git-cvsimport-script

   1 #!/usr/bin/perl -w
   2
   3 # This tool is copyright (c) 2005, Matthias Urlichs.
   4 # It is released under the Gnu Public License, version 2.
   5 #
   6 # The basic idea is to aggregate CVS check-ins into related changes.
   7 # Fortunately, "cvsps" does that for us; all we have to do is to parse
   8 # its output.
   9 #
  10 # Checking out the files is done by a single long-running CVS connection
  11 # / server process.
  12 #
  13 # The head revision is on branch "origin" by default.
  14 # You can change that with the '-o' option.
  15
  16 use strict;
  17 use warnings;
  18 use Getopt::Std;
  19 use File::Path qw(mkpath);
  20 use File::Basename qw(basename dirname);
  21 use Time::Local;
  22 use IO::Socket;
  23 use IO::Pipe;
  24 use POSIX qw(strftime dup2);
  25
  26 $SIG{'PIPE'}="IGNORE";
  27 $ENV{'TZ'}="UTC";
  28
  29 our($opt_h,$opt_o,$opt_v,$opt_d);
  30
  31 sub usage() {
  32         print STDERR <<END;
  33 Usage: ${\basename $0}     # fetch/update GIT from CVS
  34            [ -o branch-for-HEAD ] [ -h ] [ -v ] [ -d CVSROOT ]
  35        CVS_module [ GIT_repository ]
  36 END
  37         exit(1);
  38 }
  39
  40 getopts("hqvo:d:") or usage();
  41 usage if $opt_h;
  42
  43 @ARGV == 1 or @ARGV == 2 or usage();
  44
  45 my($cvs_tree, $git_tree) = @ARGV;
  46
  47 if($opt_d) {
  48         $ENV{"CVSROOT"} = $opt_d;
  49 } elsif($ENV{"CVSROOT"}) {
  50         $opt_d = $ENV{"CVSROOT"};
  51 } else {
  52         die "CVSROOT needs to be set";
  53 }
  54 $opt_o ||= "origin";
  55 $git_tree ||= ".";
  56
  57 select(STDERR); $|=1; select(STDOUT);
  58
  59
  60 package CVSconn;
  61 # Basic CVS dialog.
  62 # We're only interested in connecting and downloading, so ...
  63
  64 use POSIX qw(strftime dup2);
  65
  66 sub new {
  67         my($what,$repo,$subdir) = @_;
  68         $what=ref($what) if ref($what);
  69
  70         my $self = {};
  71         $self->{'buffer'} = "";
  72         bless($self,$what);
  73
  74         $repo =~ s#/+$##;
  75         $self->{'fullrep'} = $repo;
  76         $self->conn();
  77
  78         $self->{'subdir'} = $subdir;
  79         $self->{'lines'} = undef;
  80
  81         return $self;
  82 }
  83
  84 sub conn {
  85         my $self = shift;
  86         my $repo = $self->{'fullrep'};
  87         if($repo =~ s/^:pserver:(?:(.*?)(?::(.*?))?@)?([^:\/]*)(?::(\d*))?//) {
  88                 my($user,$pass,$serv,$port) = ($1,$2,$3,$4);
  89                 $user="anonymous" unless defined $user;
  90                 my $rr2 = "-";
  91                 unless($port) {
  92                         $rr2 = ":pserver:$user\@$serv:$repo";
  93                         $port=2401;
  94                 }
  95                 my $rr = ":pserver:$user\@$serv:$port$repo";
  96
  97                 unless($pass) {
  98                         open(H,$ENV{'HOME'}."/.cvspass") and do {
  99                                 # :pserver:cvs@mea.tmt.tele.fi:/cvsroot/zmailer Ah<Z
 100                                 while(<H>) {
 101                                         chomp;
 102                                         s/^\/\d+\s+//;
 103                                         my ($w,$p) = split(/\s/,$_,2);
 104                                         if($w eq $rr or $w eq $rr2) {
 105                                                 $pass = $p;
 106                                                 last;
 107                                         }
 108                                 }
 109                         };
 110                 }
 111                 $pass="A" unless $pass;
 112
 113                 my $s = IO::Socket::INET->new(PeerHost => $serv, PeerPort => $port);
 114                 die "Socket to $serv: $!\n" unless defined $s;
 115                 $s->write("BEGIN AUTH REQUEST\n$repo\n$user\n$pass\nEND AUTH REQUEST\n")
 116                         or die "Write to $serv: $!\n";
 117                 $s->flush();
 118
 119                 my $rep = <$s>;
 120
 121                 if($rep ne "I LOVE YOU\n") {
 122                         $rep="<unknown>" unless $rep;
 123                         die "AuthReply: $rep\n";
 124                 }
 125                 $self->{'socketo'} = $s;
 126                 $self->{'socketi'} = $s;
 127         } else { # local: Fork off our own cvs server.
