Patchwork [1,of,4,chg-tests-fix] procutils: don't try to get `.buffer` if sys.stdin is None

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Submitter Pulkit Goyal
Date Dec. 8, 2020, 7:28 a.m.
Message ID <6bab1270ddc9b7097a58.1607412501@DESKTOP-STQPTJK>
Download mbox | patch
Permalink /patch/47831/
State Superseded
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Pulkit Goyal - Dec. 8, 2020, 7:28 a.m.
# HG changeset patch
# User Pulkit Goyal <7895pulkit@gmail.com>
# Date 1606897517 -19800
#      Wed Dec 02 13:55:17 2020 +0530
# Node ID 6bab1270ddc9b7097a58de39afacb305f3364ea7
# Parent  8b20d469a0c819c2ade8635c25e9fcf0af553796
# EXP-Topic chg-test
procutils: don't try to get `.buffer` if sys.stdin is None

While hunting down following test failure of test-chg.t on Python 3, I stumbled
the case when `.buffer` is not available as sys.stdin is None.

	--- /home/pulkit/repo/hg-committed/tests/test-chg.t
	+++ /home/pulkit/repo/hg-committed/tests/test-chg.t.err
	@@ -203,7 +203,31 @@
	   $ CHGDEBUG=1 chg version -q 0<&-
		 chg: debug: * stdio fds are missing (glob)
	     chg: debug: * execute original hg (glob)
		 -  Mercurial Distributed SCM * (glob)
		 +  Traceback (most recent call last):
		 +    File "/tmp/hgtests.avspvsq4/install/bin/hg", line 43, in <module>
		 +      dispatch.run()
		 +    File "/usr/lib/python3.6/importlib/util.py", line 233, in
		 __getattribute__
		 +      self.__spec__.loader.exec_module(self)
		 +    File "<frozen importlib._bootstrap_external>", line 678, in
		 exec_module
		 +    File "<frozen importlib._bootstrap>", line 219, in
		 _call_with_frames_removed
		 +    File
		 "/tmp/hgtests.avspvsq4/install/lib/python/mercurial/dispatch.py", line
		 726, in <module>
		 +      class lazyaliasentry(object):
		 +    File
		 "/tmp/hgtests.avspvsq4/install/lib/python/mercurial/dispatch.py", line
		 737, in lazyaliasentry
		 +      @util.propertycache
		 +    File "/usr/lib/python3.6/importlib/util.py", line 233, in
		 __getattribute__
		 +      self.__spec__.loader.exec_module(self)
		 +    File "<frozen importlib._bootstrap_external>", line 678, in
		 exec_module
		 +    File "<frozen importlib._bootstrap>", line 219, in
		 _call_with_frames_removed
		 +    File "/tmp/hgtests.avspvsq4/install/lib/python/mercurial/util.py",
		 line 3473, in <module>
		 +      f=procutil.stderr,
		 +    File "/usr/lib/python3.6/importlib/util.py", line 233, in
		 __getattribute__
		 +      self.__spec__.loader.exec_module(self)
		 +    File "<frozen importlib._bootstrap_external>", line 678, in
		 exec_module
		 +    File "<frozen importlib._bootstrap>", line 219, in
		 _call_with_frames_removed
		 +    File
		 "/tmp/hgtests.avspvsq4/install/lib/python/mercurial/utils/procutil.py",
		 line 127, in <module>
		 +      stdin = sys.stdin.buffer
		 +  AttributeError: 'NoneType' object has no attribute 'buffer'
		 +  [1]

		  server lifecycle
		   ----------------

Differential Revision: https://phab.mercurial-scm.org/D9500
Yuya Nishihara - Dec. 8, 2020, 10:57 a.m.
On Tue, 08 Dec 2020 12:58:21 +0530, Pulkit Goyal wrote:
> # HG changeset patch
> # User Pulkit Goyal <7895pulkit@gmail.com>
> # Date 1606897517 -19800
> #      Wed Dec 02 13:55:17 2020 +0530
> # Node ID 6bab1270ddc9b7097a58de39afacb305f3364ea7
> # Parent  8b20d469a0c819c2ade8635c25e9fcf0af553796
> # EXP-Topic chg-test
> procutils: don't try to get `.buffer` if sys.stdin is None

