v1.5.0

Related to https://github.com/extism/python-sdk/issues/23 - there is
currently no way to get the length of the error message, so we need to
make sure it is a valid C string.

kernel/src/lib.rs

@@ -546,7 +546,8 @@ pub unsafe fn reset() {
     MemoryRoot::new().reset()
 }
 
-/// Set the error message offset
+/// Set the error message offset, the handle passed to this
+/// function should not be freed after this call
 #[no_mangle]
 pub unsafe fn error_set(h: Handle) {
     let root = MemoryRoot::new();

runtime/Cargo.toml

@@ -9,8 +9,8 @@ repository.workspace = true
 version.workspace = true
 
 [dependencies]
-wasmtime = ">= 20.0.0, < 22.0.0"
-wasi-common = ">= 20.0.0, < 22.0.0"
+wasmtime = ">= 20.0.0, < 23.0.0"
+wasi-common = ">= 20.0.0, < 23.0.0"
 anyhow = "1"
 serde = {version = "1", features = ["derive"]}
 serde_json = "1"

runtime/README.md

@@ -12,7 +12,7 @@ To use the `extism` crate, you can add it to your Cargo file:
 
 ```toml
 [dependencies]
-extism = "1.2.0"
+extism = "1.4.1"
 ```
 
 ## Environment variables

runtime/benches/bench.rs

@@ -35,6 +35,21 @@ pub fn create_plugin(c: &mut Criterion) {
     });
 }
 
+pub fn create_plugin_no_cache(c: &mut Criterion) {
+    let mut g = c.benchmark_group("create");
+    g.noise_threshold(1.0);
+    g.significance_level(0.2);
+    g.bench_function("create_plugin_no_cache", |b| {
+        b.iter(|| {
+            let _plugin = PluginBuilder::new(COUNT_VOWELS)
+                .with_cache_disabled()
+                .with_wasi(true)
+                .build()
+                .unwrap();
+        })
+    });
+}
+
 #[derive(Debug, serde::Deserialize, PartialEq)]
 struct Count {
     count: u32,
@@ -251,6 +266,7 @@ criterion_group!(
     reflect_linked,
     basic,
     create_plugin,
+    create_plugin_no_cache,
     count_vowels
 );
 criterion_main!(benches);

runtime/src/function.rs

@@ -279,7 +279,7 @@ impl Function {
 /// For example, the following defines a host function named `add_newline` that takes a
 /// string parameter and returns a string result:
 /// ```rust
-/// extism::host_fn!(add_newline(_user_data: (), a: String) -> String { Ok(a + "\n") });
+/// extism::host_fn!(add_newline(_user_data: (); a: String) -> String { Ok(a + "\n") });
 /// ```
 /// A few things worth noting:
 /// - The function always returns a `Result` that wraps the specified return type

runtime/src/plugin.rs

@@ -81,6 +81,8 @@ pub struct Plugin {
     pub(crate) store_needs_reset: bool,
 
     pub(crate) debug_options: DebugOptions,
+
+    pub(crate) error_msg: Option<Vec<u8>>,
 }
 
 unsafe impl Send for Plugin {}
@@ -361,6 +363,7 @@ impl Plugin {
             store_needs_reset: false,
             debug_options,
             _functions: imports,
+            error_msg: None,
         };
 
         plugin.current_plugin_mut().store = &mut plugin.store;

runtime/src/sdk.rs

@@ -505,6 +505,8 @@ pub unsafe extern "C" fn extism_plugin_call_with_host_context(
     let lock = plugin.instance.clone();
     let mut lock = lock.lock().unwrap();
 
+    plugin.error_msg = None;
+
     // Get function name
     let name = std::ffi::CStr::from_ptr(func_name);
     let name = match name.to_str() {
@@ -551,10 +553,19 @@ pub unsafe extern "C" fn extism_plugin_error(plugin: *mut Plugin) -> *const c_ch
         return std::ptr::null();
     }
 
-    plugin
+    let offs = plugin.output.error_offset;
+
+    let ptr = plugin.current_plugin_mut().memory_ptr().add(offs as usize) as *const _;
+
+    let len = plugin
         .current_plugin_mut()
-        .memory_ptr()
-        .add(plugin.output.error_offset as usize) as *const _
+        .memory_length(offs)
+        .unwrap_or_default();
+
+    let mut data = std::slice::from_raw_parts(ptr, len as usize).to_vec();
+    data.push(0);
+    plugin.error_msg = Some(data);
+    plugin.error_msg.as_ref().unwrap().as_ptr() as *const _
 }
 
 /// Get the length of a plugin's output data