t0060: verify that basename() and dirname() work as expected

[git/git-svn.git] / perl / Git / SVN.pm

package Git::SVN;
use strict;
use warnings;
use Fcntl qw/:DEFAULT :seek/;
use constant rev_map_fmt => 'NH40';
use vars qw/$_no_metadata
            $_repack $_repack_flags $_use_svm_props $_head
            $_use_svnsync_props $no_reuse_existing
            $_use_log_author $_add_author_from $_localtime/;
use Carp qw/croak/;
use File::Path qw/mkpath/;
use IPC::Open3;
use Memoize;  # core since 5.8.0, Jul 2002
use POSIX qw(:signal_h);
use Time::Local;

use Git qw(
    command
    command_oneline
    command_noisy
    command_output_pipe
    command_close_pipe
    get_tz_offset
);
use Git::SVN::Utils qw(
        fatal
        can_compress
        join_paths
        canonicalize_path
        canonicalize_url
        add_path_to_url
);

my $memo_backend;
our $_follow_parent  = 1;
our $_minimize_url   = 'unset';
our $default_repo_id = 'svn';
our $default_ref_id  = $ENV{GIT_SVN_ID} || 'git-svn';

my ($_gc_nr, $_gc_period);

# properties that we do not log:
my %SKIP_PROP;
BEGIN {
        %SKIP_PROP = map { $_ => 1 } qw/svn:wc:ra_dav:version-url
                                        svn:special svn:executable
                                        svn:entry:committed-rev
                                        svn:entry:last-author
                                        svn:entry:uuid
                                        svn:entry:committed-date/;

        # some options are read globally, but can be overridden locally
        # per [svn-remote "..."] section.  Command-line options will *NOT*
        # override options set in an [svn-remote "..."] section
        no strict 'refs';
        for my $option (qw/follow_parent no_metadata use_svm_props
                           use_svnsync_props/) {
                my $key = $option;
                $key =~ tr/_//d;
                my $prop = "-$option";
                *$option = sub {
                        my ($self) = @_;
                        return $self->{$prop} if exists $self->{$prop};
                        my $k = "svn-remote.$self->{repo_id}.$key";
                        eval { command_oneline(qw/config --get/, $k) };
                        if ($@) {
                                $self->{$prop} = ${"Git::SVN::_$option"};
                        } else {
                                my $v = command_oneline(qw/config --bool/,$k);
                                $self->{$prop} = $v eq 'false' ? 0 : 1;
                        }
                        return $self->{$prop};
                }
        }
}


my (%LOCKFILES, %INDEX_FILES);
END {
        unlink keys %LOCKFILES if %LOCKFILES;
        unlink keys %INDEX_FILES if %INDEX_FILES;
}

sub resolve_local_globs {
        my ($url, $fetch, $glob_spec) = @_;
        return unless defined $glob_spec;
        my $ref = $glob_spec->{ref};
        my $path = $glob_spec->{path};
        foreach (command(qw#for-each-ref --format=%(refname) refs/#)) {
                next unless m#^$ref->{regex}$#;
                my $p = $1;
                my $pathname = desanitize_refname($path->full_path($p));
                my $refname = desanitize_refname($ref->full_path($p));
                if (my $existing = $fetch->{$pathname}) {
                        if ($existing ne $refname) {
                                die "Refspec conflict:\n",
                                    "existing: $existing\n",
                                    " globbed: $refname\n";
                        }
                        my $u = (::cmt_metadata("$refname"))[0];
                        $u =~ s!^\Q$url\E(/|$)!! or die
                          "$refname: '$url' not found in '$u'\n";
                        if ($pathname ne $u) {
                                warn "W: Refspec glob conflict ",
                                     "(ref: $refname):\n",
                                     "expected path: $pathname\n",
                                     "    real path: $u\n",
                                     "Continuing ahead with $u\n";
                                next;
                        }
                } else {
                        $fetch->{$pathname} = $refname;
                }
        }
}

sub parse_revision_argument {
        my ($base, $head) = @_;
        if (!defined $::_revision || $::_revision eq 'BASE:HEAD') {
                return ($base, $head);
        }
        return ($1, $2) if ($::_revision =~ /^(\d+):(\d+)$/);
        return ($::_revision, $::_revision) if ($::_revision =~ /^\d+$/);
        return ($head, $head) if ($::_revision eq 'HEAD');
        return ($base, $1) if ($::_revision =~ /^BASE:(\d+)$/);
        return ($1, $head) if ($::_revision =~ /^(\d+):HEAD$/);
        die "revision argument: $::_revision not understood by git-svn\n";
}

sub fetch_all {
        my ($repo_id, $remotes) = @_;
        if (ref $repo_id) {
                my $gs = $repo_id;
                $repo_id = undef;
                $repo_id = $gs->{repo_id};
        }
        $remotes ||= read_all_remotes();
        my $remote = $remotes->{$repo_id} or
                     die "[svn-remote \"$repo_id\"] unknown\n";
        my $fetch = $remote->{fetch};
        my $url = $remote->{url} or die "svn-remote.$repo_id.url not defined\n";
        my (@gs, @globs);
        my $ra = Git::SVN::Ra->new($url);
        my $uuid = $ra->get_uuid;
        my $head = $ra->get_latest_revnum;

        # ignore errors, $head revision may not even exist anymore
        eval { $ra->get_log("", $head, 0, 1, 0, 1, sub { $head = $_[1] }) };
        warn "W: $@\n" if $@;

        my $base = defined $fetch ? $head : 0;

        # read the max revs for wildcard expansion (branches/*, tags/*)
        foreach my $t (qw/branches tags/) {
                defined $remote->{$t} or next;
                push @globs, @{$remote->{$t}};

                my $max_rev = eval { tmp_config(qw/--int --get/,
                                         "svn-remote.$repo_id.${t}-maxRev") };
                if (defined $max_rev && ($max_rev < $base)) {
                        $base = $max_rev;
                } elsif (!defined $max_rev) {
                        $base = 0;
                }
        }

        if ($fetch) {
                foreach my $p (sort keys %$fetch) {
                        my $gs = Git::SVN->new($fetch->{$p}, $repo_id, $p);
                        my $lr = $gs->rev_map_max;
                        if (defined $lr) {
                                $base = $lr if ($lr < $base);
                        }
                        push @gs, $gs;
                }
        }

