wasmerio · bors · Dec 1, 2020 · Dec 1, 2020 · Dec 1, 2020 · Dec 1, 2020
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -23,6 +23,7 @@
 
 ### Fixed
 
+- [#1855](https://github.com/wasmerio/wasmer/pull/1855) Fix memory leak when using `wat2wasm` in the C API, the function now takes its output parameter by pointer rather than returning an allocated `wasm_byte_vec_t`.
 - [#1841](https://github.com/wasmerio/wasmer/pull/1841) We will now panic when attempting to use a native function with a captured env as a host function. Previously this would silently do the wrong thing. See [#1840](https://github.com/wasmerio/wasmer/pull/1840) for info about Wasmer's support of closures as host functions.
 - [#1764](https://github.com/wasmerio/wasmer/pull/1764) Fix bug in WASI `path_rename` allowing renamed files to be 1 directory below a preopened directory.
 

diff --git a/lib/c-api/src/deprecated/import/wasi.rs b/lib/c-api/src/deprecated/import/wasi.rs
@@ -212,7 +212,7 @@ pub unsafe extern "C" fn wasmer_wasi_generate_default_import_object() -> *mut wa
     let store = get_global_store();
     let mut wasi_state_builder = wasi::WasiState::new("wasmer-wasi-default-program-name");
     let wasi_state = wasi_state_builder.build().unwrap();
-    let mut wasi_env = wasi::WasiEnv::new(wasi_state);
+    let wasi_env = wasi::WasiEnv::new(wasi_state);
     let import_object_inner: Box<dyn NamedResolver> = Box::new(
         wasi::generate_import_object_from_env(store, wasi_env, wasi::WasiVersion::Latest),
     );

diff --git a/lib/c-api/src/wasm_c_api/macros.rs b/lib/c-api/src/wasm_c_api/macros.rs
@@ -102,12 +102,13 @@ macro_rules! wasm_declare_vec {
 
 
             #[no_mangle]
-            pub unsafe extern "C" fn [<wasm_ $name _vec_delete>](ptr: *mut [<wasm_ $name _vec_t>]) {
-                let vec = &mut *ptr;
-                if !vec.data.is_null() {
-                    Vec::from_raw_parts(vec.data, vec.size, vec.size);
-                    vec.data = ::std::ptr::null_mut();
-                    vec.size = 0;
+            pub unsafe extern "C" fn [<wasm_ $name _vec_delete>](ptr: Option<&mut [<wasm_ $name _vec_t>]>) {
+                if let Some(vec) = ptr {
+                    if !vec.data.is_null() {
+                        Vec::from_raw_parts(vec.data, vec.size, vec.size);
+                        vec.data = ::std::ptr::null_mut();
+                        vec.size = 0;
+                    }
                 }
             }
         }

diff --git a/lib/c-api/src/wasm_c_api/module.rs b/lib/c-api/src/wasm_c_api/module.rs
@@ -38,12 +38,13 @@ pub struct wasm_module_t {
 ///    
 ///     wasm_byte_vec_t wat;
 ///     wasmer_byte_vec_new_from_string(&wat, "(module)");
-///     wasm_byte_vec_t* wasm = wat2wasm(&wat);
+///     wasm_byte_vec_t wasm;
+///     wat2wasm(&wat, &wasm);
 ///    
-///     wasm_module_t* module = wasm_module_new(store, wasm);
+///     wasm_module_t* module = wasm_module_new(store, &wasm);
 ///     assert(module);
 ///    
-///     wasm_byte_vec_delete(wasm);
+///     wasm_byte_vec_delete(&wasm);
 ///     wasm_byte_vec_delete(&wat);
 ///     wasm_module_delete(module);
 ///     wasm_store_delete(store);
@@ -190,11 +191,12 @@ mod tests {
 
                 wasm_byte_vec_t wat;
                 wasmer_byte_vec_new_from_string(&wat, "(module)");
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                assert(wasm_module_validate(store, wasm));
+                assert(wasm_module_validate(store, &wasm));
 
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_store_delete(store);
                 wasm_engine_delete(engine);
@@ -216,12 +218,13 @@ mod tests {
 
                 wasm_byte_vec_t wat;
                 wasmer_byte_vec_new_from_string(&wat, "(module)");
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                wasm_module_t* module = wasm_module_new(store, wasm);
+                wasm_module_t* module = wasm_module_new(store, &wasm);
                 assert(module);
 
