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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: James M Snell <jasnell@gmail.com>
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Date: Wed, 16 Mar 2022 08:59:21 -0700
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Subject: Allow manually setting ValueSerializer format version
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Refs: https://bitbucket.cfdata.org/projects/MIRRORS/repos/v8/pull-requests/2/overview
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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 40ad805c7970cc9379e69f046205836dbd760373..596be18adeb3a5a81794aaa44b1d347dec6c0c7d 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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@@ -154,6 +154,11 @@ class V8_EXPORT ValueSerializer {
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   ValueSerializer(Isolate* isolate, Delegate* delegate);
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   ~ValueSerializer();
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+  /**
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+   * Instruct the ValueSerializer to write at a specific serializer version.
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+   */
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+  Maybe<bool> SetWriteVersion(uint32_t version);
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+
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   /**
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    * Writes out a header, which includes the format version.
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    */
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diff --git a/src/api/api.cc b/src/api/api.cc
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index e98a1d272b663f26e41313f10b99cd564793c5f8..73f38d9a2b25d7420b73f96c34e8aa1764a69223 100644
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--- a/src/api/api.cc
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+++ b/src/api/api.cc
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@@ -3578,6 +3578,10 @@ ValueSerializer::ValueSerializer(Isolate* v8_isolate, Delegate* delegate)
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 ValueSerializer::~ValueSerializer() { delete private_; }
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+Maybe<bool> ValueSerializer::SetWriteVersion(uint32_t version) {
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+  return private_->serializer.SetWriteVersion(version);
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+}
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+
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 void ValueSerializer::WriteHeader() { private_->serializer.WriteHeader(); }
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 void ValueSerializer::SetTreatArrayBufferViewsAsHostObjects(bool mode) {
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diff --git a/src/objects/value-serializer.cc b/src/objects/value-serializer.cc
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index b32852867593bcfd3d0d1b87539d9f904f054aa8..6dc0e13d885aa537a09d580cfc147546cf6fc432 100644
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--- a/src/objects/value-serializer.cc
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+++ b/src/objects/value-serializer.cc
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@@ -298,6 +298,7 @@ ValueSerializer::ValueSerializer(Isolate* isolate,
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     : isolate_(isolate),
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       delegate_(delegate),
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       zone_(isolate->allocator(), ZONE_NAME),
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+      version_(kLatestVersion),
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       id_map_(isolate->heap(), ZoneAllocationPolicy(&zone_)),
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       array_buffer_transfer_map_(isolate->heap(),
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                                  ZoneAllocationPolicy(&zone_)) {
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@@ -317,9 +318,17 @@ ValueSerializer::~ValueSerializer() {
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   }
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 }
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+Maybe<bool> ValueSerializer::SetWriteVersion(uint32_t version) {
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+  if (version < 13 || version > kLatestVersion) {
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+    return ThrowDataCloneError(MessageTemplate::kDataCloneError);
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+  }
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+  version_ = version;
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+  return Just(true);
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+}
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+
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 void ValueSerializer::WriteHeader() {
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   WriteTag(SerializationTag::kVersion);
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-  WriteVarint(kLatestVersion);
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+  WriteVarint(version_);
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 }
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 void ValueSerializer::SetTreatArrayBufferViewsAsHostObjects(bool mode) {
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@@ -1112,10 +1121,12 @@ Maybe<bool> ValueSerializer::WriteJSArrayBufferView(
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   WriteVarint(static_cast<uint8_t>(tag));
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   WriteVarint(static_cast<uint32_t>(view->byte_offset()));
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   WriteVarint(static_cast<uint32_t>(view->byte_length()));
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-  uint32_t flags =
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+  if (version_ >= 14) {
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+    uint32_t flags =
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       JSArrayBufferViewIsLengthTracking::encode(view->is_length_tracking()) |
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       JSArrayBufferViewIsBackedByRab::encode(view->is_backed_by_rab());
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-  WriteVarint(flags);
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+    WriteVarint(flags);
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+  }
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   return ThrowIfOutOfMemory();
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 }
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diff --git a/src/objects/value-serializer.h b/src/objects/value-serializer.h
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index b84dcc77d4060d13c389b4afed101847c85998da..06475f7b9c2a797066f5cfd32b232e5aa55f1f75 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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@@ -54,6 +54,11 @@ class ValueSerializer {
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   ValueSerializer(const ValueSerializer&) = delete;
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   ValueSerializer& operator=(const ValueSerializer&) = delete;
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+  /*
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+   * Instruct the ValueSerializer to write at a specific serializer version.
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+   */
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+  Maybe<bool> SetWriteVersion(uint32_t version);
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+
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   /*
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    * Writes out a header, which includes the format version.
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    */
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@@ -182,6 +187,7 @@ class ValueSerializer {
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   bool treat_array_buffer_views_as_host_objects_ = false;
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   bool out_of_memory_ = false;
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   Zone zone_;
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+  uint32_t version_;
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   // To avoid extra lookups in the identity map, ID+1 is actually stored in the
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   // map (checking if the used identity is zero is the fast way of checking if