threads / discuss / 48231

git 2.17.0: uninitialized value $rec in scalar chomp at ...Git.pm line 557

Subject: git 2.17.0: uninitialized value $rec in scalar chomp at ...Git.pm line 557

## tl;dr

11 messages between Apr 6, 2018 and Apr 9, 2018.

replies: 10people: 6as markdown or json

Joseph Mingrone· Apr 6, 2018, 12:01 UTC · lore
Hello,

After upgrading to version 2.17.0, this message appears repeatedly when running `git svn rebase`:

Use of uninitialized value $rec in scalar chomp at /usr/local/lib/perl5/site_perl/Git.pm line 557, <$fh> chunk 1.

The value of chunk varies. For example the message above may end with '...<$fh> chunk 5.' This is with the FreeBSD packages git-2.17.0 and perl 5.26.1.

Regards,
J.
Johannes Schindelin· Apr 6, 2018, 12:21 UTC · re: Joseph Mingrone · lore

Re: git 2.17.0: uninitialized value $rec in scalar chomp at ...Git.pm line 557

Hi Joseph,
On Fri, 6 Apr 2018, Joseph Mingrone wrote:
Show 8 quoted lines
> After upgrading to version 2.17.0, this message appears repeatedly when
> running `git svn rebase`:
> 
> Use of uninitialized value $rec in scalar chomp at /usr/local/lib/perl5/site_perl/Git.pm line 557, <$fh> chunk 1.
> 
> The value of chunk varies.  For example the message above may end with
> '...<$fh> chunk 5.'  This is with the FreeBSD packages git-2.17.0 and
> perl 5.26.1.
Does this stop the `rebase`?
Also: could you publish the unrebased branch so that others can reproduce
the error? (I am not claiming that I have enough time; I don't...)

Thanks, Johannes

Joseph Mingrone· Apr 6, 2018, 12:32 UTC · re: Johannes Schindelin · lore

Re: git 2.17.0: uninitialized value $rec in scalar chomp at ...Git.pm line 557

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> Hi Joseph,
> On Fri, 6 Apr 2018, Joseph Mingrone wrote:
>> After upgrading to version 2.17.0, this message appears repeatedly when
>> running `git svn rebase`:
>> Use of uninitialized value $rec in scalar chomp at /usr/local/lib/perl5/site_perl/Git.pm line 557, <$fh> chunk 1.
>> The value of chunk varies.  For example the message above may end with
>> '...<$fh> chunk 5.'  This is with the FreeBSD packages git-2.17.0 and
>> perl 5.26.1.
> Does this stop the `rebase`?
> Also: could you publish the unrebased branch so that others can reproduce
> the error? (I am not claiming that I have enough time; I don't...)
> Thanks,
> Johannes
Hi Johannes,
No, this does not stop the `svn rebase`.  This is with the FreeBSD ports tree, svn.freebsd.org/ports, following the setup described at https://wiki.freebsd.org/GitWorkflow/GitSvn .
J.
Ævar Arnfjörð Bjarmason· Apr 6, 2018, 13:15 UTC · re: Joseph Mingrone · lore

[PATCH] git-svn: avoid warning on undef readline()

Change code in Git.pm that sometimes calls chomp() on undef to only do so the value is defined.

This code has been chomping undef values ever since it was added in b26098fc2f ("git-svn: reduce scope of input record separator change", 2016-10-14), but started warning due to the introduction of "use warnings" to Git.pm in my f0e19cb7ce ("Git.pm: add the "use warnings" pragma", 2018-02-25) released with 2.17.0.

Since this function will return undef in those cases it's still possible that the code using it will warn if it does a chomp of its own, as the code added in b26098fc2f ("git-svn: reduce scope of input record separator change", 2016-10-14) might do, but since git-svn has "use warnings" already that's clearly not a codepath that's going to warn.

