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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Alex Robinson <arobinson@cloudflare.com>
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Date: Wed, 2 Mar 2022 15:58:04 -0600
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Subject: Allow manually setting ValueDeserializer format version
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For many years, V8's serialization version didn't change. In the meantime,
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we accidentally stored data that was missing a version header. This patch
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allows us to start using a header while still being able to correctly
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interpret our existing stored data that was missing a header, using code
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like:
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  auto maybeHeader = deserializer.ReadHeader(isolate->GetCurrentContext());
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  KJ_ASSERT(maybeHeader.IsNothing() || maybeHeader.FromJust());
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  if (deserializer.GetWireFormatVersion() == 0) {
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    deserializer.SetWireFormatVersion(13);
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  }
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  auto maybeValue = deserializer.ReadValue(isolate->GetCurrentContext());
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Signed-off-by: James M Snell <jsnell@cloudflare.com>
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diff --git a/include/v8-value-serializer.h b/include/v8-value-serializer.h
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index 0cb3e045bc46ec732956318b980e749d1847d06d..40ad805c7970cc9379e69f046205836dbd760373 100644
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--- a/include/v8-value-serializer.h
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+++ b/include/v8-value-serializer.h
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@@ -293,6 +293,13 @@ class V8_EXPORT ValueDeserializer {
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    */
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   uint32_t GetWireFormatVersion() const;
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+  /**
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+   * Sets the underlying wire format version. Should only be used if there's no
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+   * header specifying the wire format version but you're confident you know
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+   * what version was used to serialize the data.
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+   */
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+  void SetWireFormatVersion(uint32_t version);
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+
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   /**
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    * Reads raw data in various common formats to the buffer.
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    * Note that integer types are read in base-128 varint format, not with a
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diff --git a/src/api/api.cc b/src/api/api.cc
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index 32fc059d6d2375fd87cb2f263a5846444fd9d0d1..e98a1d272b663f26e41313f10b99cd564793c5f8 100644
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--- a/src/api/api.cc
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+++ b/src/api/api.cc
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@@ -3706,6 +3706,10 @@ uint32_t ValueDeserializer::GetWireFormatVersion() const {
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   return private_->deserializer.GetWireFormatVersion();
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 }
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+void ValueDeserializer::SetWireFormatVersion(uint32_t version) {
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+  private_->deserializer.SetWireFormatVersion(version);
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+}
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+
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 MaybeLocal<Value> ValueDeserializer::ReadValue(Local<Context> context) {
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   PrepareForExecutionScope api_scope{context,
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                                      RCCId::kAPI_ValueDeserializer_ReadValue};
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diff --git a/src/objects/value-serializer.h b/src/objects/value-serializer.h
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index 43dc34d6189d7332e019db758760eb5c71a9fe99..b84dcc77d4060d13c389b4afed101847c85998da 100644
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--- a/src/objects/value-serializer.h
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+++ b/src/objects/value-serializer.h
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@@ -221,6 +221,13 @@ class ValueDeserializer {
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    */
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   uint32_t GetWireFormatVersion() const { return version_; }
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+  /*
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+   * Sets the underlying wire format version. Should only be used if there's no
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+   * header specifying the wire format version but you're confident you know
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+   * what version was used to serialize the data.
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+   */
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+  void SetWireFormatVersion(uint32_t version) { version_ = version; }
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+
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   /*
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    * Deserializes a V8 object from the buffer.
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    */