 128                 my $pr = IO::Pipe->new();
 129                 my $pw = IO::Pipe->new();
 130                 my $pid = fork();
 131                 die "Fork: $!\n" unless defined $pid;
 132                 unless($pid) {
 133                         $pr->writer();
 134                         $pw->reader();
 135                         dup2($pw->fileno(),0);
 136                         dup2($pr->fileno(),1);
 137                         $pr->close();
 138                         $pw->close();
 139                         exec("cvs","server");
 140                 }
 141                 $pw->writer();
 142                 $pr->reader();
 143                 $self->{'socketo'} = $pw;
 144                 $self->{'socketi'} = $pr;
 145         }
 146         $self->{'socketo'}->write("Root $repo\n");
 147
 148         # Trial and error says that this probably is the minimum set
 149         $self->{'socketo'}->write("Valid-responses ok error Valid-requests Mode M Mbinary E F Checked-in Created Updated Merged Removed\n");
 150
 151         $self->{'socketo'}->write("valid-requests\n");
 152         $self->{'socketo'}->flush();
 153
 154         chomp(my $rep=$self->readline());
 155         if($rep !~ s/^Valid-requests\s*//) {
 156                 $rep="<unknown>" unless $rep;
 157                 die "Expected Valid-requests from server, but got: $rep\n";
 158         }
 159         chomp(my $res=$self->readline());
 160         die "validReply: $res\n" if $res ne "ok";
 161
 162         $self->{'socketo'}->write("UseUnchanged\n") if $rep =~ /\bUseUnchanged\b/;
 163         $self->{'repo'} = $repo;
 164 }
 165
 166 sub readline {
 167         my($self) = @_;
 168         return $self->{'socketi'}->getline();
 169 }
 170
 171 sub _file {
 172         # Request a file with a given revision.
 173         # Trial and error says this is a good way to do it. :-/
 174         my($self,$fn,$rev) = @_;
 175         $self->{'socketo'}->write("Argument -N\n") or return undef;
 176         $self->{'socketo'}->write("Argument -P\n") or return undef;
 177         # $self->{'socketo'}->write("Argument -ko\n") or return undef;
 178         # -ko: Linus' version doesn't use it
 179         $self->{'socketo'}->write("Argument -r\n") or return undef;
 180         $self->{'socketo'}->write("Argument $rev\n") or return undef;
 181         $self->{'socketo'}->write("Argument --\n") or return undef;
 182         $self->{'socketo'}->write("Argument $self->{'subdir'}/$fn\n") or return undef;
 183         $self->{'socketo'}->write("Directory .\n") or return undef;
 184         $self->{'socketo'}->write("$self->{'repo'}\n") or return undef;
 185         # $self->{'socketo'}->write("Sticky T1.0\n") or return undef;
 186         $self->{'socketo'}->write("co\n") or return undef;
 187         $self->{'socketo'}->flush() or return undef;
 188         $self->{'lines'} = 0;
 189         return 1;
 190 }
 191 sub _line {
 192         # Read a line from the server.