See https://public-inbox.org/git/86h8oobl36.fsf@phe.ftfl.ca/ for the original report.

Reported-by: Joseph Mingrone <jrm@ftfl.ca>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 perl/Git.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/perl/Git.pm b/perl/Git.pm
index 16ebcc612c..6b6079c456 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -554,7 +554,7 @@ sub get_record {
 	my ($fh, $rs) = @_;
 	local $/ = $rs;
 	my $rec = <$fh>;
-	chomp $rec if defined $rs;
+	chomp $rec if defined $rs and defined $rec;
 	$rec;
 }
 
-- 
2.17.0.rc1.321.gba9d0f2565
Johannes Schindelin· Apr 6, 2018, 14:30 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

Hi Ævar,
On Fri, 6 Apr 2018, Ævar Arnfjörð Bjarmason wrote:
Show 37 quoted lines
> Change code in Git.pm that sometimes calls chomp() on undef to only do
> so the value is defined.
> 
> This code has been chomping undef values ever since it was added in
> b26098fc2f ("git-svn: reduce scope of input record separator change",
> 2016-10-14), but started warning due to the introduction of "use
> warnings" to Git.pm in my f0e19cb7ce ("Git.pm: add the "use warnings"
> pragma", 2018-02-25) released with 2.17.0.
> 
> Since this function will return undef in those cases it's still
> possible that the code using it will warn if it does a chomp of its
> own, as the code added in b26098fc2f ("git-svn: reduce scope of input
> record separator change", 2016-10-14) might do, but since git-svn has
> "use warnings" already that's clearly not a codepath that's going to
> warn.
> 
> See https://public-inbox.org/git/86h8oobl36.fsf@phe.ftfl.ca/ for the
> original report.
> 
> Reported-by: Joseph Mingrone <jrm@ftfl.ca>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  perl/Git.pm | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/perl/Git.pm b/perl/Git.pm
> index 16ebcc612c..6b6079c456 100644
> --- a/perl/Git.pm
> +++ b/perl/Git.pm
> @@ -554,7 +554,7 @@ sub get_record {
>  	my ($fh, $rs) = @_;
>  	local $/ = $rs;
>  	my $rec = <$fh>;
> -	chomp $rec if defined $rs;
> +	chomp $rec if defined $rs and defined $rec;
>  	$rec;
>  }
The explanation as well as the patch make a total lot of sense to me.

Ciao, Dscho

Eric Wong· Apr 6, 2018, 16:56 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> See https://public-inbox.org/git/86h8oobl36.fsf@phe.ftfl.ca/ for the
> original report.
Thanks for taking a look at this.  Also https://bugs.debian.org/894997
Show 8 quoted lines
> --- a/perl/Git.pm
> +++ b/perl/Git.pm
> @@ -554,7 +554,7 @@ sub get_record {
>  	my ($fh, $rs) = @_;
>  	local $/ = $rs;
>  	my $rec = <$fh>;
> -	chomp $rec if defined $rs;
> +	chomp $rec if defined $rs and defined $rec;

I'm struggling to understand the reason for the "defined $rs" check. I think it was a braino on my part and meant to use:

	chomp $rec if defined $rec;
Ævar Arnfjörð Bjarmason· Apr 6, 2018, 18:23 UTC · re: Eric Wong · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

On Fri, Apr 06 2018, Eric Wong wrote:
Show 19 quoted lines
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> See https://public-inbox.org/git/86h8oobl36.fsf@phe.ftfl.ca/ for the
>> original report.
>
> Thanks for taking a look at this.  Also https://bugs.debian.org/894997
>
>> --- a/perl/Git.pm
>> +++ b/perl/Git.pm
>> @@ -554,7 +554,7 @@ sub get_record {
>>  	my ($fh, $rs) = @_;
>>  	local $/ = $rs;
>>  	my $rec = <$fh>;
>> -	chomp $rec if defined $rs;
>> +	chomp $rec if defined $rs and defined $rec;
>
> I'm struggling to understand the reason for the "defined $rs"
> check.  I think it was a braino on my part and meant to use:
>
> 	chomp $rec if defined $rec;