        ($base, $head) = parse_revision_argument($base, $head);
        $ra->gs_fetch_loop_common($base, $head, \@gs, \@globs);
}

sub read_all_remotes {
        my $r = {};
        my $use_svm_props = eval { command_oneline(qw/config --bool
            svn.useSvmProps/) };
        $use_svm_props = $use_svm_props eq 'true' if $use_svm_props;
        my $svn_refspec = qr{\s*(.*?)\s*:\s*(.+?)\s*};
        foreach (grep { s/^svn-remote\.// } command(qw/config -l/)) {
                if (m!^(.+)\.fetch=$svn_refspec$!) {
                        my ($remote, $local_ref, $remote_ref) = ($1, $2, $3);
                        die("svn-remote.$remote: remote ref '$remote_ref' "
                            . "must start with 'refs/'\n")
                                unless $remote_ref =~ m{^refs/};
                        $local_ref = uri_decode($local_ref);
                        $r->{$remote}->{fetch}->{$local_ref} = $remote_ref;
                        $r->{$remote}->{svm} = {} if $use_svm_props;
                } elsif (m!^(.+)\.usesvmprops=\s*(.*)\s*$!) {
                        $r->{$1}->{svm} = {};
                } elsif (m!^(.+)\.url=\s*(.*)\s*$!) {
                        $r->{$1}->{url} = canonicalize_url($2);
                } elsif (m!^(.+)\.pushurl=\s*(.*)\s*$!) {
                        $r->{$1}->{pushurl} = canonicalize_url($2);
                } elsif (m!^(.+)\.ignore-refs=\s*(.*)\s*$!) {
                        $r->{$1}->{ignore_refs_regex} = $2;
                } elsif (m!^(.+)\.(branches|tags)=$svn_refspec$!) {
                        my ($remote, $t, $local_ref, $remote_ref) =
                                                             ($1, $2, $3, $4);
                        die("svn-remote.$remote: remote ref '$remote_ref' ($t) "
                            . "must start with 'refs/'\n")
                                unless $remote_ref =~ m{^refs/};
                        $local_ref = uri_decode($local_ref);

                        require Git::SVN::GlobSpec;
                        my $rs = {
                            t => $t,
                            remote => $remote,
                            path => Git::SVN::GlobSpec->new($local_ref, 1),
                            ref => Git::SVN::GlobSpec->new($remote_ref, 0) };
                        if (length($rs->{ref}->{right}) != 0) {
                                die "The '*' glob character must be the last ",
                                    "character of '$remote_ref'\n";
                        }
                        push @{ $r->{$remote}->{$t} }, $rs;
                }
        }

        map {
                if (defined $r->{$_}->{svm}) {
                        my $svm;
                        eval {
                                my $section = "svn-remote.$_";
                                $svm = {
                                        source => tmp_config('--get',
                                            "$section.svm-source"),
                                        replace => tmp_config('--get',
                                            "$section.svm-replace"),
                                }
                        };
                        $r->{$_}->{svm} = $svm;
                }
        } keys %$r;

        foreach my $remote (keys %$r) {
                foreach ( grep { defined $_ }
                          map { $r->{$remote}->{$_} } qw(branches tags) ) {
                        foreach my $rs ( @$_ ) {
                                $rs->{ignore_refs_regex} =
                                    $r->{$remote}->{ignore_refs_regex};
                        }
                }
        }

        $r;
}

sub init_vars {
        $_gc_nr = $_gc_period = 1000;
        if (defined $_repack || defined $_repack_flags) {
               warn "Repack options are obsolete; they have no effect.\n";
        }
}

sub verify_remotes_sanity {
        return unless -d $ENV{GIT_DIR};
        my %seen;
        foreach (command(qw/config -l/)) {
                if (m!^svn-remote\.(?:.+)\.fetch=.*:refs/remotes/(\S+)\s*$!) {
                        if ($seen{$1}) {
                                die "Remote ref refs/remote/$1 is tracked by",
                                    "\n  \"$_\"\nand\n  \"$seen{$1}\"\n",
                                    "Please resolve this ambiguity in ",
                                    "your git configuration file before ",
                                    "continuing\n";
                        }
                        $seen{$1} = $_;
                }
        }
}

sub find_existing_remote {
        my ($url, $remotes) = @_;
        return undef if $no_reuse_existing;
        my $existing;
        foreach my $repo_id (keys %$remotes) {
                my $u = $remotes->{$repo_id}->{url} or next;
                next if $u ne $url;
                $existing = $repo_id;
                last;
        }
        $existing;
}

sub init_remote_config {
        my ($self, $url, $no_write) = @_;
        $url = canonicalize_url($url);
        my $r = read_all_remotes();
        my $existing = find_existing_remote($url, $r);
        if ($existing) {
                unless ($no_write) {
                        print STDERR "Using existing ",
                                     "[svn-remote \"$existing\"]\n";
                }
                $self->{repo_id} = $existing;
        } elsif ($_minimize_url) {
                my $min_url = Git::SVN::Ra->new($url)->minimize_url;
                $existing = find_existing_remote($min_url, $r);
                if ($existing) {
                        unless ($no_write) {
                                print STDERR "Using existing ",
                                             "[svn-remote \"$existing\"]\n";
                        }
                        $self->{repo_id} = $existing;
                }
                if ($min_url ne $url) {
                        unless ($no_write) {
                                print STDERR "Using higher level of URL: ",
                                             "$url => $min_url\n";
                        }
                        my $old_path = $self->path;
                        $url =~ s!^\Q$min_url\E(/|$)!!;
                        $url = join_paths($url, $old_path);
                        $self->path($url);
                        $url = $min_url;
                }
        }
        my $orig_url;
        if (!$existing) {
                # verify that we aren't overwriting anything:
                $orig_url = eval {
                        command_oneline('config', '--get',
                                        "svn-remote.$self->{repo_id}.url")
                };
                if ($orig_url && ($orig_url ne $url)) {
                        die "svn-remote.$self->{repo_id}.url already set: ",
                            "$orig_url\nwanted to set to: $url\n";
                }
        }
        my ($xrepo_id, $xpath) = find_ref($self->refname);
        if (!$no_write && defined $xpath) {
                die "svn-remote.$xrepo_id.fetch already set to track ",
                    "$xpath:", $self->refname, "\n";
        }
        unless ($no_write) {
                command_noisy('config',
                              "svn-remote.$self->{repo_id}.url", $url);
                my $path = $self->path;
                $path =~ s{^/}{};
                $path =~ s{%([0-9A-F]{2})}{chr hex($1)}ieg;
                $self->path($path);
                command_noisy('config', '--add',
                              "svn-remote.$self->{repo_id}.fetch",
                              $self->path.":".$self->refname);
        }
        $self->url($url);
}

sub find_by_url { # repos_root and, path are optional
        my ($class, $full_url, $repos_root, $path) = @_;

        $full_url = canonicalize_url($full_url);

        return undef unless defined $full_url;
        remove_username($full_url);
        remove_username($repos_root) if defined $repos_root;
        my $remotes = read_all_remotes();
        if (defined $full_url && defined $repos_root && !defined $path) {
                $path = $full_url;
                $path =~ s#^\Q$repos_root\E(?:/|$)##;
        }
        foreach my $repo_id (keys %$remotes) {
                my $u = $remotes->{$repo_id}->{url} or next;
                remove_username($u);
                next if defined $repos_root && $repos_root ne $u;

                my $fetch = $remotes->{$repo_id}->{fetch} || {};
                foreach my $t (qw/branches tags/) {
                        foreach my $globspec (@{$remotes->{$repo_id}->{$t}}) {
                                resolve_local_globs($u, $fetch, $globspec);
                        }
                }
                my $p = $path;
                my $rwr = rewrite_root({repo_id => $repo_id});
                my $svm = $remotes->{$repo_id}->{svm}
                        if defined $remotes->{$repo_id}->{svm};
                unless (defined $p) {
                        $p = $full_url;
                        my $z = $u;
                        my $prefix = '';
                        if ($rwr) {
                                $z = $rwr;
                                remove_username($z);
                        } elsif (defined $svm) {
                                $z = $svm->{source};
                                $prefix = $svm->{replace};
                                $prefix =~ s#^\Q$u\E(?:/|$)##;
                                $prefix =~ s#/$##;
                        }
                        $p =~ s#^\Q$z\E(?:/|$)#$prefix# or next;
                }

