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deps: V8: add CopyArrayBufferBytes API · nodejs/node@0bf8e12 · GitHub

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ronag
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aduh95
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deps: V8: add CopyArrayBufferBytes API
Add v8::ArrayBuffer::CopyArrayBufferBytes and v8::SharedArrayBuffer::CopyArrayBufferBytes, which copy a byte range from one backing store to another. V8 clamps the byte range and handles detached and immutable buffers: nothing is copied when the source is detached or the target is detached or immutable, and the number of bytes actually copied is returned. The SharedArrayBuffer overload uses a relaxed-atomic memmove that honors the SharedArrayBuffer memory model. Carried as a floating patch cherry-picked from: https://chromium-review.googlesource.com/c/v8/v8/+/7735151 That CL is authored by a Node.js collaborator (Ben Noordhuis) and is expected to land upstream, so the floating patch should be easy to maintain: it touches nothing but the public ArrayBuffer API and can be dropped wholesale on the next V8 upgrade that includes it. v8_embedder_string is bumped to -node.21 accordingly. Refs: https://chromium-review.googlesource.com/c/v8/v8/+/7735151 Signed-off-by: Robert Nagy <ronagy@icloud.com> PR-URL: #63828 Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com> Reviewed-By: René <contact.9a5d6388@renegade334.me.uk>
1 parent 394d0bb commit 0bf8e12

4 files changed

Lines changed: 125 additions & 1 deletion

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‎common.gypi‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -40,7 +40,7 @@
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# Reset this number to 0 on major V8 upgrades.
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# Increment by one for each non-official patch applied to deps/v8.
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'v8_embedder_string': '-node.20',
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'v8_embedder_string': '-node.21',
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##### V8 defaults for Node.js #####
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‎deps/v8/include/v8-array-buffer.h‎

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Original file line numberDiff line numberDiff line change
@@ -338,6 +338,17 @@ class V8_EXPORT ArrayBuffer : public Object {
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*/
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bool IsImmutable() const;
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/**
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* Copy up to |bytes_to_copy| bytes from this ArrayBuffer starting at
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* position |source_start| to the target ArrayBuffer starting at position
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* |target_start|. Nothing is copied if the source ArrayBuffer is detached,
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* or if the target ArrayBuffer is detached or immutable.
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* Returns the number of bytes actually copied.
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*/
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size_t CopyArrayBufferBytes(size_t source_start, size_t bytes_to_copy,
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Local<ArrayBuffer> target,
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size_t target_start) const;
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341352
/**
342353
* Detaches this ArrayBuffer and all its views (typed arrays).
343354
* Detaching sets the byte length of the buffer and all typed arrays to zero,
@@ -605,6 +616,16 @@ class V8_EXPORT SharedArrayBuffer : public Object {
605616
*/
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void* Data() const;
607618

619+
/**
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* Copy up to |bytes_to_copy| bytes from this SharedArrayBuffer starting at
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* position |source_start| to the target SharedArrayBuffer starting at
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* position |target_start|.
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* Returns the number of bytes actually copied.
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*/
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size_t CopyArrayBufferBytes(size_t source_start, size_t bytes_to_copy,
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Local<SharedArrayBuffer> target,
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size_t target_start) const;
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V8_INLINE static SharedArrayBuffer* Cast(Value* value) {
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#ifdef V8_ENABLE_CHECKS
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CheckCast(value);

‎deps/v8/src/api/api.cc‎

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Original file line numberDiff line numberDiff line change
@@ -4221,6 +4221,44 @@ void* v8::SharedArrayBuffer::Data() const {
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return Utils::OpenDirectHandle(this)->backing_store();
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}
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template <bool is_shared>
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static size_t CopyArrayBufferBytesImpl(const void* source_buffer,
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size_t source_start,
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size_t source_length,
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void* target_buffer, size_t target_start,
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size_t target_length,
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size_t bytes_to_copy) {
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source_start = std::min(source_start, source_length);
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target_start = std::min(target_start, target_length);
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size_t source_size = source_length - source_start;
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size_t target_size = target_length - target_start;
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bytes_to_copy = std::min({bytes_to_copy, source_size, target_size});
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if (bytes_to_copy == 0) return 0;
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const char* src = static_cast<const char*>(source_buffer) + source_start;
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char* dst = static_cast<char*>(target_buffer) + target_start;
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if (is_shared) {
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base::Relaxed_Memmove(reinterpret_cast<base::Atomic8*>(dst),
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reinterpret_cast<const base::Atomic8*>(src),
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bytes_to_copy);
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} else {
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std::memmove(dst, src, bytes_to_copy);
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}
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return bytes_to_copy;
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}
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size_t v8::SharedArrayBuffer::CopyArrayBufferBytes(
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size_t source_start, size_t bytes_to_copy, Local<SharedArrayBuffer> target,
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size_t target_start) const {
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i::DisallowGarbageCollection no_gc;
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auto self = Utils::OpenDirectHandle(this);
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auto that = Utils::OpenDirectHandle(*target);
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DCHECK(!that->is_immutable());
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return CopyArrayBufferBytesImpl<true>(self->backing_store(), source_start,
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self->GetByteLength(),
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that->backing_store(), target_start,
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that->GetByteLength(), bytes_to_copy);
4260+
}
4261+
42244262
void v8::ArrayBuffer::CheckCast(Value* that) {
42254263
auto obj = *Utils::OpenDirectHandle(that);
42264264
Utils::ApiCheck(
@@ -8907,6 +8945,21 @@ bool v8::ArrayBuffer::IsImmutable() const {
89078945
return Utils::OpenDirectHandle(this)->is_immutable();
89088946
}
89098947

