Andrew's git / gitweb.git / git-cvsimport-script
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git-cvsimport-scripton commit cvsimport: Added option '-p': pass options to cvsps (2be4fcc)
   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
  16use strict;
  17use warnings;
  18use Getopt::Std;
  19use File::Path qw(mkpath);
  20use File::Basename qw(basename dirname);
  21use Time::Local;
  22use IO::Socket;
  23use IO::Pipe;
  24use POSIX qw(strftime dup2);
  25
  26$SIG{'PIPE'}="IGNORE";
  27$ENV{'TZ'}="UTC";
  28
  29our($opt_h,$opt_o,$opt_v,$opt_d,$opt_p);
  30
  31sub usage() {
  32        print STDERR <<END;
  33Usage: ${\basename $0}     # fetch/update GIT from CVS
  34           [ -o branch-for-HEAD ] [ -h ] [ -v ] [ -d CVSROOT ]
  35       [ -p opts-for-cvsps ]
  36       CVS_module [ GIT_repository ]
  37END
  38        exit(1);
  39}
  40
  41getopts("hqvo:d:p:") or usage();
  42usage if $opt_h;
  43
  44@ARGV == 1 or @ARGV == 2 or usage();
  45
  46my($cvs_tree, $git_tree) = @ARGV;
  47
  48if($opt_d) {
  49        $ENV{"CVSROOT"} = $opt_d;
  50} elsif($ENV{"CVSROOT"}) {
  51        $opt_d = $ENV{"CVSROOT"};
  52} else {
  53        die "CVSROOT needs to be set";
  54}
  55$opt_o ||= "origin";
  56$git_tree ||= ".";
  57
  58select(STDERR); $|=1; select(STDOUT);
  59
  60
  61package CVSconn;
  62# Basic CVS dialog.
  63# We're only interested in connecting and downloading, so ...
  64
  65use POSIX qw(strftime dup2);
  66
  67sub new {
  68        my($what,$repo,$subdir) = @_;
  69        $what=ref($what) if ref($what);
  70
  71        my $self = {};
  72        $self->{'buffer'} = "";
  73        bless($self,$what);
  74
  75        $repo =~ s#/+$##;
  76        $self->{'fullrep'} = $repo;
  77        $self->conn();
  78
  79        $self->{'subdir'} = $subdir;
  80        $self->{'lines'} = undef;
  81
  82        return $self;
  83}
  84
  85sub conn {
  86        my $self = shift;
  87        my $repo = $self->{'fullrep'};
  88        if($repo =~ s/^:pserver:(?:(.*?)(?::(.*?))?@)?([^:\/]*)(?::(\d*))?//) {
  89                my($user,$pass,$serv,$port) = ($1,$2,$3,$4);
  90                $user="anonymous" unless defined $user;
  91                my $rr2 = "-";
  92                unless($port) {
  93                        $rr2 = ":pserver:$user\@$serv:$repo";
  94                        $port=2401;
  95                }
  96                my $rr = ":pserver:$user\@$serv:$port$repo";
  97
  98                unless($pass) {
  99                        open(H,$ENV{'HOME'}."/.cvspass") and do {
 100                                # :pserver:cvs@mea.tmt.tele.fi:/cvsroot/zmailer Ah<Z
 101                                while(<H>) {
 102                                        chomp;
 103                                        s/^\/\d+\s+//;
 104                                        my ($w,$p) = split(/\s/,$_,2);
 105                                        if($w eq $rr or $w eq $rr2) {
 106                                                $pass = $p;
 107                                                last;
 108                                        }
 109                                }
 110                        };
 111                }
 112                $pass="A" unless $pass;
 113
 114                my $s = IO::Socket::INET->new(PeerHost => $serv, PeerPort => $port);
 115                die "Socket to $serv: $!\n" unless defined $s;
 116                $s->write("BEGIN AUTH REQUEST\n$repo\n$user\n$pass\nEND AUTH REQUEST\n")
 117                        or die "Write to $serv: $!\n";
 118                $s->flush();
 119
 120                my $rep = <$s>;
 121
 122                if($rep ne "I LOVE YOU\n") {
 123                        $rep="<unknown>" unless $rep;
 124                        die "AuthReply: $rep\n";
 125                }
 126                $self->{'socketo'} = $s;
 127                $self->{'socketi'} = $s;
 128        } else { # local: Fork off our own cvs server.
