gh-109276: libregrtest: WASM use filename for JSON

On Emscripten and WASI platforms, libregrtest now uses a filename for the JSON file. Passing a file descriptor to a child process doesn't work on these platforms.

Author: vstinner

Lib/test/libregrtest/main.py

@@ -406,7 +406,7 @@ def create_run_tests(self, tests: TestTuple):
 python_cmd=self.python_cmd,
 randomize=self.randomize,
 random_seed=self.random_seed,
-json_fd=None,
+json_file=None,
  )
 
 def_run_tests(self, selected: TestTuple, tests: TestList|None) ->int:

Lib/test/libregrtest/run_workers.py

@@ -17,7 +17,7 @@
 from .loggerimportLogger
 from .resultimportTestResult, State
 from .resultsimportTestResults
-from .runtestsimportRunTests
+from .runtestsimportRunTests, JsonFileType, JSON_FILE_USE_FILENAME
 from .singleimportPROGRESS_MIN_TIME
 from .utilsimport (
 StrPath, StrJSON, TestName, MS_WINDOWS,
@@ -155,10 +155,11 @@ def mp_result_error(
  ) ->MultiprocessResult:
 returnMultiprocessResult(test_result, stdout, err_msg)
 
-def_run_process(self, runtests: RunTests, output_fd: int, json_fd: int,
+def_run_process(self, runtests: RunTests, output_fd: int,
+json_file: JsonFileType,
 tmp_dir: StrPath|None=None) ->int:
 try:
-popen=create_worker_process(runtests, output_fd, json_fd,
+popen=create_worker_process(runtests, output_fd, json_file,
 tmp_dir)
 
 self._killed=False
@@ -226,21 +227,29 @@ def _runtest(self, test_name: TestName) -> MultiprocessResult:
 match_tests=None
 err_msg=None
 
+stdout_file=tempfile.TemporaryFile('w+', encoding=encoding)
+ifJSON_FILE_USE_FILENAME:
+json_tmpfile=tempfile.NamedTemporaryFile('w+', encoding='utf8')
+else:
+json_tmpfile=tempfile.TemporaryFile('w+', encoding='utf8')
+
 # gh-94026: Write stdout+stderr to a tempfile as workaround for
 # non-blocking pipes on Emscripten with NodeJS.
-with (tempfile.TemporaryFile('w+', encoding=encoding) asstdout_file,
-tempfile.TemporaryFile('w+', encoding='utf8') asjson_file):
+with (stdout_file, json_tmpfile):
 stdout_fd=stdout_file.fileno()
-json_fd=json_file.fileno()
-ifMS_WINDOWS:
-json_fd=msvcrt.get_osfhandle(json_fd)
+ifJSON_FILE_USE_FILENAME:
+json_file=json_tmpfile.name
+else:
+json_file=json_tmpfile.fileno()
+ifMS_WINDOWS:
+json_file=msvcrt.get_osfhandle(json_file)
 
 kwargs={}
 ifmatch_tests:
 kwargs['match_tests'] =match_tests
 worker_runtests=self.runtests.copy(
 tests=tests,
-json_fd=json_fd,
+json_file=json_file,
 **kwargs)
 
 # gh-93353: Check for leaked temporary files in the parent process,
@@ -254,13 +263,13 @@ def _runtest(self, test_name: TestName) -> MultiprocessResult:
 tmp_dir=os.path.abspath(tmp_dir)
 try:
 retcode=self._run_process(worker_runtests,
-stdout_fd, json_fd, tmp_dir)
+stdout_fd, json_file, tmp_dir)
 finally:
 tmp_files=os.listdir(tmp_dir)
 os_helper.rmtree(tmp_dir)
 else:
 retcode=self._run_process(worker_runtests,
-stdout_fd, json_fd)
+stdout_fd, json_file)
 tmp_files= ()
 stdout_file.seek(0)
 
@@ -275,8 +284,8 @@ def _runtest(self, test_name: TestName) -> MultiprocessResult:
 
 try:
 # deserialize run_tests_worker() output
-json_file.seek(0)
-worker_json: StrJSON=json_file.read()
+json_tmpfile.seek(0)
+worker_json: StrJSON=json_tmpfile.read()
 ifworker_json:
 result=TestResult.from_json(worker_json)
 else:

Lib/test/libregrtest/runtests.py

@@ -6,6 +6,19 @@
 StrPath, StrJSON, TestTuple, FilterTuple, FilterDict)
 
