windows: always work around EINVAL in case of broken pipe for stdout / stderr

windows: always work around EINVAL in case of broken pipe for stdout / stderr

In 29a905fe23ae, I missed the fact that the `winstdout` class works around two
unrelated bugs (size limit when writing to consoles and EINVAL in case of
broken pipe) and that the latter bug happens even when no console is involved.
When writing a test for this, I realized that the same problem applies to
stderr, so I applied the workaround for EINVAL to both stdout and stderr.

The size limit is worked around in the same case as before (consoles on Windows
on Python 2). For that, I changed the `winstdout` class.

--- a/mercurial/utils/procutil.py	Fri Jul 17 00:37:33 2020 +0200
+++ b/mercurial/utils/procutil.py	Fri Jul 17 03:28:52 2020 +0200
@@ -119,18 +119,25 @@
     # a silly wrapper to make a bytes stream backed by a unicode one.
     stdin = sys.stdin.buffer
     stdout = _make_write_all(sys.stdout.buffer)
+    stderr = _make_write_all(sys.stderr.buffer)
+    if pycompat.iswindows:
+        # Work around Windows bugs.
+        stdout = platform.winstdout(stdout)
+        stderr = platform.winstdout(stderr)
     if isatty(stdout):
         # The standard library doesn't offer line-buffered binary streams.
         stdout = make_line_buffered(stdout)
-    stderr = _make_write_all(sys.stderr.buffer)
 else:
     # Python 2 uses the I/O streams provided by the C library.
     stdin = sys.stdin
     stdout = sys.stdout
+    stderr = sys.stderr
+    if pycompat.iswindows:
+        # Work around Windows bugs.
+        stdout = platform.winstdout(stdout)
+        stderr = platform.winstdout(stderr)
     if isatty(stdout):
         if pycompat.iswindows:
-            # Work around size limit when writing to console.
-            stdout = platform.winstdout(stdout)
             # The Windows C runtime library doesn't support line buffering.
             stdout = make_line_buffered(stdout)
         else:
@@ -138,7 +145,6 @@
             # replace a TTY destined stdout with a pipe destined stdout (e.g.
             # pager), we want line buffering.
             stdout = os.fdopen(stdout.fileno(), 'wb', 1)
-    stderr = sys.stderr
 
 
 findexe = platform.findexe

--- a/mercurial/windows.py	Fri Jul 17 00:37:33 2020 +0200
+++ b/mercurial/windows.py	Fri Jul 17 03:28:52 2020 +0200
@@ -197,6 +197,7 @@
 
     def __init__(self, fp):
         self.fp = fp
+        self.throttle = not pycompat.ispy3 and fp.isatty()
 
     def __getattr__(self, key):
         return getattr(self.fp, key)
@@ -208,13 +209,16 @@
             pass
 
     def write(self, s):
+        if not pycompat.ispy3:
+            self.softspace = 0
         try:
+            if not self.throttle:
+                return self.fp.write(s)
             # This is workaround for "Not enough space" error on
             # writing large size of data to console.
             limit = 16000
             l = len(s)
             start = 0
-            self.softspace = 0
             while start < l:
                 end = start + limit
                 self.fp.write(s[start:end])

--- a/tests/test-stdio.py	Fri Jul 17 00:37:33 2020 +0200
+++ b/tests/test-stdio.py	Fri Jul 17 03:28:52 2020 +0200
@@ -13,7 +13,7 @@
 import tempfile
 import unittest
 
-from mercurial import pycompat
+from mercurial import pycompat, util
 
 
 if pycompat.ispy3:
@@ -71,6 +71,34 @@
 '''
 
 
+TEST_BROKEN_PIPE_CHILD_SCRIPT = r'''
+import os
+import pickle
+
+from mercurial import dispatch
+from mercurial.utils import procutil
+
+dispatch.initstdio()
+procutil.stdin.read(1)  # wait until parent process closed pipe
+try:
+    procutil.{stream}.write(b'test')
+    procutil.{stream}.flush()
+except EnvironmentError as e:
+    with os.fdopen(
+        os.open(
+            {err_fn!r},
+            os.O_WRONLY
+            | getattr(os, 'O_BINARY', 0)
+            | getattr(os, 'O_TEMPORARY', 0),
+        ),
+        'wb',
+    ) as err_f:
+        pickle.dump(e, err_f)
+# Exit early to suppress further broken pipe errors at interpreter shutdown.
+os._exit(0)
+'''
+
+
 @contextlib.contextmanager
 def _closing(fds):
     try:
@@ -148,11 +176,15 @@
         check_output,
         python_args=[],
         post_child_check=None,
+        stdin_generator=None,
     ):
         assert stream in ('stdout', 'stderr')
-        with rwpair_generator() as (stream_receiver, child_stream), open(
-            os.devnull, 'rb'
-        ) as child_stdin:
+        if stdin_generator is None:
+            stdin_generator = open(os.devnull, 'rb')
+        with rwpair_generator() as (
+            stream_receiver,
+            child_stream,
+        ), stdin_generator as child_stdin:
             proc = subprocess.Popen(
                 [sys.executable] + python_args + ['-c', child_script],
                 stdin=child_stdin,
@@ -295,6 +327,37 @@
     def test_large_write_stderr_ptys_unbuffered(self):
         self._test_large_write('stderr', _ptys, python_args=['-u'])
 
+    def _test_broken_pipe(self, stream):
+        assert stream in ('stdout', 'stderr')
+
+        def check_output(stream_receiver, proc):
+            os.close(stream_receiver)
+            proc.stdin.write(b'x')
+            proc.stdin.close()
+
+        def post_child_check():
+            err = util.pickle.load(err_f)
+            self.assertEqual(err.errno, errno.EPIPE)
+            self.assertEqual(err.strerror, "Broken pipe")
+
+        with tempfile.NamedTemporaryFile('rb') as err_f:
+            self._test(
+                TEST_BROKEN_PIPE_CHILD_SCRIPT.format(
+                    stream=stream, err_fn=err_f.name
+                ),
+                stream,
+                _pipes,
+                check_output,
+                post_child_check=post_child_check,
+                stdin_generator=util.nullcontextmanager(subprocess.PIPE),
+            )
+
+    def test_broken_pipe_stdout(self):
+        self._test_broken_pipe('stdout')
+
+    def test_broken_pipe_stderr(self):
+        self._test_broken_pipe('stderr')
+
 
 if __name__ == '__main__':
     import silenttestrunner