feat(serde_v8): DetachedBuffer (#14102)

8 files changed, 183 insertions, 25 deletions

diff --git a/core/runtime.rs b/core/runtime.rs
index bea9908ed..cb8b242e9 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -3052,6 +3052,82 @@ assertEquals(1, notify_return_value);
   }
 
   #[test]
+  fn test_op_detached_buffer() {
+    use serde_v8::DetachedBuffer;
+
+    #[op]
+    fn op_sum_take(b: DetachedBuffer) -> Result<u64, anyhow::Error> {
+      Ok(b.as_ref().iter().clone().map(|x| *x as u64).sum())
+    }
+
+    #[op]
+    fn op_boomerang(
+      b: DetachedBuffer,
+    ) -> Result<DetachedBuffer, anyhow::Error> {
+      Ok(b)
+    }
+
+    let ext = Extension::builder()
+      .ops(vec![op_sum_take::decl(), op_boomerang::decl()])
+      .build();
+
+    let mut runtime = JsRuntime::new(RuntimeOptions {
+      extensions: vec![ext],
+      ..Default::default()
+    });
+
+    runtime
+      .execute_script(
+        "test.js",
+        r#"
+        const a1 = new Uint8Array([1,2,3]);
+        const a1b = a1.subarray(0, 3);
+        const a2 = new Uint8Array([5,10,15]);
+        const a2b = a2.subarray(0, 3);
+        
+        
+        if (!(a1.length > 0 && a1b.length > 0)) {
+          throw new Error("a1 & a1b should have a length");
+        }
+        let sum = Deno.core.opSync('op_sum_take', a1b);
+        if (sum !== 6) {
+          throw new Error(`Bad sum: ${sum}`);
+        }
+        if (a1.length > 0 || a1b.length > 0) {
+          throw new Error("expecting a1 & a1b to be detached");
+        }
+
+        const a3 = Deno.core.opSync('op_boomerang', a2b);
+        if (a3.byteLength != 3) {
+          throw new Error(`Expected a3.byteLength === 3, got ${a3.byteLength}`);
+        }
+        if (a3[0] !== 5 || a3[1] !== 10) {
+          throw new Error(`Invalid a3: ${a3[0]}, ${a3[1]}`);
+        }
+        if (a2.byteLength > 0 || a2b.byteLength > 0) {
+          throw new Error("expecting a2 & a2b to be detached, a3 re-attached");
+        }
+        
+        const wmem = new WebAssembly.Memory({ initial: 1, maximum: 2 });
+        const w32 = new Uint32Array(wmem.buffer);
+        w32[0] = 1; w32[1] = 2; w32[2] = 3;
+        const assertWasmThrow = (() => {
+          try {
+            let sum = Deno.core.opSync('op_sum_take', w32.subarray(0, 2));
+            return false;
+          } catch(e) {
+            return e.message.includes('ExpectedDetachable');
+          }
+        });
+        if (!assertWasmThrow()) {
+          throw new Error("expected wasm mem to not be detachable");
+        }
+      "#,
+      )
+      .unwrap();
+  }
+
+  #[test]
   fn test_op_unstable_disabling() {
     #[op]
     fn op_foo() -> Result<i64, anyhow::Error> {
diff --git a/serde_v8/de.rs b/serde_v8/de.rs
index 002b741cf..f5024e5ea 100644
--- a/serde_v8/de.rs
+++ b/serde_v8/de.rs
@@ -7,7 +7,7 @@ use crate::keys::{v8_struct_key, KeyCache};
 use crate::magic::transl8::FromV8;
 use crate::magic::transl8::{visit_magic, MagicType};
 use crate::payload::ValueType;
-use crate::{magic, Buffer, ByteString, U16String};
+use crate::{magic, Buffer, ByteString, DetachedBuffer, U16String};
 
 pub struct Deserializer<'a, 'b, 's> {
   input: v8::Local<'a, v8::Value>,
@@ -328,6 +328,9 @@ impl<'de, 'a, 'b, 's, 'x> de::Deserializer<'de>
       Buffer::MAGIC_NAME => {
         visit_magic(visitor, Buffer::from_v8(self.scope, self.input)?)
       }
+      DetachedBuffer::MAGIC_NAME => {
+        visit_magic(visitor, DetachedBuffer::from_v8(self.scope, self.input)?)
+      }
       ByteString::MAGIC_NAME => {
         visit_magic(visitor, ByteString::from_v8(self.scope, self.input)?)
       }
diff --git a/serde_v8/error.rs b/serde_v8/error.rs
index e4f7f363b..cf66f8e86 100644
--- a/serde_v8/error.rs
+++ b/serde_v8/error.rs
@@ -17,6 +17,7 @@ pub enum Error {
   ExpectedEnum,
   ExpectedObject,
   ExpectedBuffer,
+  ExpectedDetachable,
 
