Horton

Re: Is this a bug in pg_current_logfile() on Windows?

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

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From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Kellerer <shammat@gmx.net>, pgsql-hackers@lists.postgresql.org
Date: 2020-07-09T13:43:53Z
Lists: pgsql-hackers, pgsql-general

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On 7/8/20 10:40 PM, Tom Lane wrote:
> I wrote:
>> Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
>>> Seems reasonable. If we rip it out completely we'll have to find all the
>>> places it breaks and fix them. And we'll almost certainly get new
>>> breakage. If it's hiding a real bug we'll have to do that, but I'd be
>>> reluctant unless there's actual proof.
>> Hard to tell.  What I propose to do right now is change the \r filters
>> as shown above, and see if the test I added in 004_logrotate.pl starts
>> to show failures on Windows.  If it does, and no other place does,
>> I'm willing to be satisfied with that.  If we see *other* failures then
>> that'd prove that the problem is real, no?
> So I did that, and the first report is from bowerbird and it's still
> green.  Unless I'm completely misinterpreting what's happening (always
> a possibility), that means we're still managing to remove "data"
> occurrences of \r.
>
> The most likely theory about that, I think, is that IPC::Run::run already
> translated any \r\n occurrences in the psql command's output to plain \n.
> Then, the \r generated by pg_current_logfile() would butt up against the
> line-ending \n, allowing the "fix" in sub psql to remove valid data.


It's possible. I do see some mangling of that kind in IPC::Run's
Win32IO.pm and Win32Pump.pm.


Attached for reference is the IPC::Run package I usually use on Windows.


>
> One thing I noticed while making 91bdf499b is that some of these
> substitutions are conditioned on "if $TestLib::windows_os" while others
> are conditioned on "if $Config{osname} eq 'msys'".  What is the reason
> for this difference?  Is it possible that we only really need to do it
> in the latter case?
>
> 			


In general I make the condition for such hacks as restrictive as
possible. I don't guarantee that I have been perfectly consistent about
that, though.


cheers


andrew


-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Tighten up Windows CRLF conversion in our TAP test scripts.

  2. Fix pg_current_logfile() to not emit a carriage return on Windows.

  3. Further tighten Windows CRLF conversion in our TAP test scripts.

  4. Add test coverage for pg_current_logfile() function.

  5. Fix failures to ignore \r when reading Windows-style newlines.

  6. Fix TAP infrastructure to support Mingw better