Whether this makes any sense is another question, but you seem to have explicitly meant this at the time. The full function definition with documentation:

    =item get_record ( FILEHANDLE, INPUT_RECORD_SEPARATOR )
    Read one record from FILEHANDLE delimited by INPUT_RECORD_SEPARATOR,
    removing any trailing INPUT_RECORD_SEPARATOR.
    =cut
    sub get_record {
    	my ($fh, $rs) = @_;
    	local $/ = $rs;
    	my $rec = <$fh>;
    	chomp $rec if defined $rs;
    	$rec;
    }

It doesn't make to remove the trailing record separator if it's not defined, otherwise we'd be coercing undef to "\n" while at the same time returning multiple records. But then of course the only user of this with an "undef" argument just does:

    chomp($log_entry{log} = get_record($log_fh, undef));

So we could also remove that chomp(), adn not check defined $rs, but IMO it's cleaner & more consistent this way.

Eric Wong· Apr 6, 2018, 20:49 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
Show 25 quoted lines
> On Fri, Apr 06 2018, Eric Wong wrote:
> > Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> >
> >> --- a/perl/Git.pm
> >> +++ b/perl/Git.pm
> >> @@ -554,7 +554,7 @@ sub get_record {
> >>  	my ($fh, $rs) = @_;
> >>  	local $/ = $rs;
> >>  	my $rec = <$fh>;
> >> -	chomp $rec if defined $rs;
> >> +	chomp $rec if defined $rs and defined $rec;
> >
> > I'm struggling to understand the reason for the "defined $rs"
> > check.  I think it was a braino on my part and meant to use:
> >
> > 	chomp $rec if defined $rec;
> 
> Whether this makes any sense is another question, but you seem to have
> explicitly meant this at the time. The full function definition with
> documentation:
> 
>     =item get_record ( FILEHANDLE, INPUT_RECORD_SEPARATOR )
> 
>     Read one record from FILEHANDLE delimited by INPUT_RECORD_SEPARATOR,
>     removing any trailing INPUT_RECORD_SEPARATOR.

I've always known chomp to respect the value of $/; so chomp($rec) whould only cut out whatever $rs is, and be a no-op if $rs is undef.

Show 6 quoted lines
> It doesn't make to remove the trailing record separator if it's not
> defined, otherwise we'd be coercing undef to "\n" while at the same time
> returning multiple records. But then of course the only user of this
> with an "undef" argument just does:
> 
>     chomp($log_entry{log} = get_record($log_fh, undef));

Subtle difference, that chomp() still sees $/ as "\n". $/ is only undef inside get_record.

> So we could also remove that chomp(), adn not check defined $rs, but IMO
> it's cleaner & more consistent this way.
I think the chomp is necessary. In git-svn.perl /^sub get_commit_entry {:
	# <snip>
	open my $log_fh, '>', $commit_editmsg or croak $!;
	# <snip>
		$msgbuf =~ s/\s+$//s;
	# <snip>
		print $log_fh $msgbuf or croak $!;
	# <snip>
	close $log_fh or croak $!;
# Above, we ensured the contents of $commit_editmsg has no trailing newline
	if ($_edit || ($type eq 'tree')) {
		chomp(my $editor = command_oneline(qw(var GIT_EDITOR)));
		system('sh', '-c', $editor.' "$@"', $editor, $commit_editmsg);
	}
# However, $editor is likely to introduce a trailing newline
	rename $commit_editmsg, $commit_msg or croak $!;
	{
		require Encode;
		# SVN requires messages to be UTF-8 when entering the repo
		open $log_fh, '<', $commit_msg or croak $!;
		binmode $log_fh;
# chomp trailing newline introduced by $editor:
		chomp($log_entry{log} = get_record($log_fh, undef));
Ævar Arnfjörð Bjarmason· Apr 6, 2018, 21:05 UTC · re: Eric Wong · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

On Fri, Apr 06 2018, Eric Wong wrote:
Show 29 quoted lines
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> On Fri, Apr 06 2018, Eric Wong wrote:
>> > Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> >
>> >> --- a/perl/Git.pm
>> >> +++ b/perl/Git.pm
>> >> @@ -554,7 +554,7 @@ sub get_record {
>> >>  	my ($fh, $rs) = @_;
>> >>  	local $/ = $rs;
>> >>  	my $rec = <$fh>;
>> >> -	chomp $rec if defined $rs;
>> >> +	chomp $rec if defined $rs and defined $rec;
>> >
>> > I'm struggling to understand the reason for the "defined $rs"
>> > check.  I think it was a braino on my part and meant to use:
>> >
>> > 	chomp $rec if defined $rec;
>>
>> Whether this makes any sense is another question, but you seem to have
>> explicitly meant this at the time. The full function definition with
>> documentation:
>>
>>     =item get_record ( FILEHANDLE, INPUT_RECORD_SEPARATOR )
>>
>>     Read one record from FILEHANDLE delimited by INPUT_RECORD_SEPARATOR,
>>     removing any trailing INPUT_RECORD_SEPARATOR.
>
> I've always known chomp to respect the value of $/; so chomp($rec)
> whould only cut out whatever $rs is, and be a no-op if $rs is undef.
Yup, you're right. I missed that.
Junio C Hamano· Apr 9, 2018, 02:09 UTC · re: Eric Wong · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

Eric Wong <e@80x24.org> writes:
Show 19 quoted lines
> Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> See https://public-inbox.org/git/86h8oobl36.fsf@phe.ftfl.ca/ for the
>> original report.
>
> Thanks for taking a look at this.  Also https://bugs.debian.org/894997
>
>> --- a/perl/Git.pm
>> +++ b/perl/Git.pm
>> @@ -554,7 +554,7 @@ sub get_record {
>>  	my ($fh, $rs) = @_;
>>  	local $/ = $rs;
>>  	my $rec = <$fh>;
>> -	chomp $rec if defined $rs;
>> +	chomp $rec if defined $rs and defined $rec;
>
> I'm struggling to understand the reason for the "defined $rs"
> check.  I think it was a braino on my part and meant to use:
>
> 	chomp $rec if defined $rec;

That sounds quite plausible, so if there is no further discussion, let me queue a version that does s/rs/rec/ on that line myself (bypassing a pull from your repository at bogomips.org/).

Thanks.
brian m. carlson· Apr 7, 2018, 19:20 UTC · re: Ævar Arnfjörð Bjarmason · lore

Re: [PATCH] git-svn: avoid warning on undef readline()

On Fri, Apr 06, 2018 at 01:15:14PM +0000, Ævar Arnfjörð Bjarmason wrote:
Show 15 quoted lines
> Change code in Git.pm that sometimes calls chomp() on undef to only do
> so the value is defined.
> 
> This code has been chomping undef values ever since it was added in
> b26098fc2f ("git-svn: reduce scope of input record separator change",
> 2016-10-14), but started warning due to the introduction of "use
> warnings" to Git.pm in my f0e19cb7ce ("Git.pm: add the "use warnings"
> pragma", 2018-02-25) released with 2.17.0.
> 
> Since this function will return undef in those cases it's still
> possible that the code using it will warn if it does a chomp of its
> own, as the code added in b26098fc2f ("git-svn: reduce scope of input
> record separator change", 2016-10-14) might do, but since git-svn has
> "use warnings" already that's clearly not a codepath that's going to
> warn.

Thanks for this patch. I ran into this earlier this week (with git svn fetch) and had intended to send a patch, but you clearly got to it before I did.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204

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