Skip to content

src: simplify and fix FFI ArrayBuffer accesses #62857

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
addaleax wants to merge 2 commits into
base: main
Choose a base branch
from
Open

src: simplify and fix FFI ArrayBuffer accesses #62857

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
147fc50
src: simplify and fix FFI ArrayBuffer accesses
addaleax Apr 20, 2026
b6651d8
fixup! src: simplify and fix FFI ArrayBuffer accesses
addaleax Apr 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
68 changes: 32 additions & 36 deletions src/ffi/data.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ using v8::MaybeLocal;
using v8::NewStringType;
using v8::Number;
using v8::Object;
using v8::SharedArrayBuffer;
using v8::String;
using v8::Value;

Expand Down Expand Up @@ -675,26 +676,17 @@ void ExportBytes(const FunctionCallbackInfo<Value>& args) {
return;
}

const uint8_t* source_data = nullptr;
size_t source_len = 0;
// This needs to be kept alive until the data
// is actually copied.
ArrayBufferViewContents<uint8_t> view;

if (args[0]->IsArrayBuffer()) {
Local<ArrayBuffer> array_buffer = args[0].As<ArrayBuffer>();
std::shared_ptr<BackingStore> store = array_buffer->GetBackingStore();
if (!store) {
THROW_ERR_INVALID_ARG_VALUE(env, "Invalid ArrayBuffer backing store");
return;
}
source_data = static_cast<const uint8_t*>(store->Data());
source_len = array_buffer->ByteLength();
} else if (args[0]->IsArrayBufferView()) {
ArrayBufferViewContents<uint8_t> view(args[0]);
if (args[0]->IsArrayBuffer() || args[0]->IsSharedArrayBuffer() ||
args[0]->IsArrayBufferView()) {
view.ReadValue(args[0]);
if (view.WasDetached()) {
THROW_ERR_INVALID_ARG_VALUE(env, "Invalid ArrayBufferView backing store");
return;
}
source_data = view.data();
source_len = view.length();
} else {
THROW_ERR_INVALID_ARG_TYPE(
env,
Expand All @@ -713,12 +705,12 @@ void ExportBytes(const FunctionCallbackInfo<Value>& args) {
return;
}

if (len < source_len) {
if (len < view.length()) {
THROW_ERR_OUT_OF_RANGE(env, "The length must be >= source byte length");
return;
}

if (ptr == 0 && source_len > 0) {
if (ptr == 0 && view.length() > 0) {
THROW_ERR_FFI_INVALID_POINTER(env,
"Cannot create a buffer from a null pointer");
return;
Expand All @@ -733,9 +725,7 @@ void ExportBytes(const FunctionCallbackInfo<Value>& args) {
return;
}

if (source_len > 0) {
std::memcpy(reinterpret_cast<void*>(ptr), source_data, source_len);
}
std::memcpy(reinterpret_cast<void*>(ptr), view.data(), view.length());
}

void GetRawPointer(const FunctionCallbackInfo<Value>& args) {
Expand All @@ -752,28 +742,34 @@ void GetRawPointer(const FunctionCallbackInfo<Value>& args) {
}

uintptr_t ptr = 0;
size_t offset = 0;
std::shared_ptr<BackingStore> store;

if (args[0]->IsArrayBuffer()) {
Local<ArrayBuffer> array_buffer = args[0].As<ArrayBuffer>();
std::shared_ptr<BackingStore> store = array_buffer->GetBackingStore();
if (!store) {
THROW_ERR_INVALID_ARG_VALUE(env, "Invalid ArrayBuffer backing store");
return;
}
ptr = reinterpret_cast<uintptr_t>(store->Data());
store = args[0].As<ArrayBuffer>()->GetBackingStore();
} else if (args[0]->IsSharedArrayBuffer()) {
store = args[0].As<SharedArrayBuffer>()->GetBackingStore();
} else if (args[0]->IsArrayBufferView()) {
ArrayBufferViewContents<uint8_t> view(args[0]);
if (view.WasDetached()) {
THROW_ERR_INVALID_ARG_VALUE(env, "Invalid ArrayBufferView backing store");
return;
}
ptr = reinterpret_cast<uintptr_t>(view.data());
// Access the store here to ensure that it exists. Small typed arrays
// may not have a store until this point and can instead be stored
// entirely in-heap.
store = args[0].As<ArrayBufferView>()->Buffer()->GetBackingStore();
offset = args[0].As<ArrayBufferView>()->ByteOffset();
} else {
THROW_ERR_INVALID_ARG_TYPE(
env,
"The first argument must be a Buffer, ArrayBuffer, or ArrayBufferView");
THROW_ERR_INVALID_ARG_TYPE(env,
"The first argument must be a Buffer, "
"ArrayBuffer, or ArrayBufferView");
return;
}

// WARNING: There is no inherent guarantee that the pointer returned
// from this function will be valid beyond the lifetime of the BackingStore
// instance!
if (!store) {
THROW_ERR_INVALID_ARG_VALUE(env, "Invalid ArrayBuffer backing store");
return;
}
ptr = reinterpret_cast<uintptr_t>(store->Data()) + offset;

args.GetReturnValue().Set(
BigInt::NewFromUnsigned(isolate, static_cast<uint64_t>(ptr)));
Expand Down
Loading