replce libcontainer_instance with the simplified API

Signed-off-by: Jorge Prendes <jorge.prendes@gmail.com>

crates/containerd-shim-wasm/src/libcontainer_instance/easy/context.rs → crates/containerd-shim-wasm/src/libcontainer_instance/context.rs

@@ -1,8 +1,13 @@
+use std::path::{Path, PathBuf};
+
+use anyhow::{ensure, Context, Result};
 use oci_spec::runtime::Spec;
 
 use crate::sandbox::{oci, Stdio};
 
+/// Context where the container is going to run
 pub struct RuntimeContext {
+    ///
     pub module: Option<String>,
     pub method: String,
     pub args: Vec<String>,
@@ -24,6 +29,29 @@ impl From<&Spec> for RuntimeContext {
     }
 }
 
+impl RuntimeContext {
+    pub fn resolve_with_path(&self, file: impl AsRef<Path>) -> Result<PathBuf> {
+        let executable = file.as_ref();
+        let cwd = std::env::current_dir()?;
+
+        if executable.to_string_lossy().contains('/') {
+            let path = cwd.join(executable);
+            ensure!(path.is_file(), "file not found");
+            Ok(path)
+        } else {
+            self.envs
+                .iter()
+                .find(|(key, _)| key == "PATH")
+                .context("PATH not defined")?
+                .1
+                .split(':')
+                .map(|p| cwd.join(p).join(executable))
+                .find(|p| p.is_file())
+                .context("file not found")
+        }
+    }
+}
+
 fn envs_from_spec(spec: &Spec) -> Vec<(String, String)> {
     spec.process()
         .as_ref()