add FCE config validation

engine/src/engine.rs

@@ -80,6 +80,7 @@ impl FCE {
         wasm_bytes: &[u8],
         config: FCEModuleConfig,
     ) -> Result<()> {
+        Self::validate_config(&config)?;
         let _prepared_wasm_bytes = crate::misc::prepare_module(wasm_bytes, config.mem_pages_count)?;
 
         let module = FCEModule::new(&wasm_bytes, config, &self.modules)?;
@@ -136,6 +137,43 @@ impl FCE {
             })
             .collect::<Vec<_>>()
     }
+
+    #[rustfmt::skip]
+    fn validate_config(config: &FCEModuleConfig) -> Result<()> {
+        use boolinator::Boolinator;
+
+        fn has_only_unique_elements<T>(mut iter: T) -> bool
+        where
+            T: Iterator,
+            T::Item: Eq + std::hash::Hash,
+        {
+            let mut uniq = std::collections::HashSet::new();
+            iter.all(move |x| uniq.insert(x))
+        }
+
+        has_only_unique_elements(config.wasi_envs.iter()).as_result(
+            (),
+            FCEError::InvalidConfig(String::from(
+                "Supplied config contains environment variable with the same names",
+            )),
+        )?;
+
+        has_only_unique_elements(config.wasi_mapped_dirs.iter().map(|(alias, _)| alias)).as_result(
+            (),
+            FCEError::InvalidConfig(String::from(
+                "Supplied config contains mapped dirs with the same aliases",
+            )),
+        )?;
+
+        has_only_unique_elements(config.wasi_preopened_files.iter()).as_result(
+            (),
+            FCEError::InvalidConfig(String::from(
+                "Supplied config contains preopened files with the same file names",
+            )),
+        )?;
+
+        Ok(())
+    }
 }
 
 impl Default for FCE {