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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/wasm/module-decoder.h"
#include "src/base/functional.h"
#include "src/base/platform/platform.h"
#include "src/base/platform/wrappers.h"
#include "src/flags/flags.h"
#include "src/init/v8.h"
#include "src/logging/counters.h"
#include "src/logging/metrics.h"
#include "src/objects/objects-inl.h"
#include "src/utils/ostreams.h"
#include "src/wasm/decoder.h"
#include "src/wasm/function-body-decoder-impl.h"
#include "src/wasm/init-expr-interface.h"
#include "src/wasm/struct-types.h"
#include "src/wasm/wasm-constants.h"
#include "src/wasm/wasm-engine.h"
#include "src/wasm/wasm-limits.h"
#include "src/wasm/wasm-opcodes-inl.h"
namespace v8 {
namespace internal {
namespace wasm {
#define TRACE(...) \
do { \
if (FLAG_trace_wasm_decoder) PrintF(__VA_ARGS__); \
} while (false)
namespace {
constexpr char kNameString[] = "name";
constexpr char kSourceMappingURLString[] = "sourceMappingURL";
constexpr char kCompilationHintsString[] = "compilationHints";
constexpr char kBranchHintsString[] = "branchHints";
constexpr char kDebugInfoString[] = ".debug_info";
constexpr char kExternalDebugInfoString[] = "external_debug_info";
const char* ExternalKindName(ImportExportKindCode kind) {
switch (kind) {
case kExternalFunction:
return "function";
case kExternalTable:
return "table";
case kExternalMemory:
return "memory";
case kExternalGlobal:
return "global";
case kExternalTag:
return "tag";
}
return "unknown";
}
} // namespace
const char* SectionName(SectionCode code) {
switch (code) {
case kUnknownSectionCode:
return "Unknown";
case kTypeSectionCode:
return "Type";
case kImportSectionCode:
return "Import";
case kFunctionSectionCode:
return "Function";
case kTableSectionCode:
return "Table";
case kMemorySectionCode:
return "Memory";
case kGlobalSectionCode:
return "Global";
case kExportSectionCode:
return "Export";
case kStartSectionCode:
return "Start";
case kCodeSectionCode:
return "Code";
case kElementSectionCode:
return "Element";
case kDataSectionCode:
return "Data";
case kTagSectionCode:
return "Tag";
case kDataCountSectionCode:
return "DataCount";
case kNameSectionCode:
return kNameString;
case kSourceMappingURLSectionCode:
return kSourceMappingURLString;
case kDebugInfoSectionCode:
return kDebugInfoString;
case kExternalDebugInfoSectionCode:
return kExternalDebugInfoString;
case kCompilationHintsSectionCode:
return kCompilationHintsString;
case kBranchHintsSectionCode:
return kBranchHintsString;
default:
return "<unknown>";
}
}
namespace {
bool validate_utf8(Decoder* decoder, WireBytesRef string) {
return unibrow::Utf8::ValidateEncoding(
decoder->start() + decoder->GetBufferRelativeOffset(string.offset()),
string.length());
}
// Reads a length-prefixed string, checking that it is within bounds. Returns
// the offset of the string, and the length as an out parameter.
WireBytesRef consume_string(Decoder* decoder, bool validate_utf8,
const char* name) {
uint32_t length = decoder->consume_u32v("string length");
uint32_t offset = decoder->pc_offset();
const byte* string_start = decoder->pc();
// Consume bytes before validation to guarantee that the string is not oob.
if (length > 0) {
decoder->consume_bytes(length, name);
if (decoder->ok() && validate_utf8 &&
!unibrow::Utf8::ValidateEncoding(string_start, length)) {
decoder->errorf(string_start, "%s: no valid UTF-8 string", name);
}
}
return {offset, decoder->failed() ? 0 : length};
}
namespace {
SectionCode IdentifyUnknownSectionInternal(Decoder* decoder) {
WireBytesRef string = consume_string(decoder, true, "section name");
if (decoder->failed()) {
return kUnknownSectionCode;
}
const byte* section_name_start =
decoder->start() + decoder->GetBufferRelativeOffset(string.offset());
TRACE(" +%d section name : \"%.*s\"\n",
static_cast<int>(section_name_start - decoder->start()),
string.length() < 20 ? string.length() : 20, section_name_start);
using SpecialSectionPair = std::pair<base::Vector<const char>, SectionCode>;
static constexpr SpecialSectionPair kSpecialSections[]{
{base::StaticCharVector(kNameString), kNameSectionCode},
{base::StaticCharVector(kSourceMappingURLString),
kSourceMappingURLSectionCode},
{base::StaticCharVector(kCompilationHintsString),
kCompilationHintsSectionCode},
{base::StaticCharVector(kBranchHintsString), kBranchHintsSectionCode},
{base::StaticCharVector(kDebugInfoString), kDebugInfoSectionCode},
{base::StaticCharVector(kExternalDebugInfoString),
kExternalDebugInfoSectionCode}};
auto name_vec = base::Vector<const char>::cast(
base::VectorOf(section_name_start, string.length()));
for (auto& special_section : kSpecialSections) {
if (name_vec == special_section.first) return special_section.second;
}
return kUnknownSectionCode;
}
} // namespace
// An iterator over the sections in a wasm binary module.
// Automatically skips all unknown sections.
class WasmSectionIterator {
public:
explicit WasmSectionIterator(Decoder* decoder)
: decoder_(decoder),
section_code_(kUnknownSectionCode),
section_start_(decoder->pc()),
section_end_(decoder->pc()) {
next();
}
bool more() const { return decoder_->ok() && decoder_->more(); }
SectionCode section_code() const { return section_code_; }
const byte* section_start() const { return section_start_; }
uint32_t section_length() const {
return static_cast<uint32_t>(section_end_ - section_start_);
}
base::Vector<const uint8_t> payload() const {
return {payload_start_, payload_length()};
}
const byte* payload_start() const { return payload_start_; }
uint32_t payload_length() const {
return static_cast<uint32_t>(section_end_ - payload_start_);
}
const byte* section_end() const { return section_end_; }
// Advances to the next section, checking that decoding the current section
// stopped at {section_end_}.
void advance(bool move_to_section_end = false) {
if (move_to_section_end && decoder_->pc() < section_end_) {
decoder_->consume_bytes(
static_cast<uint32_t>(section_end_ - decoder_->pc()));
}
if (decoder_->pc() != section_end_) {
const char* msg = decoder_->pc() < section_end_ ? "shorter" : "longer";
decoder_->errorf(decoder_->pc(),
"section was %s than expected size "
"(%u bytes expected, %zu decoded)",
msg, section_length(),
static_cast<size_t>(decoder_->pc() - section_start_));
}
next();
}
private:
Decoder* decoder_;
SectionCode section_code_;
const byte* section_start_;
const byte* payload_start_;
const byte* section_end_;
// Reads the section code/name at the current position and sets up
// the embedder fields.
void next() {
if (!decoder_->more()) {
section_code_ = kUnknownSectionCode;
return;
}
section_start_ = decoder_->pc();
uint8_t section_code = decoder_->consume_u8("section code");
// Read and check the section size.
uint32_t section_length = decoder_->consume_u32v("section length");
payload_start_ = decoder_->pc();
if (decoder_->checkAvailable(section_length)) {
// Get the limit of the section within the module.
section_end_ = payload_start_ + section_length;
} else {
// The section would extend beyond the end of the module.
section_end_ = payload_start_;
}
if (section_code == kUnknownSectionCode) {
// Check for the known "name", "sourceMappingURL", or "compilationHints"
// section.
// To identify the unknown section we set the end of the decoder bytes to
// the end of the custom section, so that we do not read the section name
// beyond the end of the section.
const byte* module_end = decoder_->end();
decoder_->set_end(section_end_);
section_code = IdentifyUnknownSectionInternal(decoder_);
if (decoder_->ok()) decoder_->set_end(module_end);
// As a side effect, the above function will forward the decoder to after
// the identifier string.
payload_start_ = decoder_->pc();
} else if (!IsValidSectionCode(section_code)) {
decoder_->errorf(decoder_->pc(), "unknown section code #0x%02x",
section_code);
section_code = kUnknownSectionCode;
}
section_code_ = decoder_->failed() ? kUnknownSectionCode
: static_cast<SectionCode>(section_code);
if (section_code_ == kUnknownSectionCode && section_end_ > decoder_->pc()) {
// skip to the end of the unknown section.
uint32_t remaining = static_cast<uint32_t>(section_end_ - decoder_->pc());
decoder_->consume_bytes(remaining, "section payload");
}
}
};
} // namespace
// The main logic for decoding the bytes of a module.
class ModuleDecoderImpl : public Decoder {
public:
explicit ModuleDecoderImpl(const WasmFeatures& enabled, ModuleOrigin origin)
: Decoder(nullptr, nullptr),
enabled_features_(enabled),
origin_(origin) {}
ModuleDecoderImpl(const WasmFeatures& enabled, const byte* module_start,
const byte* module_end, ModuleOrigin origin)
: Decoder(module_start, module_end),
enabled_features_(enabled),
module_start_(module_start),
module_end_(module_end),
origin_(origin) {
if (end_ < start_) {
error(start_, "end is less than start");
end_ = start_;
}
}
void onFirstError() override {
pc_ = end_; // On error, terminate section decoding loop.
}
void DumpModule(const base::Vector<const byte> module_bytes) {
std::string path;
if (FLAG_dump_wasm_module_path) {
path = FLAG_dump_wasm_module_path;
if (path.size() &&
!base::OS::isDirectorySeparator(path[path.size() - 1])) {
path += base::OS::DirectorySeparator();
}
}
// File are named `HASH.{ok,failed}.wasm`.
size_t hash = base::hash_range(module_bytes.begin(), module_bytes.end());
base::EmbeddedVector<char, 32> buf;
SNPrintF(buf, "%016zx.%s.wasm", hash, ok() ? "ok" : "failed");
path += buf.begin();
size_t rv = 0;
if (FILE* file = base::OS::FOpen(path.c_str(), "wb")) {
rv = fwrite(module_bytes.begin(), module_bytes.length(), 1, file);
base::Fclose(file);
}
if (rv != 1) {
OFStream os(stderr);
os << "Error while dumping wasm file to " << path << std::endl;
}
}
void StartDecoding(Counters* counters, AccountingAllocator* allocator) {
CHECK_NULL(module_);
SetCounters(counters);
module_.reset(
new WasmModule(std::make_unique<Zone>(allocator, "signatures")));
module_->initial_pages = 0;
module_->maximum_pages = 0;
module_->mem_export = false;
module_->origin = origin_;
}
void DecodeModuleHeader(base::Vector<const uint8_t> bytes, uint8_t offset) {
if (failed()) return;
Reset(bytes, offset);
const byte* pos = pc_;
uint32_t magic_word = consume_u32("wasm magic");
#define BYTES(x) (x & 0xFF), (x >> 8) & 0xFF, (x >> 16) & 0xFF, (x >> 24) & 0xFF
if (magic_word != kWasmMagic) {
errorf(pos,
"expected magic word %02x %02x %02x %02x, "
"found %02x %02x %02x %02x",
BYTES(kWasmMagic), BYTES(magic_word));
}
pos = pc_;
{
uint32_t magic_version = consume_u32("wasm version");
if (magic_version != kWasmVersion) {
errorf(pos,
"expected version %02x %02x %02x %02x, "
"found %02x %02x %02x %02x",
BYTES(kWasmVersion), BYTES(magic_version));
}
}
#undef BYTES
}
bool CheckSectionOrder(SectionCode section_code,
SectionCode prev_section_code,
SectionCode next_section_code) {
if (next_ordered_section_ > next_section_code) {
errorf(pc(), "The %s section must appear before the %s section",
SectionName(section_code), SectionName(next_section_code));
return false;
}
if (next_ordered_section_ <= prev_section_code) {
next_ordered_section_ = prev_section_code + 1;
}
return true;
}
bool CheckUnorderedSection(SectionCode section_code) {
if (has_seen_unordered_section(section_code)) {
errorf(pc(), "Multiple %s sections not allowed",
SectionName(section_code));
return false;
}
set_seen_unordered_section(section_code);
return true;
}
void DecodeSection(SectionCode section_code,
base::Vector<const uint8_t> bytes, uint32_t offset,
bool verify_functions = true) {
if (failed()) return;
Reset(bytes, offset);
TRACE("Section: %s\n", SectionName(section_code));
TRACE("Decode Section %p - %p\n", bytes.begin(), bytes.end());
// Check if the section is out-of-order.
if (section_code < next_ordered_section_ &&
section_code < kFirstUnorderedSection) {
errorf(pc(), "unexpected section <%s>", SectionName(section_code));
return;
}
switch (section_code) {
case kUnknownSectionCode:
break;
case kDataCountSectionCode:
if (!CheckUnorderedSection(section_code)) return;
if (!CheckSectionOrder(section_code, kElementSectionCode,
kCodeSectionCode))
return;
break;
case kTagSectionCode:
if (!CheckUnorderedSection(section_code)) return;
if (!CheckSectionOrder(section_code, kMemorySectionCode,
kGlobalSectionCode))
return;
break;
case kNameSectionCode:
// TODO(titzer): report out of place name section as a warning.
// Be lenient with placement of name section. All except first
// occurrence are ignored.
case kSourceMappingURLSectionCode:
// sourceMappingURL is a custom section and currently can occur anywhere
// in the module. In case of multiple sourceMappingURL sections, all
// except the first occurrence are ignored.
case kDebugInfoSectionCode:
// .debug_info is a custom section containing core DWARF information
// if produced by compiler. Its presence likely means that Wasm was
// built in a debug mode.
case kExternalDebugInfoSectionCode:
// external_debug_info is a custom section containing a reference to an
// external symbol file.
case kCompilationHintsSectionCode:
// TODO(frgossen): report out of place compilation hints section as a
// warning.
// Be lenient with placement of compilation hints section. All except
// first occurrence after function section and before code section are
// ignored.
break;
case kBranchHintsSectionCode:
// TODO(yuri): report out of place branch hints section as a
// warning.
// Be lenient with placement of compilation hints section. All except
// first occurrence after function section and before code section are
// ignored.
break;
default:
next_ordered_section_ = section_code + 1;
break;
}
switch (section_code) {
case kUnknownSectionCode:
break;
case kTypeSectionCode:
DecodeTypeSection();
break;
case kImportSectionCode:
DecodeImportSection();
break;
case kFunctionSectionCode:
DecodeFunctionSection();
break;
case kTableSectionCode:
DecodeTableSection();
break;
case kMemorySectionCode:
DecodeMemorySection();
break;
case kGlobalSectionCode:
DecodeGlobalSection();
break;
case kExportSectionCode:
DecodeExportSection();
break;
case kStartSectionCode:
DecodeStartSection();
break;
case kCodeSectionCode:
DecodeCodeSection(verify_functions);
break;
case kElementSectionCode:
DecodeElementSection();
break;
case kDataSectionCode:
DecodeDataSection();
break;
case kNameSectionCode:
DecodeNameSection();
break;
case kSourceMappingURLSectionCode:
DecodeSourceMappingURLSection();
break;
case kDebugInfoSectionCode:
// If there is an explicit source map, prefer it over DWARF info.
if (module_->debug_symbols.type == WasmDebugSymbols::Type::None) {
module_->debug_symbols = {WasmDebugSymbols::Type::EmbeddedDWARF, {}};
}
consume_bytes(static_cast<uint32_t>(end_ - start_), ".debug_info");
break;
case kExternalDebugInfoSectionCode:
DecodeExternalDebugInfoSection();
break;
case kCompilationHintsSectionCode:
if (enabled_features_.has_compilation_hints()) {
DecodeCompilationHintsSection();
} else {
// Ignore this section when feature was disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kBranchHintsSectionCode:
if (enabled_features_.has_branch_hinting()) {
DecodeBranchHintsSection();
} else {
// Ignore this section when feature was disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kDataCountSectionCode:
DecodeDataCountSection();
break;
case kTagSectionCode:
if (enabled_features_.has_eh()) {
DecodeTagSection();
} else {
errorf(pc(),
"unexpected section <%s> (enable with --experimental-wasm-eh)",
SectionName(section_code));
}
break;
default:
errorf(pc(), "unexpected section <%s>", SectionName(section_code));
return;
}
if (pc() != bytes.end()) {
const char* msg = pc() < bytes.end() ? "shorter" : "longer";
errorf(pc(),
"section was %s than expected size "
"(%zu bytes expected, %zu decoded)",
msg, bytes.size(), static_cast<size_t>(pc() - bytes.begin()));
}
}
void DecodeTypeSection() {
uint32_t signatures_count = consume_count("types count", kV8MaxWasmTypes);
module_->types.reserve(signatures_count);
for (uint32_t i = 0; ok() && i < signatures_count; ++i) {
TRACE("DecodeSignature[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
uint8_t kind = consume_u8("type kind");
switch (kind) {
case kWasmFunctionTypeCode: {
const FunctionSig* s = consume_sig(module_->signature_zone.get());
module_->add_signature(s);
break;
}
case kWasmFunctionExtendingTypeCode: {
if (!enabled_features_.has_gc_experiments()) {
errorf(pc(),
"nominal types need --experimental-wasm-gc-experiments");
break;
}
const FunctionSig* s = consume_sig(module_->signature_zone.get());
module_->add_signature(s);
uint32_t super_index = consume_u32v("supertype");
if (!module_->has_signature(super_index)) {
errorf(pc(), "invalid function supertype index: %d", super_index);
break;
}
break;
}
case kWasmStructTypeCode: {
if (!enabled_features_.has_gc()) {
errorf(pc(),
"invalid struct type definition, enable with "
"--experimental-wasm-gc");
break;
}
const StructType* s = consume_struct(module_->signature_zone.get());
module_->add_struct_type(s);
// TODO(7748): Should we canonicalize struct types, like
// {signature_map} does for function signatures?
break;
}
case kWasmStructExtendingTypeCode: {
if (!enabled_features_.has_gc_experiments()) {
errorf(pc(),
"nominal types need --experimental-wasm-gc-experiments");
break;
}
const StructType* s = consume_struct(module_->signature_zone.get());
module_->add_struct_type(s);
uint32_t super_index = consume_u32v("supertype");
if (!module_->has_struct(super_index)) {
errorf(pc(), "invalid struct supertype: %d", super_index);
break;
}
break;
}
case kWasmArrayTypeCode: {
if (!enabled_features_.has_gc()) {
errorf(pc(),
"invalid array type definition, enable with "
"--experimental-wasm-gc");
break;
}
const ArrayType* type = consume_array(module_->signature_zone.get());
module_->add_array_type(type);
break;
}
case kWasmArrayExtendingTypeCode: {
if (!enabled_features_.has_gc_experiments()) {
errorf(pc(),
"nominal types need --experimental-wasm-gc-experiments");
break;
}
const ArrayType* type = consume_array(module_->signature_zone.get());
module_->add_array_type(type);
uint32_t super_index = consume_u32v("supertype");
if (!module_->has_array(super_index)) {
errorf(pc(), "invalid array supertype: %d", super_index);
break;
}
break;
}
default:
errorf(pc(), "unknown type form: %d", kind);
break;
}
}
module_->signature_map.Freeze();
}
void DecodeImportSection() {
uint32_t import_table_count =
consume_count("imports count", kV8MaxWasmImports);
module_->import_table.reserve(import_table_count);
for (uint32_t i = 0; ok() && i < import_table_count; ++i) {
TRACE("DecodeImportTable[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
module_->import_table.push_back({
{0, 0}, // module_name
{0, 0}, // field_name
kExternalFunction, // kind
0 // index
});
WasmImport* import = &module_->import_table.back();
const byte* pos = pc_;
import->module_name = consume_string(this, true, "module name");
import->field_name = consume_string(this, true, "field name");
import->kind =
static_cast<ImportExportKindCode>(consume_u8("import kind"));
switch (import->kind) {
case kExternalFunction: {
// ===== Imported function ===========================================
import->index = static_cast<uint32_t>(module_->functions.size());
module_->num_imported_functions++;
module_->functions.push_back({nullptr, // sig
import->index, // func_index
0, // sig_index
{0, 0}, // code
true, // imported
false, // exported
false}); // declared
WasmFunction* function = &module_->functions.back();
function->sig_index =
consume_sig_index(module_.get(), &function->sig);
break;
}
case kExternalTable: {
// ===== Imported table ==============================================
if (!AddTable(module_.get())) break;
import->index = static_cast<uint32_t>(module_->tables.size());
module_->num_imported_tables++;
module_->tables.emplace_back();
WasmTable* table = &module_->tables.back();
table->imported = true;
const byte* type_position = pc();
ValueType type = consume_reference_type();
if (!WasmTable::IsValidTableType(type, module_.get())) {
error(
type_position,
"Currently, only externref and function references are allowed "
"as table types");
break;
}
table->type = type;
uint8_t flags = validate_table_flags("element count");
consume_resizable_limits(
"element count", "elements", std::numeric_limits<uint32_t>::max(),
&table->initial_size, &table->has_maximum_size,
std::numeric_limits<uint32_t>::max(), &table->maximum_size,
flags);
break;
}
case kExternalMemory: {
// ===== Imported memory =============================================
if (!AddMemory(module_.get())) break;
uint8_t flags = validate_memory_flags(&module_->has_shared_memory,
&module_->is_memory64);
consume_resizable_limits(
"memory", "pages", kSpecMaxMemoryPages, &module_->initial_pages,
&module_->has_maximum_pages, kSpecMaxMemoryPages,
&module_->maximum_pages, flags);
break;
}
case kExternalGlobal: {
// ===== Imported global =============================================
import->index = static_cast<uint32_t>(module_->globals.size());
module_->globals.push_back({kWasmVoid, false, {}, {0}, true, false});
WasmGlobal* global = &module_->globals.back();
global->type = consume_value_type();
global->mutability = consume_mutability();
if (global->mutability) {
module_->num_imported_mutable_globals++;
}
break;
}
case kExternalTag: {
// ===== Imported tag ================================================
if (!enabled_features_.has_eh()) {
errorf(pos, "unknown import kind 0x%02x", import->kind);
break;
}
import->index = static_cast<uint32_t>(module_->tags.size());
const WasmTagSig* tag_sig = nullptr;
consume_exception_attribute(); // Attribute ignored for now.
consume_tag_sig_index(module_.get(), &tag_sig);
module_->tags.emplace_back(tag_sig);
break;
}
default:
errorf(pos, "unknown import kind 0x%02x", import->kind);
break;
}
}
}
void DecodeFunctionSection() {
uint32_t functions_count =
consume_count("functions count", kV8MaxWasmFunctions);
auto counter =
SELECT_WASM_COUNTER(GetCounters(), origin_, wasm_functions_per, module);
counter->AddSample(static_cast<int>(functions_count));
DCHECK_EQ(module_->functions.size(), module_->num_imported_functions);
uint32_t total_function_count =
module_->num_imported_functions + functions_count;
module_->functions.reserve(total_function_count);
module_->num_declared_functions = functions_count;
for (uint32_t i = 0; i < functions_count; ++i) {
uint32_t func_index = static_cast<uint32_t>(module_->functions.size());
module_->functions.push_back({nullptr, // sig
func_index, // func_index
0, // sig_index
{0, 0}, // code
false, // imported
false, // exported
false}); // declared
WasmFunction* function = &module_->functions.back();
function->sig_index = consume_sig_index(module_.get(), &function->sig);
if (!ok()) return;
}
DCHECK_EQ(module_->functions.size(), total_function_count);
}
void DecodeTableSection() {
// TODO(ahaas): Set the correct limit to {kV8MaxWasmTables} once the
// implementation of ExternRef landed.
uint32_t max_count =
enabled_features_.has_reftypes() ? 100000 : kV8MaxWasmTables;
uint32_t table_count = consume_count("table count", max_count);
for (uint32_t i = 0; ok() && i < table_count; i++) {
if (!AddTable(module_.get())) break;
module_->tables.emplace_back();
WasmTable* table = &module_->tables.back();
const byte* type_position = pc();
ValueType table_type = consume_reference_type();
if (!WasmTable::IsValidTableType(table_type, module_.get())) {
error(type_position,
"Currently, only externref and function references are allowed "
"as table types");
continue;
}
table->type = table_type;
uint8_t flags = validate_table_flags("table elements");
consume_resizable_limits(
"table elements", "elements", std::numeric_limits<uint32_t>::max(),
&table->initial_size, &table->has_maximum_size,
std::numeric_limits<uint32_t>::max(), &table->maximum_size, flags);
if (!table_type.is_defaultable()) {
table->initial_value = consume_init_expr(module_.get(), table_type);
}
}
}
void DecodeMemorySection() {
uint32_t memory_count = consume_count("memory count", kV8MaxWasmMemories);
for (uint32_t i = 0; ok() && i < memory_count; i++) {
if (!AddMemory(module_.get())) break;
uint8_t flags = validate_memory_flags(&module_->has_shared_memory,
&module_->is_memory64);
consume_resizable_limits("memory", "pages", kSpecMaxMemoryPages,
&module_->initial_pages,
&module_->has_maximum_pages, kSpecMaxMemoryPages,
&module_->maximum_pages, flags);
}
}
void DecodeGlobalSection() {
uint32_t globals_count = consume_count("globals count", kV8MaxWasmGlobals);
uint32_t imported_globals = static_cast<uint32_t>(module_->globals.size());
module_->globals.reserve(imported_globals + globals_count);
for (uint32_t i = 0; ok() && i < globals_count; ++i) {
TRACE("DecodeGlobal[%d] module+%d\n", i, static_cast<int>(pc_ - start_));
ValueType type = consume_value_type();
bool mutability = consume_mutability();
if (failed()) break;
WireBytesRef init = consume_init_expr(module_.get(), type);
module_->globals.push_back({type, mutability, init, {0}, false, false});
}
if (ok()) CalculateGlobalOffsets(module_.get());
}
void DecodeExportSection() {
uint32_t export_table_count =
consume_count("exports count", kV8MaxWasmExports);
module_->export_table.reserve(export_table_count);
for (uint32_t i = 0; ok() && i < export_table_count; ++i) {
TRACE("DecodeExportTable[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
module_->export_table.push_back({
{0, 0}, // name
kExternalFunction, // kind
0 // index
});
WasmExport* exp = &module_->export_table.back();
exp->name = consume_string(this, true, "field name");
const byte* pos = pc();
exp->kind = static_cast<ImportExportKindCode>(consume_u8("export kind"));
switch (exp->kind) {
case kExternalFunction: {
WasmFunction* func = nullptr;
exp->index =
consume_func_index(module_.get(), &func, "export function index");
if (failed()) break;
DCHECK_NOT_NULL(func);
module_->num_exported_functions++;
func->exported = true;
// Exported functions are considered "declared".
func->declared = true;
break;
}
case kExternalTable: {
WasmTable* table = nullptr;
exp->index = consume_table_index(module_.get(), &table);
if (table) table->exported = true;
break;
}
case kExternalMemory: {
uint32_t index = consume_u32v("memory index");
// TODO(titzer): This should become more regular
// once we support multiple memories.
if (!module_->has_memory || index != 0) {
error("invalid memory index != 0");
}
module_->mem_export = true;
break;
}
case kExternalGlobal: {
WasmGlobal* global = nullptr;
exp->index = consume_global_index(module_.get(), &global);
if (global) {
global->exported = true;
}
break;
}
case kExternalTag: {
if (!enabled_features_.has_eh()) {
errorf(pos, "invalid export kind 0x%02x", exp->kind);
break;
}
WasmTag* tag = nullptr;
exp->index = consume_tag_index(module_.get(), &tag);
break;
}
default:
errorf(pos, "invalid export kind 0x%02x", exp->kind);
break;
}
}
// Check for duplicate exports (except for asm.js).
if (ok() && origin_ == kWasmOrigin && module_->export_table.size() > 1) {
std::vector<WasmExport> sorted_exports(module_->export_table);
auto cmp_less = [this](const WasmExport& a, const WasmExport& b) {
// Return true if a < b.
if (a.name.length() != b.name.length()) {
return a.name.length() < b.name.length();
}
const byte* left = start() + GetBufferRelativeOffset(a.name.offset());
const byte* right = start() + GetBufferRelativeOffset(b.name.offset());
return memcmp(left, right, a.name.length()) < 0;
};
std::stable_sort(sorted_exports.begin(), sorted_exports.end(), cmp_less);
auto it = sorted_exports.begin();
WasmExport* last = &*it++;
for (auto end = sorted_exports.end(); it != end; last = &*it++) {
DCHECK(!cmp_less(*it, *last)); // Vector must be sorted.
if (!cmp_less(*last, *it)) {
const byte* pc = start() + GetBufferRelativeOffset(it->name.offset());
TruncatedUserString<> name(pc, it->name.length());
errorf(pc, "Duplicate export name '%.*s' for %s %d and %s %d",
name.length(), name.start(), ExternalKindName(last->kind),
last->index, ExternalKindName(it->kind), it->index);
break;
}
}
}
}
void DecodeStartSection() {
WasmFunction* func;
const byte* pos = pc_;
module_->start_function_index =
consume_func_index(module_.get(), &func, "start function index");
if (func &&
(func->sig->parameter_count() > 0 || func->sig->return_count() > 0)) {
error(pos, "invalid start function: non-zero parameter or return count");
}
}
void DecodeElementSection() {
uint32_t element_count =
consume_count("element count", FLAG_wasm_max_table_size);
for (uint32_t i = 0; i < element_count; ++i) {
bool expressions_as_elements;
WasmElemSegment segment =
consume_element_segment_header(&expressions_as_elements);
if (failed()) return;
DCHECK_NE(segment.type, kWasmBottom);
uint32_t num_elem =
consume_count("number of elements", max_table_init_entries());
for (uint32_t j = 0; j < num_elem; j++) {
WasmElemSegment::Entry init =
expressions_as_elements
? consume_element_expr()
: WasmElemSegment::Entry(WasmElemSegment::Entry::kRefFuncEntry,
consume_element_func_index());
if (failed()) return;
if (!IsSubtypeOf(TypeOf(init), segment.type, module_.get())) {
errorf(pc_,
"Invalid type in the init expression. The expected type is "
"'%s', but the actual type is '%s'.",
segment.type.name().c_str(), TypeOf(init).name().c_str());
return;
}
segment.entries.push_back(init);
}
module_->elem_segments.push_back(std::move(segment));
}
}
void DecodeCodeSection(bool verify_functions) {
StartCodeSection();
uint32_t code_section_start = pc_offset();
uint32_t functions_count = consume_u32v("functions count");
CheckFunctionsCount(functions_count, code_section_start);
for (uint32_t i = 0; ok() && i < functions_count; ++i) {
const byte* pos = pc();
uint32_t size = consume_u32v("body size");
if (size > kV8MaxWasmFunctionSize) {
errorf(pos, "size %u > maximum function size %zu", size,
kV8MaxWasmFunctionSize);
return;
}
uint32_t offset = pc_offset();
consume_bytes(size, "function body");
if (failed()) break;
DecodeFunctionBody(i, size, offset, verify_functions);
}
DCHECK_GE(pc_offset(), code_section_start);
set_code_section(code_section_start, pc_offset() - code_section_start);
}
void StartCodeSection() {
if (ok()) {
// Make sure global offset were calculated before they get accessed during
// function compilation.