 129                my $pr = IO::Pipe->new();
 130                my $pw = IO::Pipe->new();
 131                my $pid = fork();
 132                die "Fork: $!\n" unless defined $pid;
 133                unless($pid) {
 134                        $pr->writer();
 135                        $pw->reader();
 136                        dup2($pw->fileno(),0);
 137                        dup2($pr->fileno(),1);
 138                        $pr->close();
 139                        $pw->close();
 140                        exec("cvs","server");
 141                }
 142                $pw->writer();
 143                $pr->reader();
 144                $self->{'socketo'} = $pw;
 145                $self->{'socketi'} = $pr;
 146        }
 147        $self->{'socketo'}->write("Root $repo\n");
 148
 149        # Trial and error says that this probably is the minimum set
 150        $self->{'socketo'}->write("Valid-responses ok error Valid-requests Mode M Mbinary E F Checked-in Created Updated Merged Removed\n");
 151
 152        $self->{'socketo'}->write("valid-requests\n");
 153        $self->{'socketo'}->flush();
 154
 155        chomp(my $rep=$self->readline());
 156        if($rep !~ s/^Valid-requests\s*//) {
 157                $rep="<unknown>" unless $rep;
 158                die "Expected Valid-requests from server, but got: $rep\n";
 159        }
 160        chomp(my $res=$self->readline());
 161        die "validReply: $res\n" if $res ne "ok";
 162
 163        $self->{'socketo'}->write("UseUnchanged\n") if $rep =~ /\bUseUnchanged\b/;
 164        $self->{'repo'} = $repo;
 165}
 166
 167sub readline {
 168        my($self) = @_;
 169        return $self->{'socketi'}->getline();
 170}
 171
 172sub _file {
 173        # Request a file with a given revision.
 174        # Trial and error says this is a good way to do it. :-/
 175        my($self,$fn,$rev) = @_;
 176        $self->{'socketo'}->write("Argument -N\n") or return undef;
 177        $self->{'socketo'}->write("Argument -P\n") or return undef;
 178        # $self->{'socketo'}->write("Argument -ko\n") or return undef;
 179        # -ko: Linus' version doesn't use it
 180        $self->{'socketo'}->write("Argument -r\n") or return undef;
 181        $self->{'socketo'}->write("Argument $rev\n") or return undef;
 182        $self->{'socketo'}->write("Argument --\n") or return undef;
 183        $self->{'socketo'}->write("Argument $self->{'subdir'}/$fn\n") or return undef;
 184        $self->{'socketo'}->write("Directory .\n") or return undef;
 185        $self->{'socketo'}->write("$self->{'repo'}\n") or return undef;
 186        # $self->{'socketo'}->write("Sticky T1.0\n") or return undef;
 187        $self->{'socketo'}->write("co\n") or return undef;
 188        $self->{'socketo'}->flush() or return undef;
 189        $self->{'lines'} = 0;
 190        return 1;
 191}
 192sub _line {
 193        # Read a line from the server.