8948+
size_t v8::ArrayBuffer::CopyArrayBufferBytes(size_t source_start,
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size_t bytes_to_copy,
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Local<ArrayBuffer> target,
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size_t target_start) const {
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i::DisallowGarbageCollection no_gc;
8953+
auto self = Utils::OpenDirectHandle(this);
8954+
auto that = Utils::OpenDirectHandle(*target);
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if (self->was_detached()) return 0;
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if (that->was_detached() || that->is_immutable()) return 0;
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return CopyArrayBufferBytesImpl<false>(self->backing_store(), source_start,
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self->GetByteLength(),
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that->backing_store(), target_start,
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that->GetByteLength(), bytes_to_copy);
8961+
}
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89108963
namespace {
89118964
std::shared_ptr<i::BackingStore> ToInternal(
89128965
std::shared_ptr<i::BackingStoreBase> backing_store) {

‎deps/v8/test/cctest/test-api-array-buffer.cc‎

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Original file line numberDiff line numberDiff line change
@@ -1301,3 +1301,53 @@ TEST(ArrayBuffer_ImmutableBackingStore) {
13011301

13021302
CHECK(ab->IsImmutable());
13031303
}
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1305+
TEST(ArrayBuffer_CopyArrayBufferBytes) {
1306+
LocalContext env;
1307+
v8::Isolate* isolate = env.isolate();
1308+
v8::HandleScope scope(isolate);
1309+
auto ab1 = v8::ArrayBuffer::New(isolate, 6);
1310+
auto ab2 = v8::ArrayBuffer::New(isolate, 4);
1311+
std::memcpy(ab1->Data(), "123456", 6);
1312+
std::memcpy(ab2->Data(), "ABCD", 4);
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CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 0, ab2, 0));
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CHECK_EQ(0, ab1->CopyArrayBufferBytes(6, 0, ab2, 6));
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CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 4, ab2, 6));
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CHECK_EQ(0, std::memcmp(ab2->Data(), "ABCD", 4));
1317+
CHECK_EQ(4, ab1->CopyArrayBufferBytes(0, 6, ab2, 0));
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CHECK_EQ(0, std::memcmp(ab2->Data(), "1234", 4));
1319+
CHECK_EQ(2, ab1->CopyArrayBufferBytes(0, 6, ab2, 2));
1320+
CHECK_EQ(0, std::memcmp(ab2->Data(), "1212", 4));
1321+
ab2->Detach(v8::Local<v8::Value>()).Check();
1322+
CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 6, ab2, 0));
1323+
std::unique_ptr<v8::BackingStore> backing_store =
1324+
v8::ArrayBuffer::NewBackingStore(isolate, 6);
1325+
CHECK(backing_store);
1326+
v8::internal::BackingStore* i_backing_store =
1327+
reinterpret_cast<v8::internal::BackingStore*>(backing_store.get());
1328+
i_backing_store->set_is_immutable(true);
1329+
CHECK(i_backing_store->is_immutable());
1330+
std::shared_ptr<v8::BackingStore> shared_backing_store =
1331+
std::move(backing_store);
1332+
auto ab3 = v8::ArrayBuffer::New(isolate, shared_backing_store);
1333+
CHECK(ab3->IsImmutable());
1334+
CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 6, ab3, 0));
1335+
}
1336+
1337+
TEST(SharedArrayBuffer_CopyArrayBufferBytes) {
1338+
LocalContext env;
1339+
v8::Isolate* isolate = env.isolate();
1340+
v8::HandleScope scope(isolate);
1341+
auto ab1 = v8::SharedArrayBuffer::New(isolate, 6);
1342+
auto ab2 = v8::SharedArrayBuffer::New(isolate, 4);
1343+
std::memcpy(ab1->Data(), "123456", 6);
1344+
std::memcpy(ab2->Data(), "ABCD", 4);
1345+
CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 0, ab2, 0));
1346+
CHECK_EQ(0, ab1->CopyArrayBufferBytes(6, 0, ab2, 6));
1347+
CHECK_EQ(0, ab1->CopyArrayBufferBytes(0, 4, ab2, 6));
1348+
CHECK_EQ(0, std::memcmp(ab2->Data(), "ABCD", 4));
1349+
CHECK_EQ(4, ab1->CopyArrayBufferBytes(0, 6, ab2, 0));
1350+
CHECK_EQ(0, std::memcmp(ab2->Data(), "1234", 4));
1351+
CHECK_EQ(2, ab1->CopyArrayBufferBytes(0, 6, ab2, 2));
1352+
CHECK_EQ(0, std::memcmp(ab2->Data(), "1212", 4));
1353+
}

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