CalculateGlobalOffsets(module_.get());
}
}
bool CheckFunctionsCount(uint32_t functions_count, uint32_t error_offset) {
if (functions_count != module_->num_declared_functions) {
errorf(error_offset, "function body count %u mismatch (%u expected)",
functions_count, module_->num_declared_functions);
return false;
}
return true;
}
void DecodeFunctionBody(uint32_t index, uint32_t length, uint32_t offset,
bool verify_functions) {
WasmFunction* function =
&module_->functions[index + module_->num_imported_functions];
function->code = {offset, length};
if (verify_functions) {
ModuleWireBytes bytes(module_start_, module_end_);
VerifyFunctionBody(module_->signature_zone->allocator(),
index + module_->num_imported_functions, bytes,
module_.get(), function);
}
}
bool CheckDataSegmentsCount(uint32_t data_segments_count) {
if (has_seen_unordered_section(kDataCountSectionCode) &&
data_segments_count != module_->num_declared_data_segments) {
errorf(pc(), "data segments count %u mismatch (%u expected)",
data_segments_count, module_->num_declared_data_segments);
return false;
}
return true;
}
void DecodeDataSection() {
uint32_t data_segments_count =
consume_count("data segments count", kV8MaxWasmDataSegments);
if (!CheckDataSegmentsCount(data_segments_count)) return;
module_->data_segments.reserve(data_segments_count);
for (uint32_t i = 0; ok() && i < data_segments_count; ++i) {
const byte* pos = pc();
TRACE("DecodeDataSegment[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
bool is_active;
uint32_t memory_index;
WireBytesRef dest_addr;
consume_data_segment_header(&is_active, &memory_index, &dest_addr);
if (failed()) break;
if (is_active) {
if (!module_->has_memory) {
error("cannot load data without memory");
break;
}
if (memory_index != 0) {
errorf(pos, "illegal memory index %u != 0", memory_index);
break;
}
}
uint32_t source_length = consume_u32v("source size");
uint32_t source_offset = pc_offset();
if (is_active) {
module_->data_segments.emplace_back(std::move(dest_addr));
} else {
module_->data_segments.emplace_back();
}
WasmDataSegment* segment = &module_->data_segments.back();
consume_bytes(source_length, "segment data");
if (failed()) break;
segment->source = {source_offset, source_length};
}
}
void DecodeNameSection() {
// TODO(titzer): find a way to report name errors as warnings.
// Ignore all but the first occurrence of name section.
if (!has_seen_unordered_section(kNameSectionCode)) {
set_seen_unordered_section(kNameSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
// Decode all name subsections.
// Be lenient with their order.
while (inner.ok() && inner.more()) {
uint8_t name_type = inner.consume_u8("name type");
if (name_type & 0x80) inner.error("name type if not varuint7");
uint32_t name_payload_len = inner.consume_u32v("name payload length");
if (!inner.checkAvailable(name_payload_len)) break;
// Decode module name, ignore the rest.
// Function and local names will be decoded when needed.
if (name_type == NameSectionKindCode::kModule) {
WireBytesRef name = consume_string(&inner, false, "module name");
if (inner.ok() && validate_utf8(&inner, name)) {
module_->name = name;
}
} else {
inner.consume_bytes(name_payload_len, "name subsection payload");
}
}
}
// Skip the whole names section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeSourceMappingURLSection() {
Decoder inner(start_, pc_, end_, buffer_offset_);
WireBytesRef url = wasm::consume_string(&inner, true, "module name");
if (inner.ok() &&
module_->debug_symbols.type != WasmDebugSymbols::Type::SourceMap) {
module_->debug_symbols = {WasmDebugSymbols::Type::SourceMap, url};
}
set_seen_unordered_section(kSourceMappingURLSectionCode);
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeExternalDebugInfoSection() {
Decoder inner(start_, pc_, end_, buffer_offset_);
WireBytesRef url =
wasm::consume_string(&inner, true, "external symbol file");
// If there is an explicit source map, prefer it over DWARF info.
if (inner.ok() &&
module_->debug_symbols.type != WasmDebugSymbols::Type::SourceMap) {
module_->debug_symbols = {WasmDebugSymbols::Type::ExternalDWARF, url};
set_seen_unordered_section(kExternalDebugInfoSectionCode);
}
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeCompilationHintsSection() {
TRACE("DecodeCompilationHints module+%d\n", static_cast<int>(pc_ - start_));
// TODO(frgossen): Find a way to report compilation hint errors as warnings.
// All except first occurrence after function section and before code
// section are ignored.
const bool before_function_section =
next_ordered_section_ <= kFunctionSectionCode;
const bool after_code_section = next_ordered_section_ > kCodeSectionCode;
if (before_function_section || after_code_section ||
has_seen_unordered_section(kCompilationHintsSectionCode)) {
return;
}
set_seen_unordered_section(kCompilationHintsSectionCode);
// TODO(frgossen) Propagate errors to outer decoder in experimental phase.
// We should use an inner decoder later and propagate its errors as
// warnings.
Decoder& decoder = *this;
// Decoder decoder(start_, pc_, end_, buffer_offset_);
// Ensure exactly one compilation hint per function.
uint32_t hint_count = decoder.consume_u32v("compilation hint count");
if (hint_count != module_->num_declared_functions) {
decoder.errorf(decoder.pc(), "Expected %u compilation hints (%u found)",
module_->num_declared_functions, hint_count);
}
// Decode sequence of compilation hints.
if (decoder.ok()) {
module_->compilation_hints.reserve(hint_count);
}
for (uint32_t i = 0; decoder.ok() && i < hint_count; i++) {
TRACE("DecodeCompilationHints[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
// Compilation hints are encoded in one byte each.
// +-------+----------+---------------+----------+
// | 2 bit | 2 bit | 2 bit | 2 bit |
// | ... | Top tier | Baseline tier | Strategy |
// +-------+----------+---------------+----------+
uint8_t hint_byte = decoder.consume_u8("compilation hint");
if (!decoder.ok()) break;
// Decode compilation hint.
WasmCompilationHint hint;
hint.strategy =
static_cast<WasmCompilationHintStrategy>(hint_byte & 0x03);
hint.baseline_tier =
static_cast<WasmCompilationHintTier>(hint_byte >> 2 & 0x3);
hint.top_tier =
static_cast<WasmCompilationHintTier>(hint_byte >> 4 & 0x3);
// Ensure that the top tier never downgrades a compilation result.
// If baseline and top tier are the same compilation will be invoked only
// once.
if (hint.top_tier < hint.baseline_tier &&
hint.top_tier != WasmCompilationHintTier::kDefault) {
decoder.errorf(decoder.pc(),
"Invalid compilation hint %#x (forbidden downgrade)",
hint_byte);
}
// Happily accept compilation hint.
if (decoder.ok()) {
module_->compilation_hints.push_back(std::move(hint));
}
}
// If section was invalid reset compilation hints.
if (decoder.failed()) {
module_->compilation_hints.clear();
}
// @TODO(frgossen) Skip the whole compilation hints section in the outer
// decoder if inner decoder was used.
// consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeBranchHintsSection() {
TRACE("DecodeBranchHints module+%d\n", static_cast<int>(pc_ - start_));
if (!has_seen_unordered_section(kBranchHintsSectionCode)) {
set_seen_unordered_section(kBranchHintsSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
BranchHintInfo branch_hints;
uint32_t func_count = inner.consume_u32v("number of functions");
// Keep track of the previous function index to validate the ordering
int64_t last_func_idx = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_idx = inner.consume_u32v("function index");
if (int64_t(func_idx) <= last_func_idx) {
inner.errorf("Invalid function index: %d", func_idx);
break;
}
last_func_idx = func_idx;
uint8_t reserved = inner.consume_u8("reserved byte");
if (reserved != 0x0) {
inner.errorf("Invalid reserved byte: %#x", reserved);
break;
}
uint32_t num_hints = inner.consume_u32v("number of hints");
BranchHintMap func_branch_hints;
TRACE("DecodeBranchHints[%d] module+%d\n", func_idx,
static_cast<int>(inner.pc() - inner.start()));
// Keep track of the previous branch offset to validate the ordering
int64_t last_br_off = -1;
for (uint32_t j = 0; j < num_hints; ++j) {
uint32_t br_dir = inner.consume_u32v("branch direction");
uint32_t br_off = inner.consume_u32v("branch instruction offset");
if (int64_t(br_off) <= last_br_off) {
inner.errorf("Invalid branch offset: %d", br_off);
break;
}
last_br_off = br_off;
TRACE("DecodeBranchHints[%d][%d] module+%d\n", func_idx, br_off,
static_cast<int>(inner.pc() - inner.start()));
WasmBranchHint hint;
switch (br_dir) {
case 0:
hint = WasmBranchHint::kUnlikely;
break;
case 1:
hint = WasmBranchHint::kLikely;
break;
default:
hint = WasmBranchHint::kNoHint;
inner.errorf(inner.pc(), "Invalid branch hint %#x", br_dir);
break;
}
if (!inner.ok()) {
break;
}
func_branch_hints.insert(br_off, hint);
}
if (!inner.ok()) {
break;
}
branch_hints.emplace(func_idx, std::move(func_branch_hints));
}
// Extra unexpected bytes are an error.
