fixup! src: allow blobs instead of FILE*s in embedder snapshot API

Author: addaleax

src/api/embed_helpers.cc

@@ -304,22 +304,15 @@ EmbedderSnapshotData::Pointer EmbedderSnapshotData::FromBlob(
 }
 
 EmbedderSnapshotData::Pointer EmbedderSnapshotData::FromFile(FILE* in) {
-  SnapshotData* snapshot_data = new SnapshotData();
-  CHECK_EQ(snapshot_data->data_ownership, SnapshotData::DataOwnership::kOwned);
-  EmbedderSnapshotData::Pointer result{
-      new EmbedderSnapshotData(snapshot_data, true)};
-  if (!SnapshotData::FromBlob(snapshot_data, in)) {
-    return {};
-  }
-  return result;
+  return FromBlob(ReadFileSync(in));
 }
 
 std::vector<char> EmbedderSnapshotData::ToBlob() const {
   return impl_->ToBlob();
 }
 
 void EmbedderSnapshotData::ToFile(FILE* out) const {
-  impl_->ToBlob(out);
+  impl_->ToFile(out);
 }
 
 EmbedderSnapshotData::EmbedderSnapshotData(const SnapshotData* impl,

src/env.h

@@ -517,12 +517,12 @@ struct SnapshotData {
   // v8::ScriptCompiler::CachedData is not copyable.
   std::vector<builtins::CodeCacheInfo> code_cache;
 
-  void ToBlob(FILE* out) const;
+  void ToFile(FILE* out) const;
   std::vector<char> ToBlob() const;
   // If returns false, the metadata doesn't match the current Node.js binary,
   // and the caller should not consume the snapshot data.
   bool Check() const;
-  static bool FromBlob(SnapshotData* out, FILE* in);
+  static bool FromFile(SnapshotData* out, FILE* in);
   static bool FromBlob(SnapshotData* out, const std::vector<char>& in);
   static const SnapshotData* FromEmbedderWrapper(
       const EmbedderSnapshotData* data);

src/node.cc

@@ -1146,7 +1146,7 @@ ExitCode GenerateAndWriteSnapshotData(const SnapshotData** snapshot_data_ptr,
 
   FILE* fp = fopen(snapshot_blob_path.c_str(), "wb");
   if (fp != nullptr) {
-    (*snapshot_data_ptr)->ToBlob(fp);
+    (*snapshot_data_ptr)->ToFile(fp);
     fclose(fp);
   } else {
     fprintf(stderr,
@@ -1174,7 +1174,7 @@ ExitCode LoadSnapshotDataAndRun(const SnapshotData** snapshot_data_ptr,
       return exit_code;
     }
     std::unique_ptr<SnapshotData> read_data = std::make_unique<SnapshotData>();
-    if (!SnapshotData::FromBlob(read_data.get(), fp)) {
+    if (!SnapshotData::FromFile(read_data.get(), fp)) {
       // If we fail to read the customized snapshot, simply exit with 1.
       // TODO(joyeecheung): should be kStartupSnapshotFailure.
       exit_code = ExitCode::kGenericUserError;

src/node_snapshotable.cc

@@ -862,7 +862,7 @@ std::vector<char> SnapshotData::ToBlob() const {
   return w.sink;
 }
 
-void SnapshotData::ToBlob(FILE* out) const {
+void SnapshotData::ToFile(FILE* out) const {
   const std::vector<char> sink = ToBlob();
   size_t num_written = fwrite(sink.data(), sink.size(), 1, out);
   CHECK_EQ(num_written, 1);
@@ -877,18 +877,8 @@ EmbedderSnapshotData::Pointer SnapshotData::AsEmbedderWrapper() const {
   return EmbedderSnapshotData::Pointer{new EmbedderSnapshotData(this, false)};
 }
 
-bool SnapshotData::FromBlob(SnapshotData* out, FILE* in) {
-  CHECK_EQ(ftell(in), 0);
-  int err = fseek(in, 0, SEEK_END);
-  CHECK_EQ(err, 0);
-  size_t size = ftell(in);
-  err = fseek(in, 0, SEEK_SET);
-  CHECK_EQ(err, 0);
-
-  std::vector<char> sink(size);
-  size_t num_read = fread(sink.data(), size, 1, in);
-  CHECK_EQ(num_read, 1);
-  return FromBlob(out, sink);
+bool SnapshotData::FromFile(SnapshotData* out, FILE* in) {
+  return FromBlob(out, ReadFileSync(in));
 }
 
 bool SnapshotData::FromBlob(SnapshotData* out, const std::vector<char>& in) {

src/util.cc

@@ -267,6 +267,20 @@ int ReadFileSync(std::string* result, const char* path) {
   return 0;
 }
 
+std::vector<char> ReadFileSync(FILE* fp) {
+  CHECK_EQ(ftell(fp), 0);
+  int err = fseek(fp, 0, SEEK_END);
+  CHECK_EQ(err, 0);
+  size_t size = ftell(fp);
+  err = fseek(fp, 0, SEEK_SET);
+  CHECK_EQ(err, 0);
+
+  std::vector<char> contents(size);
+  size_t num_read = fread(contents.data(), size, 1, fp);
+  CHECK_EQ(num_read, 1);
+  return contents;
+}
+
 void DiagnosticFilename::LocalTime(TIME_TYPE* tm_struct) {
 #ifdef _WIN32
   GetLocalTime(tm_struct);

src/util.h

@@ -867,6 +867,8 @@ std::unique_ptr<T> static_unique_pointer_cast(std::unique_ptr<U>&& ptr) {
 // Returns a non-zero code if it fails to open or read the file,
 // aborts if it fails to close the file.
 int ReadFileSync(std::string* result, const char* path);
+// Reads all contents of a FILE*, aborts if it fails.
+std::vector<char> ReadFileSync(FILE* fp);
 
 v8::Local<v8::FunctionTemplate> NewFunctionTemplate(
     v8::Isolate* isolate,