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Allow wasm embedders to reject wasm modules with unsupported features. (#345)

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Define `WasmError` (and an accompanying `WasmResult`) to represent
errors translating WebAssembly functions. Make `translate_call` and
related functions return `WasmResult`s so that embedders have the
flexibility to reject features they don't support.

Move `InvalidInput` out of `CtonError` and into `WasmError`, where it's
now named `InvalidWebAssembly`, as it's a WebAssembly-specific error
condition. Also extend it to preserve the original error message and
bytecode offset.
This commit is contained in:
Dan Gohman
2018-05-21 20:49:19 -07:00
committed by GitHub
parent 923ea8ada9
commit 89e7d56120
11 changed files with 185 additions and 177 deletions
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34
lib/wasm/src/environ/dummy.rs
View File

@@ -4,7 +4,7 @@ use cretonne_codegen::cursor::FuncCursor;
use cretonne_codegen::ir::types::*;
use cretonne_codegen::ir::{self, InstBuilder};
use cretonne_codegen::settings;
use environ::{FuncEnvironment, GlobalValue, ModuleEnvironment};
use environ::{FuncEnvironment, GlobalValue, ModuleEnvironment, WasmResult};
use func_translator::FuncTranslator;
use std::string::String;
use std::vec::Vec;
@@ -196,7 +196,7 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
sig_ref: ir::SigRef,
callee: ir::Value,
call_args: &[ir::Value],
) -> ir::Inst {
) -> WasmResult<ir::Inst> {
// Pass the current function's vmctx parameter on to the callee.
let vmctx = pos.func
.special_param(ir::ArgumentPurpose::VMContext)
@@ -224,9 +224,11 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
args.extend(call_args.iter().cloned(), &mut pos.func.dfg.value_lists);
args.push(vmctx, &mut pos.func.dfg.value_lists);
pos.ins()
.CallIndirect(ir::Opcode::CallIndirect, VOID, sig_ref, args)
.0
Ok(
pos.ins()
.CallIndirect(ir::Opcode::CallIndirect, VOID, sig_ref, args)
.0,
)
}
fn translate_call(
@@ -235,7 +237,7 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
_callee_index: FunctionIndex,
callee: ir::FuncRef,
call_args: &[ir::Value],
) -> ir::Inst {
) -> WasmResult<ir::Inst> {
// Pass the current function's vmctx parameter on to the callee.
let vmctx = pos.func
.special_param(ir::ArgumentPurpose::VMContext)
@@ -247,7 +249,7 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
args.extend(call_args.iter().cloned(), &mut pos.func.dfg.value_lists);
args.push(vmctx, &mut pos.func.dfg.value_lists);
pos.ins().Call(ir::Opcode::Call, VOID, callee, args).0
Ok(pos.ins().Call(ir::Opcode::Call, VOID, callee, args).0)
}
fn translate_grow_memory(
@@ -256,8 +258,8 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
_index: MemoryIndex,
_heap: ir::Heap,
_val: ir::Value,
) -> ir::Value {
pos.ins().iconst(I32, -1)
) -> WasmResult<ir::Value> {
Ok(pos.ins().iconst(I32, -1))
}
fn translate_current_memory(
@@ -265,8 +267,8 @@ impl<'dummy_environment> FuncEnvironment for DummyFuncEnvironment<'dummy_environ
mut pos: FuncCursor,
_index: MemoryIndex,
_heap: ir::Heap,
) -> ir::Value {
pos.ins().iconst(I32, -1)
) -> WasmResult<ir::Value> {
Ok(pos.ins().iconst(I32, -1))
}
}
@@ -385,7 +387,7 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
self.info.start_func = Some(func_index);
}
fn define_function_body(&mut self, body_bytes: &'data [u8]) -> Result<(), String> {
fn define_function_body(&mut self, body_bytes: &'data [u8]) -> WasmResult<()> {
let func = {
let mut func_environ = DummyFuncEnvironment::new(&self.info);
let function_index = self.get_num_func_imports() + self.info.function_bodies.len();
@@ -393,9 +395,11 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
let sig = func_environ.vmctx_sig(self.get_func_type(function_index));
let mut func = ir::Function::with_name_signature(name, sig);
let reader = wasmparser::BinaryReader::new(body_bytes);
self.trans
.translate_from_reader(reader, &mut func, &mut func_environ)
.map_err(|e| format!("{}", e))?;
self.trans.translate_from_reader(
reader,
&mut func,
&mut func_environ,
)?;
func
};
self.func_bytecode_sizes.push(body_bytes.len());