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_module_delete(module);
                 wasm_store_delete(store);
@@ -251,9 +254,10 @@ mod tests {
                     "  (table (export \"table\") 0 funcref)\n"
                     "  (memory (export \"memory\") 1))"
                 );
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                wasm_module_t* module = wasm_module_new(store, wasm);
+                wasm_module_t* module = wasm_module_new(store, &wasm);
                 assert(module);
 
                 wasm_exporttype_vec_t export_types;
@@ -328,7 +332,7 @@ mod tests {
                 }
 
                 wasm_exporttype_vec_delete(&export_types);
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_module_delete(module);
                 wasm_store_delete(store);
@@ -356,9 +360,10 @@ mod tests {
                     "  (import \"ns\" \"table\" (table 1 2 anyfunc))\n"
                     "  (import \"ns\" \"memory\" (memory 3 4)))"
                 );
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                wasm_module_t* module = wasm_module_new(store, wasm);
+                wasm_module_t* module = wasm_module_new(store, &wasm);
                 assert(module);
 
                 wasm_importtype_vec_t import_types;
@@ -444,7 +449,7 @@ mod tests {
 
                 wasm_importtype_vec_delete(&import_types);
                 wasm_module_delete(module);
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_store_delete(store);
                 wasm_engine_delete(engine);
@@ -464,9 +469,10 @@ mod tests {
 
                 wasm_byte_vec_t wat;
                 wasmer_byte_vec_new_from_string(&wat, "(module)");
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                wasm_module_t* module = wasm_module_new(store, wasm);
+                wasm_module_t* module = wasm_module_new(store, &wasm);
                 assert(module);
 
                 wasm_byte_vec_t serialized_module;
@@ -475,7 +481,7 @@ mod tests {
 
                 wasm_module_delete(module);
                 wasm_byte_vec_delete(&serialized_module);
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_store_delete(store);
                 wasm_engine_delete(engine);
@@ -502,9 +508,10 @@ mod tests {
                     "  (table (export \"table\") 0 funcref)\n"
                     "  (memory (export \"memory\") 1))"
                 );
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                wasm_module_t* module = wasm_module_new(store, wasm);
+                wasm_module_t* module = wasm_module_new(store, &wasm);
                 assert(module);
 
                 wasm_byte_vec_t serialized_module;
@@ -526,7 +533,7 @@ mod tests {
 
                 wasm_exporttype_vec_delete(&export_types);
                 wasm_module_delete(deserialized_module);
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_store_delete(store);
                 wasm_engine_delete(engine);

diff --git a/lib/c-api/src/wasm_c_api/wasi/mod.rs b/lib/c-api/src/wasm_c_api/wasi/mod.rs
@@ -208,7 +208,7 @@ pub unsafe extern "C" fn wasi_env_read_stdout(
     buffer_len: usize,
 ) -> isize {
     let inner_buffer = slice::from_raw_parts_mut(buffer as *mut _, buffer_len as usize);
-    let mut state = env.inner.state_mut();
+    let mut state = env.inner.state();
 
     let stdout = if let Ok(stdout) = state.fs.stdout_mut() {
         if let Some(stdout) = stdout.as_mut() {
@@ -232,7 +232,7 @@ pub unsafe extern "C" fn wasi_env_read_stderr(
     buffer_len: usize,
 ) -> isize {
     let inner_buffer = slice::from_raw_parts_mut(buffer as *mut _, buffer_len as usize);
-    let mut state = env.inner.state_mut();
+    let mut state = env.inner.state();
     let stderr = if let Ok(stderr) = state.fs.stderr_mut() {
         if let Some(stderr) = stderr.as_mut() {
             stderr

diff --git a/lib/c-api/src/wasm_c_api/wat.rs b/lib/c-api/src/wasm_c_api/wat.rs
@@ -6,11 +6,26 @@ use super::types::wasm_byte_vec_t;
 /// In case of failure, `wat2wasm` returns `NULL`.
 #[cfg(feature = "wat")]
 #[no_mangle]
-pub unsafe extern "C" fn wat2wasm(wat: &wasm_byte_vec_t) -> Option<Box<wasm_byte_vec_t>> {
-    let wat: &[u8] = wat.into_slice()?;
-    let result: wasm_byte_vec_t = c_try!(wasmer::wat2wasm(wat)).into_owned().into();
+pub unsafe extern "C" fn wat2wasm(wat: &wasm_byte_vec_t, out: &mut wasm_byte_vec_t) {
+    let wat: &[u8] = match wat.into_slice() {
+        Some(v) => v,
+        _ => {
+            out.data = std::ptr::null_mut();
+            out.size = 0;
+            return;
+        }
+    };
+    let result: wasm_byte_vec_t = match wasmer::wat2wasm(wat) {
+        Ok(val) => val.into_owned().into(),
+        Err(err) => {
+            crate::error::update_last_error(err);
+            out.data = std::ptr::null_mut();
+            out.size = 0;
+            return;
+        }
+    };
 
