Merge #1657

1657: Add early exit example r=MarkMcCaskey a=MarkMcCaskey

Resolves #1597

This PR currently contains the example in both C and Rust

# Review

- [x] Add a short description of the the change to the CHANGELOG.md file


Co-authored-by: Mark McCaskey <mark@wasmer.io>

lib/c-api/src/wasm_c_api/mod.rs

@@ -17,9 +17,9 @@ use crate::c_try;
 
 use crate::ordered_resolver::OrderedResolver;
 use wasmer::{
-    Engine, ExportType, Extern, ExternType, Function, FunctionType, Global, GlobalType, ImportType,
-    Instance, Memory, MemoryType, Module, Mutability, Pages, RuntimeError, Store, Table, TableType,
-    Val, ValType,
+    Engine, ExportType, Extern, ExternType, FrameInfo, Function, FunctionType, Global, GlobalType,
+    ImportType, Instance, Memory, MemoryType, Module, Mutability, Pages, RuntimeError, Store,
+    Table, TableType, Val, ValType,
 };
 #[cfg(feature = "jit")]
 use wasmer_engine_jit::JIT;
@@ -712,8 +712,11 @@ pub unsafe extern "C" fn wasm_func_new(
             num_rets
         ];
 
-        let _traps = callback(processed_args.as_ptr(), results.as_mut_ptr());
-        // TODO: do something with `traps`
+        let trap = callback(processed_args.as_ptr(), results.as_mut_ptr());
+        if !trap.is_null() {
+            let trap: Box<wasm_trap_t> = Box::from_raw(trap);
+            RuntimeError::raise(Box::new(trap.inner));
+        }
 
         let processed_results = results
             .into_iter()
@@ -783,7 +786,7 @@ pub unsafe extern "C" fn wasm_func_call(
     func: &wasm_func_t,
     args: *const wasm_val_t,
     results: *mut wasm_val_t,
-) -> Option<NonNull<wasm_trap_t>> {
+) -> Option<Box<wasm_trap_t>> {
     let num_params = func.inner.ty().params().len();
     let params: Vec<Val> = (0..num_params)
         .map(|i| (&(*args.add(i))).try_into())
@@ -798,7 +801,7 @@ pub unsafe extern "C" fn wasm_func_call(
             }
             None
         }
-        Err(e) => Some(NonNull::new_unchecked(Box::into_raw(Box::new(e)) as _)),
+        Err(e) => Some(Box::new(e.into())),
     }
 }
 
@@ -1050,6 +1053,38 @@ macro_rules! wasm_declare_vec {
                 }
             }
 
+
+            impl<'a> From<Vec<[<wasm_ $name _t>]>> for [<wasm_ $name _vec_t>] {
+                fn from(other: Vec<[<wasm_ $name _t>]>) -> Self {
+                    let mut boxed_slice = other.into_boxed_slice();
+                    let size = boxed_slice.len();
+                    let data = boxed_slice.as_mut_ptr();
+                    mem::forget(boxed_slice);
+                    Self {
+                        size,
+                        data,
+                    }
+                }
+            }
+
+            impl<'a, T: Into<[<wasm_ $name _t>]> + Clone> From<&'a [T]> for [<wasm_ $name _vec_t>] {
+                fn from(other: &'a [T]) -> Self {
+                    let size = other.len();
+                    let mut copied_data = other
+                        .iter()
+                        .cloned()
+                        .map(Into::into)
+                        .collect::<Vec<[<wasm_ $name _t>]>>()
+                        .into_boxed_slice();
+                    let data = copied_data.as_mut_ptr();
+                    mem::forget(copied_data);
+                    Self {
+                        size,
+                        data,
+                    }
+                }
+            }
+
             // TODO: investigate possible memory leak on `init` (owned pointer)
             #[no_mangle]
             pub unsafe extern "C" fn [<wasm_ $name _vec_new>](out: *mut [<wasm_ $name _vec_t>], length: usize, init: *mut [<wasm_ $name _t>]) {
@@ -1150,44 +1185,53 @@ pub struct wasm_ref_t;
 
 // opaque type which is a `RuntimeError`
 #[repr(C)]
-pub struct wasm_trap_t {}
+pub struct wasm_trap_t {
+    inner: RuntimeError,
+}
 