 193         # ... except that 'line' may be an entire file. ;-)
 194         my($self) = @_;
 195         die "Not in lines" unless defined $self->{'lines'};
 196
 197         my $line;
 198         my $res="";
 199         while(defined($line = $self->readline())) {
 200                 # M U gnupg-cvs-rep/AUTHORS
 201                 # Updated gnupg-cvs-rep/
 202                 # /daten/src/rsync/gnupg-cvs-rep/AUTHORS
 203                 # /AUTHORS/1.1///T1.1
 204                 # u=rw,g=rw,o=rw
 205                 # 0
 206                 # ok
 207
 208                 if($line =~ s/^(?:Created|Updated) //) {
 209                         $line = $self->readline(); # path
 210                         $line = $self->readline(); # Entries line
 211                         my $mode = $self->readline(); chomp $mode;
 212                         $self->{'mode'} = $mode;
 213                         defined (my $cnt = $self->readline())
 214                                 or die "EOF from server after 'Changed'\n";
 215                         chomp $cnt;
 216                         die "Duh: Filesize $cnt" if $cnt !~ /^\d+$/;
 217                         $line="";
 218                         $res="";
 219                         while($cnt) {
 220                                 my $buf;
 221                                 my $num = $self->{'socketi'}->read($buf,$cnt);
 222                                 die "Server: Filesize $cnt: $num: $!\n" if not defined $num or $num<=0;
 223                                 $res .= $buf;
 224                                 $cnt -= $num;
 225                         }
 226                 } elsif($line =~ s/^ //) {
 227                         $res .= $line;
 228                 } elsif($line =~ /^M\b/) {
 229                         # output, do nothing
 230                 } elsif($line =~ /^Mbinary\b/) {
 231                         my $cnt;
 232                         die "EOF from server after 'Mbinary'" unless defined ($cnt = $self->readline());
 233                         chomp $cnt;
 234                         die "Duh: Mbinary $cnt" if $cnt !~ /^\d+$/ or $cnt<1;
 235                         $line="";
 236                         while($cnt) {
 237                                 my $buf;
 238                                 my $num = $self->{'socketi'}->read($buf,$cnt);
 239                                 die "S: Mbinary $cnt: $num: $!\n" if not defined $num or $num<=0;
 240                                 $res .= $buf;
 241                                 $cnt -= $num;
 242                         }
 243                 } else {
 244                         chomp $line;
 245                         if($line eq "ok") {
 246                                 # print STDERR "S: ok (".length($res).")\n";
 247                                 return $res;
 248                         } elsif($line =~ s/^E //) {
 249                                 # print STDERR "S: $line\n";
 250                         } else {
 251                                 die "Unknown: $line\n";
 252                         }
 253                 }
 254         }
 255 }
 256 sub file {
 257         my($self,$fn,$rev) = @_;
 258         my $res;
 259
 260         if ($self->_file($fn,$rev)) {
 261                 $res = $self->_line();
 262                 return $res if defined $res;
 263         }
 264
 265         # retry
 266         $self->conn();
 267         $self->_file($fn,$rev)
 268                 or die "No file command send\n";
 269         $res = $self->_line();
 270         die "No input: $fn $rev\n" unless defined $res;
 271         return $res;
 272 }
 273
 274
 275 package main;
 276
 277 my $cvs = CVSconn->new($opt_d, $cvs_tree);
 278
 279
 280 sub pdate($) {
 281         my($d) = @_;
 282         m#(\d{2,4})/(\d\d)/(\d\d)\s(\d\d):(\d\d)(?::(\d\d))?#
 283                 or die "Unparseable date: $d\n";
 284         my $y=$1; $y-=1900 if $y>1900;
 285         return timegm($6||0,$5,$4,$3,$2-1,$y);
 286 }
 287
 288 sub pmode($) {
 289         my($mode) = @_;
 290         my $m = 0;
 291         my $mm = 0;
 292         my $um = 0;
 293         for my $x(split(//,$mode)) {
 294                 if($x eq ",") {
 295                         $m |= $mm&$um;
 296                         $mm = 0;
 297                         $um = 0;
 298                 } elsif($x eq "u") { $um |= 0700;
 299                 } elsif($x eq "g") { $um |= 0070;
 300                 } elsif($x eq "o") { $um |= 0007;
 301                 } elsif($x eq "r") { $mm |= 0444;
 302                 } elsif($x eq "w") { $mm |= 0222;
