src: add allocation utils to env

Add a RAII utility for managing blocks of memory that have
been allocated with the `ArrayBuffer::Allocator` for a given
`Isolate`.

PR-URL: https://github.com/nodejs/node/pull/26207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

1 files changed, 98 insertions, 0 deletions

diff --git a/src/env-inl.h b/src/env-inl.h
index 51c7e0d7b0..63b71daf15 100644
--- a/src/env-inl.h
+++ b/src/env-inl.h
@@ -715,6 +715,104 @@ inline IsolateData* Environment::isolate_data() const {
   return isolate_data_;
 }
 
+inline char* Environment::AllocateUnchecked(size_t size) {
+  return static_cast<char*>(
+      isolate_data()->allocator()->AllocateUninitialized(size));
+}
+
+inline char* Environment::Allocate(size_t size) {
+  char* ret = AllocateUnchecked(size);
+  CHECK_NE(ret, nullptr);
+  return ret;
+}
+
+inline void Environment::Free(char* data, size_t size) {
+  if (data != nullptr)
+    isolate_data()->allocator()->Free(data, size);
+}
+
+inline AllocatedBuffer Environment::AllocateManaged(size_t size, bool checked) {
+  char* data = checked ? Allocate(size) : AllocateUnchecked(size);
+  if (data == nullptr) size = 0;
+  return AllocatedBuffer(this, uv_buf_init(data, size));
+}
+
+inline AllocatedBuffer::AllocatedBuffer(Environment* env, uv_buf_t buf)
+    : env_(env), buffer_(buf) {}
+
+inline void AllocatedBuffer::Resize(size_t len) {
+  char* new_data = env_->Reallocate(buffer_.base, buffer_.len, len);
+  CHECK_IMPLIES(len > 0, new_data != nullptr);
+  buffer_ = uv_buf_init(new_data, len);
+}
+
+inline uv_buf_t AllocatedBuffer::release() {
+  uv_buf_t ret = buffer_;
+  buffer_ = uv_buf_init(nullptr, 0);
+  return ret;
+}
+
+inline char* AllocatedBuffer::data() {
+  return buffer_.base;
+}
+
+inline const char* AllocatedBuffer::data() const {
+  return buffer_.base;
+}
+
+inline size_t AllocatedBuffer::size() const {
+  return buffer_.len;
+}
+
+inline AllocatedBuffer::AllocatedBuffer(Environment* env)
+    : env_(env), buffer_(uv_buf_init(nullptr, 0)) {}
+
+inline AllocatedBuffer::AllocatedBuffer(AllocatedBuffer&& other)
+    : AllocatedBuffer() {
+  *this = std::move(other);
+}
+
+inline AllocatedBuffer& AllocatedBuffer::operator=(AllocatedBuffer&& other) {
+  clear();
+  env_ = other.env_;
+  buffer_ = other.release();
+  return *this;
+}
+
+inline AllocatedBuffer::~AllocatedBuffer() {
+  clear();
+}
+
+inline void AllocatedBuffer::clear() {
+  uv_buf_t buf = release();
+  env_->Free(buf.base, buf.len);
+}
+
+// It's a bit awkward to define this Buffer::New() overload here, but it
+// avoids a circular dependency with node_internals.h.
+namespace Buffer {
+v8::MaybeLocal<v8::Object> New(Environment* env,
+                               char* data,
+                               size_t length,
+                               bool uses_malloc);
+}
+
+inline v8::MaybeLocal<v8::Object> AllocatedBuffer::ToBuffer() {
+  CHECK_NOT_NULL(env_);
+  v8::MaybeLocal<v8::Object> obj = Buffer::New(env_, data(), size(), false);
+  if (!obj.IsEmpty()) release();
+  return obj;
+}
+
+inline v8::Local<v8::ArrayBuffer> AllocatedBuffer::ToArrayBuffer() {
+  CHECK_NOT_NULL(env_);
+  uv_buf_t buf = release();
+  return v8::ArrayBuffer::New(env_->isolate(),
+                              buf.base,
+                              buf.len,
+                              v8::ArrayBufferCreationMode::kInternalized);
+}
+
 inline void Environment::ThrowError(const char* errmsg) {
   ThrowError(v8::Exception::Error, errmsg);
 }