From bc9706e3c6d94776140a8c5581c99e5ef5d24430 Mon Sep 17 00:00:00 2001
From: Mark McCaskey <mark@wasmer.io>
Date: Thu, 22 Apr 2021 08:32:08 -0700
Subject: [PATCH] Add flag to deny multiple WASI versions

---
 CHANGELOG.md                     |  1 +
 lib/cli/src/commands/run.rs      | 20 ++++++++++++++++++--
 lib/cli/src/commands/run/wasi.rs |  3 +++
 lib/wasi/src/lib.rs              |  9 +++------
 lib/wasi/src/utils.rs            | 11 +++++++++++
 5 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09ba0f76593..ba22bdaa13e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ Looking for changes that affect our C API? See the [C API Changelog](lib/c-api/C
 - [#2135](https://github.com/wasmerio/wasmer/pull/2135) [Documentation](./PACKAGING.md) for linux distribution maintainers
 
 ### Changed
+- [#2251](https://github.com/wasmerio/wasmer/pull/2251) Wasmer CLI will now execute WASI modules with multiple WASI namespaces in them by default. Use `--allow-multiple-wasi-versions` to suppress the warning and use `--deny-multiple-wasi-versions` to make it an error.
 - [#2201](https://github.com/wasmerio/wasmer/pull/2201) Implement `loupe::MemoryUsage` for `wasmer::Instance`.
 - [#2200](https://github.com/wasmerio/wasmer/pull/2200) Implement `loupe::MemoryUsage` for `wasmer::Module`.
 - [#2199](https://github.com/wasmerio/wasmer/pull/2199) Implement `loupe::MemoryUsage` for `wasmer::Store`.
diff --git a/lib/cli/src/commands/run.rs b/lib/cli/src/commands/run.rs
index 2dfac57e5c7..3e0904d44e2 100644
--- a/lib/cli/src/commands/run.rs
+++ b/lib/cli/src/commands/run.rs
@@ -152,10 +152,26 @@ impl Run {
         // If WASI is enabled, try to execute it with it
         #[cfg(feature = "wasi")]
         {
+            use std::collections::BTreeSet;
+            use wasmer_wasi::WasiVersion;
+
             let wasi_versions = Wasi::get_versions(&module);
             if let Some(wasi_versions) = wasi_versions {
-                if wasi_versions.len() >= 2 && !self.wasi.allow_multiple_wasi_versions {
-                    warning!("Found more than 1 WASI version in this module. If this is intentional, pass `--allow-multiple-wasi-versions` to suppress this warning.");
+                if wasi_versions.len() >= 2 {
+                    let get_version_list = |versions: &BTreeSet<WasiVersion>| -> String {
+                        versions
+                            .iter()
+                            .map(|v| format!("`{}`", v.get_namespace_str()))
+                            .collect::<Vec<String>>()
+                            .join(", ")
+                    };
+                    if self.wasi.deny_multiple_wasi_versions {
+                        let version_list = get_version_list(&wasi_versions);
+                        bail!("Found more than 1 WASI version in this module ({}) and `--deny-multiple-wasi-versions` is enabled.", version_list);
+                    } else if !self.wasi.allow_multiple_wasi_versions {
+                        let version_list = get_version_list(&wasi_versions);
+                        warning!("Found more than 1 WASI version in this module ({}). If this is intentional, pass `--allow-multiple-wasi-versions` to suppress this warning.", version_list);
+                    }
                 }
 
                 let program_name = self
diff --git a/lib/cli/src/commands/run/wasi.rs b/lib/cli/src/commands/run/wasi.rs
index c64fdac9f1c..9d9662a978c 100644
--- a/lib/cli/src/commands/run/wasi.rs
+++ b/lib/cli/src/commands/run/wasi.rs
@@ -29,6 +29,9 @@ pub struct Wasi {
 
     #[clap(long = "allow-multiple-wasi-versions")]
     pub allow_multiple_wasi_versions: bool,
+
+    #[clap(long = "deny-multiple-wasi-versions")]
+    pub deny_multiple_wasi_versions: bool,
 }
 
 #[allow(dead_code)]
diff --git a/lib/wasi/src/lib.rs b/lib/wasi/src/lib.rs
index c93fc6526c1..ea7ca43cd84 100644
--- a/lib/wasi/src/lib.rs
+++ b/lib/wasi/src/lib.rs
@@ -89,7 +89,7 @@ impl WasiEnv {
         let wasi_versions =
             get_wasi_versions(module, false).ok_or(WasiError::UnknownWasiVersion)?;
         let mut version_iter = wasi_versions.iter();
-        let mut resolver: Box<dyn NamedResolver>  = {
+        let mut resolver: Box<dyn NamedResolver> = {
             let version = version_iter.next().ok_or(WasiError::UnknownWasiVersion)?;
             Box::new(generate_import_object_from_env(
                 module.store(),
@@ -98,11 +98,8 @@ impl WasiEnv {
             ))
         };
         for version in version_iter {
-            let new_import_object = generate_import_object_from_env(
-                module.store(),
-                self.clone(),
-                *version,
-            );
+            let new_import_object =
+                generate_import_object_from_env(module.store(), self.clone(), *version);
             resolver = Box::new(new_import_object.chain_front(resolver));
         }
         Ok(resolver)
diff --git a/lib/wasi/src/utils.rs b/lib/wasi/src/utils.rs
index 5eee8b5ccf1..153bf1d55e5 100644
--- a/lib/wasi/src/utils.rs
+++ b/lib/wasi/src/utils.rs
@@ -31,6 +31,17 @@ pub enum WasiVersion {
     Latest,
 }
 
+impl WasiVersion {
+    /// Get the version as its namespace str as it appears in Wasm modules.
+    pub const fn get_namespace_str(&self) -> &'static str {
+        match *self {
+            WasiVersion::Snapshot0 => SNAPSHOT0_NAMESPACE,
+            WasiVersion::Snapshot1 => SNAPSHOT1_NAMESPACE,
+            WasiVersion::Latest => SNAPSHOT1_NAMESPACE,
+        }
+    }
+}
+
 impl PartialEq<WasiVersion> for WasiVersion {
     fn eq(&self, other: &Self) -> bool {
         match (*self, *other) {