                # remote fetch paths are not URI escaped.  Decode ours
                # so they match
                $p = uri_decode($p);

                foreach my $f (keys %$fetch) {
                        next if $f ne $p;
                        return Git::SVN->new($fetch->{$f}, $repo_id, $f);
                }
        }
        undef;
}

sub init {
        my ($class, $url, $path, $repo_id, $ref_id, $no_write) = @_;
        my $self = _new($class, $repo_id, $ref_id, $path);
        if (defined $url) {
                $self->init_remote_config($url, $no_write);
        }
        $self;
}

sub find_ref {
        my ($ref_id) = @_;
        foreach (command(qw/config -l/)) {
                next unless m!^svn-remote\.(.+)\.fetch=
                              \s*(.*?)\s*:\s*(.+?)\s*$!x;
                my ($repo_id, $path, $ref) = ($1, $2, $3);
                if ($ref eq $ref_id) {
                        $path = '' if ($path =~ m#^\./?#);
                        return ($repo_id, $path);
                }
        }
        (undef, undef, undef);
}

sub new {
        my ($class, $ref_id, $repo_id, $path) = @_;
        if (defined $ref_id && !defined $repo_id && !defined $path) {
                ($repo_id, $path) = find_ref($ref_id);
                if (!defined $repo_id) {
                        die "Could not find a \"svn-remote.*.fetch\" key ",
                            "in the repository configuration matching: ",
                            "$ref_id\n";
                }
        }
        my $self = _new($class, $repo_id, $ref_id, $path);
        if (!defined $self->path || !length $self->path) {
                my $fetch = command_oneline('config', '--get',
                                            "svn-remote.$repo_id.fetch",
                                            ":$ref_id\$") or
                     die "Failed to read \"svn-remote.$repo_id.fetch\" ",
                         "\":$ref_id\$\" in config\n";
                my($path) = split(/\s*:\s*/, $fetch);
                $self->path($path);
        }
        {
                my $path = $self->path;
                $path =~ s{\A/}{};
                $path =~ s{/\z}{};
                $self->path($path);
        }
        my $url = command_oneline('config', '--get',
                                  "svn-remote.$repo_id.url") or
                  die "Failed to read \"svn-remote.$repo_id.url\" in config\n";
        $self->url($url);
        $self->{pushurl} = eval { command_oneline('config', '--get',
                                  "svn-remote.$repo_id.pushurl") };
        $self->rebuild;
        $self;
}

sub refname {
        my ($refname) = $_[0]->{ref_id} ;

        # It cannot end with a slash /, we'll throw up on this because
        # SVN can't have directories with a slash in their name, either:
        if ($refname =~ m{/$}) {
                die "ref: '$refname' ends with a trailing slash; this is ",
                    "not permitted by git or Subversion\n";
        }

        # It cannot have ASCII control character space, tilde ~, caret ^,
        # colon :, question-mark ?, asterisk *, space, or open bracket [
        # anywhere.
        #
        # Additionally, % must be escaped because it is used for escaping
        # and we want our escaped refname to be reversible
        $refname =~ s{([ \%~\^:\?\*\[\t])}{sprintf('%%%02X',ord($1))}eg;

        # no slash-separated component can begin with a dot .
        # /.* becomes /%2E*
        $refname =~ s{/\.}{/%2E}g;

        # It cannot have two consecutive dots .. anywhere
        # .. becomes %2E%2E
        $refname =~ s{\.\.}{%2E%2E}g;

        # trailing dots and .lock are not allowed
        # .$ becomes %2E and .lock becomes %2Elock
        $refname =~ s{\.(?=$|lock$)}{%2E};

        # the sequence @{ is used to access the reflog
        # @{ becomes %40{
        $refname =~ s{\@\{}{%40\{}g;

        return $refname;
}

sub desanitize_refname {
        my ($refname) = @_;
        $refname =~ s{%(?:([0-9A-F]{2}))}{chr hex($1)}eg;
        return $refname;
}

sub svm_uuid {
        my ($self) = @_;
        return $self->{svm}->{uuid} if $self->svm;
        $self->ra;
        unless ($self->{svm}) {
                die "SVM UUID not cached, and reading remotely failed\n";
        }
        $self->{svm}->{uuid};
}

sub svm {
        my ($self) = @_;
        return $self->{svm} if $self->{svm};
        my $svm;
        # see if we have it in our config, first:
        eval {
                my $section = "svn-remote.$self->{repo_id}";
                $svm = {
                  source => tmp_config('--get', "$section.svm-source"),
                  uuid => tmp_config('--get', "$section.svm-uuid"),
                  replace => tmp_config('--get', "$section.svm-replace"),
                }
        };
        if ($svm && $svm->{source} && $svm->{uuid} && $svm->{replace}) {
                $self->{svm} = $svm;
        }
        $self->{svm};
}

sub _set_svm_vars {
        my ($self, $ra) = @_;
        return $ra if $self->svm;

        my @err = ( "useSvmProps set, but failed to read SVM properties\n",
                    "(svm:source, svm:uuid) ",
                    "from the following URLs:\n" );
        sub read_svm_props {
                my ($self, $ra, $path, $r) = @_;
                my $props = ($ra->get_dir($path, $r))[2];
                my $src = $props->{'svm:source'};
                my $uuid = $props->{'svm:uuid'};
                return undef if (!$src || !$uuid);

                chomp($src, $uuid);

                $uuid =~ m{^[0-9a-f\-]{30,}$}i
                    or die "doesn't look right - svm:uuid is '$uuid'\n";

                # the '!' is used to mark the repos_root!/relative/path
                $src =~ s{/?!/?}{/};
                $src =~ s{/+$}{}; # no trailing slashes please
                # username is of no interest
                $src =~ s{(^[a-z\+]*://)[^/@]*@}{$1};

                my $replace = add_path_to_url($ra->url, $path);

                my $section = "svn-remote.$self->{repo_id}";
                tmp_config("$section.svm-source", $src);
                tmp_config("$section.svm-replace", $replace);
                tmp_config("$section.svm-uuid", $uuid);
                $self->{svm} = {
                        source => $src,
                        uuid => $uuid,
                        replace => $replace
                };
        }

        my $r = $ra->get_latest_revnum;
        my $path = $self->path;
        my %tried;
        while (length $path) {
                my $try = add_path_to_url($self->url, $path);
                unless ($tried{$try}) {
                        return $ra if $self->read_svm_props($ra, $path, $r);
                        $tried{$try} = 1;
                }
                $path =~ s#/?[^/]+$##;
        }
        die "Path: '$path' should be ''\n" if $path ne '';
        return $ra if $self->read_svm_props($ra, $path, $r);
        $tried{ add_path_to_url($self->url, $path) } = 1;

        if ($ra->{repos_root} eq $self->url) {
                die @err, (map { "  $_\n" } keys %tried), "\n";
        }

