Add env var funcs.

CHANGELOG.md

@@ -10,6 +10,14 @@
 - [Rust](https://github.com/moonrepo/rust-plugin/blob/master/CHANGELOG.md)
 - [Schema](https://github.com/moonrepo/schema-plugin/blob/master/CHANGELOG.md)
 
+## 0.19.1
+
+#### 🚀 Updates
+
+- WASM API
+  - Added `get_env_var` and `set_env_var` host functions.
+  - Added `host_env!` macro.
+
 ## 0.19.0
 
 #### 💥 Breaking

crates/core/src/error.rs

@@ -76,7 +76,7 @@ pub enum ProtoError {
         code(proto::version::undetected),
         help = "Has the tool been installed?"
     )]
-    #[error("Failed to detect an applicable version to run {} with. Try pinning a local or global version, or passing the version as an argument.", .tool.style(Style::Id))]
+    #[error("Failed to detect an applicable version to run {} with. Try pinning a version or passing the version as an argument.", .tool.style(Style::Id))]
     VersionDetectFailed { tool: Id },
 
     #[diagnostic(code(proto::version::unresolved))]

crates/pdk/src/macros.rs

@@ -44,6 +44,24 @@ macro_rules! exec_command {
     };
 }
 
+#[macro_export]
+macro_rules! host_env {
+    ($name:literal, $value:expr) => {
+        unsafe { set_env_var($name, $value)? };
+    };
+    ($name:literal) => {
+        unsafe {
+            let inner = get_env_var($name)?;
+
+            if inner.is_empty() {
+                None
+            } else {
+                Some(inner)
+            }
+        }
+    };
+}
+
 #[macro_export]
 macro_rules! host_log {
     ($($arg:tt)+) => {

crates/wasm-plugin/src/host_funcs.rs

@@ -13,16 +13,28 @@ pub struct HostData {
 
 pub fn create_host_functions(data: HostData) -> Vec<Function> {
     vec![
-        Function::new("host_log", [ValType::I64], [], None, host_log),
         Function::new(
             "exec_command",
             [ValType::I64],
             [ValType::I64],
             Some(UserData::new(data)),
             exec_command,
         ),
-        // Backwards compatibility
-        Function::new("trace", [ValType::I64], [], None, host_log),
+        Function::new(
+            "get_env_var",
+            [ValType::I64],
+            [ValType::I64],
+            None,
+            get_env_var,
+        ),
+        Function::new("host_log", [ValType::I64], [], None, host_log),
+        Function::new(
+            "set_env_var",
+            [ValType::I64, ValType::I64],
+            [],
+            None,
+            set_env_var,
+        ),
     ]
 }
 
@@ -136,3 +148,52 @@ fn exec_command(
 
     Ok(())
 }
+
+fn get_env_var(
+    plugin: &mut CurrentPlugin,
+    inputs: &[Val],
+    outputs: &mut [Val],
+    _user_data: UserData,
+) -> Result<(), Error> {
+    let name = plugin.memory_read_str(inputs[0].unwrap_i64() as u64)?;
+    let value = env::var(name).unwrap_or_default();
+
+    trace!(
+        target: "proto_wasm::get_env_var",
+        name,
+        value = &value,
+        "Reading environment variable from host"
+    );
+
+    let ptr = plugin.memory_alloc_bytes(value)?;
+
+    outputs[0] = Val::I64(ptr as i64);
+
+    Ok(())
+}
+
+fn set_env_var(
+    plugin: &mut CurrentPlugin,
+    inputs: &[Val],
+    _outputs: &mut [Val],
+    _user_data: UserData,
+) -> Result<(), Error> {
+    let name = plugin
+        .memory_read_str(inputs[0].unwrap_i64() as u64)?
+        .to_owned();
+
+    let value = plugin
+        .memory_read_str(inputs[1].unwrap_i64() as u64)?
+        .to_owned();
+
+    trace!(
+        target: "proto_wasm::set_env_var",
+        name = &name,
+        value = &value,
+        "Writing environment variable to host"
+    );
+
+    env::set_var(name, value);
+
+    Ok(())
+}

plugins/wasm-test/src/lib.rs

@@ -5,14 +5,21 @@ use std::collections::HashMap;
 
 #[host_fn]
 extern "ExtismHost" {
-    fn host_log(input: Json<HostLogInput>);
     fn exec_command(input: Json<ExecCommandInput>) -> Json<ExecCommandOutput>;
+    fn get_env_var(name: &str) -> String;
+    fn host_log(input: Json<HostLogInput>);
+    fn set_env_var(name: &str, value: &str);
 }
 
 #[plugin_fn]
 pub fn register_tool(_: ()) -> FnResult<Json<ToolMetadataOutput>> {
     host_log!("Registering tool");
 
+    let value = host_env!("WASM_KEY");
+
+    host_log!("WASM_KEY = {:?}", value);
+    host_env!("WASM_SOURCE", "guest");
+
     Ok(Json(ToolMetadataOutput {
         name: "WASM Test".into(),
         type_of: PluginType::CLI,