feat: Added the ability to provide additional host functions to `Wasi…

…Runner`

lib/wasix/src/runners/wasi.rs

@@ -188,6 +188,30 @@ impl WasiRunner {
         self
     }
 
+    /// Add an item to the list of importable items provided to the instance.
+    pub fn with_import(
+        &mut self,
+        namespace: impl Into<String>,
+        name: impl Into<String>,
+        value: impl Into<Extern>,
+    ) -> &mut Self {
+        self.with_imports([((namespace, name), value)])
+    }
+
+    pub fn with_imports<I, S1, S2, E>(&mut self, imports: I) -> &mut Self
+    where
+        I: IntoIterator<Item = ((S1, S2), E)>,
+        S1: Into<String>,
+        S2: Into<String>,
+        E: Into<Extern>,
+    {
+        let imports = imports
+            .into_iter()
+            .map(|((ns, n), e)| ((ns.into(), n.into()), e.into()));
+        self.wasi.additional_imports.extend(imports);
+        self
+    }
+
     #[tracing::instrument(level = "debug", skip_all)]
     pub(crate) fn prepare_webc_env(
         &self,

lib/wasix/src/runners/wasi_common.rs

@@ -8,6 +8,7 @@ use anyhow::{Context, Error};
 use derivative::Derivative;
 use futures::future::BoxFuture;
 use virtual_fs::{FileSystem, FsError, OverlayFileSystem, RootFileSystemBuilder, TmpFileSystem};
+use wasmer::Imports;
 use webc::metadata::annotations::Wasi as WasiAnnotation;
 
 use crate::{
@@ -40,6 +41,7 @@ pub(crate) struct CommonWasiOptions {
     pub(crate) snapshot_on: Vec<SnapshotTrigger>,
     pub(crate) snapshot_interval: Option<std::time::Duration>,
     pub(crate) current_dir: Option<PathBuf>,
+    pub(crate) additional_imports: Imports,
 }
 
 impl CommonWasiOptions {
@@ -77,6 +79,8 @@ impl CommonWasiOptions {
 
         *builder.capabilities_mut() = self.capabilities.clone();
 
+        builder.add_imports(&self.additional_imports);
+
         Ok(())
     }