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// Copyright 2018 Ryan Dahl <ry@tinyclouds.org>
// All rights reserved. MIT License.
// Hint: --trace_serializer is a useful debugging flag.
#include "deno_internal.h"
#include "file_util.h"
#include "include/deno.h"
#include "v8/include/v8.h"
#include "v8/src/base/logging.h"
namespace deno {
v8::StartupData SerializeInternalFields(v8::Local<v8::Object> holder, int index,
void* data) {
DCHECK_EQ(data, nullptr);
InternalFieldData* embedder_field = static_cast<InternalFieldData*>(
holder->GetAlignedPointerFromInternalField(index));
if (embedder_field == nullptr) return {nullptr, 0};
int size = sizeof(*embedder_field);
char* payload = new char[size];
// We simply use memcpy to serialize the content.
memcpy(payload, embedder_field, size);
return {payload, size};
}
v8::StartupData MakeSnapshot(const char* js_filename, const char* js_source) {
auto* creator = new v8::SnapshotCreator(external_references);
auto* isolate = creator->GetIsolate();
v8::Isolate::Scope isolate_scope(isolate);
{
v8::HandleScope handle_scope(isolate);
auto context = v8::Context::New(isolate);
InitializeContext(isolate, context, js_filename, js_source);
creator->SetDefaultContext(context, v8::SerializeInternalFieldsCallback(
SerializeInternalFields, nullptr));
}
// Note that using kKeep here will cause segfaults. This is demoed in the
// "SnapshotBug" test case.
auto snapshot_blob =
creator->CreateBlob(v8::SnapshotCreator::FunctionCodeHandling::kClear);
return snapshot_blob;
}
// Wrap the js_source in an IIFE to work around a bug in the V8 snapshot
// serializer. Without it, CreateBlob() triggers the following assert:
// Debug check failed : outer_scope_info()->IsScopeInfo() || is_toplevel().
// ==== C stack trace ====
// v8::internal::SharedFunctionInfo::FlushCompiled
// v8::SnapshotCreator::CreateBlob
// deno::MakeSnapshot
// Avoid misaligning the source map, and ensure that the sourceMappingUrl
// comment remains at the last line.
// Try removing this when this bug is fixed:
// https://bugs.chromium.org/p/v8/issues/detail?id=7857
std::string WrapSourceCode(const std::string& js_source) {
auto smu_offset = js_source.rfind("//# sourceMappingURL=");
std::string tail =
smu_offset == std::string::npos ? "" : js_source.substr(smu_offset);
auto wrapped_js_source =
"(function() {" + js_source.substr(0, smu_offset) + "\n})();\n" + tail;
// Double check that the source mapping url comment is at the last line.
auto last_line = wrapped_js_source.substr(wrapped_js_source.rfind('\n'));
CHECK(smu_offset == std::string::npos ||
last_line.find("sourceMappingURL") != std::string::npos);
return wrapped_js_source;
}
} // namespace deno
int main(int argc, char** argv) {
const char* js_fn = argv[1];
const char* snapshot_out_cc = argv[2];
v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
CHECK_EQ(argc, 3);
CHECK_NE(js_fn, nullptr);
CHECK_NE(snapshot_out_cc, nullptr);
std::string js_source;
CHECK(deno::ReadFileToString(js_fn, &js_source));
auto wrapped_js_source = deno::WrapSourceCode(js_source);
deno_init();
auto snapshot_blob = deno::MakeSnapshot(js_fn, wrapped_js_source.c_str());
std::string snapshot_str(snapshot_blob.data, snapshot_blob.raw_size);
CHECK(deno::WriteDataAsCpp("snapshot", snapshot_out_cc, snapshot_str));
}
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