 194        # ... except that 'line' may be an entire file. ;-)
 195        my($self) = @_;
 196        die "Not in lines" unless defined $self->{'lines'};
 197
 198        my $line;
 199        my $res="";
 200        while(defined($line = $self->readline())) {
 201                # M U gnupg-cvs-rep/AUTHORS
 202                # Updated gnupg-cvs-rep/
 203                # /daten/src/rsync/gnupg-cvs-rep/AUTHORS
 204                # /AUTHORS/1.1///T1.1
 205                # u=rw,g=rw,o=rw
 206                # 0
 207                # ok
 208
 209                if($line =~ s/^(?:Created|Updated) //) {
 210                        $line = $self->readline(); # path
 211                        $line = $self->readline(); # Entries line
 212                        my $mode = $self->readline(); chomp $mode;
 213                        $self->{'mode'} = $mode;
 214                        defined (my $cnt = $self->readline())
 215                                or die "EOF from server after 'Changed'\n";
 216                        chomp $cnt;
 217                        die "Duh: Filesize $cnt" if $cnt !~ /^\d+$/;
 218                        $line="";
 219                        $res="";
 220                        while($cnt) {
 221                                my $buf;
 222                                my $num = $self->{'socketi'}->read($buf,$cnt);
 223                                die "Server: Filesize $cnt: $num: $!\n" if not defined $num or $num<=0;
 224                                $res .= $buf;
 225                                $cnt -= $num;
 226                        }
 227                } elsif($line =~ s/^ //) {
 228                        $res .= $line;
 229                } elsif($line =~ /^M\b/) {
 230                        # output, do nothing
 231                } elsif($line =~ /^Mbinary\b/) {
 232                        my $cnt;
 233                        die "EOF from server after 'Mbinary'" unless defined ($cnt = $self->readline());
 234                        chomp $cnt;
 235                        die "Duh: Mbinary $cnt" if $cnt !~ /^\d+$/ or $cnt<1;
 236                        $line="";
 237                        while($cnt) {
 238                                my $buf;
 239                                my $num = $self->{'socketi'}->read($buf,$cnt);
 240                                die "S: Mbinary $cnt: $num: $!\n" if not defined $num or $num<=0;
 241                                $res .= $buf;
 242                                $cnt -= $num;
 243                        }
 244                } else {
 245                        chomp $line;
 246                        if($line eq "ok") {
 247                                # print STDERR "S: ok (".length($res).")\n";
 248                                return $res;
 249                        } elsif($line =~ s/^E //) {
 250                                # print STDERR "S: $line\n";
 251                        } else {
 252                                die "Unknown: $line\n";
 253                        }
 254                }
 255        }
 256}
 257sub file {
 258        my($self,$fn,$rev) = @_;
 259        my $res;
 260
 261        if ($self->_file($fn,$rev)) {
 262                $res = $self->_line();
 263                return $res if defined $res;
 264        }
 265
 266        # retry
 267        $self->conn();
 268        $self->_file($fn,$rev)
 269                or die "No file command send\n";
 270        $res = $self->_line();
 271        die "No input: $fn $rev\n" unless defined $res;
 272        return $res;
 273}
 274
 275
 276package main;
 277
 278my $cvs = CVSconn->new($opt_d, $cvs_tree);
 279
 280
 281sub pdate($) {
 282        my($d) = @_;
 283        m#(\d{2,4})/(\d\d)/(\d\d)\s(\d\d):(\d\d)(?::(\d\d))?#
 284                or die "Unparseable date: $d\n";
 285        my $y=$1; $y-=1900 if $y>1900;
 286        return timegm($6||0,$5,$4,$3,$2-1,$y);
 287}
 288
 289sub pmode($) {
 290        my($mode) = @_;
 291        my $m = 0;
 292        my $mm = 0;
 293        my $um = 0;
 294        for my $x(split(//,$mode)) {
 295                if($x eq ",") {
 296                        $m |= $mm&$um;
 297                        $mm = 0;
 298                        $um = 0;
 299                } elsif($x eq "u") { $um |= 0700;
 300                } elsif($x eq "g") { $um |= 0070;
 301                } elsif($x eq "o") { $um |= 0007;
 302                } elsif($x eq "r") { $mm |= 0444;
 303                } elsif($x eq "w") { $mm |= 0222;
 304                } elsif($x eq "x") { $mm |= 0111;
 305                } elsif($x eq "=") { # do nothing
 306                } else { die "Unknown mode: $mode\n";
 307                }
 308        }
 309        $m |= $mm&$um;
 310        return $m;
 311}
 312
 313my $tmpcv = "/var/cache/cvs";
 314
 315sub getwd() {
 316        my $pwd = `pwd`;
 317        chomp $pwd;
 318        return $pwd;
 319}
 320
 321-d $git_tree
 322        or mkdir($git_tree,0777)
 323        or die "Could not create $git_tree: $!";
 324chdir($git_tree);
 325
 326my $last_branch = "";
 327my $orig_branch = "";
 328my %branch_date;
 329
 330my $git_dir = $ENV{"GIT_DIR"} || ".git";
 331$git_dir = getwd()."/".$git_dir unless $git_dir =~ m#^/#;
 332$ENV{"GIT_DIR"} = $git_dir;
 333unless(-d $git_dir) {
 334        system("git-init-db");
 335        die "Cannot init the GIT db at $git_tree: $?\n" if $?;
 336        system("git-read-tree");
 337        die "Cannot init an empty tree: $?\n" if $?;
 338
 339        $last_branch = $opt_o;
 340        $orig_branch = "";
 341} else {
 342        -f "$git_dir/refs/head/$opt_o"
 343                or die "Branch '$opt_o' does not exist.\n".
