From deec3ddad5f0f94cbbc6f9f2513c389128ebe381 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Mon, 14 Dec 2020 01:32:32 +0100
Subject: [PATCH 1/6] Avoid dependency on Wasmer's Bytes to Pages conversion

---
 packages/vm/src/wasm_backend/store.rs | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/packages/vm/src/wasm_backend/store.rs b/packages/vm/src/wasm_backend/store.rs
index 9db5e12094..a69b4e647e 100644
--- a/packages/vm/src/wasm_backend/store.rs
+++ b/packages/vm/src/wasm_backend/store.rs
@@ -1,17 +1,24 @@
+use std::convert::TryInto;
 #[cfg(feature = "cranelift")]
 use wasmer::Cranelift;
 #[cfg(not(feature = "cranelift"))]
 use wasmer::Singlepass;
 use wasmer::{
-    Bytes, Engine, Pages, Store, Target,
+    Engine, Pages, Store, Target,
     Tunables as ReferenceTunables, /* See https://github.com/wasmerio/wasmer/issues/1872 */
-    JIT,
+    JIT, WASM_PAGE_SIZE,
 };
 
 use crate::size::Size;
 
 use super::limiting_tunables::LimitingTunables;
 
+/// WebAssembly linear memory objects have sizes measured in pages. Each page
+/// is 65536 (2^16) bytes. In WebAssembly version 1, a linear memory can have at
+/// most 65536 pages, for a total of 2^32 bytes (4 gibibytes).
+/// https://github.com/WebAssembly/memory64/blob/master/proposals/memory64/Overview.md
+const MAX_WASM_MEMORY: usize = 4 * 1024 * 1024 * 1024;
+
 /// Created a store with the default compiler and the given memory limit (in bytes)
 /// If memory_limit is None, no limit is applied.
 pub fn make_store(memory_limit: Option<Size>) -> Store {
@@ -42,9 +49,13 @@ pub fn make_store_headless(memory_limit: Option<Size>) -> Store {
 fn make_store_with_engine(engine: &dyn Engine, memory_limit: Option<Size>) -> Store {
     match memory_limit {
         Some(limit) => {
-            let pages = Pages::from(Bytes(limit.0));
+            let capped = std::cmp::max(limit.0, MAX_WASM_MEMORY);
+            // round down to ensure the limit is less than or equal to the config
+            let pages: u32 = (capped / WASM_PAGE_SIZE)
+                .try_into()
+                .expect("Value must be <= 4 GiB/64KiB, i.e. fit in uint32. This is a bug.");
             let base = ReferenceTunables::for_target(&Target::default());
-            let tunables = LimitingTunables::new(base, pages);
+            let tunables = LimitingTunables::new(base, Pages(pages));
             Store::new_with_tunables(engine, tunables)
         }
         None => Store::new(engine),

From d3e09f292c56f5161230191d5227a291bc16a549 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Mon, 14 Dec 2020 00:12:42 +0100
Subject: [PATCH 2/6] Update contracts build instructions

---
 README.md | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 1bf22e9c3b..6c675ba2a3 100644
--- a/README.md
+++ b/README.md
@@ -319,13 +319,19 @@ cargo fmt \
 
 **Contracts**
 
-Step 1 (fast checks)
+Step 1 (fast checks, rebuilds lock files)
+
+```sh
+for contract_dir in contracts/*/; do (cd "$contract_dir" && cargo check --tests) || break; done
+```
+
+Step 2 (medium fast checks)
 
 ```sh
 for contract_dir in contracts/*/; do (cd "$contract_dir" && cargo fmt && cargo check --tests && cargo wasm-debug && cargo unit-test && cargo clippy -- -D warnings && cargo schema) || break; done
 ```
 
