Improved wasmer script

src/integrations/mod.rs

@@ -1,18 +1,24 @@
 use libc::putchar;
+use crate::webassembly::ImportObject;
+
+pub fn generate_libc_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
+    let mut import_object = ImportObject::new();
+    import_object.set("env", "putchar", putchar as *const u8);
+    import_object
+}
 
 #[cfg(test)]
 mod tests {
     use crate::webassembly::{
         instantiate, ErrorKind, Export, ImportObject, Instance, Module, ResultObject,
     };
+    use super::generate_libc_env;
     use libc::putchar;
 
     #[test]
     fn test_putchar() {
         let wasm_bytes = include_wast2wasm_bytes!("tests/putchar.wast");
-        let mut import_object = ImportObject::new();
-        import_object.set("env", "putchar", putchar as *const u8);
-
+        let import_object = generate_libc_env();
         let result_object =
             instantiate(wasm_bytes, Some(import_object)).expect("Not compiled properly");
         let module = result_object.module;

src/macros.rs

@@ -9,6 +9,7 @@ macro_rules! get_instance_function {
     }};
 }
 
+#[macro_export]
 macro_rules! include_wast2wasm_bytes {
     ($x:expr) => {{
         use wabt::wat2wasm;
@@ -17,9 +18,16 @@ macro_rules! include_wast2wasm_bytes {
     }};
 }
 
-// #[cfg(feature = "debug")]
+#[cfg(feature= "debug")]
 #[macro_export]
 macro_rules! debug {
     ($fmt:expr) => (println!(concat!("Wasmer::", $fmt)));
     ($fmt:expr, $($arg:tt)*) => (println!(concat!("Wasmer::", $fmt, "\n"), $($arg)*));
 }
+
+#[cfg(not(feature= "debug"))]
+#[macro_export]
+macro_rules! debug {
+    ($fmt:expr) => {};
+    ($fmt:expr, $($arg:tt)*) => {};
+}

src/main.rs

@@ -70,7 +70,16 @@ fn execute_wasm(wasm_path: PathBuf) -> Result<(), String> {
         wasm_binary = wat2wasm(wasm_binary).map_err(|err| String::from(err.description()))?;
     }
 
-    webassembly::instantiate(wasm_binary, None).map_err(|err| String::from(err.description()))?;
+    let import_object = integrations::generate_libc_env();
+    let webassembly::ResultObject {module, instance} = webassembly::instantiate(wasm_binary, Some(import_object)).map_err(|err| String::from(err.description()))?;
+    let func_index = instance.start_func.unwrap_or_else(|| {
+        match module.info.exports.get("main") {
+            Some(&webassembly::Export::Function(index)) => index,
+            _ => panic!("Main function not found"),
+        }
+    });
+    let main: fn() = get_instance_function!(instance, func_index);
+    main();
     Ok(())
 }
 

src/webassembly/instance.rs

@@ -121,7 +121,7 @@ pub struct Instance {
     import_functions: Vec<*const u8>,
 
     /// The module start function
-    start_func: Option<FuncIndex>,
+    pub start_func: Option<FuncIndex>,
     // Region start memory location
     // code_base: *const (),
 }