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[web snapshots] Add a magic number to the binary format

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Bug: v8:11525
Change-Id: I848167e13c7aa47d712a4315902eb8748e86c949
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3217192
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77317}
This commit is contained in:
Marja Hölttä 2021-10-11 14:17:44 +02:00 committed by V8 LUCI CQ
parent 12ecb4f567
commit 7b70036ec8
2 changed files with 19 additions and 6 deletions
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23
src/web-snapshot/web-snapshot.cc
View File

@ -22,6 +22,8 @@
namespace v8 {
namespace internal {
constexpr uint8_t WebSnapshotSerializerDeserializer::kMagicNumber[4];
// When encountering an error during deserializing, we note down the error but
// don't bail out from processing the snapshot further. This is to speed up
// deserialization; the error case is now slower since we don't bail out, but
@ -258,6 +260,7 @@ void WebSnapshotSerializer::SerializePendingItems() {
}
// Format (full snapshot):
// - Magic number (4 bytes)
// - String count
// - For each string:
// - Serialized string
@ -282,16 +285,16 @@ void WebSnapshotSerializer::WriteSnapshot(uint8_t*& buffer,
ValueSerializer total_serializer(isolate_, nullptr);
size_t needed_size =
string_serializer_.buffer_size_ + map_serializer_.buffer_size_ +
context_serializer_.buffer_size_ + function_serializer_.buffer_size_ +
class_serializer_.buffer_size_ + array_serializer_.buffer_size_ +
object_serializer_.buffer_size_ + export_serializer_.buffer_size_ +
8 * sizeof(uint32_t);
sizeof(kMagicNumber) + string_serializer_.buffer_size_ +
map_serializer_.buffer_size_ + context_serializer_.buffer_size_ +
function_serializer_.buffer_size_ + class_serializer_.buffer_size_ +
array_serializer_.buffer_size_ + object_serializer_.buffer_size_ +
export_serializer_.buffer_size_ + 8 * sizeof(uint32_t);
if (total_serializer.ExpandBuffer(needed_size).IsNothing()) {
Throw("Web snapshot: Out of memory");
return;
}
total_serializer.WriteRawBytes(kMagicNumber, 4);
total_serializer.WriteUint32(static_cast<uint32_t>(string_count()));
total_serializer.WriteRawBytes(string_serializer_.buffer_,
string_serializer_.buffer_size_);
@ -778,6 +781,14 @@ bool WebSnapshotDeserializer::UseWebSnapshot(const uint8_t* data,
deserializer_.reset(new ValueDeserializer(isolate_, data, buffer_size));
deferred_references_ = ArrayList::New(isolate_, 30);
const void* magic_bytes;
if (!deserializer_->ReadRawBytes(sizeof(kMagicNumber), &magic_bytes) ||
memcmp(magic_bytes, kMagicNumber, sizeof(kMagicNumber)) != 0) {
Throw("Web snapshot: Invalid magic number");
return false;
}
DeserializeStrings();
DeserializeMaps();
DeserializeContexts();

2
src/web-snapshot/web-snapshot.h
View File

@ -56,6 +56,8 @@ class WebSnapshotSerializerDeserializer {
REGEXP
};
static constexpr uint8_t kMagicNumber[4] = {'+', '+', '+', ';'};
enum ContextType : uint8_t { FUNCTION, BLOCK };
enum PropertyAttributesType : uint8_t { DEFAULT, CUSTOM };