-Step 2 (slower checks)
+Step 3 (slower checks)
 
 ```sh
 for contract_dir in contracts/*/; do (cd "$contract_dir" && cargo wasm && cargo integration-test) || break; done

From a2121387f8822d5b81171f32185cb43602c22bd8 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Mon, 14 Dec 2020 01:41:38 +0100
Subject: [PATCH 3/6] Update Wasmer to 3709c9d8264 (latest master)

---
 Cargo.lock                    | 23 ++++++++++++-----------
 contracts/burner/Cargo.lock   | 23 ++++++++++++-----------
 contracts/hackatom/Cargo.lock | 23 ++++++++++++-----------
 contracts/queue/Cargo.lock    | 23 ++++++++++++-----------
 contracts/reflect/Cargo.lock  | 23 ++++++++++++-----------
 contracts/staking/Cargo.lock  | 23 ++++++++++++-----------
 packages/vm/Cargo.toml        |  4 ++--
 7 files changed, 74 insertions(+), 68 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index ac3dc800e2..02d52c9e3d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1357,7 +1357,7 @@ checksum = "7e7811dd7f9398f14cc76efd356f98f03aa30419dea46aa810d71e819fc97158"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1379,7 +1379,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1396,7 +1396,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1414,7 +1414,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1432,7 +1432,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1443,7 +1443,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1462,7 +1462,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1479,7 +1479,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1499,7 +1499,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object 0.22.0",
  "thiserror",
@@ -1510,16 +1510,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/contracts/burner/Cargo.lock b/contracts/burner/Cargo.lock
index bda9e1ecb4..cdd1f6d49c 100644
--- a/contracts/burner/Cargo.lock
+++ b/contracts/burner/Cargo.lock
@@ -1032,7 +1032,7 @@ checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1054,7 +1054,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1071,7 +1071,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1089,7 +1089,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1107,7 +1107,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1118,7 +1118,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1137,7 +1137,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1154,7 +1154,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1174,7 +1174,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object",
  "thiserror",
@@ -1185,16 +1185,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/contracts/hackatom/Cargo.lock b/contracts/hackatom/Cargo.lock
index fe166554c7..6632697eb3 100644
--- a/contracts/hackatom/Cargo.lock
+++ b/contracts/hackatom/Cargo.lock
@@ -1043,7 +1043,7 @@ checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1065,7 +1065,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1082,7 +1082,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1100,7 +1100,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1118,7 +1118,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1129,7 +1129,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1148,7 +1148,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1165,7 +1165,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1185,7 +1185,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object",
  "thiserror",
@@ -1196,16 +1196,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/contracts/queue/Cargo.lock b/contracts/queue/Cargo.lock
index 75af29e165..93ea23d985 100644
--- a/contracts/queue/Cargo.lock
+++ b/contracts/queue/Cargo.lock
@@ -1032,7 +1032,7 @@ checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1054,7 +1054,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1071,7 +1071,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1089,7 +1089,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1107,7 +1107,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1118,7 +1118,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1137,7 +1137,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1154,7 +1154,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1174,7 +1174,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object",
  "thiserror",
@@ -1185,16 +1185,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/contracts/reflect/Cargo.lock b/contracts/reflect/Cargo.lock
index 451cc67c0a..56ba5b2f06 100644
--- a/contracts/reflect/Cargo.lock
+++ b/contracts/reflect/Cargo.lock
@@ -1042,7 +1042,7 @@ checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1064,7 +1064,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1081,7 +1081,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1099,7 +1099,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1117,7 +1117,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1128,7 +1128,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1147,7 +1147,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1164,7 +1164,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1184,7 +1184,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object",