-    Some(Box::new(result))
+    *out = result;
 }
 
 #[cfg(test)]
@@ -28,22 +43,23 @@ mod tests {
 
                 wasm_byte_vec_t wat;
                 wasmer_byte_vec_new_from_string(&wat, "(module)");
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                assert(wasm);
-                assert(wasm->size == 8);
+                assert(wasm.data);
+                assert(wasm.size == 8);
                 assert(
-                    wasm->data[0] == 0 &&
-                        wasm->data[1] == 'a' &&
-                        wasm->data[2] == 's' &&
-                        wasm->data[3] == 'm' &&
-                        wasm->data[4] == 1 &&
-                        wasm->data[5] == 0 &&
-                        wasm->data[6] == 0 &&
-                        wasm->data[7] == 0
+                    wasm.data[0] == 0 &&
+                        wasm.data[1] == 'a' &&
+                        wasm.data[2] == 's' &&
+                        wasm.data[3] == 'm' &&
+                        wasm.data[4] == 1 &&
+                        wasm.data[5] == 0 &&
+                        wasm.data[6] == 0 &&
+                        wasm.data[7] == 0
                 );
 
-                wasm_byte_vec_delete(wasm);
+                wasm_byte_vec_delete(&wasm);
                 wasm_byte_vec_delete(&wat);
                 wasm_store_delete(store);
                 wasm_engine_delete(engine);
@@ -65,9 +81,10 @@ mod tests {
 
                 wasm_byte_vec_t wat;
                 wasmer_byte_vec_new_from_string(&wat, "(module");
-                wasm_byte_vec_t* wasm = wat2wasm(&wat);
+                wasm_byte_vec_t wasm;
+                wat2wasm(&wat, &wasm);
 
-                assert(!wasm);
+                assert(!wasm.data);
                 assert(wasmer_last_error_length() > 0);
 
                 wasm_byte_vec_delete(&wat);

diff --git a/lib/c-api/tests/wasm_c_api/test-wat2wasm.c b/lib/c-api/tests/wasm_c_api/test-wat2wasm.c
@@ -20,31 +20,32 @@ int main(int argc, const char* argv[]) {
     .data = "(module)",
     .size = 8,
   };
-  wasm_byte_vec_t *wasm = wat2wasm(&wat);
+  wasm_byte_vec_t wasm;
+  wat2wasm(&wat, &wasm);
 
-  if (!wasm) {
+  if (!wasm.data) {
     printf("> Error compiler WAT to Wasm!\n");
     return 1;
   }
 
-  if (wasm->size != 8) {
+  if (wasm.size != 8) {
     printf("The Wasm size is incorrect!\n");
     return 1;
   }
 
-  if (!(wasm->data[0] == 0 &&
-        wasm->data[1] == 'a' &&
-        wasm->data[2] == 's' &&
-        wasm->data[3] == 'm' &&
-        wasm->data[4] == 1 &&
-        wasm->data[5] == 0 &&
-        wasm->data[6] == 0 &&
-        wasm->data[7] == 0)) {
+  if (!(wasm.data[0] == 0 &&
+        wasm.data[1] == 'a' &&
+        wasm.data[2] == 's' &&
+        wasm.data[3] == 'm' &&
+        wasm.data[4] == 1 &&
+        wasm.data[5] == 0 &&
+        wasm.data[6] == 0 &&
+        wasm.data[7] == 0)) {
     printf("The Wasm data is incorrect!\n");
     return 1;
   }
 
-  wasm_byte_vec_delete(wasm);
+  wasm_byte_vec_delete(&wasm);
 
   // All done.
   printf("Done.\n");

diff --git a/lib/c-api/wasmer_wasm.h b/lib/c-api/wasmer_wasm.h
@@ -239,6 +239,6 @@ int wasmer_last_error_message(char *buffer, int length);
  *
  * In case of failure, `wat2wasm` returns `NULL`.
  */
-wasm_byte_vec_t *wat2wasm(const wasm_byte_vec_t *wat);
+void wat2wasm(const wasm_byte_vec_t *wat, wasm_byte_vec_t *out);
 
 #endif /* WASMER_WASM_H */