 344                       "Either use the correct '-o branch' option,\n".
 345                       "or import to a new repository.\n";
 346
 347        $last_branch = basename(readlink("$git_dir/HEAD"));
 348        unless($last_branch) {
 349                warn "Cannot read the last branch name: $! -- assuming 'master'\n";
 350                $last_branch = "master";
 351        }
 352        $orig_branch = $last_branch;
 353
 354        # Get the last import timestamps
 355        opendir(D,"$git_dir/refs/heads");
 356        while(defined(my $head = readdir(D))) {
 357                next if $head =~ /^\./;
 358                open(F,"$git_dir/refs/heads/$head")
 359                        or die "Bad head branch: $head: $!\n";
 360                chomp(my $ftag = <F>);
 361                close(F);
 362                open(F,"git-cat-file commit $ftag |");
 363                while(<F>) {
 364                        next unless /^author\s.*\s(\d+)\s[-+]\d{4}$/;
 365                        $branch_date{$head} = $1;
 366                        last;
 367                }
 368                close(F);
 369        }
 370        closedir(D);
 371}
 372
 373-d $git_dir
 374        or die "Could not create git subdir ($git_dir).\n";
 375
 376my $pid = open(CVS,"-|");
 377die "Cannot fork: $!\n" unless defined $pid;
 378unless($pid) {
 379        my @opt;
 380        @opt = split(/,/,$opt_p) if defined $opt_p;
 381        exec("cvsps",@opt,"-x","-A","--cvs-direct",$cvs_tree);
 382        die "Could not start cvsps: $!\n";
 383}
 384
 385
 386## cvsps output:
 387#---------------------
 388#PatchSet 314
 389#Date: 1999/09/18 13:03:59
 390#Author: wkoch
 391#Branch: STABLE-BRANCH-1-0
 392#Ancestor branch: HEAD
 393#Tag: (none)
 394#Log:
 395#    See ChangeLog: Sat Sep 18 13:03:28 CEST 1999  Werner Koch
 396#Members:
 397#       README:1.57->1.57.2.1
 398#       VERSION:1.96->1.96.2.1
 399#
 400#---------------------
 401
 402my $state = 0;
 403
 404my($patchset,$date,$author,$branch,$ancestor,$tag,$logmsg);
 405my(@old,@new);
 406my $commit = sub {
 407        my $pid;
 408        while(@old) {
 409                my @o2;
 410                if(@old > 55) {
 411                        @o2 = splice(@old,0,50);
 412                } else {
 413                        @o2 = @old;
 414                        @old = ();
 415                }
 416                system("git-update-cache","--force-remove","--",@o2);
 417                die "Cannot remove files: $?\n" if $?;
 418        }
 419        while(@new) {
 420                my @n2;
 421                if(@new > 55) {
 422                        @n2 = splice(@new,0,50);
 423                } else {
 424                        @n2 = @new;
 425                        @new = ();
 426                }
 427                system("git-update-cache","--add","--",@n2);
 428                die "Cannot add files: $?\n" if $?;
 429        }
 430
 431        $pid = open(C,"-|");
 432        die "Cannot fork: $!" unless defined $pid;
 433        unless($pid) {
 434                exec("git-write-tree");
 435                die "Cannot exec git-write-tree: $!\n";
 436        }
 437        chomp(my $tree = <C>);
 438        length($tree) == 40
 439                or die "Cannot get tree id ($tree): $!\n";
 440        close(C)
 441                or die "Error running git-write-tree: $?\n";
 442        print "Tree ID $tree\n" if $opt_v;
 443
 444        my $parent = "";
 445        if(open(C,"$git_dir/refs/heads/$last_branch")) {
 446                chomp($parent = <C>);
 447                close(C);
 448                length($parent) == 40
 449                        or die "Cannot get parent id ($parent): $!\n";
 450                print "Parent ID $parent\n" if $opt_v;
 451        }
 452
 453        my $pr = IO::Pipe->new();
 454        my $pw = IO::Pipe->new();
 455        $pid = fork();
 456        die "Fork: $!\n" unless defined $pid;
 457        unless($pid) {
 458                $pr->writer();
 459                $pw->reader();
 460                dup2($pw->fileno(),0);
 461                dup2($pr->fileno(),1);
 462                $pr->close();
 463                $pw->close();
 464
 465                my @par = ();
