git-svn: better attempt to handle broken symlink updates

This is a followup to 7fc35e0e94782bbbefb920875813519038659930,
(workaround a for broken symlinks in SVN).

Since broken SVN clients can commit svn:special files without
the magic "link " prefix, this can affect delta application
when we update the broken svn:special file.  So now we fall
back and retry the delta application on symlinks if having
a "link " prefix fails.

Our behavior differs from svn(1) (v1.5.1) slightly:

When a svn:special file is created w/o a "link " prefix, svn
will create a regular file (mode 100644 to git) with the
contents of the blob as-is.

Our behavior is to continue creating the symlink (mode 120000
to git) with the contents of the blob as-is.  While this
differs from current svn(1) behavior, this is easier and more
efficient to implement (and the correctness of the svn(1) is
debatable, since it's a workaround for a bug in the first
place).

More information on this SVN bug is described here:
http://subversion.tigris.org/issues/show_bug.cgi?id=2692

Signed-off-by: Eric Wong <normalperson@yhbt.net>

diff --git a/git-svn.perl b/git-svn.perl
index 1b87a652996ee0961fa64b6484e3401bb65e80ab..b0e3d7c79a56dc8e167a3b72e49043b4a2553b0b 100755 (executable)
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -3380,19 +3380,35 @@ sub apply_textdelta {
        open my $dup, '<&', $fh or croak $!;
        my $base = $::_repository->temp_acquire('git_blob');
        if ($fb->{blob}) {
+               my ($base_is_link, $size);
+
                if ($fb->{mode_a} eq '120000' &&
                    ! $self->{empty_symlinks}->{$fb->{path}}) {
                        print $base 'link ' or die "print $!\n";
+                       $base_is_link = 1;
                }
-               my $size = $::_repository->cat_blob($fb->{blob}, $base);
+       retry:
+               $size = $::_repository->cat_blob($fb->{blob}, $base);
                die "Failed to read object $fb->{blob}" if ($size < 0);
 
                if (defined $exp) {
                        seek $base, 0, 0 or croak $!;
                        my $got = ::md5sum($base);
-                       die "Checksum mismatch: $fb->{path} $fb->{blob}\n",
-                           "expected: $exp\n",
-                           "     got: $got\n" if ($got ne $exp);
+                       if ($got ne $exp) {
+                               my $err = "Checksum mismatch: ".
+                                      "$fb->{path} $fb->{blob}\n" .
+                                      "expected: $exp\n" .
+                                      "     got: $got\n";
+                               if ($base_is_link) {
+                                       warn $err,
+                                            "Retrying... (possibly ",
+                                            "a bad symlink from SVN)\n";
+                                       $::_repository->temp_reset($base);
+                                       $base_is_link = 0;
+                                       goto retry;
+                               }
+                               die $err;
+                       }
                }
        }
        seek $base, 0, 0 or croak $!;

diff --git a/t/t9132-git-svn-broken-symlink.sh b/t/t9132-git-svn-broken-symlink.sh
new file mode 100755 (executable)
index 0000000..b8de59e
--- /dev/null
+++ b/t/t9132-git-svn-broken-symlink.sh
@@ -0,0 +1,102 @@
+#!/bin/sh
+
+test_description='test that git handles an svn repository with empty symlinks'
+
+. ./lib-git-svn.sh
+test_expect_success 'load svn dumpfile' '
+       svnadmin load "$rawsvnrepo" <<EOF
+SVN-fs-dump-format-version: 2
+
+UUID: 60780f9a-7df5-43b4-83ab-60e2c0673ef7
+
+Revision-number: 0
+Prop-content-length: 56
+Content-length: 56
+
+K 8
+svn:date
+V 27
+2008-11-26T07:17:27.590577Z
+PROPS-END
+
+Revision-number: 1
+Prop-content-length: 111
+Content-length: 111
+
+K 7
+svn:log
+V 4
+test
+K 10
+svn:author
+V 12
+normalperson
+K 8
+svn:date
+V 27
+2008-11-26T07:18:03.511836Z
+PROPS-END
+
+Node-path: bar
+Node-kind: file
+Node-action: add
+Prop-content-length: 33
+Text-content-length: 4
+Text-content-md5: 912ec803b2ce49e4a541068d495ab570
+Content-length: 37
+
+K 11
+svn:special
+V 1
+*
+PROPS-END
+asdf
+
+Revision-number: 2
+Prop-content-length: 121
+Content-length: 121
+
+K 7
+svn:log
+V 13
+bar => doink
+
+K 10
+svn:author
+V 12
+normalperson
+K 8
+svn:date
+V 27
+2008-11-27T03:55:31.601672Z
+PROPS-END
+
+Node-path: bar
+Node-kind: file
+Node-action: change
+Text-content-length: 10
+Text-content-md5: 92ca4fe7a9721f877f765c252dcd66c9
+Content-length: 10
+
+link doink
+
+EOF
+'
+
+test_expect_success 'clone using git svn' 'git svn clone -r1 "$svnrepo" x'
+
+test_expect_success '"bar" is a symlink that points to "asdf"' '
+       test -L x/bar &&
+       (cd x && test xasdf = x"`git cat-file blob HEAD:bar`")
+'
+
+test_expect_success 'get "bar" => symlink fix from svn' '
+       (cd x && git svn rebase)
+'
+
+test_expect_success '"bar" remains a proper symlink' '
+       test -L x/bar &&
+       (cd x && test xdoink = x"`git cat-file blob HEAD:bar`")
+'
+
+test_done