  "thiserror",
@@ -1195,16 +1195,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/contracts/staking/Cargo.lock b/contracts/staking/Cargo.lock
index 3a8c7ca2ea..191e768e02 100644
--- a/contracts/staking/Cargo.lock
+++ b/contracts/staking/Cargo.lock
@@ -1069,7 +1069,7 @@ checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 [[package]]
 name = "wasmer"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cfg-if 0.1.10",
  "indexmap",
@@ -1091,7 +1091,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "enumset",
  "raw-cpuid",
@@ -1108,7 +1108,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-cranelift"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-codegen",
  "cranelift-frontend",
@@ -1126,7 +1126,7 @@ dependencies = [
 [[package]]
 name = "wasmer-compiler-singlepass"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "byteorder",
  "dynasm",
@@ -1144,7 +1144,7 @@ dependencies = [
 [[package]]
 name = "wasmer-derive"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -1155,7 +1155,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "bincode",
@@ -1174,7 +1174,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-jit"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1191,7 +1191,7 @@ dependencies = [
 [[package]]
 name = "wasmer-engine-native"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "bincode",
  "cfg-if 0.1.10",
@@ -1211,7 +1211,7 @@ dependencies = [
 [[package]]
 name = "wasmer-object"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "object",
  "thiserror",
@@ -1222,16 +1222,17 @@ dependencies = [
 [[package]]
 name = "wasmer-types"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "cranelift-entity",
  "serde",
+ "thiserror",
 ]
 
 [[package]]
 name = "wasmer-vm"
 version = "1.0.0-beta1"
-source = "git+https://github.com/wasmerio/wasmer?rev=df3a21160a9a#df3a21160a9a9353db5913b521b66e9724ab8fef"
+source = "git+https://github.com/wasmerio/wasmer?rev=3709c9d8264#3709c9d826447d334ad12005609dbb94270fa8ac"
 dependencies = [
  "backtrace",
  "cc",
diff --git a/packages/vm/Cargo.toml b/packages/vm/Cargo.toml
index 078b1eaee0..ace8ab53a5 100644
--- a/packages/vm/Cargo.toml
+++ b/packages/vm/Cargo.toml
@@ -42,8 +42,8 @@ serde = { version = "1.0.103", default-features = false, features = ["derive", "
 serde_json = "1.0"
 sha2 = "0.9.1"
 thiserror = "1.0"
-wasmer = { git = "https://github.com/wasmerio/wasmer", rev = "df3a21160a9a", default-features = false, features = ["jit", "singlepass"] }
-wasmer-engine = { git = "https://github.com/wasmerio/wasmer", rev = "df3a21160a9a" }
+wasmer = { git = "https://github.com/wasmerio/wasmer", rev = "3709c9d8264", default-features = false, features = ["jit", "singlepass"] }
+wasmer-engine = { git = "https://github.com/wasmerio/wasmer", rev = "3709c9d8264" }
 
 # Wasmer local (used for quick local debugging or patching)
 # wasmer = { path = "../../../wasmer/lib/api", default-features = false, features = ["jit", "singlepass"] }

From b694fb1d598b82a360b46e95ce9bf8ada79832ff Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Mon, 14 Dec 2020 01:56:24 +0100
Subject: [PATCH 4/6] Benchmark branch update-wasmer

---
 .circleci/config.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8003775578..79b5a01cd2 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -26,7 +26,7 @@ workflows:
                 - master
                 # 👇 Add your branch here if benchmarking matters to your work
                 - benchmarking
-                - upgrade-to-wasmer-reborn
+                - update-wasmer
   deploy:
     jobs:
       - build_and_upload_devcontracts:

From 1f086082f9f36f0257ad73666fe90934e50d9e2e Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Mon, 14 Dec 2020 01:57:30 +0100
Subject: [PATCH 5/6] Add branch module-helpers to benchmarking

---
 .circleci/config.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 79b5a01cd2..f4232334f5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -27,6 +27,7 @@ workflows:
                 # 👇 Add your branch here if benchmarking matters to your work
                 - benchmarking
                 - update-wasmer
+                - module-helpers
   deploy:
     jobs:
       - build_and_upload_devcontracts:

From 5e3d21225ae1b273ec3ff39cd08dc2d4ada7b62a Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Thu, 10 Dec 2020 23:31:48 +0100
Subject: [PATCH 6/6] Use serialize_to_file/deserialize_from_file from Wasmer

---
 Cargo.lock                                   |  1 -
 contracts/burner/Cargo.lock                  |  1 -
 contracts/hackatom/Cargo.lock                |  1 -
 contracts/queue/Cargo.lock                   |  1 -
 contracts/reflect/Cargo.lock                 |  1 -
 contracts/staking/Cargo.lock                 |  1 -
 packages/vm/Cargo.toml                       |  1 -
 packages/vm/src/modules/file_system_cache.rs | 57 ++++++++------------
 8 files changed, 22 insertions(+), 42 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 02d52c9e3d..06dc7425b5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -201,7 +201,6 @@ dependencies = [