 303                 } elsif($x eq "x") { $mm |= 0111;
 304                 } elsif($x eq "=") { # do nothing
 305                 } else { die "Unknown mode: $mode\n";
 306                 }
 307         }
 308         $m |= $mm&$um;
 309         return $m;
 310 }
 311
 312 my $tmpcv = "/var/cache/cvs";
 313
 314 sub getwd() {
 315         my $pwd = `pwd`;
 316         chomp $pwd;
 317         return $pwd;
 318 }
 319
 320 -d $git_tree
 321         or mkdir($git_tree,0777)
 322         or die "Could not create $git_tree: $!";
 323 chdir($git_tree);
 324
 325 my $last_branch = "";
 326 my $orig_branch = "";
 327 my %branch_date;
 328
 329 my $git_dir = $ENV{"GIT_DIR"} || ".git";
 330 $git_dir = getwd()."/".$git_dir unless $git_dir =~ m#^/#;
 331 $ENV{"GIT_DIR"} = $git_dir;
 332 unless(-d $git_dir) {
 333         system("git-init-db");
 334         die "Cannot init the GIT db at $git_tree: $?\n" if $?;
 335         system("git-read-tree");
 336         die "Cannot init an empty tree: $?\n" if $?;
 337
 338         $last_branch = $opt_o;
 339         $orig_branch = "";
 340 } else {
 341         $last_branch = basename(readlink("$git_dir/HEAD"));
 342         unless($last_branch) {
 343                 warn "Cannot read the last branch name: $! -- assuming 'master'\n";
 344                 $last_branch = "master";
 345         }
 346         $orig_branch = $last_branch;
 347
 348         # Get the last import timestamps
 349         opendir(D,"$git_dir/refs/heads");
 350         while(defined(my $head = readdir(D))) {
 351                 next if $head =~ /^\./;
 352                 open(F,"$git_dir/refs/heads/$head")
 353                         or die "Bad head branch: $head: $!\n";
 354                 chomp(my $ftag = <F>);
 355                 close(F);
 356                 open(F,"git-cat-file commit $ftag |");
 357                 while(<F>) {
 358                         next unless /^author\s.*\s(\d+)\s[-+]\d{4}$/;
 359                         $branch_date{$head} = $1;
 360                         last;
 361                 }
 362                 close(F);
 363         }
 364         closedir(D);
 365 }
 366
 367 -d $git_dir
 368         or die "Could not create git subdir ($git_dir).\n";
 369
 370 my $pid = open(CVS,"-|");
 371 die "Cannot fork: $!\n" unless defined $pid;
 372 unless($pid) {
 373         exec("cvsps","-A","--cvs-direct",$cvs_tree);
 374         die "Could not start cvsps: $!\n";
 375 }
 376
 377
 378 ## cvsps output:
 379 #---------------------
 380 #PatchSet 314
 381 #Date: 1999/09/18 13:03:59
 382 #Author: wkoch
 383 #Branch: STABLE-BRANCH-1-0
 384 #Ancestor branch: HEAD
 385 #Tag: (none)
 386 #Log:
 387 #    See ChangeLog: Sat Sep 18 13:03:28 CEST 1999  Werner Koch
 388 #Members:
 389 #       README:1.57->1.57.2.1
 390 #       VERSION:1.96->1.96.2.1
 391 #
 392 #---------------------
 393
 394 my $state = 0;
 395
 396 my($patchset,$date,$author,$branch,$ancestor,$tag,$logmsg);
 397 my(@old,@new);
 398 my $commit = sub {
 399         my $pid;
 400         while(@old) {
 401                 my @o2;
 402                 if(@old > 55) {
 403                         @o2 = splice(@old,0,50);
 404                 } else {
 405                         @o2 = @old;
 406                         @old = ();
 407                 }
 408                 system("git-update-cache","--force-remove","--",@o2);
 409                 die "Cannot remove files: $?\n" if $?;
 410         }
 411         while(@new) {
 412                 my @n2;
 413                 if(@new > 55) {
 414                         @n2 = splice(@new,0,50);
 415                 } else {
 416                         @n2 = @new;
 417                         @new = ();
 418                 }
 419                 system("git-update-cache","--add","--",@n2);
 420                 die "Cannot add files: $?\n" if $?;
 421         }
 422
 423         $pid = open(C,"-|");
 424         die "Cannot fork: $!" unless defined $pid;
 425         unless($pid) {
 426                 exec("git-write-tree");
 427                 die "Cannot exec git-write-tree: $!\n";
 428         }
 429         chomp(my $tree = <C>);
 430         length($tree) == 40
 431                 or die "Cannot get tree id ($tree): $!\n";
 432         close(C)
 433                 or die "Error running git-write-tree: $?\n";
 434         print "Tree ID $tree\n" if $opt_v;
 435
 436         my $parent = "";
 437         if(open(C,"$git_dir/refs/heads/$last_branch")) {
 438                 chomp($parent = <C>);
 439                 close(C);
 440                 length($parent) == 40