if (inner.more()) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the hints for the module.
if (inner.ok()) {
module_->branch_hints = std::move(branch_hints);
}
}
// Skip the whole branch hints section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeDataCountSection() {
module_->num_declared_data_segments =
consume_count("data segments count", kV8MaxWasmDataSegments);
}
void DecodeTagSection() {
uint32_t tag_count = consume_count("tag count", kV8MaxWasmTags);
for (uint32_t i = 0; ok() && i < tag_count; ++i) {
TRACE("DecodeTag[%d] module+%d\n", i, static_cast<int>(pc_ - start_));
const WasmTagSig* tag_sig = nullptr;
consume_exception_attribute(); // Attribute ignored for now.
consume_tag_sig_index(module_.get(), &tag_sig);
module_->tags.emplace_back(tag_sig);
}
}
bool CheckMismatchedCounts() {
// The declared vs. defined function count is normally checked when
// decoding the code section, but we have to check it here too in case the
// code section is absent.
if (module_->num_declared_functions != 0) {
DCHECK_LT(module_->num_imported_functions, module_->functions.size());
// We know that the code section has been decoded if the first
// non-imported function has its code set.
if (!module_->functions[module_->num_imported_functions].code.is_set()) {
errorf(pc(), "function count is %u, but code section is absent",
module_->num_declared_functions);
return false;
}
}
// Perform a similar check for the DataCount and Data sections, where data
// segments are declared but the Data section is absent.
if (!CheckDataSegmentsCount(
static_cast<uint32_t>(module_->data_segments.size()))) {
return false;
}
return true;
}
ModuleResult FinishDecoding(bool verify_functions = true) {
if (ok() && CheckMismatchedCounts()) {
// We calculate the global offsets here, because there may not be a global
// section and code section that would have triggered the calculation
// before. Even without the globals section the calculation is needed
// because globals can also be defined in the import section.
CalculateGlobalOffsets(module_.get());
}
ModuleResult result = toResult(std::move(module_));
if (verify_functions && result.ok() && intermediate_error_.has_error()) {
// Copy error message and location.
return ModuleResult{std::move(intermediate_error_)};
}
return result;
}
void set_code_section(uint32_t offset, uint32_t size) {
module_->code = {offset, size};
}
// Decodes an entire module.
ModuleResult DecodeModule(Counters* counters, AccountingAllocator* allocator,
bool verify_functions = true) {
StartDecoding(counters, allocator);
uint32_t offset = 0;
base::Vector<const byte> orig_bytes(start(), end() - start());
DecodeModuleHeader(base::VectorOf(start(), end() - start()), offset);
if (failed()) {
return FinishDecoding(verify_functions);
}
// Size of the module header.
offset += 8;
Decoder decoder(start_ + offset, end_, offset);
WasmSectionIterator section_iter(&decoder);
while (ok()) {
// Shift the offset by the section header length
offset += section_iter.payload_start() - section_iter.section_start();
if (section_iter.section_code() != SectionCode::kUnknownSectionCode) {
DecodeSection(section_iter.section_code(), section_iter.payload(),
offset, verify_functions);
}
// Shift the offset by the remaining section payload
offset += section_iter.payload_length();
if (!section_iter.more()) break;
section_iter.advance(true);
}
if (FLAG_dump_wasm_module) DumpModule(orig_bytes);
if (decoder.failed()) {
return decoder.toResult<std::unique_ptr<WasmModule>>(nullptr);
}
return FinishDecoding(verify_functions);
}
// Decodes a single anonymous function starting at {start_}.
FunctionResult DecodeSingleFunction(Zone* zone,
const ModuleWireBytes& wire_bytes,
const WasmModule* module,
std::unique_ptr<WasmFunction> function) {
pc_ = start_;
expect_u8("type form", kWasmFunctionTypeCode);
if (!ok()) return FunctionResult{std::move(intermediate_error_)};
function->sig = consume_sig(zone);
function->code = {off(pc_), static_cast<uint32_t>(end_ - pc_)};
if (ok())
VerifyFunctionBody(zone->allocator(), 0, wire_bytes, module,
function.get());
if (intermediate_error_.has_error()) {
return FunctionResult{std::move(intermediate_error_)};
}
return FunctionResult(std::move(function));
}
// Decodes a single function signature at {start}.
const FunctionSig* DecodeFunctionSignature(Zone* zone, const byte* start) {
pc_ = start;
if (!expect_u8("type form", kWasmFunctionTypeCode)) return nullptr;
const FunctionSig* result = consume_sig(zone);
return ok() ? result : nullptr;
}
WireBytesRef DecodeInitExprForTesting(ValueType expected) {
return consume_init_expr(module_.get(), expected);
}
const std::shared_ptr<WasmModule>& shared_module() const { return module_; }
Counters* GetCounters() const {
DCHECK_NOT_NULL(counters_);
return counters_;
}
void SetCounters(Counters* counters) {
DCHECK_NULL(counters_);
counters_ = counters;
}
private:
const WasmFeatures enabled_features_;
std::shared_ptr<WasmModule> module_;
const byte* module_start_ = nullptr;
const byte* module_end_ = nullptr;
Counters* counters_ = nullptr;
// The type section is the first section in a module.
uint8_t next_ordered_section_ = kFirstSectionInModule;
// We store next_ordered_section_ as uint8_t instead of SectionCode so that
// we can increment it. This static_assert should make sure that SectionCode
// does not get bigger than uint8_t accidentially.
static_assert(sizeof(ModuleDecoderImpl::next_ordered_section_) ==
sizeof(SectionCode),
"type mismatch");
uint32_t seen_unordered_sections_ = 0;
static_assert(kBitsPerByte *
sizeof(ModuleDecoderImpl::seen_unordered_sections_) >
kLastKnownModuleSection,
"not enough bits");
WasmError intermediate_error_;
ModuleOrigin origin_;
AccountingAllocator allocator_;
Zone init_expr_zone_{&allocator_, "initializer expression zone"};
ValueType TypeOf(WasmElemSegment::Entry entry) {
switch (entry.kind) {
case WasmElemSegment::Entry::kGlobalGetEntry:
return module_->globals[entry.index].type;
case WasmElemSegment::Entry::kRefFuncEntry:
return ValueType::Ref(module_->functions[entry.index].sig_index,
kNonNullable);
case WasmElemSegment::Entry::kRefNullEntry:
return ValueType::Ref(entry.index, kNullable);
}
}
bool has_seen_unordered_section(SectionCode section_code) {
return seen_unordered_sections_ & (1 << section_code);
}
void set_seen_unordered_section(SectionCode section_code) {
seen_unordered_sections_ |= 1 << section_code;
}
uint32_t off(const byte* ptr) {
return static_cast<uint32_t>(ptr - start_) + buffer_offset_;
}
bool AddTable(WasmModule* module) {
if (enabled_features_.has_reftypes()) return true;
if (module->tables.size() > 0) {
error("At most one table is supported");
return false;
} else {
return true;
}
}
bool AddMemory(WasmModule* module) {
if (module->has_memory) {
error("At most one memory is supported");
return false;
} else {
module->has_memory = true;
return true;
}
}
// Calculate individual global offsets and total size of globals table.
// This function should be called after all globals have been defined, which
// is after the import section and the global section, but before the global
// offsets are accessed, e.g. by the function compilers. The moment when this
// function should be called is not well-defined, as the global section may
// not exist. Therefore this function is called multiple times.
void CalculateGlobalOffsets(WasmModule* module) {
if (module->globals.empty() || module->untagged_globals_buffer_size != 0 ||
module->tagged_globals_buffer_size != 0) {
// This function has already been executed before, so we don't have to
// execute it again.
return;
}
uint32_t untagged_offset = 0;
uint32_t tagged_offset = 0;
uint32_t num_imported_mutable_globals = 0;
for (WasmGlobal& global : module->globals) {
if (global.mutability && global.imported) {
global.index = num_imported_mutable_globals++;
} else if (global.type.is_reference()) {
global.offset = tagged_offset;
// All entries in the tagged_globals_buffer have size 1.
tagged_offset++;
} else {
int size = global.type.element_size_bytes();
untagged_offset = (untagged_offset + size - 1) & ~(size - 1); // align
global.offset = untagged_offset;
untagged_offset += size;
}
}
module->untagged_globals_buffer_size = untagged_offset;
module->tagged_globals_buffer_size = tagged_offset;
}
// Verifies the body (code) of a given function.
void VerifyFunctionBody(AccountingAllocator* allocator, uint32_t func_num,
const ModuleWireBytes& wire_bytes,
const WasmModule* module, WasmFunction* function) {
WasmFunctionName func_name(function,
wire_bytes.GetNameOrNull(function, module));
if (FLAG_trace_wasm_decoder) {
StdoutStream{} << "Verifying wasm function " << func_name << std::endl;
}
FunctionBody body = {
function->sig, function->code.offset(),
start_ + GetBufferRelativeOffset(function->code.offset()),
start_ + GetBufferRelativeOffset(function->code.end_offset())};
WasmFeatures unused_detected_features = WasmFeatures::None();
DecodeResult result = VerifyWasmCode(allocator, enabled_features_, module,
&unused_detected_features, body);
// If the decode failed and this is the first error, set error code and
// location.
if (result.failed() && intermediate_error_.empty()) {
// Wrap the error message from the function decoder.
