feat: implement ArrayBuffer realloc (#669)

* feat: implement ArrayBuffer realloc

patches/common/chromium/.patches.yaml

@@ -1,5 +1,16 @@
 repo: src
 patches:
+-
+  author: Shelley Vohr <shelley.vohr@gmail.com>
+  file: add_realloc.patch
+  description: |
+    Blink overrides ArrayBuffer's allocator with its own one, while Node simply
+    uses malloc and free, so we need to use v8's allocator in Node. As part of the
+    10.6.0 upgrade, we needed to make SerializerDelegate accept an allocator
+    argument in its constructor, and override ReallocateBufferMemory and
+    FreeBufferMemory to use the allocator. We cannot simply allocate and then memcpy
+    when we override ReallocateBufferMemory, so we therefore need to implement
+    Realloc on the v8 side and correspondingly in gin.
 -
   author: Ales Pergl <alpergl@microsoft.com>
   file: build_gn.patch

patches/common/chromium/add_realloc.patch

@@ -0,0 +1,70 @@
+diff --git a/gin/array_buffer.cc b/gin/array_buffer.cc
+index f84934bfd712..63bce16a9d06 100644
+--- a/gin/array_buffer.cc
++++ b/gin/array_buffer.cc
+@@ -43,6 +43,10 @@ void* ArrayBufferAllocator::AllocateUninitialized(size_t length) {
+   return malloc(length);
+ }
+
++void* ArrayBufferAllocator::Realloc(void* data, size_t length) {
++  return realloc(data, length);
++}
++
+ void ArrayBufferAllocator::Free(void* data, size_t length) {
+   free(data);
+ }
+diff --git a/gin/array_buffer.h b/gin/array_buffer.h
+index 2aef366ac819..c037808a9bb3 100644
+--- a/gin/array_buffer.h
++++ b/gin/array_buffer.h
+@@ -21,6 +21,7 @@ class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
+  public:
+   void* Allocate(size_t length) override;
+   void* AllocateUninitialized(size_t length) override;
++  void* Realloc(void* data, size_t length) override;
+   void Free(void* data, size_t length) override;
+
+   GIN_EXPORT static ArrayBufferAllocator* SharedInstance();
+diff --git a/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.cc b/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.cc
+index 053babce1051..e33d6d4ceb5a 100644
+--- a/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.cc
++++ b/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.cc
+@@ -121,6 +121,11 @@ void* ArrayBufferContents::AllocateMemoryOrNull(size_t size,
+   return AllocateMemoryWithFlags(size, policy, base::PartitionAllocReturnNull);
+ }
+
++void* ArrayBufferContents::Realloc(void* data, size_t size) {
++  return Partitions::ArrayBufferPartition()->Realloc(data, size,
++      WTF_HEAP_PROFILER_TYPE_NAME(ArrayBufferContents));
++}
++
+ void ArrayBufferContents::FreeMemory(void* data) {
+   Partitions::ArrayBufferPartition()->Free(data);
+ }
+diff --git a/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.h b/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.h
+index 809229caa872..6248ad32d6b0 100644
+--- a/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.h
++++ b/third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.h
+@@ -178,6 +178,7 @@ class WTF_EXPORT ArrayBufferContents {
+   void CopyTo(ArrayBufferContents& other);
+
+   static void* AllocateMemoryOrNull(size_t, InitializationPolicy);
++  static void* Realloc(void* data, size_t);
+   static void FreeMemory(void*);
+   static DataHandle CreateDataHandle(size_t, InitializationPolicy);
+   static void Initialize(
+diff --git a/third_party/blink/renderer/bindings/core/v8/v8_initializer.cc b/third_party/blink/renderer/bindings/core/v8/v8_initializer.cc
+index cf2762ede559..f065b5ebafb8 100644
+--- a/third_party/blink/renderer/bindings/core/v8/v8_initializer.cc
++++ b/third_party/blink/renderer/bindings/core/v8/v8_initializer.cc
+@@ -555,6 +555,10 @@ class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
+         size, WTF::ArrayBufferContents::kDontInitialize);
+   }
+
++  void* Realloc(void* data, size_t size) override {
++    return WTF::ArrayBufferContents::Realloc(data, size);
++  }
++
+   void Free(void* data, size_t size) override {
+     WTF::ArrayBufferContents::FreeMemory(data);
+   }

patches/common/v8/.patches.yaml

@@ -1,5 +1,16 @@
 repo: src/v8
 patches:
+-
+  author: Shelley Vohr <shelley.vohr@gmail.com>
+  file: add_realloc.patch
+  description: |
+    Blink overrides ArrayBuffer's allocator with its own one, while Node simply
+    uses malloc and free, so we need to use v8's allocator in Node. As part of the
+    10.6.0 upgrade, we needed to make SerializerDelegate accept an allocator
+    argument in its constructor, and override ReallocateBufferMemory and
+    FreeBufferMemory to use the allocator. We cannot simply allocate and then memcpy
+    when we override ReallocateBufferMemory, so we therefore need to implement
+    Realloc on the v8 side.
 -
   author: Ales Pergl <alpergl@microsoft.com>
   file: build_gn.patch

patches/common/v8/add_realloc.patch

@@ -0,0 +1,33 @@
+diff --git a/include/v8.h b/include/v8.h
+index 573e80176d..5eefe26fe9 100644
+--- a/include/v8.h
++++ b/include/v8.h
+@@ -4318,6 +4318,13 @@ class V8_EXPORT ArrayBuffer : public Object {
+      */
+     virtual void* AllocateUninitialized(size_t length) = 0;
+
++    /**
++     * Free the memory block of size |length|, pointed to by |data|.
++     * That memory must be previously allocated by |Allocate| and not yet freed
++     * with a call to |Free| or |Realloc|
++     */
++    virtual void* Realloc(void* data, size_t length);
++
+     /**
+      * Free the memory block of size |length|, pointed to by |data|.
+      * That memory is guaranteed to be previously allocated by |Allocate|.
+diff --git a/src/api.cc b/src/api.cc
+index 8b177d041d..e06ca2a207 100644
+--- a/src/api.cc
++++ b/src/api.cc
+@@ -460,6 +460,10 @@ void V8::SetSnapshotDataBlob(StartupData* snapshot_blob) {
+   i::V8::SetSnapshotBlob(snapshot_blob);
+ }
+
++void* v8::ArrayBuffer::Allocator::Realloc(void* data, size_t length) {
++  UNIMPLEMENTED();
++}
++
+ namespace {
+
+ class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {