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>
This commit is contained in:
bors[bot]
2020-09-29 23:42:43 +00:00
committed by GitHub
13 changed files with 412 additions and 58 deletions

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@@ -1,17 +1,16 @@
[cranelift_coverage]
features = "cranelift,singlepass,llvm,test-no-traps,test-cranelift"
examples = ["early-exit", "engine-jit", "engine-native", "engine-headless", "cross-compilation", "compiler-cranelift", "exported-function", "wasi"]
release = true
[llvm_coverage]
features = "cranelift,singlepass,llvm,test-no-traps,test-llvm"
examples = ["compiler-llvm"]
release = true
[singlepass_coverage]
features = "cranelift,singlepass,llvm,test-no-traps,test-singlepass"
release = true
[feature_a_and_b_coverage]
features = "feature_a feature_b"
examples = ["compiler-singlepass"]
release = true
[report]

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@@ -1,6 +1,7 @@
# Changelog
## **[Unreleased]**
- [#1657](https://github.com/wasmerio/wasmer/pull/1657) Implement `wasm_trap_t` and `wasm_frame_t` for Wasm C API; add examples in Rust and C of exiting early with a host function.
- [#1645](https://github.com/wasmerio/wasmer/pull/1645) Move the install script to https://github.com/wasmerio/wasmer-install
## 1.0.0-alpha3 - 2020-09-14

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@@ -128,6 +128,11 @@ test-no-traps = ["wasmer-wast/test-no-traps"]
name = "static_and_dynamic_functions"
harness = false
[[example]]
name = "early-exit"
path = "examples/early_exit.rs"
required-features = ["cranelift"]
[[example]]
name = "engine-jit"
path = "examples/engine_jit.rs"

82
examples/early_exit.rs Normal file
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@@ -0,0 +1,82 @@
//! This example shows how the host can terminate execution of Wasm early from
//! inside a host function called by the Wasm.
use anyhow::bail;
use std::fmt;
use wasmer::{imports, wat2wasm, Function, Instance, Module, NativeFunc, RuntimeError, Store};
use wasmer_compiler_cranelift::Cranelift;
use wasmer_engine_jit::JIT;
// First we need to create an error type that we'll use to signal the end of execution.
#[derive(Debug, Clone, Copy)]
struct ExitCode(u32);
// This type must implement `std::error::Error` so we must also implement `std::fmt::Display` for it.
impl fmt::Display for ExitCode {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.0)
}
}
// And then we implement `std::error::Error`.
impl std::error::Error for ExitCode {}
// The host function that we'll use to terminate execution.
fn early_exit() {
// This is where it happens.
RuntimeError::raise(Box::new(ExitCode(1)));
}
fn main() -> anyhow::Result<()> {
// Let's declare the Wasm module with the text representation.
let wasm_bytes = wat2wasm(
br#"
(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)))
"#,
)?;
let store = Store::new(&JIT::new(&Cranelift::default()).engine());
let module = Module::new(&store, wasm_bytes)?;
let import_object = imports! {
"env" => {
"early_exit" => Function::new_native(&store, early_exit),
}
};
let instance = Instance::new(&module, &import_object)?;
// Get the `run` function which we'll use as our entrypoint.
let run_func: NativeFunc<(i32, i32), i32> =
instance.exports.get_native_function("run").unwrap();
// When we call a function it can either succeed or fail.
match run_func.call(1, 7) {
Ok(result) => {
bail!(
"Expected early termination with `ExitCode`, found: {}",
result
);
}
// We're expecting it to fail.
// We attempt to downcast the error into the error type that we were expecting.
Err(e) => match e.downcast::<ExitCode>() {
// We found the exit code used to terminate execution.
Ok(exit_code) => {
println!("Exited early with exit code: {}", exit_code);
Ok(())
}
Err(e) => {
bail!("Unknown error `{}` found. expected `ErrorCode`", e);
}
},
}
}

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@@ -27,7 +27,7 @@ use wasmer_engine_native::Native;
fn main() -> Result<(), Box<dyn std::error::Error>> {
// Let's declare the Wasm module with the text representation.
let wasm_bytes = wat2wasm(
r#"
br#"
(module
(type $sum_t (func (param i32 i32) (result i32)))
(func $sum_f (type $sum_t) (param $x i32) (param $y i32) (result i32)
@@ -35,8 +35,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
local.get $y
i32.add)
(export "sum" (func $sum_f)))
"#
.as_bytes(),
"#,
)?;
// Define a compiler configuration.

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@@ -21,9 +21,9 @@ use wasmer_engine_jit::JIT;
use wasmer_wasi::WasiState;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let wasm_path = format!(
"{}/tests/wasi-wast/wasi/unstable/hello.wasm",
std::env::var("CARGO_MANIFEST_DIR").unwrap()
let wasm_path = concat!(
env!("CARGO_MANIFEST_DIR"),
"/tests/wasi-wast/wasi/unstable/hello.wasm"
);
// Let's declare the Wasm module with the text representation.
let wasm_bytes = std::fs::read(wasm_path)?;

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@@ -70,8 +70,8 @@ pub use wasmer_compiler::{
};
pub use wasmer_compiler::{CpuFeature, Features, Target};
pub use wasmer_engine::{
ChainableNamedResolver, DeserializeError, Engine, InstantiationError, LinkError, NamedResolver,
NamedResolverChain, Resolver, RuntimeError, SerializeError,
ChainableNamedResolver, DeserializeError, Engine, FrameInfo, InstantiationError, LinkError,
NamedResolver, NamedResolverChain, Resolver, RuntimeError, SerializeError,
};
pub use wasmer_types::{
Atomically, Bytes, GlobalInit, LocalFunctionIndex, MemoryView, Pages, ValueType,

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@@ -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 {

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@@ -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)

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@@ -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)))

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@@ -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;
}

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@@ -282,7 +282,7 @@ pub fn register(
/// each frame is described by this structure.
///
/// [`Trap`]: crate::Trap
#[derive(Debug)]
#[derive(Debug, Clone)]
pub struct FrameInfo {
module_name: String,
func_index: u32,