1680402 - Make printf_stderr work on Windows when it's been redirected

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement)

Comment 1

[Jeff Muizelaar [:jrmuizel]]

Attachment: Bug 1680402. Use stderr in printf_stderr instead of reopening fd 2.

Currently, printf_stderr doesn't show up when running with ./mach run.
This is because we run with -attach-console and that redirects stderr
to a different file descriptor using freopen in UseParentConsole.

The change from just using stderr directly happened in bug 340443 and was done
to avoid some linking issues. That problem doesn't seem to apply anymore so we
should be able to go back to the straightforward implemention that works even
if stderr has been redirected.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/975163dad54f
Use stderr in printf_stderr instead of reopening fd 2. r=glandium

Comment 3

[Razvan Maries]

Backed out for perma failures.

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=Mk3Li6PqQ-i3MkrOWnz4vA.0&resultStatus=testfailed%2Cbusted%2Cexception&revision=54068f0444262ae3d54ece6023a277b64877e7e2

Logs:
https://treeherder.mozilla.org/logviewer?job_id=323535802&repo=autoland&lineNumber=4295
https://treeherder.mozilla.org/logviewer?job_id=323533749&repo=autoland&lineNumber=3463

Backout: https://hg.mozilla.org/integration/autoland/rev/6fc1c9e37981b58da91edea754d05deb10b0a137

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Looks like the intermingling of stdout and stderr confuses some harnesses.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:jrmuizel, could you have a look please?
For more information, please visit auto_nag documentation.

Comment 6

[Masatoshi Kimura [:emk]]

I think we need fflush(stderr). In the old code, fclose(fp) effectively did it.

Comment 7

[Jeff Muizelaar [:jrmuizel]]

Masatoshi, it doesn't look like we fflush(stderr) on the other platforms. Do we need to on Windows?

Comment 8

[Masatoshi Kimura [:emk]]

I thought this change is not limited to Windows because
https://hg.mozilla.org/integration/autoland/rev/975163dad54f#l1.21
is outside defined(XP_WIN) block. Is it wrong?

At least we need fflush(stderr) on Windows, I think.

Comment 9

[Masatoshi Kimura [:emk]]

Hmm, fflush(stderr) didn't help.
https://treeherder.mozilla.org/jobs?repo=try&revision=604441c192838f331f342555abdfc7abf8e7bb9b

Comment 10

[Jeff Muizelaar [:jrmuizel]]

Here's a version that instead of writing directly to stderr replaces _fdopen(_dup(2), "a"); with _fdopen(_dup(_fileno(stderr)), "a");

https://treeherder.mozilla.org/jobs?repo=try&revision=e90bcf1adc9d8d6795dc95cc95c4aa115cf3e8fd&selectedTaskRun=T9urhs3MT3CDerURj0yMYw.0

It avoids the problems of the earlier version. But I don't really understand why yet.

Comment 11

[Jeff Muizelaar [:jrmuizel]]

Ok, my theory for the reason this works is because when reopen with a new FILE* we get the default buffering instead of stderr's no buffering.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a4bf5887fc2a
Use stderr in printf_stderr instead of reopening fd 2. r=glandium

Comment 13

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/a4bf5887fc2a

Comment 14

[Cristian Brindusan [:cbrindusan]]

Backed out changeset a4bf5887fc2a (Bug 1680402) for being the most likely cause of Bug 1686387.
https://hg.mozilla.org/mozilla-central/rev/9594d105ec370e1512c20b23e9e523262ebcc4ca

Comment 15

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/93ac37a64828
Use stderr in printf_stderr instead of reopening fd 2. r=glandium

Comment 16

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/93ac37a64828