 441                         or die "Cannot get parent id ($parent): $!\n";
 442                 print "Parent ID $parent\n" if $opt_v;
 443         }
 444
 445         my $pr = IO::Pipe->new();
 446         my $pw = IO::Pipe->new();
 447         $pid = fork();
 448         die "Fork: $!\n" unless defined $pid;
 449         unless($pid) {
 450                 $pr->writer();
 451                 $pw->reader();
 452                 dup2($pw->fileno(),0);
 453                 dup2($pr->fileno(),1);
 454                 $pr->close();
 455                 $pw->close();
 456
 457                 my @par = ();
 458                 @par = ("-p",$parent) if $parent;
 459                 exec("env",
 460                         "GIT_AUTHOR_NAME=$author",
 461                         "GIT_AUTHOR_EMAIL=$author",
 462                         "GIT_AUTHOR_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
 463                         "GIT_COMMITTER_NAME=$author",
 464                         "GIT_COMMITTER_EMAIL=$author",
 465                         "GIT_COMMITTER_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
 466                         "git-commit-tree", $tree,@par);
 467                 die "Cannot exec git-commit-tree: $!\n";
 468         }
 469         $pw->writer();
 470         $pr->reader();
 471
 472         # compatibility with git2cvs
 473         substr($logmsg,32767) = "" if length($logmsg) > 32767;
 474         $logmsg =~ s/[\s\n]+\z//;
 475
 476         print $pw "$logmsg\n"
 477                 or die "Error writing to git-commit-tree: $!\n";
 478         $pw->close();
 479
 480         print "Committed patch $patchset ($branch)\n" if $opt_v;
 481         chomp(my $cid = <$pr>);
 482         length($cid) == 40
 483                 or die "Cannot get commit id ($cid): $!\n";
 484         print "Commit ID $cid\n" if $opt_v;
 485         $pr->close();
 486
 487         waitpid($pid,0);
 488         die "Error running git-commit-tree: $?\n" if $?;
 489
 490         open(C,">$git_dir/refs/heads/$branch")
 491                 or die "Cannot open branch $branch for update: $!\n";
 492         print C "$cid\n"
 493                 or die "Cannot write branch $branch for update: $!\n";
 494         close(C)
 495                 or die "Cannot write branch $branch for update: $!\n";
 496
 497         if($tag) {
 498                 open(C,">$git_dir/refs/tags/$tag")
 499                         or die "Cannot create tag $tag: $!\n";
 500                 print C "$cid\n"
 501                         or die "Cannot write tag $branch: $!\n";
 502                 close(C)
 503                         or die "Cannot write tag $branch: $!\n";
 504                 print "Created tag '$tag' on '$branch'\n" if $opt_v;
 505         }
 506 };
 507
 508 while(<CVS>) {
 509         chomp;
 510         if($state == 0 and /^-+$/) {
 511                 $state = 1;
 512         } elsif($state == 0) {
 513                 $state = 1;
 514                 redo;
 515         } elsif(($state==0 or $state==1) and s/^PatchSet\s+//) {
 516                 $patchset = 0+$_;
 517                 $state=2;
 518         } elsif($state == 2 and s/^Date:\s+//) {
 519                 $date = pdate($_);
 520                 unless($date) {
 521                         print STDERR "Could not parse date: $_\n";
 522                         $state=0;
 523                         next;
 524                 }
 525                 $state=3;
 526         } elsif($state == 3 and s/^Author:\s+//) {
 527                 s/\s+$//;
 528                 $author = $_;
 529                 $state = 4;
 530         } elsif($state == 4 and s/^Branch:\s+//) {
 531                 s/\s+$//;
 532                 $branch = $_;
 533                 $state = 5;
 534         } elsif($state == 5 and s/^Ancestor branch:\s+//) {
 535                 s/\s+$//;
 536                 $ancestor = $_;
 537                 $ancestor = $opt_o if $ancestor eq "HEAD";
 538                 $state = 6;
 539         } elsif($state == 5) {
 540                 $ancestor = undef;
 541                 $state = 6;
 542                 redo;
 543         } elsif($state == 6 and s/^Tag:\s+//) {
 544                 s/\s+$//;
 545                 if($_ eq "(none)") {
 546                         $tag = undef;
 547                 } else {
 548                         $tag = $_;
 549                 }
 550                 $state = 7;
 551         } elsif($state == 7 and /^Log:/) {
 552                 $logmsg = "";
 553                 $state = 8;
 554         } elsif($state == 8 and /^Members:/) {
 555                 $branch = $opt_o if $branch eq "HEAD";