        # nope, make sure we're connected to the repository root:
        my $ok;
        my @tried_b;
        $path = $ra->{svn_path};
        $ra = Git::SVN::Ra->new($ra->{repos_root});
        while (length $path) {
                my $try = add_path_to_url($ra->url, $path);
                unless ($tried{$try}) {
                        $ok = $self->read_svm_props($ra, $path, $r);
                        last if $ok;
                        $tried{$try} = 1;
                }
                $path =~ s#/?[^/]+$##;
        }
        die "Path: '$path' should be ''\n" if $path ne '';
        $ok ||= $self->read_svm_props($ra, $path, $r);
        $tried{ add_path_to_url($ra->url, $path) } = 1;
        if (!$ok) {
                die @err, (map { "  $_\n" } keys %tried), "\n";
        }
        Git::SVN::Ra->new($self->url);
}

sub svnsync {
        my ($self) = @_;
        return $self->{svnsync} if $self->{svnsync};

        if ($self->no_metadata) {
                die "Can't have both 'noMetadata' and ",
                    "'useSvnsyncProps' options set!\n";
        }
        if ($self->rewrite_root) {
                die "Can't have both 'useSvnsyncProps' and 'rewriteRoot' ",
                    "options set!\n";
        }
        if ($self->rewrite_uuid) {
                die "Can't have both 'useSvnsyncProps' and 'rewriteUUID' ",
                    "options set!\n";
        }

        my $svnsync;
        # see if we have it in our config, first:
        eval {
                my $section = "svn-remote.$self->{repo_id}";

                my $url = tmp_config('--get', "$section.svnsync-url");
                ($url) = ($url =~ m{^([a-z\+]+://\S+)$}) or
                   die "doesn't look right - svn:sync-from-url is '$url'\n";

                my $uuid = tmp_config('--get', "$section.svnsync-uuid");
                ($uuid) = ($uuid =~ m{^([0-9a-f\-]{30,})$}i) or
                   die "doesn't look right - svn:sync-from-uuid is '$uuid'\n";

                $svnsync = { url => $url, uuid => $uuid }
        };
        if ($svnsync && $svnsync->{url} && $svnsync->{uuid}) {
                return $self->{svnsync} = $svnsync;
        }

        my $err = "useSvnsyncProps set, but failed to read " .
                  "svnsync property: svn:sync-from-";
        my $rp = $self->ra->rev_proplist(0);

        my $url = $rp->{'svn:sync-from-url'} or die $err . "url\n";
        ($url) = ($url =~ m{^([a-z\+]+://\S+)$}) or
                   die "doesn't look right - svn:sync-from-url is '$url'\n";

        my $uuid = $rp->{'svn:sync-from-uuid'} or die $err . "uuid\n";
        ($uuid) = ($uuid =~ m{^([0-9a-f\-]{30,})$}i) or
                   die "doesn't look right - svn:sync-from-uuid is '$uuid'\n";

        my $section = "svn-remote.$self->{repo_id}";
        tmp_config('--add', "$section.svnsync-uuid", $uuid);
        tmp_config('--add', "$section.svnsync-url", $url);
        return $self->{svnsync} = { url => $url, uuid => $uuid };
}

# this allows us to memoize our SVN::Ra UUID locally and avoid a
# remote lookup (useful for 'git svn log').
sub ra_uuid {
        my ($self) = @_;
        unless ($self->{ra_uuid}) {
                my $key = "svn-remote.$self->{repo_id}.uuid";
                my $uuid = eval { tmp_config('--get', $key) };
                if (!$@ && $uuid && $uuid =~ /^([a-f\d\-]{30,})$/i) {
                        $self->{ra_uuid} = $uuid;
                } else {
                        die "ra_uuid called without URL\n" unless $self->url;
                        $self->{ra_uuid} = $self->ra->get_uuid;
                        tmp_config('--add', $key, $self->{ra_uuid});
                }
        }
        $self->{ra_uuid};
}

sub _set_repos_root {
        my ($self, $repos_root) = @_;
        my $k = "svn-remote.$self->{repo_id}.reposRoot";
        $repos_root ||= $self->ra->{repos_root};
        tmp_config($k, $repos_root);
        $repos_root;
}

sub repos_root {
        my ($self) = @_;
        my $k = "svn-remote.$self->{repo_id}.reposRoot";
        eval { tmp_config('--get', $k) } || $self->_set_repos_root;
}

sub ra {
        my ($self) = shift;
        my $ra = Git::SVN::Ra->new($self->url);
        $self->_set_repos_root($ra->{repos_root});
        if ($self->use_svm_props && !$self->{svm}) {
                if ($self->no_metadata) {
                        die "Can't have both 'noMetadata' and ",
                            "'useSvmProps' options set!\n";
                } elsif ($self->use_svnsync_props) {
                        die "Can't have both 'useSvnsyncProps' and ",
                            "'useSvmProps' options set!\n";
                }
                $ra = $self->_set_svm_vars($ra);
                $self->{-want_revprops} = 1;
        }
        $ra;
}

# prop_walk(PATH, REV, SUB)
# -------------------------
# Recursively traverse PATH at revision REV and invoke SUB for each
# directory that contains a SVN property.  SUB will be invoked as
# follows:  &SUB(gs, path, props);  where `gs' is this instance of
# Git::SVN, `path' the path to the directory where the properties
# `props' were found.  The `path' will be relative to point of checkout,
# that is, if url://repo/trunk is the current Git branch, and that
# directory contains a sub-directory `d', SUB will be invoked with `/d/'
# as `path' (note the trailing `/').
sub prop_walk {
        my ($self, $path, $rev, $sub) = @_;

        $path =~ s#^/##;
        my ($dirent, undef, $props) = $self->ra->get_dir($path, $rev);
        $path =~ s#^/*#/#g;
        my $p = $path;
        # Strip the irrelevant part of the path.
        $p =~ s#^/+\Q@{[$self->path]}\E(/|$)#/#;
        # Ensure the path is terminated by a `/'.
        $p =~ s#/*$#/#;

        # The properties contain all the internal SVN stuff nobody
        # (usually) cares about.
        my $interesting_props = 0;
        foreach (keys %{$props}) {
                # If it doesn't start with `svn:', it must be a
                # user-defined property.
                ++$interesting_props and next if $_ !~ /^svn:/;
                # FIXME: Fragile, if SVN adds new public properties,
                # this needs to be updated.
                ++$interesting_props if /^svn:(?:ignore|keywords|executable
                                                 |eol-style|mime-type
                                                 |externals|needs-lock)$/x;
        }
        &$sub($self, $p, $props) if $interesting_props;

        foreach (sort keys %$dirent) {
                next if $dirent->{$_}->{kind} != $SVN::Node::dir;
                $self->prop_walk($self->path . $p . $_, $rev, $sub);
        }
}

sub last_rev { ($_[0]->last_rev_commit)[0] }
sub last_commit { ($_[0]->last_rev_commit)[1] }