std::ostringstream error_msg;
error_msg << "in function " << func_name << ": "
<< result.error().message();
intermediate_error_ = WasmError{result.error().offset(), error_msg.str()};
}
}
uint32_t consume_sig_index(WasmModule* module, const FunctionSig** sig) {
const byte* pos = pc_;
uint32_t sig_index = consume_u32v("signature index");
if (!module->has_signature(sig_index)) {
errorf(pos, "signature index %u out of bounds (%d signatures)", sig_index,
static_cast<int>(module->types.size()));
*sig = nullptr;
return 0;
}
*sig = module->signature(sig_index);
return sig_index;
}
uint32_t consume_tag_sig_index(WasmModule* module, const FunctionSig** sig) {
const byte* pos = pc_;
uint32_t sig_index = consume_sig_index(module, sig);
if (*sig && (*sig)->return_count() != 0) {
errorf(pos, "tag signature %u has non-void return", sig_index);
*sig = nullptr;
return 0;
}
return sig_index;
}
uint32_t consume_count(const char* name, size_t maximum) {
const byte* p = pc_;
uint32_t count = consume_u32v(name);
if (count > maximum) {
errorf(p, "%s of %u exceeds internal limit of %zu", name, count, maximum);
return static_cast<uint32_t>(maximum);
}
return count;
}
uint32_t consume_func_index(WasmModule* module, WasmFunction** func,
const char* name) {
return consume_index(name, &module->functions, func);
}
uint32_t consume_global_index(WasmModule* module, WasmGlobal** global) {
return consume_index("global index", &module->globals, global);
}
uint32_t consume_table_index(WasmModule* module, WasmTable** table) {
return consume_index("table index", &module->tables, table);
}
uint32_t consume_tag_index(WasmModule* module, WasmTag** tag) {
return consume_index("tag index", &module->tags, tag);
}
template <typename T>
uint32_t consume_index(const char* name, std::vector<T>* vector, T** ptr) {
const byte* pos = pc_;
uint32_t index = consume_u32v(name);
if (index >= vector->size()) {
errorf(pos, "%s %u out of bounds (%d entr%s)", name, index,
static_cast<int>(vector->size()),
vector->size() == 1 ? "y" : "ies");
*ptr = nullptr;
return 0;
}
*ptr = &(*vector)[index];
return index;
}
uint8_t validate_table_flags(const char* name) {
uint8_t flags = consume_u8("table limits flags");
STATIC_ASSERT(kNoMaximum < kWithMaximum);
if (V8_UNLIKELY(flags > kWithMaximum)) {
errorf(pc() - 1, "invalid %s limits flags", name);
}
return flags;
}
uint8_t validate_memory_flags(bool* has_shared_memory, bool* is_memory64) {
uint8_t flags = consume_u8("memory limits flags");
*has_shared_memory = false;
switch (flags) {
case kNoMaximum:
case kWithMaximum:
break;
case kSharedNoMaximum:
case kSharedWithMaximum:
if (!enabled_features_.has_threads()) {
errorf(pc() - 1,
"invalid memory limits flags 0x%x (enable via "
"--experimental-wasm-threads)",
flags);
}
*has_shared_memory = true;
// V8 does not support shared memory without a maximum.
if (flags == kSharedNoMaximum) {
errorf(pc() - 1,
"memory limits flags must have maximum defined if shared is "
"true");
}
break;
case kMemory64NoMaximum:
case kMemory64WithMaximum:
if (!enabled_features_.has_memory64()) {
errorf(pc() - 1,
"invalid memory limits flags 0x%x (enable via "
"--experimental-wasm-memory64)",
flags);
}
*is_memory64 = true;
break;
default:
errorf(pc() - 1, "invalid memory limits flags 0x%x", flags);
break;
}
return flags;
}
void consume_resizable_limits(const char* name, const char* units,
uint32_t max_initial, uint32_t* initial,
bool* has_max, uint32_t max_maximum,
uint32_t* maximum, uint8_t flags) {
const byte* pos = pc();
// For memory64 we need to read the numbers as LEB-encoded 64-bit unsigned
// integer. All V8 limits are still within uint32_t range though.
const bool is_memory64 =
flags == kMemory64NoMaximum || flags == kMemory64WithMaximum;
uint64_t initial_64 = is_memory64 ? consume_u64v("initial size")
: consume_u32v("initial size");
if (initial_64 > max_initial) {
errorf(pos,
"initial %s size (%" PRIu64
" %s) is larger than implementation limit (%u)",
name, initial_64, units, max_initial);
}
*initial = static_cast<uint32_t>(initial_64);
if (flags & 1) {
*has_max = true;
pos = pc();
uint64_t maximum_64 = is_memory64 ? consume_u64v("maximum size")
: consume_u32v("maximum size");
if (maximum_64 > max_maximum) {
errorf(pos,
"maximum %s size (%" PRIu64
" %s) is larger than implementation limit (%u)",
name, maximum_64, units, max_maximum);
}
if (maximum_64 < *initial) {
errorf(pos,
"maximum %s size (%" PRIu64 " %s) is less than initial (%u %s)",
name, maximum_64, units, *initial, units);
}
*maximum = static_cast<uint32_t>(maximum_64);
} else {
*has_max = false;
*maximum = max_initial;
}
}
bool expect_u8(const char* name, uint8_t expected) {
const byte* pos = pc();
uint8_t value = consume_u8(name);
if (value != expected) {
errorf(pos, "expected %s 0x%02x, got 0x%02x", name, expected, value);
return false;
}
return true;
}
WireBytesRef consume_init_expr(WasmModule* module, ValueType expected) {
FunctionBody body(FunctionSig::Build(&init_expr_zone_, {expected}, {}),
buffer_offset_, pc_, end_);
WasmFeatures detected;
WasmFullDecoder<Decoder::kFullValidation, InitExprInterface,
kInitExpression>
decoder(&init_expr_zone_, module, enabled_features_, &detected, body,
module);
uint32_t offset = this->pc_offset();
decoder.DecodeFunctionBody();
this->pc_ = decoder.end();
if (decoder.failed()) {
error(decoder.error().offset(), decoder.error().message().c_str());
return {};
}
if (!decoder.interface().end_found()) {
error("Initializer expression is missing 'end'");
return {};
}
return {offset, static_cast<uint32_t>(decoder.end() - decoder.start())};
}
// Read a mutability flag
bool consume_mutability() {
byte val = consume_u8("mutability");
if (val > 1) error(pc_ - 1, "invalid mutability");
return val != 0;
}
ValueType consume_value_type() {
uint32_t type_length;
ValueType result = value_type_reader::read_value_type<kFullValidation>(
this, this->pc(), &type_length, module_.get(),
origin_ == kWasmOrigin ? enabled_features_ : WasmFeatures::None());
consume_bytes(type_length, "value type");
return result;
}
ValueType consume_storage_type() {
uint8_t opcode = read_u8<kFullValidation>(this->pc());
switch (opcode) {
case kI8Code:
consume_bytes(1, "i8");
return kWasmI8;
case kI16Code:
consume_bytes(1, "i16");
return kWasmI16;
default:
// It is not a packed type, so it has to be a value type.
return consume_value_type();
}
}
// Reads a reference type for tables and element segment headers.
// Unless extensions are enabled, only funcref is allowed.
// TODO(manoskouk): Replace this with consume_value_type (and checks against
// the returned type at callsites as needed) once the
// 'reftypes' proposal is standardized.
ValueType consume_reference_type() {
if (!enabled_features_.has_reftypes()) {
uint8_t ref_type = consume_u8("reference type");
if (ref_type != kFuncRefCode) {
error(pc_ - 1,
"invalid table type. Consider using experimental flags.");
return kWasmBottom;
}
return kWasmFuncRef;
} else {
const byte* position = pc();
ValueType result = consume_value_type();
if (!result.is_reference()) {
error(position, "expected reference type");
}
return result;
}
}
const FunctionSig* consume_sig(Zone* zone) {
// Parse parameter types.
uint32_t param_count =
consume_count("param count", kV8MaxWasmFunctionParams);
if (failed()) return nullptr;
std::vector<ValueType> params;
for (uint32_t i = 0; ok() && i < param_count; ++i) {
params.push_back(consume_value_type());
}
std::vector<ValueType> returns;
// Parse return types.
uint32_t return_count =
consume_count("return count", kV8MaxWasmFunctionReturns);
if (failed()) return nullptr;
for (uint32_t i = 0; ok() && i < return_count; ++i) {
returns.push_back(consume_value_type());
}
if (failed()) return nullptr;
// FunctionSig stores the return types first.
ValueType* buffer = zone->NewArray<ValueType>(param_count + return_count);
uint32_t b = 0;
for (uint32_t i = 0; i < return_count; ++i) buffer[b++] = returns[i];
for (uint32_t i = 0; i < param_count; ++i) buffer[b++] = params[i];
return zone->New<FunctionSig>(return_count, param_count, buffer);
}
const StructType* consume_struct(Zone* zone) {
uint32_t field_count = consume_count("field count", kV8MaxWasmStructFields);
if (failed()) return nullptr;
ValueType* fields = zone->NewArray<ValueType>(field_count);
bool* mutabilities = zone->NewArray<bool>(field_count);
for (uint32_t i = 0; ok() && i < field_count; ++i) {
ValueType field = consume_storage_type();
fields[i] = field;
bool mutability = consume_mutability();
mutabilities[i] = mutability;
}
if (failed()) return nullptr;
uint32_t* offsets = zone->NewArray<uint32_t>(field_count);
return zone->New<StructType>(field_count, offsets, fields, mutabilities);
}
const ArrayType* consume_array(Zone* zone) {
ValueType field = consume_storage_type();
if (failed()) return nullptr;
bool mutability = consume_mutability();
if (!V8_LIKELY(mutability)) {
error(this->pc() - 1, "immutable arrays are not supported yet");
}
return zone->New<ArrayType>(field, mutability);
}
// Consume the attribute field of an exception.
uint32_t consume_exception_attribute() {
const byte* pos = pc_;
uint32_t attribute = consume_u32v("exception attribute");
if (attribute != kExceptionAttribute) {
errorf(pos, "exception attribute %u not supported", attribute);
return 0;
}
return attribute;
}
WasmElemSegment consume_element_segment_header(
bool* expressions_as_elements) {
const byte* pos = pc();
// The mask for the bit in the flag which indicates if the segment is
// active or not (0 is active).
constexpr uint8_t kNonActiveMask = 1 << 0;
// The mask for the bit in the flag which indicates:
// - for active tables, if the segment has an explicit table index field.