 556                 if(defined $branch_date{$branch} and $branch_date{$branch} >= $date) {
 557                         # skip
 558                         print "skip patchset $patchset: $date before $branch_date{$branch}\n";
 559                         $state = 11;
 560                         next;
 561                 }
 562                 if($ancestor) {
 563                         if(-f "$git_dir/refs/heads/$branch") {
 564                                 print STDERR "Branch $branch already exists!\n";
 565                                 $state=11;
 566                                 next;
 567                         }
 568                         unless(open(H,"$git_dir/refs/heads/$ancestor")) {
 569                                 print STDERR "Branch $ancestor does not exist!\n";
 570                                 $state=11;
 571                                 next;
 572                         }
 573                         chomp(my $id = <H>);
 574                         close(H);
 575                         unless(open(H,"> $git_dir/refs/heads/$branch")) {
 576                                 print STDERR "Could not create branch $branch: $!\n";
 577                                 $state=11;
 578                                 next;
 579                         }
 580                         print H "$id\n"
 581                                 or die "Could not write branch $branch: $!";
 582                         close(H)
 583                                 or die "Could not write branch $branch: $!";
 584                 }
 585                 if(($ancestor || $branch) ne $last_branch) {
 586                         print "Switching from $last_branch to $branch\n" if $opt_v;
 587                         system("git-read-tree","-m","-u","$last_branch","$branch");
 588                         die "read-tree failed: $?\n" if $?;
 589                 }
 590                 if($branch ne $last_branch) {
 591                         unlink("$git_dir/HEAD");
 592                         symlink("refs/heads/$branch","$git_dir/HEAD");
 593                         $last_branch = $branch;
 594                 }
 595                 $state = 9;
 596         } elsif($state == 8) {
 597                 $logmsg .= "$_\n";
 598         } elsif($state == 9 and /^\s+(\S+):(INITIAL|\d(?:\.\d+)+)->(\d(?:\.\d+)+)\s*$/) {
 599 #       VERSION:1.96->1.96.2.1
 600                 my $init = ($2 eq "INITIAL");
 601                 my $fn = $1;
 602                 my $rev = $3;
 603                 $fn =~ s#^/+##;
 604                 my $data = $cvs->file($fn,$rev);
 605                 print "".($init ? "New" : "Update")." $fn: ".length($data)." bytes.\n";
 606                 mkpath(dirname($fn),$opt_v);
 607                 open(F,"> ./$fn")
 608                         or die "Cannot create '$fn': $!\n";
 609                 print F $data
 610                         or die "Cannot write to '$fn': $!\n";
 611                 close(F)
 612                         or die "Cannot write to '$fn': $!\n";
 613                 chmod(pmode($cvs->{'mode'}), $fn);
 614                 push(@new,$fn); # may be resurrected!
 615         } elsif($state == 9 and /^\s+(\S+):\d(?:\.\d+)+->(\d(?:\.\d+)+)\(DEAD\)\s*$/) {
 616                 my $fn = $1;
 617                 $fn =~ s#^/+##;
 618                 push(@old,$fn);
 619         } elsif($state == 9 and /^\s*$/) {
 620                 $state = 10;
 621         } elsif(($state == 9 or $state == 10) and /^-+$/) {
 622                 &$commit();
 623                 $state = 1;
 624         } elsif($state == 11 and /^-+$/) {
 625                 $state = 1;
 626         } elsif(/^-+$/) { # end of unknown-line processing
 627                 $state = 1;
 628         } elsif($state != 11) { # ignore stuff when skipping
 629                 print "* UNKNOWN LINE * $_\n";
 630         }
 631 }
 632 &$commit() if $branch and $state != 11;
 633
 634 # Now switch back to the branch we were in before all of this happened
 635 if($orig_branch) {
 636         print "DONE; switching back to $orig_branch\n" if $opt_v;
 637 } else {
 638         $orig_branch = "master";
 639         print "DONE; creating $orig_branch branch\n" if $opt_v;
 640         system("cp","$git_dir/refs/heads/$opt_o","$git_dir/refs/heads/master")
 641                 unless -f "$git_dir/refs/heads/master";
 642 }
 643
 644 system("git-read-tree","-m","-u","$last_branch","$orig_branch");
 645 die "read-tree failed: $?\n" if $?;
 646
 647 unlink("$git_dir/HEAD");
 648 symlink("refs/heads/$orig_branch","$git_dir/HEAD");
 649