+package Git::SVN::Migration;
+# these version numbers do NOT correspond to actual version numbers
+# of git nor git-svn. They are just relative.
+#
+# v0 layout: .git/$id/info/url, refs/heads/$id-HEAD
+#
+# v1 layout: .git/$id/info/url, refs/remotes/$id
+#
+# v2 layout: .git/svn/$id/info/url, refs/remotes/$id
+#
+# v3 layout: .git/svn/$id, refs/remotes/$id
+# - info/url may remain for backwards compatibility
+# - this is what we migrate up to this layout automatically,
+# - this will be used by git svn init on single branches
+#
+# v4 layout: .git/svn/$repo_id/$id, refs/remotes/$repo_id/$id
+# - this is only created for newly multi-init-ed
+# repositories. Similar in spirit to the
+# --use-separate-remotes option in git-clone (now default)
+# - we do not automatically migrate to this (following
+# the example set by core git)
+use strict;
+use warnings;
+use Carp qw/croak/;
+use File::Path qw/mkpath/;
+use File::Basename qw/dirname/;
+
+sub migrate_from_v0 {
+ my $git_dir = $ENV{GIT_DIR};
+ return undef unless -d $git_dir;
+ my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
+ my $migrated = 0;
+ while (<$fh>) {
+ chomp;
+ my ($id, $orig_ref) = ($_, $_);
+ next unless $id =~ s#^refs/heads/(.+)-HEAD$#$1#;
+ next unless -f "$git_dir/$id/info/url";
+ my $new_ref = "refs/remotes/$id";
+ if (::verify_ref("$new_ref^0")) {
+ print STDERR "W: $orig_ref is probably an old ",
+ "branch used by an ancient version of ",
+ "git-svn.\n",
+ "However, $new_ref also exists.\n",
+ "We will not be able ",
+ "to use this branch until this ",
+ "ambiguity is resolved.\n";
+ next;
+ }
+ print STDERR "Migrating from v0 layout...\n" if !$migrated;
+ print STDERR "Renaming ref: $orig_ref => $new_ref\n";
+ command_noisy('update-ref', $new_ref, $orig_ref);
+ command_noisy('update-ref', '-d', $orig_ref, $orig_ref);
+ $migrated++;
+ }
+ command_close_pipe($fh, $ctx);
+ print STDERR "Done migrating from v0 layout...\n" if $migrated;
+ $migrated;
+}
+
+sub migrate_from_v1 {
+ my $git_dir = $ENV{GIT_DIR};
+ my $migrated = 0;
+ return $migrated unless -d $git_dir;
+ my $svn_dir = "$git_dir/svn";
+
+ # just in case somebody used 'svn' as their $id at some point...
+ return $migrated if -d $svn_dir && ! -f "$svn_dir/info/url";
+
+ print STDERR "Migrating from a git-svn v1 layout...\n";
+ mkpath([$svn_dir]);
+ print STDERR "Data from a previous version of git-svn exists, but\n\t",
+ "$svn_dir\n\t(required for this version ",
+ "($::VERSION) of git-svn) does not. exist\n";
+ my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
+ while (<$fh>) {
+ my $x = $_;
+ next unless $x =~ s#^refs/remotes/##;
+ chomp $x;
+ next unless -f "$git_dir/$x/info/url";
+ my $u = eval { ::file_to_s("$git_dir/$x/info/url") };
+ next unless $u;
+ my $dn = dirname("$git_dir/svn/$x");
+ mkpath([$dn]) unless -d $dn;
+ if ($x eq 'svn') { # they used 'svn' as GIT_SVN_ID:
+ mkpath(["$git_dir/svn/svn"]);
+ print STDERR " - $git_dir/$x/info => ",
+ "$git_dir/svn/$x/info\n";
+ rename "$git_dir/$x/info", "$git_dir/svn/$x/info" or
+ croak "$!: $x";
+ # don't worry too much about these, they probably
+ # don't exist with repos this old (save for index,
+ # and we can easily regenerate that)
+ foreach my $f (qw/unhandled.log index .rev_db/) {
+ rename "$git_dir/$x/$f", "$git_dir/svn/$x/$f";
+ }
+ } else {
+ print STDERR " - $git_dir/$x => $git_dir/svn/$x\n";
+ rename "$git_dir/$x", "$git_dir/svn/$x" or
+ croak "$!: $x";
+ }
+ $migrated++;
+ }
+ command_close_pipe($fh, $ctx);
+ print STDERR "Done migrating from a git-svn v1 layout\n";
+ $migrated;
+}
+
+sub read_old_urls {
+ my ($l_map, $pfx, $path) = @_;
+ my @dir;
+ foreach (<$path/*>) {
+ if (-r "$_/info/url") {
+ $pfx .= '/' if $pfx && $pfx !~ m!/$!;
+ my $ref_id = $pfx . basename $_;
+ my $url = ::file_to_s("$_/info/url");
+ $l_map->{$ref_id} = $url;
+ } elsif (-d $_) {
+ push @dir, $_;
+ }
+ }
+ foreach (@dir) {
+ my $x = $_;
+ $x =~ s!^\Q$ENV{GIT_DIR}\E/svn/!!o;
+ read_old_urls($l_map, $x, $_);
+ }
+}
+
+sub migrate_from_v2 {
+ my @cfg = command(qw/config -l/);
+ return if grep /^svn-remote\..+\.url=/, @cfg;
+ my %l_map;
+ read_old_urls(\%l_map, '', "$ENV{GIT_DIR}/svn");
+ my $migrated = 0;
+
+ foreach my $ref_id (sort keys %l_map) {
+ Git::SVN->init($l_map{$ref_id}, $ref_id);
+ $migrated++;
+ }
+ $migrated;
+}
+
+sub migration_check {
+ migrate_from_v0();
+ migrate_from_v1();
+ migrate_from_v2();
+}
+