From 12eea421877279c5b4728bb0b03d2e3ab248fc7c Mon Sep 17 00:00:00 2001
From: ptitSeb <sebastien.chev@gmail.com>
Date: Fri, 19 Aug 2022 18:13:39 +0200
Subject: [PATCH] Added some test for LinearMemory trait

---
 lib/vm/src/memory.rs | 101 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 100 insertions(+), 1 deletion(-)

diff --git a/lib/vm/src/memory.rs b/lib/vm/src/memory.rs
index a82c48295..a127b701d 100644
--- a/lib/vm/src/memory.rs
+++ b/lib/vm/src/memory.rs
@@ -376,7 +376,6 @@ impl VMMemory {
     /// Creates VMMemory from a custom implementation - the following into implementations
     /// are natively supported
     /// - VMOwnedMemory -> VMMemory
-    /// - VMSharedMemory -> VMMemory
     /// - Box<dyn LinearMemory + 'static> -> VMMemory
     pub fn from_custom<IntoVMMemory>(memory: IntoVMMemory) -> VMMemory
     where
@@ -463,3 +462,103 @@ mod test_vmmemory_definition {
         );
     }
 }
+
+#[cfg(test)]
+mod test_linearmemory {
+    use super::LinearMemory;
+    use super::VMMemoryDefinition;
+    use crate::store::MaybeInstanceOwned;
+    use crate::VMMemory;
+    use std::cell::UnsafeCell;
+    use std::ptr::read_unaligned;
+    use std::ptr::write_unaligned;
+    use std::ptr::NonNull;
+    use wasmer_types::{MemoryError, MemoryStyle, MemoryType, Pages, WASM_PAGE_SIZE};
+
+    #[derive(Debug)]
+    struct VMTinyMemory {
+        mem: [u8; WASM_PAGE_SIZE],
+    }
+
+    unsafe impl Send for VMTinyMemory {}
+    unsafe impl Sync for VMTinyMemory {}
+
+    impl VMTinyMemory {
+        pub fn new() -> Result<Self, MemoryError> {
+            Ok(VMTinyMemory {
+                mem: [0; WASM_PAGE_SIZE],
+            })
+        }
+    }
+
+    impl LinearMemory for VMTinyMemory {
+        fn ty(&self) -> MemoryType {
+            MemoryType {
+                minimum: Pages::from(1u32),
+                maximum: Some(Pages::from(1u32)),
+                shared: false,
+            }
+        }
+        fn size(&self) -> Pages {
+            Pages::from(1u32)
+        }
+        fn style(&self) -> MemoryStyle {
+            MemoryStyle::Static {
+                bound: Pages::from(1u32),
+                offset_guard_size: 0,
+            }
+        }
+        fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError> {
+            Err(MemoryError::CouldNotGrow {
+                current: Pages::from(1u32),
+                attempted_delta: delta,
+            })
+        }
+        fn vmmemory(&self) -> NonNull<VMMemoryDefinition> {
+            MaybeInstanceOwned::Host(Box::new(UnsafeCell::new(VMMemoryDefinition {
+                base: self.mem.as_ptr() as _,
+                current_length: WASM_PAGE_SIZE,
+            })))
+            .as_ptr()
+        }
+        fn try_clone(&self) -> Option<Box<dyn LinearMemory + 'static>> {
+            None
+        }
+    }
+
+    impl From<VMTinyMemory> for VMMemory {
+        fn from(mem: VMTinyMemory) -> Self {
+            Self(Box::new(mem))
+        }
+    }
+
+    #[test]
+    fn check_linearmemory() {
+        let mut memory = VMTinyMemory::new().unwrap();
+        assert!(memory.grow(Pages::from(2u32)).is_err());
+        assert_eq!(memory.size(), Pages::from(1u32));
+
+        let vmemdef = memory.vmmemory();
+        let raw_ptr: *mut u8 = unsafe { vmemdef.as_ref().base };
+        unsafe {
+            write_unaligned(raw_ptr, 1);
+            assert_eq!(read_unaligned(raw_ptr), 1);
+            write_unaligned(raw_ptr.add(100), 200);
+            assert_eq!(read_unaligned(raw_ptr.add(100)), 200);
+        }
+        // re-borrow
+        let vmemdef = memory.vmmemory();
+        let raw_ptr: *mut u8 = unsafe { vmemdef.as_ref().base };
+        unsafe {
+            assert_eq!(read_unaligned(raw_ptr), 1);
+        }
+        // borrow as VMMemory
+        let vmmemory: VMMemory = VMMemory::from_custom(memory);
+        assert_eq!(vmmemory.size(), Pages::from(1u32));
+        let raw_ptr = unsafe { vmmemory.vmmemory().as_ref().base };
+        unsafe {
+            assert_eq!(read_unaligned(raw_ptr), 1);
+            assert_eq!(read_unaligned(raw_ptr.add(100)), 200);
+        }
+    }
+}