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.

Author: repi

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();
+    }
+}