fix(ext/node): restore llhttp parser.data after execute to handle re-entrant calls (#33832)

## Summary

Enables `test-http-parser-multiple-execute` in node_compat suite.

## Test plan
- [x] `cargo test --test node_compat --
test-http-parser-multiple-execute`

---------

Co-authored-by: divybot <divybot@users.noreply.github.com>
Co-authored-by: Divy Srivastava <me@littledivy.com>

Author: divybot

ext/node/ops/llhttp/binding.rs

@@ -814,6 +814,8 @@ unsafe fn consume_read_callback(
     callbacks: callbacks_static,
   };
 
+  // Save+restore for re-entrant execute() calls — see HTTPParser::execute.
+  let saved_data = inner.parser.data;
   inner.parser.data = &mut ctx as *mut ExecuteContext as *mut std::ffi::c_void;
 
   let err = unsafe {
@@ -824,7 +826,7 @@ unsafe fn consume_read_callback(
     )
   };
 
-  inner.parser.data = std::ptr::null_mut();
+  inner.parser.data = saved_data;
   inner.current_buffer_data = std::ptr::null();
   inner.current_buffer_len = 0;
 
@@ -971,6 +973,12 @@ impl HTTPParser {
       callbacks: callbacks_static,
     };
 
+    // Save and restore parser.data to support re-entrant execute() calls.
+    // If a JS callback (e.g. the 'information' event handler for 100 Continue)
+    // triggers another execute() call, the inner execute must restore the outer
+    // context pointer so subsequent callbacks from the outer llhttp_execute
+    // still have a valid ExecuteContext.
+    let saved_data = inner.parser.data;
     inner.parser.data =
       &mut ctx as *mut ExecuteContext as *mut std::ffi::c_void;
 
@@ -982,7 +990,7 @@ impl HTTPParser {
       )
     };
 
-    inner.parser.data = std::ptr::null_mut();
+    inner.parser.data = saved_data;
     inner.current_buffer_data = std::ptr::null();
     inner.current_buffer_len = 0;
 
@@ -1046,12 +1054,14 @@ impl HTTPParser {
       callbacks: callbacks_static,
     };
 
+    // Save+restore for re-entrant execute() calls — see HTTPParser::execute.
+    let saved_data = inner.parser.data;
     inner.parser.data =
       &mut ctx as *mut ExecuteContext as *mut std::ffi::c_void;
 
     let err = unsafe { sys::llhttp_finish(&mut inner.parser) };
 
-    inner.parser.data = std::ptr::null_mut();
+    inner.parser.data = saved_data;
 
     if err != sys::HPE_OK { -1 } else { 0 }
   }

tests/node_compat/config.jsonc

@@ -1661,6 +1661,7 @@
     "parallel/test-http-parser-free.js": {},
     "parallel/test-http-parser-freed-before-upgrade.js": {},
     "parallel/test-http-parser-freed-during-execute.js": {},
+    "parallel/test-http-parser-multiple-execute.js": {},
     "parallel/test-http-parser.js": {},
     "parallel/test-http-pause-no-dump.js": {},
     "parallel/test-http-pause-resume-one-end.js": {},