-#[no_mangle]
-pub unsafe extern "C" fn wasm_trap_delete(trap: Option<NonNull<wasm_trap_t>>) {
-    if let Some(t_inner) = trap {
-        let _ = Box::from_raw(t_inner.cast::<RuntimeError>().as_ptr());
+impl From<RuntimeError> for wasm_trap_t {
+    fn from(other: RuntimeError) -> Self {
+        Self { inner: other }
     }
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn wasm_trap_message(
-    trap: *const wasm_trap_t,
-    out_ptr: *mut wasm_byte_vec_t,
-) {
-    let re = &*(trap as *const RuntimeError);
-    // this code assumes no nul bytes appear in the message
-    let mut message = format!("{}\0", re);
-    message.shrink_to_fit();
+pub unsafe extern "C" fn wasm_trap_new(
+    _store: &mut wasm_store_t,
+    message: &wasm_message_t,
+) -> Option<Box<wasm_trap_t>> {
+    let message_bytes: &[u8] = message.into_slice()?;
+    let message_str = c_try!(std::str::from_utf8(message_bytes));
+    let runtime_error = RuntimeError::new(message_str);
+    let trap = runtime_error.into();
 
-    // TODO use `String::into_raw_parts` when it gets stabilized
-    (*out_ptr).size = message.as_bytes().len();
-    (*out_ptr).data = message.as_mut_ptr();
-    mem::forget(message);
+    Some(Box::new(trap))
 }
 
-// in trap/RuntimeError we need to store
-// 1. message
-// 2. origin (frame); frame contains:
-//    1. func index
-//    2. func offset
-//    3. module offset
-//    4. which instance this was apart of
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_delete(_trap: Option<Box<wasm_trap_t>>) {}
 
-/*#[no_mangle]
-pub unsafe extern "C" fn wasm_trap_trace(trap: *const wasm_trap_t, out_ptr: *mut wasm_frame_vec_t) {
-    let re = &*(trap as *const RuntimeError);
-    todo!()
-}*/
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_message(trap: &wasm_trap_t, out_ptr: &mut wasm_byte_vec_t) {
+    let message = trap.inner.message();
+    let byte_vec: wasm_byte_vec_t = message.into_bytes().into();
+    out_ptr.size = byte_vec.size;
+    out_ptr.data = byte_vec.data;
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_origin(trap: &wasm_trap_t) -> Option<Box<wasm_frame_t>> {
+    trap.inner.trace().first().map(Into::into).map(Box::new)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_trap_trace(trap: &wasm_trap_t, out_ptr: &mut wasm_frame_vec_t) {
+    let frames = trap.inner.trace();
+    let frame_vec: wasm_frame_vec_t = frames.into();
+
+    out_ptr.size = frame_vec.size;
+    out_ptr.data = frame_vec.data;
+}
 
 #[repr(C)]
 pub struct wasm_extern_t {
@@ -1543,9 +1587,52 @@ pub unsafe extern "C" fn wasm_functype_results(ft: &wasm_functype_t) -> *const w
     out as *const _
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 #[repr(C)]
-pub struct wasm_frame_t {}
+pub struct wasm_frame_t {
+    info: FrameInfo,
+}
+
+impl<'a> From<&'a FrameInfo> for wasm_frame_t {
+    fn from(other: &'a FrameInfo) -> Self {
+        other.clone().into()
+    }
+}
+
+impl From<FrameInfo> for wasm_frame_t {
+    fn from(other: FrameInfo) -> Self {
+        Self { info: other }
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_copy(frame: &wasm_frame_t) -> Box<wasm_frame_t> {
+    Box::new(frame.clone())
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_delete(_frame: Option<Box<wasm_frame_t>>) {}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_instance(frame: &wasm_frame_t) -> *const wasm_instance_t {
+    //todo!("wasm_frame_instance")
+    std::ptr::null()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_func_index(frame: &wasm_frame_t) -> u32 {
+    frame.info.func_index()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_func_offset(frame: &wasm_frame_t) -> usize {
+    frame.info.func_offset()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn wasm_frame_module_offset(frame: &wasm_frame_t) -> usize {
+    frame.info.module_offset()
+}
 
 wasm_declare_vec!(frame);
 