  "cosmwasm-std",
  "criterion",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/contracts/burner/Cargo.lock b/contracts/burner/Cargo.lock
index cdd1f6d49c..27e75283bf 100644
--- a/contracts/burner/Cargo.lock
+++ b/contracts/burner/Cargo.lock
@@ -139,7 +139,6 @@ dependencies = [
  "clru",
  "cosmwasm-std",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/contracts/hackatom/Cargo.lock b/contracts/hackatom/Cargo.lock
index 6632697eb3..1326a0defa 100644
--- a/contracts/hackatom/Cargo.lock
+++ b/contracts/hackatom/Cargo.lock
@@ -136,7 +136,6 @@ dependencies = [
  "clru",
  "cosmwasm-std",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/contracts/queue/Cargo.lock b/contracts/queue/Cargo.lock
index 93ea23d985..52216c4690 100644
--- a/contracts/queue/Cargo.lock
+++ b/contracts/queue/Cargo.lock
@@ -128,7 +128,6 @@ dependencies = [
  "clru",
  "cosmwasm-std",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/contracts/reflect/Cargo.lock b/contracts/reflect/Cargo.lock
index 56ba5b2f06..ac69ce1c1a 100644
--- a/contracts/reflect/Cargo.lock
+++ b/contracts/reflect/Cargo.lock
@@ -136,7 +136,6 @@ dependencies = [
  "clru",
  "cosmwasm-std",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/contracts/staking/Cargo.lock b/contracts/staking/Cargo.lock
index 191e768e02..a622dddf8d 100644
--- a/contracts/staking/Cargo.lock
+++ b/contracts/staking/Cargo.lock
@@ -136,7 +136,6 @@ dependencies = [
  "clru",
  "cosmwasm-std",
  "hex",
- "memmap",
  "parity-wasm",
  "schemars",
  "serde",
diff --git a/packages/vm/Cargo.toml b/packages/vm/Cargo.toml
index ace8ab53a5..0beb0f73e0 100644
--- a/packages/vm/Cargo.toml
+++ b/packages/vm/Cargo.toml
@@ -35,7 +35,6 @@ clru = "0.2.0"
 # Uses the path when built locally; uses the given version from crates.io when published
 cosmwasm-std = { path = "../std", version = "0.12.1" }
 hex = "0.4"
-memmap = "0.7"
 parity-wasm = "0.42"
 schemars = "0.7"
 serde = { version = "1.0.103", default-features = false, features = ["derive", "alloc"] }
diff --git a/packages/vm/src/modules/file_system_cache.rs b/packages/vm/src/modules/file_system_cache.rs
index 3a33808df8..e4185bd91b 100644
--- a/packages/vm/src/modules/file_system_cache.rs
+++ b/packages/vm/src/modules/file_system_cache.rs
@@ -1,14 +1,8 @@
-// copied from https://github.com/wasmerio/wasmer/blob/0.8.0/lib/runtime/src/cache.rs
-// with some minor modifications
+use std::fs;
+use std::io;
+use std::path::PathBuf;
 
-use memmap::Mmap;
-use std::{
-    fs::{self, File},
-    io::{self, ErrorKind, Write},
-    path::PathBuf,
-};
-
-use wasmer::Module;
+use wasmer::{DeserializeError, Module};
 
 use crate::checksum::Checksum;
 use crate::errors::{VmError, VmResult};
@@ -76,40 +70,33 @@ impl FileSystemCache {
             .join(MODULE_SERIALIZATION_VERSION)
             .join(filename);
 
-        let file = match File::open(file_path) {
-            Ok(file) => file,
-            Err(err) => match err.kind() {
-                ErrorKind::NotFound => return Ok(None),
-                _ => {
-                    return Err(VmError::cache_err(format!(
-                        "Error opening module file: {}",
-                        err
-                    )))
-                }
-            },
-        };
-
-        let mmap = unsafe { Mmap::map(&file) }
-            .map_err(|e| VmError::cache_err(format!("Mmap error: {}", e)))?;
-
         let store = make_store_headless(Some(memory_limit));
-        let module = unsafe { Module::deserialize(&store, &mmap[..]) }?;
-        Ok(Some(module))
+        let result = unsafe { Module::deserialize_from_file(&store, &file_path) };
+        match result {
+            Ok(module) => Ok(Some(module)),
+            Err(DeserializeError::Io(err)) => match err.kind() {
+                io::ErrorKind::NotFound => Ok(None),
+                _ => Err(VmError::cache_err(format!(
+                    "Error opening module file: {}",
+                    err
+                ))),
+            },
+            Err(err) => Err(VmError::cache_err(format!(
+                "Error deserializing module: {}",
+                err
+            ))),
+        }
     }
 
     pub fn store(&mut self, checksum: &Checksum, module: &Module) -> VmResult<()> {
         let modules_dir = self.path.clone().join(MODULE_SERIALIZATION_VERSION);
         fs::create_dir_all(&modules_dir)
             .map_err(|e| VmError::cache_err(format!("Error creating direcory: {}", e)))?;
-
-        let buffer = module.serialize()?;
-
         let filename = checksum.to_hex();
-        let mut file = File::create(modules_dir.join(filename))
-            .map_err(|e| VmError::cache_err(format!("Error creating module file: {}", e)))?;
-        file.write_all(&buffer)
+        let path = modules_dir.join(filename);
+        module
+            .serialize_to_file(path)
             .map_err(|e| VmError::cache_err(format!("Error writing module to disk: {}", e)))?;
-
         Ok(())
     }
 }