2
lib/wasm/src/environ/mod.rs
View File

@@ -4,4 +4,4 @@ mod dummy;
mod spec;
pub use environ::dummy::DummyEnvironment;
pub use environ::spec::{FuncEnvironment, GlobalValue, ModuleEnvironment};
pub use environ::spec::{FuncEnvironment, GlobalValue, ModuleEnvironment, WasmError, WasmResult};

57
lib/wasm/src/environ/spec.rs
View File

@@ -3,10 +3,10 @@
use cretonne_codegen::cursor::FuncCursor;
use cretonne_codegen::ir::{self, InstBuilder};
use cretonne_codegen::settings::Flags;
use std::string::String;
use std::vec::Vec;
use translation_utils::{FunctionIndex, Global, GlobalIndex, Memory, MemoryIndex, SignatureIndex,
Table, TableIndex};
use wasmparser::BinaryReaderError;
/// The value of a WebAssembly global variable.
#[derive(Clone, Copy)]
@@ -23,6 +23,49 @@ pub enum GlobalValue {
},
}
/// A WebAssembly translation error.
///
/// When a WebAssembly function can't be translated, one of these error codes will be returned
/// to describe the failure.
#[derive(Fail, Debug, PartialEq, Eq)]
pub enum WasmError {
/// The input WebAssembly code is invalid.
///
/// This error code is used by a WebAssembly translator when it encounters invalid WebAssembly
/// code. This should never happen for validated WebAssembly code.
#[fail(display = "Invalid input WebAssembly code at offset {}: {}", _1, _0)]
InvalidWebAssembly {
message: &'static str,
offset: usize,
},
/// A feature used by the WebAssembly code is not supported by the embedding environment.
///
/// Embedding environments may have their own limitations and feature restrictions.
#[fail(display = "Unsupported feature: {}", _0)]
Unsupported(&'static str),
/// An implementation limit was exceeded.
///
/// Cretonne can compile very large and complicated functions, but the [implementation has
/// limits][limits] that cause compilation to fail when they are exceeded.
///
/// [limits]: https://cretonne.readthedocs.io/en/latest/langref.html#implementation-limits
#[fail(display = "Implementation limit exceeded")]
ImplLimitExceeded,
}
impl WasmError {
/// Convert from a `BinaryReaderError` to a `WasmError`.
pub fn from_binary_reader_error(e: BinaryReaderError) -> Self {
let BinaryReaderError { message, offset } = e;
WasmError::InvalidWebAssembly { message, offset }
}
}
/// A convenient alias for a `Result` that uses `WasmError` as the error type.
pub type WasmResult<T> = Result<T, WasmError>;
/// Environment affecting the translation of a single WebAssembly function.
///
/// A `FuncEnvironment` trait object is required to translate a WebAssembly function to Cretonne
@@ -99,7 +142,7 @@ pub trait FuncEnvironment {
sig_ref: ir::SigRef,
callee: ir::Value,
call_args: &[ir::Value],
) -> ir::Inst;
) -> WasmResult<ir::Inst>;
/// Translate a `call` WebAssembly instruction at `pos`.
///
@@ -114,8 +157,8 @@ pub trait FuncEnvironment {
_callee_index: FunctionIndex,
callee: ir::FuncRef,
call_args: &[ir::Value],
) -> ir::Inst {
pos.ins().call(callee, call_args)
) -> WasmResult<ir::Inst> {
Ok(pos.ins().call(callee, call_args))
}
/// Translate a `grow_memory` WebAssembly instruction.
@@ -132,7 +175,7 @@ pub trait FuncEnvironment {
index: MemoryIndex,
heap: ir::Heap,
val: ir::Value,
) -> ir::Value;
) -> WasmResult<ir::Value>;
/// Translates a `current_memory` WebAssembly instruction.
///
@@ -145,7 +188,7 @@ pub trait FuncEnvironment {
pos: FuncCursor,
index: MemoryIndex,
heap: ir::Heap,
) -> ir::Value;
) -> WasmResult<ir::Value>;
/// Emit code at the beginning of every wasm loop.
///
@@ -229,5 +272,5 @@ pub trait ModuleEnvironment<'data> {
fn declare_start_func(&mut self, index: FunctionIndex);
/// Provides the contents of a function body.
fn define_function_body(&mut self, body_bytes: &'data [u8]) -> Result<(), String>;
fn define_function_body(&mut self, body_bytes: &'data [u8]) -> WasmResult<()>;
}