From 7f3680c27a3f7e4c41e85ee5e4d289bfd921ea87 Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan.enderlin@hoa-project.net>
Date: Mon, 2 Dec 2019 15:36:45 +0100
Subject: [PATCH 1/2] fix(wasi) `get_wasi_version` is broken with multiple
 namespaces.

If a module has multiple import namespaces, `get_wasi_version` is
broken because it assumes a module must only have a single namespace.

This patch fixes it by a slower `get_wasi_version` function, but a
correct one. As soon as the `wasi_unstable` or
`wasi_snapshot_preview1` namespace is met, `get_wasi_version` maps it
to the respective `WasiVersion` variant. It assumes however that a
module must hold a unique WASI version.
---
 lib/wasi/src/utils.rs | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/lib/wasi/src/utils.rs b/lib/wasi/src/utils.rs
index b19a404884b..e7c24aff48f 100644
--- a/lib/wasi/src/utils.rs
+++ b/lib/wasi/src/utils.rs
@@ -18,24 +18,19 @@ pub enum WasiVersion {
 
 /// Detect the version of WASI being used from the namespace
 pub fn get_wasi_version(module: &Module) -> Option<WasiVersion> {
-    let mut import_iter = module
+    let namespace_table = &module.info().namespace_table;
+
+    module
         .info()
         .imported_functions
         .iter()
-        .map(|(_, import_name)| import_name.namespace_index);
+        .find_map(|(_, import_name)| {
+            let namespace_index = import_name.namespace_index;
 
-    // returns None if empty
-    let first = import_iter.next()?;
-    if import_iter.all(|idx| idx == first) {
-        // once we know that all the namespaces are the same, we can use it to
-        // detect which version of WASI this is
-        match module.info().namespace_table.get(first) {
-            "wasi_unstable" => Some(WasiVersion::Snapshot0),
-            "wasi_snapshot_preview1" => Some(WasiVersion::Snapshot1),
-            _ => None,
-        }
-    } else {
-        // not all funcs have the same namespace, therefore it's not WASI
-        None
-    }
+            match namespace_table.get(namespace_index) {
+                "wasi_unstable" => Some(WasiVersion::Snapshot0),
+                "wasi_snapshot_preview1" => Some(WasiVersion::Snapshot1),
+                _ => None,
+            }
+        })
 }

From 8df0591ee57ef8bacbacbcb13a6c41129129ede3 Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan.enderlin@hoa-project.net>
Date: Mon, 2 Dec 2019 15:41:46 +0100
Subject: [PATCH 2/2] doc(changelog) Add #1028.

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c1de67bf893..79f9da5aa5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## **[Unreleased]**
 
+- [#1028](https://github.com/wasmerio/wasmer/pull/1028) Fix `get_wasi_version` when a module has multiple import namespaces.
 - [#1006](https://github.com/wasmerio/wasmer/pull/1006) Fix minor panic issue when `wasmer::compile_with` called with llvm backend
 - [#1009](https://github.com/wasmerio/wasmer/pull/1009) Enable LLVM verifier for all tests, add new llvm-backend-tests crate.
 - [#1004](https://github.com/wasmerio/wasmer/pull/1004) Add the Auto backend to enable to adapt backend usage depending on wasm file executed.