RE: error: Use of uninitialized value $hash in chomp

From: Andrew Shearer <andrew@terabyte.co.nz>
Date: Jan 8, 2019, 19:44 UTC
Message-ID: <SYXPR01MB102421E5DB0DC254B9058624E18A0@SYXPR01MB1024.ausprd01.prod.outlook.com>
In-Reply-To: <ME1PR01MB11218D4953017CFE06A2B16AE1B80@ME1PR01MB1121.ausprd01.prod.outlook.com>

Hi Thanks for reply, but sorry I don't know how to do that - I don't have the git source code or know how to debug it. Is there another way I can capture logging/debugging information while running "git svn clone" and send it to you? Thanks

Andrew Shearer / Web Developer DDI 021 469 888 / andrew@terabyte.co.nz

/TERABYTE

-----Original Message-----
From: Ævar Arnfjörð Bjarmason <avarab@gmail.com> 
Sent: Thursday, 20 December 2018 8:00 AM
To: Andrew Shearer <andrew@terabyte.co.nz>
Cc: git@vger.kernel.org; Eric Wong <e@80x24.org>
Subject: Re: error: Use of uninitialized value $hash in chomp

On Wed, Dec 19 2018, Andrew Shearer wrote:

Show 19 quoted lines

> Hello
>
> I am using a "git svn clone" command to extract our project history from svn into git.
> About 30m into the process it fails with:
>
> r50739 = 2a1491de1353b1e3cce50d8f9d383407218a44f1 
> (refs/remotes/git-svn)
> fatal: Cannot open '.git/Git_svn_delta_33316_0_UkxiJV': Permission 
> denied Use of uninitialized value $hash in chomp at C:/Program Files/Git/mingw64/share/perl5/Git.pm line 929, <GEN11> line 36311.
> hash-object -w --stdin-paths --no-filters: command returned error: 128
>
> error closing pipe: Bad file descriptor at C:/Program Files/Git/mingw64/libexec/git-core\git-svn line 0.
> error closing pipe: Bad file descriptor at C:/Program Files/Git/mingw64/libexec/git-core\git-svn line 0.
>         (in cleanup)  at /usr/share/perl5/vendor_perl/Error.pm line 198 during global destruction.
>
> I tried updating to the latest build, 2.20.1.windows, but it still fails.
>
> There is nothing particularly special about svn changeset 50739 that I can see compared to any other.
> Anyone know why this might be failing or how I could resolve it?

That "Permission denied" looks scary. Don't know how git-svn gets into this, but try with this patch on top:

    diff --git a/perl/Git.pm b/perl/Git.pm
    index d856930b2e..f5d15895d3 100644
    --- a/perl/Git.pm
    +++ b/perl/Git.pm
    @@ -926,7 +926,13 @@ sub hash_and_insert_object {
                    throw Error::Simple("out pipe went bad");
            }

    -       chomp(my $hash = <$in>);
    +       my $hash = <$in>;
    +       unless (defined $hash) {
    +           sub noes { die "blah" }
    +           noes();
    +       } else {
    +           chomp($hash);
    +       }
            unless (defined($hash)) {
                    $self->_close_hash_and_insert_object();
                    throw Error::Simple("in pipe went bad");

Then run:

    perl -d $(git --exec-path)/git-svn

Set a breakpoint at that "noes" with:

  DB<1> b Git::noes

Continue:

  DB<2> c

Then when it stops there get a backtrace with "T":

      DB<2> T
    @ = DB::DB called from file 'perl/Git.pm' line 931
    . = Git::noes() called from file 'perl/Git.pm' line 932
    . = Git::hash_and_insert_object(ref(Git), 'Makefile') called from -e line 1

And see if you can get any other relevant info out of the debugger. See "perldoc perldebug".