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