   ExpectedUtf8,
   ExpectedLatin1,
diff --git a/serde_v8/lib.rs b/serde_v8/lib.rs
index 203e1d004..945138384 100644
--- a/serde_v8/lib.rs
+++ b/serde_v8/lib.rs
@@ -13,6 +13,7 @@ pub use error::{Error, Result};
 pub use keys::KeyCache;
 pub use magic::buffer::MagicBuffer as Buffer;
 pub use magic::bytestring::ByteString;
+pub use magic::detached_buffer::DetachedBuffer;
 pub use magic::string_or_buffer::StringOrBuffer;
 pub use magic::u16string::U16String;
 pub use magic::Value;
diff --git a/serde_v8/magic/detached_buffer.rs b/serde_v8/magic/detached_buffer.rs
new file mode 100644
index 000000000..1435a0fa6
--- /dev/null
+++ b/serde_v8/magic/detached_buffer.rs
@@ -0,0 +1,69 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+
+use core::ops::Range;
+use std::ops::Deref;
+use std::ops::DerefMut;
+
+use super::transl8::FromV8;
+use super::transl8::ToV8;
+use super::zero_copy_buf::to_ranged_buffer;
+use super::zero_copy_buf::ZeroCopyBuf;
+use crate::magic::transl8::impl_magic;
+
+// A buffer that detaches when deserialized from JS
+pub struct DetachedBuffer(ZeroCopyBuf);
+impl_magic!(DetachedBuffer);
+
+impl AsRef<[u8]> for DetachedBuffer {
+  fn as_ref(&self) -> &[u8] {
+    self.0.as_ref()
+  }
+}
+
+impl AsMut<[u8]> for DetachedBuffer {
+  fn as_mut(&mut self) -> &mut [u8] {
+    self.0.as_mut()
+  }
+}
+
+impl Deref for DetachedBuffer {
+  type Target = [u8];
+  fn deref(&self) -> &[u8] {
+    self.0.deref()
+  }
+}
+
+impl DerefMut for DetachedBuffer {
+  fn deref_mut(&mut self) -> &mut [u8] {
+    self.0.deref_mut()
+  }
+}
+
+impl ToV8 for DetachedBuffer {
+  fn to_v8<'a>(
+    &self,
+    scope: &mut v8::HandleScope<'a>,
+  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
+    let buffer = v8::ArrayBuffer::with_backing_store(scope, &self.0.store);
+    let Range { start, end } = self.0.range;
+    let (off, len) = (start, end - start);
+    let v = v8::Uint8Array::new(scope, buffer, off, len).unwrap();
+    Ok(v.into())
+  }
+}
+
+impl FromV8 for DetachedBuffer {
+  fn from_v8(
+    scope: &mut v8::HandleScope,
+    value: v8::Local<v8::Value>,
+  ) -> Result<Self, crate::Error> {
+    let (b, range) =
+      to_ranged_buffer(scope, value).or(Err(crate::Error::ExpectedBuffer))?;
+    if !b.is_detachable() {
+      return Err(crate::Error::ExpectedDetachable);
+    }
+    let store = b.get_backing_store();
+    b.detach(); // Detach
+    Ok(Self(ZeroCopyBuf { store, range }))
+  }
+}
diff --git a/serde_v8/magic/mod.rs b/serde_v8/magic/mod.rs
index bc86c6a7c..4f5398bda 100644
--- a/serde_v8/magic/mod.rs
+++ b/serde_v8/magic/mod.rs
@@ -1,6 +1,7 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 pub mod buffer;
 pub mod bytestring;
+pub mod detached_buffer;
 pub mod string_or_buffer;
 pub mod transl8;
 pub mod u16string;
diff --git a/serde_v8/magic/zero_copy_buf.rs b/serde_v8/magic/zero_copy_buf.rs
index dcd969aea..a9dc6334c 100644
--- a/serde_v8/magic/zero_copy_buf.rs
+++ b/serde_v8/magic/zero_copy_buf.rs
@@ -19,8 +19,8 @@ use super::transl8::FromV8;
 /// `let copy = Vec::from(&*zero_copy_buf);`
 #[derive(Clone)]
 pub struct ZeroCopyBuf {
-  store: v8::SharedRef<v8::BackingStore>,
-  range: Range<usize>,
+  pub(crate) store: v8::SharedRef<v8::BackingStore>,
+  pub(crate) range: Range<usize>,
 }
 
 unsafe impl Send for ZeroCopyBuf {}
@@ -40,17 +40,6 @@ impl ZeroCopyBuf {
     Ok(Self { store, range })
   }
 
-  pub fn from_view(
-    scope: &mut v8::HandleScope,
-    view: v8::Local<v8::ArrayBufferView>,
-  ) -> Result<Self, v8::DataError> {
-    let buffer = view.buffer(scope).ok_or(v8::DataError::NoData {
-      expected: "view to have a buffer",
-    })?;
-    let (offset, len) = (view.byte_offset(), view.byte_length());
-    Self::from_buffer(buffer, offset..offset + len)
-  }
-
   fn as_slice(&self) -> &[u8] {
     unsafe { &*(&self.store[self.range.clone()] as *const _ as *const [u8]) }
   }
@@ -61,21 +50,32 @@ impl ZeroCopyBuf {
   }
 }
 