@@ -1769,6 +1856,9 @@ pub unsafe extern "C" fn wasm_tabletype_as_externtype(
 #[allow(non_camel_case_types)]
 type wasm_name_t = wasm_byte_vec_t;
 
+#[allow(non_camel_case_types)]
+type wasm_message_t = wasm_byte_vec_t;
+
 #[repr(C)]
 #[allow(non_camel_case_types)]
 pub struct wasm_exporttype_t {

lib/c-api/tests/CMakeLists.txt

@@ -31,10 +31,11 @@ add_executable(wasm-c-api-serialize wasm-c-api/example/serialize.c)
 #add_executable(wasm-c-api-start wasm-c-api/example/start.c)
 #add_executable(wasm-c-api-table wasm-c-api/example/table.c)
 #add_executable(wasm-c-api-threads wasm-c-api/example/threads.c)
-#add_executable(wasm-c-api-trap wasm-c-api/example/trap.c)
+add_executable(wasm-c-api-trap wasm-c-api/example/trap.c)
 
 # Custom Wasm C API tests
 add_executable(wasm-c-api-wasi wasm-c-api-wasi.c)
+add_executable(wasm-c-api-early-exit wasm-c-api-early-exit.c)
 
 if (DEFINED WASI_TESTS)
     add_executable(test-wasi-import-object test-wasi-import-object.c)
@@ -237,15 +238,19 @@ add_test(NAME wasm-c-api-serialize
 #         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/wasm-c-api/example/
 #)
 
-#target_link_libraries(wasm-c-api-trap general ${WASMER_LIB})
-#target_compile_options(wasm-c-api-trap PRIVATE ${COMPILER_OPTIONS})
-#add_test(NAME wasm-c-api-trap
-#         COMMAND wasm-c-api-trap
-#         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/wasm-c-api/example/
-#)
+target_link_libraries(wasm-c-api-trap general ${WASMER_LIB})
+target_compile_options(wasm-c-api-trap PRIVATE ${COMPILER_OPTIONS})
+add_test(NAME wasm-c-api-trap
+         COMMAND wasm-c-api-trap
+         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/wasm-c-api/example/
+)
 
 set_property(TARGET wasm-c-api-wasi PROPERTY C_STANDARD 11)
 target_link_libraries(wasm-c-api-wasi general ${WASMER_LIB})
 target_compile_options(wasm-c-api-wasi PRIVATE ${COMPILER_OPTIONS})
 add_test(wasm-c-api-wasi wasm-c-api-wasi)
 
+set_property(TARGET wasm-c-api-early-exit PROPERTY C_STANDARD 11)
+target_link_libraries(wasm-c-api-early-exit general ${WASMER_LIB})
+target_compile_options(wasm-c-api-early-exit PRIVATE ${COMPILER_OPTIONS})
+add_test(wasm-c-api-early-exit wasm-c-api-early-exit)

lib/c-api/tests/assets/call_trap.wat

@@ -0,0 +1,11 @@
+(module
+  (type $run_t (func (param i32 i32) (result i32)))
+  (type $early_exit_t (func (param) (result)))
+  (import "env" "early_exit" (func $early_exit (type $early_exit_t)))
+  (func $run (type $run_t) (param $x i32) (param $y i32) (result i32)
+    (call $early_exit)
+    (i32.add
+        (local.get $x)
+        (local.get $y)))
+  (export "run" (func $run)))
+