# returns the newest SVN revision number and newest commit SHA1
sub last_rev_commit {
        my ($self) = @_;
        if (defined $self->{last_rev} && defined $self->{last_commit}) {
                return ($self->{last_rev}, $self->{last_commit});
        }
        my $c = ::verify_ref($self->refname.'^0');
        if ($c && !$self->use_svm_props && !$self->no_metadata) {
                my $rev = (::cmt_metadata($c))[1];
                if (defined $rev) {
                        ($self->{last_rev}, $self->{last_commit}) = ($rev, $c);
                        return ($rev, $c);
                }
        }
        my $map_path = $self->map_path;
        unless (-e $map_path) {
                ($self->{last_rev}, $self->{last_commit}) = (undef, undef);
                return (undef, undef);
        }
        my ($rev, $commit) = $self->rev_map_max(1);
        ($self->{last_rev}, $self->{last_commit}) = ($rev, $commit);
        return ($rev, $commit);
}

sub get_fetch_range {
        my ($self, $min, $max) = @_;
        $max ||= $self->ra->get_latest_revnum;
        $min ||= $self->rev_map_max;
        (++$min, $max);
}

sub tmp_config {
        my (@args) = @_;
        my $old_def_config = "$ENV{GIT_DIR}/svn/config";
        my $config = "$ENV{GIT_DIR}/svn/.metadata";
        if (! -f $config && -f $old_def_config) {
                rename $old_def_config, $config or
                       die "Failed rename $old_def_config => $config: $!\n";
        }
        my $old_config = $ENV{GIT_CONFIG};
        $ENV{GIT_CONFIG} = $config;
        $@ = undef;
        my @ret = eval {
                unless (-f $config) {
                        mkfile($config);
                        open my $fh, '>', $config or
                            die "Can't open $config: $!\n";
                        print $fh "; This file is used internally by ",
                                  "git-svn\n" or die
                                  "Couldn't write to $config: $!\n";
                        print $fh "; You should not have to edit it\n" or
                              die "Couldn't write to $config: $!\n";
                        close $fh or die "Couldn't close $config: $!\n";
                }
                command('config', @args);
        };
        my $err = $@;
        if (defined $old_config) {
                $ENV{GIT_CONFIG} = $old_config;
        } else {
                delete $ENV{GIT_CONFIG};
        }
        die $err if $err;
        wantarray ? @ret : $ret[0];
}

sub tmp_index_do {
        my ($self, $sub) = @_;
        my $old_index = $ENV{GIT_INDEX_FILE};
        $ENV{GIT_INDEX_FILE} = $self->{index};
        $@ = undef;
        my @ret = eval {
                my ($dir, $base) = ($self->{index} =~ m#^(.*?)/?([^/]+)$#);
                mkpath([$dir]) unless -d $dir;
                &$sub;
        };
        my $err = $@;
        if (defined $old_index) {
                $ENV{GIT_INDEX_FILE} = $old_index;
        } else {
                delete $ENV{GIT_INDEX_FILE};
        }
        die $err if $err;
        wantarray ? @ret : $ret[0];
}

sub assert_index_clean {
        my ($self, $treeish) = @_;

        $self->tmp_index_do(sub {
                command_noisy('read-tree', $treeish) unless -e $self->{index};
                my $x = command_oneline('write-tree');
                my ($y) = (command(qw/cat-file commit/, $treeish) =~
                           /^tree ($::sha1)/mo);
                return if $y eq $x;

                warn "Index mismatch: $y != $x\nrereading $treeish\n";
                unlink $self->{index} or die "unlink $self->{index}: $!\n";
                command_noisy('read-tree', $treeish);
                $x = command_oneline('write-tree');
                if ($y ne $x) {
                        fatal "trees ($treeish) $y != $x\n",
                              "Something is seriously wrong...";
                }
        });
}

sub get_commit_parents {
        my ($self, $log_entry) = @_;
        my (%seen, @ret, @tmp);
        # legacy support for 'set-tree'; this is only used by set_tree_cb:
        if (my $ip = $self->{inject_parents}) {
                if (my $commit = delete $ip->{$log_entry->{revision}}) {
                        push @tmp, $commit;
                }
        }
        if (my $cur = ::verify_ref($self->refname.'^0')) {
                push @tmp, $cur;
        }
        if (my $ipd = $self->{inject_parents_dcommit}) {
                if (my $commit = delete $ipd->{$log_entry->{revision}}) {
                        push @tmp, @$commit;
                }
        }
        push @tmp, $_ foreach (@{$log_entry->{parents}}, @tmp);
        while (my $p = shift @tmp) {
                next if $seen{$p};
                $seen{$p} = 1;
                push @ret, $p;
        }
        @ret;
}

sub rewrite_root {
        my ($self) = @_;
        return $self->{-rewrite_root} if exists $self->{-rewrite_root};
        my $k = "svn-remote.$self->{repo_id}.rewriteRoot";
        my $rwr = eval { command_oneline(qw/config --get/, $k) };
        if ($rwr) {
                $rwr =~ s#/+$##;
                if ($rwr !~ m#^[a-z\+]+://#) {
                        die "$rwr is not a valid URL (key: $k)\n";
                }
        }
        $self->{-rewrite_root} = $rwr;
}

sub rewrite_uuid {
        my ($self) = @_;
        return $self->{-rewrite_uuid} if exists $self->{-rewrite_uuid};
        my $k = "svn-remote.$self->{repo_id}.rewriteUUID";
        my $rwid = eval { command_oneline(qw/config --get/, $k) };
        if ($rwid) {
                $rwid =~ s#/+$##;
                if ($rwid !~ m#^[a-f0-9]{8}-(?:[a-f0-9]{4}-){3}[a-f0-9]{12}$#) {
                        die "$rwid is not a valid UUID (key: $k)\n";
                }
        }
        $self->{-rewrite_uuid} = $rwid;
}

sub metadata_url {
        my ($self) = @_;
        my $url = $self->rewrite_root || $self->url;
        return canonicalize_url( add_path_to_url( $url, $self->path ) );
}

sub full_url {
        my ($self) = @_;
        return canonicalize_url( add_path_to_url( $self->url, $self->path ) );
}

sub full_pushurl {
        my ($self) = @_;
        if ($self->{pushurl}) {
                return canonicalize_url( add_path_to_url( $self->{pushurl}, $self->path ) );
        } else {
                return $self->full_url;
        }
}

sub set_commit_header_env {
        my ($log_entry) = @_;
        my %env;
        foreach my $ned (qw/NAME EMAIL DATE/) {
                foreach my $ac (qw/AUTHOR COMMITTER/) {
                        $env{"GIT_${ac}_${ned}"} = $ENV{"GIT_${ac}_${ned}"};
                }
        }

        $ENV{GIT_AUTHOR_NAME} = $log_entry->{name};
        $ENV{GIT_AUTHOR_EMAIL} = $log_entry->{email};
        $ENV{GIT_AUTHOR_DATE} = $ENV{GIT_COMMITTER_DATE} = $log_entry->{date};

