tools: refactor snapshot builder

This patch:

- Moves the snapshot building code to src/ so that we can reuse it
  later when generating custom snapshots from an entry point accepted
  by the node binary.
- Create a SnapshotData struct that incorporates all the data useful
  for a snapshot blob, including both the V8 data and the Node.js
  data.

PR-URL: https://github.com/nodejs/node/pull/38902
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/env.h b/src/env.h
index 4a50227ee8d..a3944eab90a 100644
--- a/src/env.h
+++ b/src/env.h
@@ -955,6 +955,13 @@ struct EnvSerializeInfo {
   friend std::ostream& operator<<(std::ostream& o, const EnvSerializeInfo& i);
 };
 
+struct SnapshotData {
+  SnapshotData() { blob.data = nullptr; }
+  v8::StartupData blob;
+  std::vector<size_t> isolate_data_indices;
+  EnvSerializeInfo env_info;
+};
+
 class Environment : public MemoryRetainer {
  public:
   Environment(const Environment&) = delete;