 466                @par = ("-p",$parent) if $parent;
 467                exec("env",
 468                        "GIT_AUTHOR_NAME=$author",
 469                        "GIT_AUTHOR_EMAIL=$author",
 470                        "GIT_AUTHOR_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
 471                        "GIT_COMMITTER_NAME=$author",
 472                        "GIT_COMMITTER_EMAIL=$author",
 473                        "GIT_COMMITTER_DATE=".strftime("+0000 %Y-%m-%d %H:%M:%S",gmtime($date)),
 474                        "git-commit-tree", $tree,@par);
 475                die "Cannot exec git-commit-tree: $!\n";
 476        }
 477        $pw->writer();
 478        $pr->reader();
 479
 480        # compatibility with git2cvs
 481        substr($logmsg,32767) = "" if length($logmsg) > 32767;
 482        $logmsg =~ s/[\s\n]+\z//;
 483
 484        print $pw "$logmsg\n"
 485                or die "Error writing to git-commit-tree: $!\n";
 486        $pw->close();
 487
 488        print "Committed patch $patchset ($branch)\n" if $opt_v;
 489        chomp(my $cid = <$pr>);
 490        length($cid) == 40
 491                or die "Cannot get commit id ($cid): $!\n";
 492        print "Commit ID $cid\n" if $opt_v;
 493        $pr->close();
 494
 495        waitpid($pid,0);
 496        die "Error running git-commit-tree: $?\n" if $?;
 497
 498        open(C,">$git_dir/refs/heads/$branch")
 499                or die "Cannot open branch $branch for update: $!\n";
 500        print C "$cid\n"
 501                or die "Cannot write branch $branch for update: $!\n";
 502        close(C)
 503                or die "Cannot write branch $branch for update: $!\n";
 504
 505        if($tag) {
 506                open(C,">$git_dir/refs/tags/$tag")
 507                        or die "Cannot create tag $tag: $!\n";
 508                print C "$cid\n"
 509                        or die "Cannot write tag $branch: $!\n";
 510                close(C)
 511                        or die "Cannot write tag $branch: $!\n";
 512                print "Created tag '$tag' on '$branch'\n" if $opt_v;
 513        }
 514};
 515
 516while(<CVS>) {
 517        chomp;
 518        if($state == 0 and /^-+$/) {
 519                $state = 1;
 520        } elsif($state == 0) {
 521                $state = 1;
 522                redo;
 523        } elsif(($state==0 or $state==1) and s/^PatchSet\s+//) {
 524                $patchset = 0+$_;
 525                $state=2;
 526        } elsif($state == 2 and s/^Date:\s+//) {
 527                $date = pdate($_);
 528                unless($date) {
 529                        print STDERR "Could not parse date: $_\n";
 530                        $state=0;
 531                        next;
 532                }
 533                $state=3;
 534        } elsif($state == 3 and s/^Author:\s+//) {
 535                s/\s+$//;
 536                $author = $_;
 537                $state = 4;
 538        } elsif($state == 4 and s/^Branch:\s+//) {
 539                s/\s+$//;
 540                $branch = $_;
 541                $state = 5;
 542        } elsif($state == 5 and s/^Ancestor branch:\s+//) {
 543                s/\s+$//;
 544                $ancestor = $_;
 545                $ancestor = $opt_o if $ancestor eq "HEAD";
 546                $state = 6;
 547        } elsif($state == 5) {
 548                $ancestor = undef;
 549                $state = 6;
 550                redo;
 551        } elsif($state == 6 and s/^Tag:\s+//) {
 552                s/\s+$//;
 553                if($_ eq "(none)") {
 554                        $tag = undef;
 555                } else {
 556                        $tag = $_;
 557                }
 558                $state = 7;
 559        } elsif($state == 7 and /^Log:/) {
 560                $logmsg = "";
 561                $state = 8;
 562        } elsif($state == 8 and /^Members:/) {
 563                $branch = $opt_o if $branch eq "HEAD";
 564                if(defined $branch_date{$branch} and $branch_date{$branch} >= $date) {
 565                        # skip
 566                        print "skip patchset $patchset: $date before $branch_date{$branch}\n";
 567                        $state = 11;