        $ENV{GIT_COMMITTER_NAME} = (defined $log_entry->{commit_name})
                                                ? $log_entry->{commit_name}
                                                : $log_entry->{name};
        $ENV{GIT_COMMITTER_EMAIL} = (defined $log_entry->{commit_email})
                                                ? $log_entry->{commit_email}
                                                : $log_entry->{email};
        \%env;
}

sub restore_commit_header_env {
        my ($env) = @_;
        foreach my $ned (qw/NAME EMAIL DATE/) {
                foreach my $ac (qw/AUTHOR COMMITTER/) {
                        my $k = "GIT_${ac}_${ned}";
                        if (defined $env->{$k}) {
                                $ENV{$k} = $env->{$k};
                        } else {
                                delete $ENV{$k};
                        }
                }
        }
}

sub gc {
        command_noisy('gc', '--auto');
};

sub do_git_commit {
        my ($self, $log_entry) = @_;
        my $lr = $self->last_rev;
        if (defined $lr && $lr >= $log_entry->{revision}) {
                die "Last fetched revision of ", $self->refname,
                    " was r$lr, but we are about to fetch: ",
                    "r$log_entry->{revision}!\n";
        }
        if (my $c = $self->rev_map_get($log_entry->{revision})) {
                croak "$log_entry->{revision} = $c already exists! ",
                      "Why are we refetching it?\n";
        }
        my $old_env = set_commit_header_env($log_entry);
        my $tree = $log_entry->{tree};
        if (!defined $tree) {
                $tree = $self->tmp_index_do(sub {
                                            command_oneline('write-tree') });
        }
        die "Tree is not a valid sha1: $tree\n" if $tree !~ /^$::sha1$/o;

        my @exec = ('git', 'commit-tree', $tree);
        foreach ($self->get_commit_parents($log_entry)) {
                push @exec, '-p', $_;
        }
        defined(my $pid = open3(my $msg_fh, my $out_fh, '>&STDERR', @exec))
                                                                   or croak $!;
        binmode $msg_fh;

        # we always get UTF-8 from SVN, but we may want our commits in
        # a different encoding.
        if (my $enc = Git::config('i18n.commitencoding')) {
                require Encode;
                Encode::from_to($log_entry->{log}, 'UTF-8', $enc);
        }
        print $msg_fh $log_entry->{log} or croak $!;
        restore_commit_header_env($old_env);
        unless ($self->no_metadata) {
                print $msg_fh "\ngit-svn-id: $log_entry->{metadata}\n"
                              or croak $!;
        }
        $msg_fh->flush == 0 or croak $!;
        close $msg_fh or croak $!;
        chomp(my $commit = do { local $/; <$out_fh> });
        close $out_fh or croak $!;
        waitpid $pid, 0;
        croak $? if $?;
        if ($commit !~ /^$::sha1$/o) {
                die "Failed to commit, invalid sha1: $commit\n";
        }

        $self->rev_map_set($log_entry->{revision}, $commit, 1);

        $self->{last_rev} = $log_entry->{revision};
        $self->{last_commit} = $commit;
        print "r$log_entry->{revision}" unless $::_q > 1;
        if (defined $log_entry->{svm_revision}) {
                 print " (\@$log_entry->{svm_revision})" unless $::_q > 1;
                 $self->rev_map_set($log_entry->{svm_revision}, $commit,
                                   0, $self->svm_uuid);
        }
        print " = $commit ($self->{ref_id})\n" unless $::_q > 1;
        if (--$_gc_nr == 0) {
                $_gc_nr = $_gc_period;
                gc();
        }
        return $commit;
}

sub match_paths {
        my ($self, $paths, $r) = @_;
        return 1 if $self->path eq '';
        if (my $path = $paths->{"/".$self->path}) {
                return ($path->{action} eq 'D') ? 0 : 1;
        }
        $self->{path_regex} ||= qr{^/\Q@{[$self->path]}\E/};
        if (grep /$self->{path_regex}/, keys %$paths) {
                return 1;
        }
        my $c = '';
        foreach (split m#/#, $self->path) {
                $c .= "/$_";
                next unless ($paths->{$c} &&
                             ($paths->{$c}->{action} =~ /^[AR]$/));
                if ($self->ra->check_path($self->path, $r) ==
                    $SVN::Node::dir) {
                        return 1;
                }
        }
        return 0;
}

sub find_parent_branch {
        my ($self, $paths, $rev) = @_;
        return undef unless $self->follow_parent;
        unless (defined $paths) {
                my $err_handler = $SVN::Error::handler;
                $SVN::Error::handler = \&Git::SVN::Ra::skip_unknown_revs;
                $self->ra->get_log([$self->path], $rev, $rev, 0, 1, 1,
                                   sub { $paths = $_[0] });
                $SVN::Error::handler = $err_handler;
        }
        return undef unless defined $paths;

        # look for a parent from another branch:
        my @b_path_components = split m#/#, $self->path;
        my @a_path_components;
        my $i;
        while (@b_path_components) {
                $i = $paths->{'/'.join('/', @b_path_components)};
                last if $i && defined $i->{copyfrom_path};
                unshift(@a_path_components, pop(@b_path_components));
        }
        return undef unless defined $i && defined $i->{copyfrom_path};
        my $branch_from = $i->{copyfrom_path};
        if (@a_path_components) {
                print STDERR "branch_from: $branch_from => ";
                $branch_from .= '/'.join('/', @a_path_components);
                print STDERR $branch_from, "\n";
        }
        my $r = $i->{copyfrom_rev};
        my $repos_root = $self->ra->{repos_root};
        my $url = $self->ra->url;
        my $new_url = canonicalize_url( add_path_to_url( $url, $branch_from ) );
        print STDERR  "Found possible branch point: ",
                      "$new_url => ", $self->full_url, ", $r\n"
                      unless $::_q > 1;
        $branch_from =~ s#^/##;
        my $gs = $self->other_gs($new_url, $url,
                                 $branch_from, $r, $self->{ref_id});
        my ($r0, $parent) = $gs->find_rev_before($r, 1);
        {
                my ($base, $head);
                if (!defined $r0 || !defined $parent) {
                        ($base, $head) = parse_revision_argument(0, $r);
                } else {
                        if ($r0 < $r) {
                                $gs->ra->get_log([$gs->path], $r0 + 1, $r, 1,
                                        0, 1, sub { $base = $_[1] - 1 });
                        }
                }
                if (defined $base && $base <= $r) {
                        $gs->fetch($base, $r);
                }
                ($r0, $parent) = $gs->find_rev_before($r, 1);
        }
        if (defined $r0 && defined $parent) {
                print STDERR "Found branch parent: ($self->{ref_id}) $parent\n"
                             unless $::_q > 1;
                my $ed;
                if ($self->ra->can_do_switch) {
                        $self->assert_index_clean($parent);
                        print STDERR "Following parent with do_switch\n"
                                     unless $::_q > 1;
                        # do_switch works with svn/trunk >= r22312, but that
                        # is not included with SVN 1.4.3 (the latest version
                        # at the moment), so we can't rely on it
                        $self->{last_rev} = $r0;
                        $self->{last_commit} = $parent;
                        $ed = Git::SVN::Fetcher->new($self, $gs->path);
                        $gs->ra->gs_do_switch($r0, $rev, $gs,
                                              $self->full_url, $ed)
                          or die "SVN connection failed somewhere...\n";
                } elsif ($self->ra->trees_match($new_url, $r0,
                                                $self->full_url, $rev)) {
                        print STDERR "Trees match:\n",
                                     "  $new_url\@$r0\n",
                                     "  ${\$self->full_url}\@$rev\n",
                                     "Following parent with no changes\n"
                                     unless $::_q > 1;
                        $self->tmp_index_do(sub {
                            command_noisy('read-tree', $parent);
                        });
                        $self->{last_commit} = $parent;
                } else {
                        print STDERR "Following parent with do_update\n"
                                     unless $::_q > 1;
                        $ed = Git::SVN::Fetcher->new($self);
                        $self->ra->gs_do_update($rev, $rev, $self, $ed)
                          or die "SVN connection failed somewhere...\n";
                }
                print STDERR "Successfully followed parent\n" unless $::_q > 1;
                return $self->make_log_entry($rev, [$parent], $ed, $r0, $branch_from);
        }
        return undef;
}