 
+ifsupport.is_emscriptenorsupport.is_wasi:
+# On Emscripten/WASI, it's a filename. Passing a file descriptor to a
+# worker process fails with "OSError: [Errno 8] Bad file descriptor" in the
+# worker process.
+JsonFileType=StrPath
+JSON_FILE_USE_FILENAME=True
+else:
+# On Unix, it's a file descriptor.
+# On Windows, it's a handle.
+JsonFileType=int
+JSON_FILE_USE_FILENAME=False
+
+
 @dataclasses.dataclass(slots=True, frozen=True)
 classHuntRefleak:
 warmups: int
@@ -38,9 +51,7 @@ class RunTests:
 python_cmd: tuple[str] |None
 randomize: bool
 random_seed: int|None
-# On Unix, it's a file descriptor.
-# On Windows, it's a handle.
-json_fd: int|None
+json_file: JsonFileType|None
 
 defcopy(self, **override):
 state=dataclasses.asdict(self)

Lib/test/libregrtest/utils.py

@@ -387,7 +387,7 @@ def get_work_dir(parent_dir: StrPath, worker: bool = False) -> StrPath:
 # testing (see the -j option).
 # Emscripten and WASI have stubbed getpid(), Emscripten has only
 # milisecond clock resolution. Use randint() instead.
-ifsys.platformin{"emscripten", "wasi"}:
+ifsupport.is_emscriptenorsupport.is_wasi:
 nounce=random.randint(0, 1_000_000)
 else:
 nounce=os.getpid()

Lib/test/libregrtest/worker.py

@@ -7,7 +7,7 @@
 fromtest.supportimportos_helper
 
 from .setupimportsetup_process, setup_test_dir
-from .runtestsimportRunTests
+from .runtestsimportRunTests, JsonFileType, JSON_FILE_USE_FILENAME
 from .singleimportrun_single_test
 from .utilsimport (
 StrPath, StrJSON, FilterTuple, MS_WINDOWS,
@@ -18,7 +18,7 @@
 
 
 defcreate_worker_process(runtests: RunTests,
-output_fd: int, json_fd: int,
+output_fd: int, json_file: JsonFileType,
 tmp_dir: StrPath|None=None) ->subprocess.Popen:
 python_cmd=runtests.python_cmd
 worker_json=runtests.as_json()
@@ -55,33 +55,42 @@ def create_worker_process(runtests: RunTests,
 close_fds=True,
 cwd=work_dir,
  )
-ifnotMS_WINDOWS:
-kwargs['pass_fds'] = [json_fd]
-else:
+ifJSON_FILE_USE_FILENAME:
+# Nothing to do to pass the JSON filename to the worker process
+pass
+elifMS_WINDOWS:
+# Pass the JSON handle to the worker process
 startupinfo=subprocess.STARTUPINFO()
-startupinfo.lpAttributeList={"handle_list": [json_fd]}
+startupinfo.lpAttributeList={"handle_list": [json_file]}
 kwargs['startupinfo'] =startupinfo
+else:
+# Pass the JSON file descriptor to the worker process
+kwargs['pass_fds'] = [json_file]
 ifUSE_PROCESS_GROUP:
 kwargs['start_new_session'] =True
 
 ifMS_WINDOWS:
-os.set_handle_inheritable(json_fd, True)
+os.set_handle_inheritable(json_file, True)
 try:
 returnsubprocess.Popen(cmd, **kwargs)
 finally:
 ifMS_WINDOWS:
-os.set_handle_inheritable(json_fd, False)
+os.set_handle_inheritable(json_file, False)
 
 
 defworker_process(worker_json: StrJSON) ->NoReturn:
 runtests=RunTests.from_json(worker_json)
 test_name=runtests.tests[0]
 match_tests: FilterTuple|None=runtests.match_tests
-json_fd: int=runtests.json_fd
+# On Unix, it's a file descriptor.
+# On Windows, it's a handle.
+# On Emscripten/WASI, it's a filename.
+json_file: JsonFileType=runtests.json_file
 
 ifMS_WINDOWS:
 importmsvcrt
-json_fd=msvcrt.open_osfhandle(json_fd, os.O_WRONLY)
+# Create a file descriptor from the handle
+json_file=msvcrt.open_osfhandle(json_file, os.O_WRONLY)
 
 
 setup_test_dir(runtests.test_dir)
@@ -96,8 +105,8 @@ def worker_process(worker_json: StrJSON) -> NoReturn:
 
 result=run_single_test(test_name, runtests)
 
-withopen(json_fd, 'w', encoding='utf-8') asjson_file:
-result.write_json_into(json_file)
+withopen(json_file, 'w', encoding='utf-8') asfp:
+result.write_json_into(fp)
 
 sys.exit(0)