caching compiled artifact.

Memory clone function wasn't able to write to new reserved memory object.

Changed so allocating Memory objects with protection flag allocates commited memory.
---
 lib/runtime-core/src/sys/windows/memory.rs | 30 +++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/runtime-core/src/sys/windows/memory.rs b/lib/runtime-core/src/sys/windows/memory.rs
index d47388170..888aeff4d 100644
--- a/lib/runtime-core/src/sys/windows/memory.rs
+++ b/lib/runtime-core/src/sys/windows/memory.rs
@@ -33,7 +33,13 @@ impl Memory {
 
         let protect = protection.to_protect_const();
 
-        let ptr = unsafe { VirtualAlloc(ptr::null_mut(), size, MEM_RESERVE, protect) };
+        let flags = if protection == Protect::None {
+            MEM_RESERVE
+        } else {
+            MEM_RESERVE | MEM_COMMIT
+        };
+
+        let ptr = unsafe { VirtualAlloc(ptr::null_mut(), size, flags, protect) };
 
         if ptr.is_null() {
             Err("unable to allocate memory".to_string())
@@ -229,3 +235,25 @@ fn round_up_to_page_size(size: usize, page_size: usize) -> usize {
 fn round_down_to_page_size(size: usize, page_size: usize) -> usize {
     size & !(page_size - 1)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn clone() {
+        // these should work
+        let _ = Memory::with_size_protect(200_000, Protect::Read)
+            .unwrap()
+            .clone();
+        let _ = Memory::with_size_protect(200_000, Protect::ReadWrite)
+            .unwrap()
+            .clone();
+        let _ = Memory::with_size_protect(200_000, Protect::ReadExec)
+            .unwrap()
+            .clone();
+
+        // this would cause segmentation fault as uncommited memory with no access
+        //let _ = Memory::with_size_protect(200_000, Protect::None).unwrap().clone();
+    }
+}