// - for non-active tables, whether the table is declarative (vs. passive).
constexpr uint8_t kHasTableIndexOrIsDeclarativeMask = 1 << 1;
// The mask for the bit in the flag which indicates if the functions of this
// segment are defined as function indices (0) or init. expressions (1).
constexpr uint8_t kExpressionsAsElementsMask = 1 << 2;
constexpr uint8_t kFullMask = kNonActiveMask |
kHasTableIndexOrIsDeclarativeMask |
kExpressionsAsElementsMask;
uint32_t flag = consume_u32v("flag");
if ((flag & kFullMask) != flag) {
errorf(pos, "illegal flag value %u. Must be between 0 and 7", flag);
return {};
}
const WasmElemSegment::Status status =
(flag & kNonActiveMask) ? (flag & kHasTableIndexOrIsDeclarativeMask)
? WasmElemSegment::kStatusDeclarative
: WasmElemSegment::kStatusPassive
: WasmElemSegment::kStatusActive;
if (status == WasmElemSegment::kStatusDeclarative &&
!enabled_features_.has_reftypes()) {
error(
"Declarative element segments require --experimental-wasm-reftypes");
return {};
}
const bool is_active = status == WasmElemSegment::kStatusActive;
*expressions_as_elements = flag & kExpressionsAsElementsMask;
const bool has_table_index =
is_active && (flag & kHasTableIndexOrIsDeclarativeMask);
uint32_t table_index = has_table_index ? consume_u32v("table index") : 0;
if (is_active && table_index >= module_->tables.size()) {
errorf(pos, "out of bounds%s table index %u",
has_table_index ? " implicit" : "", table_index);
return {};
}
ValueType table_type =
is_active ? module_->tables[table_index].type : kWasmBottom;
WireBytesRef offset;
if (is_active) {
offset = consume_init_expr(module_.get(), kWasmI32);
// Failed to parse offset initializer, return early.
if (failed()) return {};
}
// Denotes an active segment without table index, type, or element kind.
const bool backwards_compatible_mode =
is_active && !(flag & kHasTableIndexOrIsDeclarativeMask);
ValueType type;
if (*expressions_as_elements) {
type =
backwards_compatible_mode ? kWasmFuncRef : consume_reference_type();
if (is_active && !IsSubtypeOf(type, table_type, this->module_.get())) {
errorf(pos,
"Element segment of type %s is not a subtype of referenced "
"table %u (of type %s)",
type.name().c_str(), table_index, table_type.name().c_str());
return {};
}
} else {
if (!backwards_compatible_mode) {
// We have to check that there is an element kind of type Function. All
// other element kinds are not valid yet.
uint8_t val = consume_u8("element kind");
if (static_cast<ImportExportKindCode>(val) != kExternalFunction) {
errorf(pos, "illegal element kind 0x%x. Must be 0x%x", val,
kExternalFunction);
return {};
}
}
if (!is_active) {
// Declarative and passive segments without explicit type are funcref.
type = kWasmFuncRef;
} else {
type = table_type;
// Active segments with function indices must reference a function
// table. TODO(7748): Add support for anyref tables when we have them.
if (!IsSubtypeOf(table_type, kWasmFuncRef, this->module_.get())) {
errorf(pos,
"An active element segment with function indices as elements "
"must reference a table of %s. Instead, table %u of type %s "
"is referenced.",
enabled_features_.has_typed_funcref()
? "a subtype of type funcref"
: "type funcref",
table_index, table_type.name().c_str());
return {};
}
}
}
if (is_active) {
return {type, table_index, std::move(offset)};
} else {
return {type, status == WasmElemSegment::kStatusDeclarative};
}
}
void consume_data_segment_header(bool* is_active, uint32_t* index,
WireBytesRef* offset) {
const byte* pos = pc();
uint32_t flag = consume_u32v("flag");
// Some flag values are only valid for specific proposals.
if (flag != SegmentFlags::kActiveNoIndex &&
flag != SegmentFlags::kPassive &&
flag != SegmentFlags::kActiveWithIndex) {
errorf(pos, "illegal flag value %u. Must be 0, 1, or 2", flag);
return;
}
// We know now that the flag is valid. Time to read the rest.
ValueType expected_type = module_->is_memory64 ? kWasmI64 : kWasmI32;
if (flag == SegmentFlags::kActiveNoIndex) {
*is_active = true;
*index = 0;
*offset = consume_init_expr(module_.get(), expected_type);
return;
}
if (flag == SegmentFlags::kPassive) {
*is_active = false;
return;
}
if (flag == SegmentFlags::kActiveWithIndex) {
*is_active = true;
*index = consume_u32v("memory index");
*offset = consume_init_expr(module_.get(), expected_type);
}
}
uint32_t consume_element_func_index() {
WasmFunction* func = nullptr;
uint32_t index =
consume_func_index(module_.get(), &func, "element function index");
if (failed()) return index;
func->declared = true;
DCHECK_NE(func, nullptr);
DCHECK_EQ(index, func->func_index);
return index;
}
// TODO(manoskouk): When reftypes lands, consider if we can implement this
// with consume_init_expr(). It will require changes in module-instantiate.cc,
// in {LoadElemSegmentImpl}.
WasmElemSegment::Entry consume_element_expr() {
uint8_t opcode = consume_u8("element opcode");
if (failed()) return {};
switch (opcode) {
case kExprRefNull: {
HeapTypeImmediate<kFullValidation> imm(WasmFeatures::All(), this,
this->pc(), module_.get());
consume_bytes(imm.length, "ref.null immediate");
expect_u8("end opcode", kExprEnd);
return {WasmElemSegment::Entry::kRefNullEntry,
static_cast<uint32_t>(imm.type.representation())};
}
case kExprRefFunc: {
uint32_t index = consume_element_func_index();
if (failed()) return {};
expect_u8("end opcode", kExprEnd);
return {WasmElemSegment::Entry::kRefFuncEntry, index};
}
case kExprGlobalGet: {
if (!enabled_features_.has_reftypes()) {
errorf(
"Unexpected opcode 0x%x in element. Enable with "
"--experimental-wasm-reftypes",
kExprGlobalGet);
return {};
}
uint32_t index = this->consume_u32v("global index");
if (failed()) return {};
if (index >= module_->globals.size()) {
errorf("Out-of-bounds global index %d", index);
return {};
}
expect_u8("end opcode", kExprEnd);
return {WasmElemSegment::Entry::kGlobalGetEntry, index};
}
default:
error("invalid opcode in element");
return {};
}
}
};
ModuleResult DecodeWasmModule(
const WasmFeatures& enabled, const byte* module_start,
const byte* module_end, bool verify_functions, ModuleOrigin origin,
Counters* counters, std::shared_ptr<metrics::Recorder> metrics_recorder,
v8::metrics::Recorder::ContextId context_id, DecodingMethod decoding_method,
AccountingAllocator* allocator) {
size_t size = module_end - module_start;
CHECK_LE(module_start, module_end);
size_t max_size = max_module_size();
if (size > max_size) {
return ModuleResult{
WasmError{0, "size > maximum module size (%zu): %zu", max_size, size}};
}
// TODO(bradnelson): Improve histogram handling of size_t.
auto size_counter =
SELECT_WASM_COUNTER(counters, origin, wasm, module_size_bytes);
size_counter->AddSample(static_cast<int>(size));
// Signatures are stored in zone memory, which have the same lifetime
// as the {module}.
ModuleDecoderImpl decoder(enabled, module_start, module_end, origin);
v8::metrics::WasmModuleDecoded metrics_event;
base::ElapsedTimer timer;
timer.Start();
base::ThreadTicks thread_ticks = base::ThreadTicks::IsSupported()
? base::ThreadTicks::Now()
: base::ThreadTicks();
ModuleResult result =
decoder.DecodeModule(counters, allocator, verify_functions);
// Record event metrics.
metrics_event.wall_clock_duration_in_us = timer.Elapsed().InMicroseconds();
timer.Stop();
if (!thread_ticks.IsNull()) {
metrics_event.cpu_duration_in_us =
(base::ThreadTicks::Now() - thread_ticks).InMicroseconds();
}
metrics_event.success = decoder.ok() && result.ok();
metrics_event.async = decoding_method == DecodingMethod::kAsync ||
decoding_method == DecodingMethod::kAsyncStream;
metrics_event.streamed = decoding_method == DecodingMethod::kSyncStream ||
decoding_method == DecodingMethod::kAsyncStream;
if (result.ok()) {
metrics_event.function_count = result.value()->num_declared_functions;
} else if (auto&& module = decoder.shared_module()) {
metrics_event.function_count = module->num_declared_functions;
}
metrics_event.module_size_in_bytes = size;
metrics_recorder->DelayMainThreadEvent(metrics_event, context_id);
return result;
}
ModuleDecoder::ModuleDecoder(const WasmFeatures& enabled)
: enabled_features_(enabled) {}
ModuleDecoder::~ModuleDecoder() = default;
const std::shared_ptr<WasmModule>& ModuleDecoder::shared_module() const {
return impl_->shared_module();
}
void ModuleDecoder::StartDecoding(
Counters* counters, std::shared_ptr<metrics::Recorder> metrics_recorder,
v8::metrics::Recorder::ContextId context_id, AccountingAllocator* allocator,
ModuleOrigin origin) {
DCHECK_NULL(impl_);
impl_.reset(new ModuleDecoderImpl(enabled_features_, origin));
impl_->StartDecoding(counters, allocator);
}
void ModuleDecoder::DecodeModuleHeader(base::Vector<const uint8_t> bytes,
uint32_t offset) {
impl_->DecodeModuleHeader(bytes, offset);
}
void ModuleDecoder::DecodeSection(SectionCode section_code,
base::Vector<const uint8_t> bytes,
uint32_t offset, bool verify_functions) {
impl_->DecodeSection(section_code, bytes, offset, verify_functions);
}
void ModuleDecoder::DecodeFunctionBody(uint32_t index, uint32_t length,
uint32_t offset, bool verify_functions) {
impl_->DecodeFunctionBody(index, length, offset, verify_functions);
}
void ModuleDecoder::StartCodeSection() { impl_->StartCodeSection(); }
bool ModuleDecoder::CheckFunctionsCount(uint32_t functions_count,
uint32_t error_offset) {
return impl_->CheckFunctionsCount(functions_count, error_offset);
}
ModuleResult ModuleDecoder::FinishDecoding(bool verify_functions) {
return impl_->FinishDecoding(verify_functions);
}
void ModuleDecoder::set_code_section(uint32_t offset, uint32_t size) {
return impl_->set_code_section(offset, size);
}
size_t ModuleDecoder::IdentifyUnknownSection(ModuleDecoder* decoder,
base::Vector<const uint8_t> bytes,
uint32_t offset,
SectionCode* result) {
if (!decoder->ok()) return 0;
decoder->impl_->Reset(bytes, offset);
*result = IdentifyUnknownSectionInternal(decoder->impl_.get());
return decoder->impl_->pc() - bytes.begin();
}
bool ModuleDecoder::ok() { return impl_->ok(); }
const FunctionSig* DecodeWasmSignatureForTesting(const WasmFeatures& enabled,
Zone* zone, const byte* start,
const byte* end) {
ModuleDecoderImpl decoder(enabled, start, end, kWasmOrigin);
return decoder.DecodeFunctionSignature(zone, start);
}
WireBytesRef DecodeWasmInitExprForTesting(const WasmFeatures& enabled,
const byte* start, const byte* end,
ValueType expected) {
ModuleDecoderImpl decoder(enabled, start, end, kWasmOrigin);
AccountingAllocator allocator;
decoder.StartDecoding(nullptr, &allocator);
return decoder.DecodeInitExprForTesting(expected);
}
FunctionResult DecodeWasmFunctionForTesting(
const WasmFeatures& enabled, Zone* zone, const ModuleWireBytes& wire_bytes,
const WasmModule* module, const byte* function_start,
const byte* function_end, Counters* counters) {
size_t size = function_end - function_start;
CHECK_LE(function_start, function_end);
if (size > kV8MaxWasmFunctionSize) {
return FunctionResult{WasmError{0,
"size > maximum function size (%zu): %zu",
kV8MaxWasmFunctionSize, size}};
}
ModuleDecoderImpl decoder(enabled, function_start, function_end, kWasmOrigin);
decoder.SetCounters(counters);
return decoder.DecodeSingleFunction(zone, wire_bytes, module,
std::make_unique<WasmFunction>());
}
AsmJsOffsetsResult DecodeAsmJsOffsets(
base::Vector<const uint8_t> encoded_offsets) {
std::vector<AsmJsOffsetFunctionEntries> functions;
Decoder decoder(encoded_offsets);
uint32_t functions_count = decoder.consume_u32v("functions count");
// Consistency check.
