Bug#1026503: libembperl-perl: FTBFS: Expected 6 more error(s) in logfile, tagging 1026503

[Axel Beckert]

Control: tag -1 + pending patch

Hi again.

Axel Beckert wrote:
> Axel Beckert wrote:
> > > Expected 6 more error(s) in logfile
[…]
> I looked a bit deeper into it, but didn't yet understand the issue
> fully yet.
> 
> Not forgotten, but I will only continue on it in the next days, […]

This took me quite a few hours to figure out. Not sure what exactly
changed in Debian Sid/Bookworm, but it might be even kernel or gcc
related.

The cause was intercepting STDERR into a file and reading from it
while the writing file handle is still open for the purpose analyzing
STDERR's content.

The relevant hint was this one in "perldoc -f seek":

  Due to the rules and rigors of ANSI C, on some systems you have
  to do a seek whenever you switch between reading and writing.
  Amongst other things, this may have the effect of calling
  stdio's clearerr(3). A WHENCE of 1 ("SEEK_CUR") is useful for
  not moving the file position:

      seek($fh, 0, 1);

So adding a "seek(ERR, 0, 1);" before "while (<ERR>) {" in test.pl
fixes the issue and doesn't open any new one.

Will upload soon. Will first need to clean up all the printf debug
mess I added to many places in test.pl. :-)

		Regards, Axel
-- 
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