fix(ext/web): Prevent (De-)CompressionStream resource leak on stream cancellation (#21199)

Based on #21074 and #20741 I was looking for further potential use cases
of `TransformStream` `cancel()` method, so here go `CompressionStream`
and `DecompressionStream`.

Fixes #14212

ext/web/14_compression.js

@@ -50,9 +50,12 @@ class CompressionStream {
         maybeEnqueue(controller, output);
       },
       flush(controller) {
-        const output = op_compression_finish(rid);
+        const output = op_compression_finish(rid, true);
         maybeEnqueue(controller, output);
       },
+      cancel: (_reason) => {
+        op_compression_finish(rid, false);
+      },
     });
 
     this[webidl.brand] = webidl.brand;
@@ -109,9 +112,12 @@ class DecompressionStream {
         maybeEnqueue(controller, output);
       },
       flush(controller) {
-        const output = op_compression_finish(rid);
+        const output = op_compression_finish(rid, true);
         maybeEnqueue(controller, output);
       },
+      cancel: (_reason) => {
+        op_compression_finish(rid, false);
+      },
     });
 
     this[webidl.brand] = webidl.brand;

ext/web/compression.rs

@@ -116,25 +116,35 @@ pub fn op_compression_write(
 pub fn op_compression_finish(
   state: &mut OpState,
   #[smi] rid: ResourceId,
+  report_errors: bool,
 ) -> Result<ToJsBuffer, AnyError> {
   let resource = state.resource_table.take::<CompressionResource>(rid)?;
   let resource = Rc::try_unwrap(resource).unwrap();
   let inner = resource.0.into_inner();
-  let out: Vec<u8> = match inner {
+  let out = match inner {
     Inner::DeflateDecoder(d) => {
-      d.finish().map_err(|e| type_error(e.to_string()))?
+      d.finish().map_err(|e| type_error(e.to_string()))
     }
     Inner::DeflateEncoder(d) => {
-      d.finish().map_err(|e| type_error(e.to_string()))?
+      d.finish().map_err(|e| type_error(e.to_string()))
     }
     Inner::DeflateRawDecoder(d) => {
-      d.finish().map_err(|e| type_error(e.to_string()))?
+      d.finish().map_err(|e| type_error(e.to_string()))
     }
     Inner::DeflateRawEncoder(d) => {
-      d.finish().map_err(|e| type_error(e.to_string()))?
+      d.finish().map_err(|e| type_error(e.to_string()))
     }
-    Inner::GzDecoder(d) => d.finish().map_err(|e| type_error(e.to_string()))?,
-    Inner::GzEncoder(d) => d.finish().map_err(|e| type_error(e.to_string()))?,
+    Inner::GzDecoder(d) => d.finish().map_err(|e| type_error(e.to_string())),
+    Inner::GzEncoder(d) => d.finish().map_err(|e| type_error(e.to_string())),
   };
-  Ok(out.into())
+  match out {
+    Err(err) => {
+      if report_errors {
+        Err(err)
+      } else {
+        Ok(Vec::with_capacity(0).into())
+      }
+    }
+    Ok(out) => Ok(out.into()),
+  }
 }

tests/unit/streams_test.ts

@@ -1,5 +1,5 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
-import { assertEquals, fail } from "./test_util.ts";
+import { assertEquals, assertRejects, fail } from "./test_util.ts";
 
 const {
   core,
@@ -476,3 +476,60 @@ for (const packetCount of [1, 1024]) {
     assertEquals(await promise, "resource closed");
   });
 }
+
+Deno.test(async function compressionStreamWritableMayBeAborted() {
+  await Promise.all([
+    new CompressionStream("gzip").writable.getWriter().abort(),
+    new CompressionStream("deflate").writable.getWriter().abort(),
+    new CompressionStream("deflate-raw").writable.getWriter().abort(),
+  ]);
+});
+
+Deno.test(async function compressionStreamReadableMayBeCancelled() {
+  await Promise.all([
+    new CompressionStream("gzip").readable.getReader().cancel(),
+    new CompressionStream("deflate").readable.getReader().cancel(),
+    new CompressionStream("deflate-raw").readable.getReader().cancel(),
+  ]);
+});
+
+Deno.test(async function decompressionStreamWritableMayBeAborted() {
+  await Promise.all([
+    new DecompressionStream("gzip").writable.getWriter().abort(),
+    new DecompressionStream("deflate").writable.getWriter().abort(),
+    new DecompressionStream("deflate-raw").writable.getWriter().abort(),
+  ]);
+});
+
+Deno.test(async function decompressionStreamReadableMayBeCancelled() {
+  await Promise.all([
+    new DecompressionStream("gzip").readable.getReader().cancel(),
+    new DecompressionStream("deflate").readable.getReader().cancel(),
+    new DecompressionStream("deflate-raw").readable.getReader().cancel(),
+  ]);
+});
+
+Deno.test(async function decompressionStreamValidGzipDoesNotThrow() {
+  const cs = new CompressionStream("gzip");
+  const ds = new DecompressionStream("gzip");
+  cs.readable.pipeThrough(ds);
+  const writer = cs.writable.getWriter();
+  await writer.write(new Uint8Array([1]));
+  writer.releaseLock();
+  await cs.writable.close();
+  let result = new Uint8Array();
+  for await (const chunk of ds.readable.values()) {
+    result = new Uint8Array([...result, ...chunk]);
+  }
+  assertEquals(result, new Uint8Array([1]));
+});
+
+Deno.test(async function decompressionStreamInvalidGzipStillReported() {
+  await assertRejects(
+    async () => {
+      await new DecompressionStream("gzip").writable.close();
+    },
+    TypeError,
+    "corrupt gzip stream does not have a matching checksum",
+  );
+});