DCHECK_GE(encoded_offsets.size(), functions_count);
functions.reserve(functions_count);
for (uint32_t i = 0; i < functions_count; ++i) {
uint32_t size = decoder.consume_u32v("table size");
if (size == 0) {
functions.emplace_back();
continue;
}
DCHECK(decoder.checkAvailable(size));
const byte* table_end = decoder.pc() + size;
uint32_t locals_size = decoder.consume_u32v("locals size");
int function_start_position = decoder.consume_u32v("function start pos");
int function_end_position = function_start_position;
int last_byte_offset = locals_size;
int last_asm_position = function_start_position;
std::vector<AsmJsOffsetEntry> func_asm_offsets;
func_asm_offsets.reserve(size / 4); // conservative estimation
// Add an entry for the stack check, associated with position 0.
func_asm_offsets.push_back(
{0, function_start_position, function_start_position});
while (decoder.pc() < table_end) {
DCHECK(decoder.ok());
last_byte_offset += decoder.consume_u32v("byte offset delta");
int call_position =
last_asm_position + decoder.consume_i32v("call position delta");
int to_number_position =
call_position + decoder.consume_i32v("to_number position delta");
last_asm_position = to_number_position;
if (decoder.pc() == table_end) {
// The last entry is the function end marker.
DCHECK_EQ(call_position, to_number_position);
function_end_position = call_position;
} else {
func_asm_offsets.push_back(
{last_byte_offset, call_position, to_number_position});
}
}
DCHECK_EQ(decoder.pc(), table_end);
functions.emplace_back(AsmJsOffsetFunctionEntries{
function_start_position, function_end_position,
std::move(func_asm_offsets)});
}
DCHECK(decoder.ok());
DCHECK(!decoder.more());
return decoder.toResult(AsmJsOffsets{std::move(functions)});
}
std::vector<CustomSectionOffset> DecodeCustomSections(const byte* start,
const byte* end) {
Decoder decoder(start, end);
decoder.consume_bytes(4, "wasm magic");
decoder.consume_bytes(4, "wasm version");
std::vector<CustomSectionOffset> result;
while (decoder.more()) {
byte section_code = decoder.consume_u8("section code");
uint32_t section_length = decoder.consume_u32v("section length");
uint32_t section_start = decoder.pc_offset();
if (section_code != 0) {
// Skip known sections.
decoder.consume_bytes(section_length, "section bytes");
continue;
}
uint32_t name_length = decoder.consume_u32v("name length");
uint32_t name_offset = decoder.pc_offset();
decoder.consume_bytes(name_length, "section name");
uint32_t payload_offset = decoder.pc_offset();
if (section_length < (payload_offset - section_start)) {
decoder.error("invalid section length");
break;
}
uint32_t payload_length = section_length - (payload_offset - section_start);
decoder.consume_bytes(payload_length);
if (decoder.failed()) break;
result.push_back({{section_start, section_length},
{name_offset, name_length},
{payload_offset, payload_length}});
}
return result;
}
namespace {
bool FindNameSection(Decoder* decoder) {
static constexpr int kModuleHeaderSize = 8;
decoder->consume_bytes(kModuleHeaderSize, "module header");
WasmSectionIterator section_iter(decoder);
while (decoder->ok() && section_iter.more() &&
section_iter.section_code() != kNameSectionCode) {
section_iter.advance(true);
}
if (!section_iter.more()) return false;
// Reset the decoder to not read beyond the name section end.
decoder->Reset(section_iter.payload(), decoder->pc_offset());
return true;
}
} // namespace
void DecodeFunctionNames(const byte* module_start, const byte* module_end,
std::unordered_map<uint32_t, WireBytesRef>* names) {
DCHECK_NOT_NULL(names);
DCHECK(names->empty());
Decoder decoder(module_start, module_end);
if (FindNameSection(&decoder)) {
while (decoder.ok() && decoder.more()) {
uint8_t name_type = decoder.consume_u8("name type");
if (name_type & 0x80) break; // no varuint7
uint32_t name_payload_len = decoder.consume_u32v("name payload length");
if (!decoder.checkAvailable(name_payload_len)) break;
if (name_type != NameSectionKindCode::kFunction) {
decoder.consume_bytes(name_payload_len, "name subsection payload");
continue;
}
uint32_t functions_count = decoder.consume_u32v("functions count");
for (; decoder.ok() && functions_count > 0; --functions_count) {
uint32_t function_index = decoder.consume_u32v("function index");
WireBytesRef name = consume_string(&decoder, false, "function name");
// Be lenient with errors in the name section: Ignore non-UTF8 names.
// You can even assign to the same function multiple times (last valid
// one wins).
if (decoder.ok() && validate_utf8(&decoder, name)) {
names->insert(std::make_pair(function_index, name));
}
}
}
}
}
NameMap DecodeNameMap(base::Vector<const uint8_t> module_bytes,
uint8_t name_section_kind) {
Decoder decoder(module_bytes);
if (!FindNameSection(&decoder)) return NameMap{{}};
std::vector<NameAssoc> names;
while (decoder.ok() && decoder.more()) {
uint8_t name_type = decoder.consume_u8("name type");
if (name_type & 0x80) break; // no varuint7
uint32_t name_payload_len = decoder.consume_u32v("name payload length");
if (!decoder.checkAvailable(name_payload_len)) break;
if (name_type != name_section_kind) {
decoder.consume_bytes(name_payload_len, "name subsection payload");
continue;
}
uint32_t count = decoder.consume_u32v("names count");
for (uint32_t i = 0; i < count; i++) {
uint32_t index = decoder.consume_u32v("index");
WireBytesRef name = consume_string(&decoder, false, "name");
if (!decoder.ok()) break;
if (index > kMaxInt) continue;
if (!validate_utf8(&decoder, name)) continue;
names.emplace_back(static_cast<int>(index), name);
}
}
std::stable_sort(names.begin(), names.end(), NameAssoc::IndexLess{});
return NameMap{std::move(names)};
}
IndirectNameMap DecodeIndirectNameMap(base::Vector<const uint8_t> module_bytes,
uint8_t name_section_kind) {
Decoder decoder(module_bytes);
if (!FindNameSection(&decoder)) return IndirectNameMap{{}};
std::vector<IndirectNameMapEntry> entries;
while (decoder.ok() && decoder.more()) {
uint8_t name_type = decoder.consume_u8("name type");
if (name_type & 0x80) break; // no varuint7
uint32_t name_payload_len = decoder.consume_u32v("name payload length");
if (!decoder.checkAvailable(name_payload_len)) break;
if (name_type != name_section_kind) {
decoder.consume_bytes(name_payload_len, "name subsection payload");
continue;
}
uint32_t outer_count = decoder.consume_u32v("outer count");
for (uint32_t i = 0; i < outer_count; ++i) {
uint32_t outer_index = decoder.consume_u32v("outer index");
if (outer_index > kMaxInt) continue;
std::vector<NameAssoc> names;
uint32_t inner_count = decoder.consume_u32v("inner count");
for (uint32_t k = 0; k < inner_count; ++k) {
uint32_t inner_index = decoder.consume_u32v("inner index");
WireBytesRef name = consume_string(&decoder, false, "name");
if (!decoder.ok()) break;
if (inner_index > kMaxInt) continue;
// Ignore non-utf8 names.
if (!validate_utf8(&decoder, name)) continue;
names.emplace_back(static_cast<int>(inner_index), name);
}
// Use stable sort to get deterministic names (the first one declared)
// even in the presence of duplicates.
std::stable_sort(names.begin(), names.end(), NameAssoc::IndexLess{});
entries.emplace_back(static_cast<int>(outer_index), std::move(names));
}
}
std::stable_sort(entries.begin(), entries.end(),
IndirectNameMapEntry::IndexLess{});
return IndirectNameMap{std::move(entries)};
}
#undef TRACE
} // namespace wasm
} // namespace internal
} // namespace v8
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