+pub(crate) fn to_ranged_buffer<'s>(
+  scope: &mut v8::HandleScope<'s>,
+  value: v8::Local<v8::Value>,
+) -> Result<(v8::Local<'s, v8::ArrayBuffer>, Range<usize>), v8::DataError> {
+  if value.is_array_buffer_view() {
+    let view: v8::Local<v8::ArrayBufferView> = value.try_into()?;
+    let (offset, len) = (view.byte_offset(), view.byte_length());
+    let buffer = view.buffer(scope).ok_or(v8::DataError::NoData {
+      expected: "view to have a buffer",
+    })?;
+    let buffer = v8::Local::new(scope, buffer); // recreate handle to avoid lifetime issues
+    return Ok((buffer, offset..offset + len));
+  }
+  let b: v8::Local<v8::ArrayBuffer> = value.try_into()?;
+  let b = v8::Local::new(scope, b); // recreate handle to avoid lifetime issues
+  Ok((b, 0..b.byte_length()))
+}
+
 impl FromV8 for ZeroCopyBuf {
   fn from_v8(
     scope: &mut v8::HandleScope,
     value: v8::Local<v8::Value>,
   ) -> Result<Self, crate::Error> {
-    if value.is_array_buffer() {
-      value
-        .try_into()
-        .and_then(|b| Self::from_buffer(b, 0..b.byte_length()))
-    } else {
-      value
-        .try_into()
-        .and_then(|view| Self::from_view(scope, view))
-    }
-    .map_err(|_| crate::Error::ExpectedBuffer)
+    to_ranged_buffer(scope, value)
+      .and_then(|(b, r)| Self::from_buffer(b, r))
+      .map_err(|_| crate::Error::ExpectedBuffer)
   }
 }
 
diff --git a/serde_v8/ser.rs b/serde_v8/ser.rs
index 5241aeaef..867d4b795 100644
--- a/serde_v8/ser.rs
+++ b/serde_v8/ser.rs
@@ -8,7 +8,7 @@ use crate::error::{Error, Result};
 use crate::keys::v8_struct_key;
 use crate::magic::transl8::MAGIC_FIELD;
 use crate::magic::transl8::{opaque_deref, opaque_recv, MagicType, ToV8};
-use crate::{magic, Buffer, ByteString, U16String};
+use crate::{magic, Buffer, ByteString, DetachedBuffer, U16String};
 
 type JsValue<'s> = v8::Local<'s, v8::Value>;
 type JsResult<'s> = Result<JsValue<'s>>;
@@ -261,6 +261,7 @@ impl<'a, 'b, 'c, T: MagicType + ToV8> ser::SerializeStruct
 pub enum StructSerializers<'a, 'b, 'c> {
   Magic(MagicalSerializer<'a, 'b, 'c, magic::Value<'a>>),
   MagicBuffer(MagicalSerializer<'a, 'b, 'c, Buffer>),
+  MagicDetached(MagicalSerializer<'a, 'b, 'c, DetachedBuffer>),
   MagicByteString(MagicalSerializer<'a, 'b, 'c, ByteString>),
   MagicU16String(MagicalSerializer<'a, 'b, 'c, U16String>),
   Regular(ObjectSerializer<'a, 'b, 'c>),
@@ -278,6 +279,7 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
     match self {
       StructSerializers::Magic(s) => s.serialize_field(key, value),
       StructSerializers::MagicBuffer(s) => s.serialize_field(key, value),
+      StructSerializers::MagicDetached(s) => s.serialize_field(key, value),
       StructSerializers::MagicByteString(s) => s.serialize_field(key, value),
       StructSerializers::MagicU16String(s) => s.serialize_field(key, value),
       StructSerializers::Regular(s) => s.serialize_field(key, value),
@@ -288,6 +290,7 @@ impl<'a, 'b, 'c> ser::SerializeStruct for StructSerializers<'a, 'b, 'c> {
     match self {
       StructSerializers::Magic(s) => s.end(),
       StructSerializers::MagicBuffer(s) => s.end(),
+      StructSerializers::MagicDetached(s) => s.end(),
       StructSerializers::MagicByteString(s) => s.end(),
       StructSerializers::MagicU16String(s) => s.end(),
       StructSerializers::Regular(s) => s.end(),
@@ -528,6 +531,10 @@ impl<'a, 'b, 'c> ser::Serializer for Serializer<'a, 'b, 'c> {
         let m = MagicalSerializer::<Buffer>::new(self.scope);
         Ok(StructSerializers::MagicBuffer(m))
       }
+      DetachedBuffer::MAGIC_NAME => {
+        let m = MagicalSerializer::<DetachedBuffer>::new(self.scope);
+        Ok(StructSerializers::MagicDetached(m))
+      }
       magic::Value::MAGIC_NAME => {
         let m = MagicalSerializer::<magic::Value<'a>>::new(self.scope);
         Ok(StructSerializers::Magic(m))