sub do_fetch {
        my ($self, $paths, $rev) = @_;
        my $ed;
        my ($last_rev, @parents);
        if (my $lc = $self->last_commit) {
                # we can have a branch that was deleted, then re-added
                # under the same name but copied from another path, in
                # which case we'll have multiple parents (we don't
                # want to break the original ref or lose copypath info):
                if (my $log_entry = $self->find_parent_branch($paths, $rev)) {
                        push @{$log_entry->{parents}}, $lc;
                        return $log_entry;
                }
                $ed = Git::SVN::Fetcher->new($self);
                $last_rev = $self->{last_rev};
                $ed->{c} = $lc;
                @parents = ($lc);
        } else {
                $last_rev = $rev;
                if (my $log_entry = $self->find_parent_branch($paths, $rev)) {
                        return $log_entry;
                }
                $ed = Git::SVN::Fetcher->new($self);
        }
        unless ($self->ra->gs_do_update($last_rev, $rev, $self, $ed)) {
                die "SVN connection failed somewhere...\n";
        }
        $self->make_log_entry($rev, \@parents, $ed, $last_rev, $self->path);
}

sub mkemptydirs {
        my ($self, $r) = @_;

        sub scan {
                my ($r, $empty_dirs, $line) = @_;
                if (defined $r && $line =~ /^r(\d+)$/) {
                        return 0 if $1 > $r;
                } elsif ($line =~ /^  \+empty_dir: (.+)$/) {
                        $empty_dirs->{$1} = 1;
                } elsif ($line =~ /^  \-empty_dir: (.+)$/) {
                        my @d = grep {m[^\Q$1\E(/|$)]} (keys %$empty_dirs);
                        delete @$empty_dirs{@d};
                }
                1; # continue
        };

        my %empty_dirs = ();
        my $gz_file = "$self->{dir}/unhandled.log.gz";
        if (-f $gz_file) {
                if (!can_compress()) {
                        warn "Compress::Zlib could not be found; ",
                             "empty directories in $gz_file will not be read\n";
                } else {
                        my $gz = Compress::Zlib::gzopen($gz_file, "rb") or
                                die "Unable to open $gz_file: $!\n";
                        my $line;
                        while ($gz->gzreadline($line) > 0) {
                                scan($r, \%empty_dirs, $line) or last;
                        }
                        $gz->gzclose;
                }
        }

        if (open my $fh, '<', "$self->{dir}/unhandled.log") {
                binmode $fh or croak "binmode: $!";
                while (<$fh>) {
                        scan($r, \%empty_dirs, $_) or last;
                }
                close $fh;
        }

        my $strip = qr/\A\Q@{[$self->path]}\E(?:\/|$)/;
        foreach my $d (sort keys %empty_dirs) {
                $d = uri_decode($d);
                $d =~ s/$strip//;
                next unless length($d);
                next if -d $d;
                if (-e $d) {
                        warn "$d exists but is not a directory\n";
                } else {
                        print "creating empty directory: $d\n";
                        mkpath([$d]);
                }
        }
}

sub get_untracked {
        my ($self, $ed) = @_;
        my @out;
        my $h = $ed->{empty};
        foreach (sort keys %$h) {
                my $act = $h->{$_} ? '+empty_dir' : '-empty_dir';
                push @out, "  $act: " . uri_encode($_);
                warn "W: $act: $_\n";
        }
        foreach my $t (qw/dir_prop file_prop/) {
                $h = $ed->{$t} or next;
                foreach my $path (sort keys %$h) {
                        my $ppath = $path eq '' ? '.' : $path;
                        foreach my $prop (sort keys %{$h->{$path}}) {
                                next if $SKIP_PROP{$prop};
                                my $v = $h->{$path}->{$prop};
                                my $t_ppath_prop = "$t: " .
                                                    uri_encode($ppath) . ' ' .
                                                    uri_encode($prop);
                                if (defined $v) {
                                        push @out, "  +$t_ppath_prop " .
                                                   uri_encode($v);
                                } else {
                                        push @out, "  -$t_ppath_prop";
                                }
                        }
                }
        }
        foreach my $t (qw/absent_file absent_directory/) {
                $h = $ed->{$t} or next;
                foreach my $parent (sort keys %$h) {
                        foreach my $path (sort @{$h->{$parent}}) {
                                push @out, "  $t: " .
                                           uri_encode("$parent/$path");
                                warn "W: $t: $parent/$path ",
                                     "Insufficient permissions?\n";
                        }
                }
        }
        \@out;
}

# parse_svn_date(DATE)
# --------------------
# Given a date (in UTC) from Subversion, return a string in the format
# "<TZ Offset> <local date/time>" that Git will use.
#
# By default the parsed date will be in UTC; if $Git::SVN::_localtime
# is true we'll convert it to the local timezone instead.
sub parse_svn_date {
        my $date = shift || return '+0000 1970-01-01 00:00:00';
        my ($Y,$m,$d,$H,$M,$S) = ($date =~ /^(\d{4})\-(\d\d)\-(\d\d)T
                                            (\d\d?)\:(\d\d)\:(\d\d)\.\d*Z$/x) or
                                         croak "Unable to parse date: $date\n";
        my $parsed_date;    # Set next.

        if ($Git::SVN::_localtime) {
                # Translate the Subversion datetime to an epoch time.
                # Begin by switching ourselves to $date's timezone, UTC.
                my $old_env_TZ = $ENV{TZ};
                $ENV{TZ} = 'UTC';

                my $epoch_in_UTC =
                    Time::Local::timelocal($S, $M, $H, $d, $m - 1, $Y - 1900);

                # Determine our local timezone (including DST) at the
                # time of $epoch_in_UTC.  $Git::SVN::Log::TZ stored the
                # value of TZ, if any, at the time we were run.
                if (defined $Git::SVN::Log::TZ) {
                        $ENV{TZ} = $Git::SVN::Log::TZ;
                } else {
                        delete $ENV{TZ};
                }

                my $our_TZ = get_tz_offset();

                # This converts $epoch_in_UTC into our local timezone.
                my ($sec, $min, $hour, $mday, $mon, $year,
                    $wday, $yday, $isdst) = localtime($epoch_in_UTC);

                $parsed_date = sprintf('%s %04d-%02d-%02d %02d:%02d:%02d',
                                       $our_TZ, $year + 1900, $mon + 1,
                                       $mday, $hour, $min, $sec);