 568                        next;
 569                }
 570                if($ancestor) {
 571                        if(-f "$git_dir/refs/heads/$branch") {
 572                                print STDERR "Branch $branch already exists!\n";
 573                                $state=11;
 574                                next;
 575                        }
 576                        unless(open(H,"$git_dir/refs/heads/$ancestor")) {
 577                                print STDERR "Branch $ancestor does not exist!\n";
 578                                $state=11;
 579                                next;
 580                        }
 581                        chomp(my $id = <H>);
 582                        close(H);
 583                        unless(open(H,"> $git_dir/refs/heads/$branch")) {
 584                                print STDERR "Could not create branch $branch: $!\n";
 585                                $state=11;
 586                                next;
 587                        }
 588                        print H "$id\n"
 589                                or die "Could not write branch $branch: $!";
 590                        close(H)
 591                                or die "Could not write branch $branch: $!";
 592                }
 593                if(($ancestor || $branch) ne $last_branch) {
 594                        print "Switching from $last_branch to $branch\n" if $opt_v;
 595                        system("git-read-tree","-m","-u","$last_branch","$branch");
 596                        die "read-tree failed: $?\n" if $?;
 597                }
 598                if($branch ne $last_branch) {
 599                        unlink("$git_dir/HEAD");
 600                        symlink("refs/heads/$branch","$git_dir/HEAD");
 601                        $last_branch = $branch;
 602                }
 603                $state = 9;
 604        } elsif($state == 8) {
 605                $logmsg .= "$_\n";
 606        } elsif($state == 9 and /^\s+(\S+):(INITIAL|\d(?:\.\d+)+)->(\d(?:\.\d+)+)\s*$/) {
 607#       VERSION:1.96->1.96.2.1
 608                my $init = ($2 eq "INITIAL");
 609                my $fn = $1;
 610                my $rev = $3;
 611                $fn =~ s#^/+##;
 612                my $data = $cvs->file($fn,$rev);
 613                print "".($init ? "New" : "Update")." $fn: ".length($data)." bytes.\n";
 614                mkpath(dirname($fn),$opt_v);
 615                open(F,"> ./$fn")
 616                        or die "Cannot create '$fn': $!\n";
 617                print F $data
 618                        or die "Cannot write to '$fn': $!\n";
 619                close(F)
 620                        or die "Cannot write to '$fn': $!\n";
 621                chmod(pmode($cvs->{'mode'}), $fn);
 622                push(@new,$fn); # may be resurrected!
 623        } elsif($state == 9 and /^\s+(\S+):\d(?:\.\d+)+->(\d(?:\.\d+)+)\(DEAD\)\s*$/) {
 624                my $fn = $1;
 625                $fn =~ s#^/+##;
 626                push(@old,$fn);
 627        } elsif($state == 9 and /^\s*$/) {
 628                $state = 10;
 629        } elsif(($state == 9 or $state == 10) and /^-+$/) {
 630                &$commit();
 631                $state = 1;
 632        } elsif($state == 11 and /^-+$/) {
 633                $state = 1;
 634        } elsif(/^-+$/) { # end of unknown-line processing
 635                $state = 1;
 636        } elsif($state != 11) { # ignore stuff when skipping
 637                print "* UNKNOWN LINE * $_\n";
 638        }
 639}
 640&$commit() if $branch and $state != 11;
 641
 642# Now switch back to the branch we were in before all of this happened
 643if($orig_branch) {
 644        print "DONE; switching back to $orig_branch\n" if $opt_v;
 645} else {
 646        $orig_branch = "master";
 647        print "DONE; creating $orig_branch branch\n" if $opt_v;
 648        system("cp","$git_dir/refs/heads/$opt_o","$git_dir/refs/heads/master")
 649                unless -f "$git_dir/refs/heads/master";
 650}
 651
 652system("git-read-tree","-m","-u","$last_branch","$orig_branch");
 653die "read-tree failed: $?\n" if $?;
 654
 655unlink("$git_dir/HEAD");
 656symlink("refs/heads/$orig_branch","$git_dir/HEAD");
 657