lib/c-api/tests/wasm-c-api-early-exit.c

@@ -0,0 +1,162 @@
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "wasm.h"
+#include "wasmer_wasm.h"
+
+// Use the last_error API to retrieve error messages
+void print_wasmer_error() {
+  int error_len = wasmer_last_error_length();
+  printf("Error len: `%d`\n", error_len);
+  char *error_str = malloc(error_len);
+  wasmer_last_error_message(error_str, error_len);
+  printf("Error str: `%s`\n", error_str);
+}
+
+void print_frame(wasm_frame_t* frame) {
+  printf("> %p @ 0x%zx = %"PRIu32".0x%zx\n",
+    wasm_frame_instance(frame),
+    wasm_frame_module_offset(frame),
+    wasm_frame_func_index(frame),
+    wasm_frame_func_offset(frame)
+  );
+}
+
+wasm_store_t *store = NULL;
+
+own wasm_trap_t *early_exit(const wasm_val_t args[], wasm_val_t results[]) {
+  own wasm_message_t trap_message;
+  wasm_name_new_from_string(&trap_message, "trapping from a host import");
+  own wasm_trap_t *trap = wasm_trap_new(store, &trap_message);
+  wasm_name_delete(&trap_message);
+  return trap;
+}
+
+int main(int argc, const char *argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t *engine = wasm_engine_new();
+  store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+  FILE *file = fopen("assets/call_trap.wasm", "r");
+  if (!file) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fseek(file, 0L, SEEK_END);
+  size_t file_size = ftell(file);
+  fseek(file, 0L, SEEK_SET);
+  wasm_byte_vec_t binary;
+  wasm_byte_vec_new_uninitialized(&binary, file_size);
+  if (fread(binary.data, file_size, 1, file) != 1) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fclose(file);
+
+  // Compile.
+  printf("Compiling module...\n");
+  own wasm_module_t *module = wasm_module_new(store, &binary);
+  if (!module) {
+    printf("> Error compiling module!\n");
+    return 1;
+  }
+
+  wasm_byte_vec_delete(&binary);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+
+  wasm_functype_t *host_func_type = wasm_functype_new_0_0();
+  wasm_func_t *host_func = wasm_func_new(store, host_func_type, early_exit);
+
+  wasm_functype_delete(host_func_type);
+
+  const wasm_extern_t *imports[] = {wasm_func_as_extern(host_func)};
+  own wasm_instance_t *instance =
+      wasm_instance_new(store, module, imports, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    print_wasmer_error();
+    return 1;
+  }
+
+  wasm_func_delete(host_func);
+
+  // Extract export.
+  printf("Extracting export...\n");
+  own wasm_extern_vec_t exports;
+  wasm_instance_exports(instance, &exports);
+  if (exports.size == 0) {
+    printf("> Error accessing exports!\n");
+    return 1;
+  }
+  fprintf(stderr, "found %zu exports\n", exports.size);
+
+  wasm_module_delete(module);
+  wasm_instance_delete(instance);
+
+  wasm_func_t *run_func = wasm_extern_as_func(exports.data[0]);
+  if (run_func == NULL) {
+    printf("> Error accessing export!\n");
+    print_wasmer_error();
+    return 1;
+  }
+
+  // Call.
+  printf("Calling export...\n");
+  own const wasm_val_t args[] = {
+      {.kind = WASM_I32, .of = {.i32 = 1}},
+      {.kind = WASM_I32, .of = {.i32 = 7}},
+  };
+  own wasm_val_t rets[1] = {};
+  own wasm_trap_t *trap = wasm_func_call(run_func, args, rets);
+  if (!trap) {
+    printf("> Error calling function: expected trap!\n");
+    return 1;
+  }
+
+  printf("Printing message...\n");
+  own wasm_name_t message;
+  wasm_trap_message(trap, &message);
+  printf("> %s\n", message.data);
+
+  printf("Printing origin...\n");
+  own wasm_frame_t* frame = wasm_trap_origin(trap);
+  if (frame) {
+    print_frame(frame);
+    wasm_frame_delete(frame);
+  } else {
+    printf("> Empty origin.\n");
+  }
+
+  printf("Printing trace...\n");
+  own wasm_frame_vec_t trace;
+  wasm_trap_trace(trap, &trace);
+  if (trace.size > 0) {
+    for (size_t i = 0; i < trace.size; ++i) {
+      print_frame(trace.data[i]);
+    }
+  } else {
+    printf("> Empty trace.\n");
+  }
+
+  wasm_frame_vec_delete(&trace);
+  wasm_trap_delete(trap);
+  wasm_name_delete(&message);
+
+  wasm_extern_vec_delete(&exports);
+
+  // Shut down.
+  printf("Shutting down...\n");
+  wasm_store_delete(store);
+  wasm_engine_delete(engine);
+
+  // All done.
+  printf("Done.\n");
+  return 0;
+}