> diff -r 8b20d469a0c8 -r 6bab1270ddc9 mercurial/utils/procutil.py
> --- a/mercurial/utils/procutil.py	Fri Apr 03 20:30:36 2020 +0530
> +++ b/mercurial/utils/procutil.py	Wed Dec 02 13:55:17 2020 +0530
> @@ -124,7 +124,9 @@
>      # Python 3 implements its own I/O streams.
>      # TODO: .buffer might not exist if std streams were replaced; we'll need
>      # a silly wrapper to make a bytes stream backed by a unicode one.
> -    stdin = sys.stdin.buffer
> +
> +    # sys.stdin can be None
> +    stdin = sys.stdin.buffer if sys.stdin else sys.stdin

It's probably better to make procutil.stdin/out/err always available.

  stdin = open(os.devnull, 'rb')

I don't think we'll want to deal with None stdin/out/err everywhere stdio
is involved. That's insane.
Yuya Nishihara - Dec. 8, 2020, 11:44 a.m.
On Tue, 8 Dec 2020 19:57:13 +0900, Yuya Nishihara wrote:
> On Tue, 08 Dec 2020 12:58:21 +0530, Pulkit Goyal wrote:
> > # HG changeset patch
> > # User Pulkit Goyal <7895pulkit@gmail.com>
> > # Date 1606897517 -19800
> > #      Wed Dec 02 13:55:17 2020 +0530
> > # Node ID 6bab1270ddc9b7097a58de39afacb305f3364ea7
> > # Parent  8b20d469a0c819c2ade8635c25e9fcf0af553796
> > # EXP-Topic chg-test
> > procutils: don't try to get `.buffer` if sys.stdin is None
> 
> > diff -r 8b20d469a0c8 -r 6bab1270ddc9 mercurial/utils/procutil.py
> > --- a/mercurial/utils/procutil.py	Fri Apr 03 20:30:36 2020 +0530
> > +++ b/mercurial/utils/procutil.py	Wed Dec 02 13:55:17 2020 +0530
> > @@ -124,7 +124,9 @@
> >      # Python 3 implements its own I/O streams.
> >      # TODO: .buffer might not exist if std streams were replaced; we'll need
> >      # a silly wrapper to make a bytes stream backed by a unicode one.
> > -    stdin = sys.stdin.buffer
> > +
> > +    # sys.stdin can be None
> > +    stdin = sys.stdin.buffer if sys.stdin else sys.stdin
> 
> It's probably better to make procutil.stdin/out/err always available.
> 
>   stdin = open(os.devnull, 'rb')

or maybe fdopen(0, 'rb'), which should be close to Python 2 behavior.

  % python2 -c 'import sys; print(sys.stdin.fileno()); sys.stdin.read()' 0<&-
  0
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  IOError: [Errno 9] Bad file descriptor

Patch

diff -r 8b20d469a0c8 -r 6bab1270ddc9 mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py	Fri Apr 03 20:30:36 2020 +0530
+++ b/mercurial/utils/procutil.py	Wed Dec 02 13:55:17 2020 +0530
@@ -124,7 +124,9 @@ 
     # Python 3 implements its own I/O streams.
     # TODO: .buffer might not exist if std streams were replaced; we'll need
     # a silly wrapper to make a bytes stream backed by a unicode one.
-    stdin = sys.stdin.buffer
+
+    # sys.stdin can be None
+    stdin = sys.stdin.buffer if sys.stdin else sys.stdin
     stdout = _make_write_all(sys.stdout.buffer)
     stderr = _make_write_all(sys.stderr.buffer)
     if pycompat.iswindows: