[PATCH v2] git-svn: workaround for a bug in svn serf backend

[Roman Kagan <rkagan@mail.ru>]

Subversion serf backend in versions 1.8.5 and below has a bug that the
function creating the descriptor of a file change -- add_file() --
doesn't make a copy of its third argument when storing it on the
returned descriptor.  As a result, by the time this field is used (in
transactions of file copying or renaming) it may well be released, and
the memory reused.

One of its possible manifestations is the svn assertion triggering on an
invalid path, with a message

svn_fspath__skip_ancestor: Assertion
`svn_fspath__is_canonical(child_fspath)' failed.

This patch works around this bug, by storing the value to be passed as
the third argument to add_file() in a local variable with the same scope
as the file change descriptor, making sure their lifetime is the same.

Cc: Benjamin Pabst <benjamin.pabst85@gmail.com>
Cc: Eric Wong <normalperson@yhbt.net>
Cc: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Roman Kagan <rkagan@mail.ru>
---
changes since v1:
  - fix grammar in the patch and the log message
  - refer to the triggered error message

 perl/Git/SVN/Editor.pm | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/perl/Git/SVN/Editor.pm b/perl/Git/SVN/Editor.pm
index b3bcd47..34e8af9 100644
--- a/perl/Git/SVN/Editor.pm
+++ b/perl/Git/SVN/Editor.pm
@@ -304,8 +304,12 @@ sub C {
 	my ($self, $m, $deletions) = @_;
 	my ($dir, $file) = split_path($m->{file_b});
 	my $pbat = $self->ensure_path($dir, $deletions);
+	# workaround for a bug in svn serf backend (v1.8.5 and below):
+	# store third argument to ->add_file() in a local variable, to make it
+	# have the same lifetime as $fbat
+	my $upa = $self->url_path($m->{file_a});
 	my $fbat = $self->add_file($self->repo_path($m->{file_b}), $pbat,
-				$self->url_path($m->{file_a}), $self->{r});
+				$upa, $self->{r});
 	print "\tC\t$m->{file_a} => $m->{file_b}\n" unless $::_q;
 	$self->chg_file($fbat, $m);
 	$self->close_file($fbat,undef,$self->{pool});
@@ -323,8 +327,10 @@ sub R {
 	my ($self, $m, $deletions) = @_;
 	my ($dir, $file) = split_path($m->{file_b});
 	my $pbat = $self->ensure_path($dir, $deletions);
+	# workaround for a bug in svn serf backend, see comment in C() above
+	my $upa = $self->url_path($m->{file_a});
 	my $fbat = $self->add_file($self->repo_path($m->{file_b}), $pbat,
-				$self->url_path($m->{file_a}), $self->{r});
+				$upa, $self->{r});
 	print "\tR\t$m->{file_a} => $m->{file_b}\n" unless $::_q;
 	$self->apply_autoprops($file, $fbat);
 	$self->chg_file($fbat, $m);
-- 
1.8.4.2