                # Reset us to the timezone in effect when we entered
                # this routine.
                if (defined $old_env_TZ) {
                        $ENV{TZ} = $old_env_TZ;
                } else {
                        delete $ENV{TZ};
                }
        } else {
                $parsed_date = "+0000 $Y-$m-$d $H:$M:$S";
        }

        return $parsed_date;
}

sub other_gs {
        my ($self, $new_url, $url,
            $branch_from, $r, $old_ref_id) = @_;
        my $gs = Git::SVN->find_by_url($new_url, $url, $branch_from);
        unless ($gs) {
                my $ref_id = $old_ref_id;
                $ref_id =~ s/\@\d+-*$//;
                $ref_id .= "\@$r";
                # just grow a tail if we're not unique enough :x
                $ref_id .= '-' while find_ref($ref_id);
                my ($u, $p, $repo_id) = ($new_url, '', $ref_id);
                if ($u =~ s#^\Q$url\E(/|$)##) {
                        $p = $u;
                        $u = $url;
                        $repo_id = $self->{repo_id};
                }
                while (1) {
                        # It is possible to tag two different subdirectories at
                        # the same revision.  If the url for an existing ref
                        # does not match, we must either find a ref with a
                        # matching url or create a new ref by growing a tail.
                        $gs = Git::SVN->init($u, $p, $repo_id, $ref_id, 1);
                        my (undef, $max_commit) = $gs->rev_map_max(1);
                        last if (!$max_commit);
                        my ($url) = ::cmt_metadata($max_commit);
                        last if ($url eq $gs->metadata_url);
                        $ref_id .= '-';
                }
                print STDERR "Initializing parent: $ref_id\n" unless $::_q > 1;
        }
        $gs
}

sub call_authors_prog {
        my ($orig_author) = @_;
        $orig_author = command_oneline('rev-parse', '--sq-quote', $orig_author);
        my $author = `$::_authors_prog $orig_author`;
        if ($? != 0) {
                die "$::_authors_prog failed with exit code $?\n"
        }
        if ($author =~ /^\s*(.+?)\s*<(.*)>\s*$/) {
                my ($name, $email) = ($1, $2);
                $email = undef if length $2 == 0;
                return [$name, $email];
        } else {
                die "Author: $orig_author: $::_authors_prog returned "
                        . "invalid author format: $author\n";
        }
}

sub check_author {
        my ($author) = @_;
        if (!defined $author || length $author == 0) {
                $author = '(no author)';
        }
        if (!defined $::users{$author}) {
                if (defined $::_authors_prog) {
                        $::users{$author} = call_authors_prog($author);
                } elsif (defined $::_authors) {
                        die "Author: $author not defined in $::_authors file\n";
                }
        }
        $author;
}

sub find_extra_svk_parents {
        my ($self, $tickets, $parents) = @_;
        # aha!  svk:merge property changed...
        my @tickets = split "\n", $tickets;
        my @known_parents;
        for my $ticket ( @tickets ) {
                my ($uuid, $path, $rev) = split /:/, $ticket;
                if ( $uuid eq $self->ra_uuid ) {
                        my $repos_root = $self->url;
                        my $branch_from = $path;
                        $branch_from =~ s{^/}{};
                        my $gs = $self->other_gs(add_path_to_url( $repos_root, $branch_from ),
                                                 $repos_root,
                                                 $branch_from,
                                                 $rev,
                                                 $self->{ref_id});
                        if ( my $commit = $gs->rev_map_get($rev, $uuid) ) {
                                # wahey!  we found it, but it might be
                                # an old one (!)
                                push @known_parents, [ $rev, $commit ];
                        }
                }
        }
        # Ordering matters; highest-numbered commit merge tickets
        # first, as they may account for later merge ticket additions
        # or changes.
        @known_parents = map {$_->[1]} sort {$b->[0] <=> $a->[0]} @known_parents;
        for my $parent ( @known_parents ) {
                my @cmd = ('rev-list', $parent, map { "^$_" } @$parents );
                my ($msg_fh, $ctx) = command_output_pipe(@cmd);
                my $new;
                while ( <$msg_fh> ) {
                        $new=1;last;
                }
                command_close_pipe($msg_fh, $ctx);
                if ( $new ) {
                        print STDERR
                            "Found merge parent (svk:merge ticket): $parent\n";
                        push @$parents, $parent;
                }
        }
}

sub lookup_svn_merge {
        my $uuid = shift;
        my $url = shift;
        my $source = shift;
        my $revs = shift;

        my $path = $source;
        $path =~ s{^/}{};
        my $gs = Git::SVN->find_by_url($url.$source, $url, $path);
        if ( !$gs ) {
                warn "Couldn't find revmap for $url$source\n";
                return;
        }
        my @ranges = split ",", $revs;
        my ($tip, $tip_commit);
        my @merged_commit_ranges;
        # find the tip
        for my $range ( @ranges ) {
                if ($range =~ /[*]$/) {
                        warn "W: Ignoring partial merge in svn:mergeinfo "
                                ."dirprop: $source:$range\n";
                        next;
                }
                my ($bottom, $top) = split "-", $range;
                $top ||= $bottom;
                my $bottom_commit = $gs->find_rev_after( $bottom, 1, $top );
                my $top_commit = $gs->find_rev_before( $top, 1, $bottom );

                unless ($top_commit and $bottom_commit) {
                        warn "W: unknown path/rev in svn:mergeinfo "
                                ."dirprop: $source:$range\n";
                        next;
                }

                if (scalar(command('rev-parse', "$bottom_commit^@"))) {
                        push @merged_commit_ranges,
                             "$bottom_commit^..$top_commit";
                } else {
                        push @merged_commit_ranges, "$top_commit";
                }

                if ( !defined $tip or $top > $tip ) {
                        $tip = $top;
                        $tip_commit = $top_commit;
                }
        }
        return ($tip_commit, @merged_commit_ranges);
}

sub _rev_list {
        my ($msg_fh, $ctx) = command_output_pipe(
                "rev-list", @_,
               );
        my @rv;
        while ( <$msg_fh> ) {
                chomp;
                push @rv, $_;
        }
        command_close_pipe($msg_fh, $ctx);
        @rv;
}

sub check_cherry_pick2 {
        my $base = shift;
        my $tip = shift;
        my $parents = shift;
        my @ranges = @_;
        my %commits = map { $_ => 1 }
                _rev_list("--no-merges", $tip, "--not", $base, @$parents, "--");
        for my $range ( @ranges ) {
                delete @commits{_rev_list($range, "--")};
        }
        for my $commit (keys %commits) {
                if (has_no_changes($commit)) {
                        delete $commits{$commit};
                }
        }
        my @k = (keys %commits);
        return (scalar @k, $k[0]);
}

sub has_no_changes {
        my $commit = shift;

        my @revs = split / /, command_oneline(
                qw(rev-list --parents -1 -m), $commit);

        # Commits with no parents, e.g. the start of a partial branch,
        # have changes by definition.
        return 1 if (@revs < 2);

        # Commits with multiple parents, e.g a merge, have no changes
        # by definition.
        return 0 if (@revs > 2);

        return (command_oneline("rev-parse", "$commit^{tree}") eq
                command_oneline("rev-parse", "$commit~1^{tree}"));
}

sub tie_for_persistent_memoization {
        my $hash = shift;
        my $path = shift;

        unless ($memo_backend) {
                if (eval { require Git::SVN::Memoize::YAML; 1}) {
                        $memo_backend = 1;
                } else {
                        require Memoize::Storable;
                        $memo_backend = -1;
                }
        }

        if ($memo_backend > 0) {
                tie %$hash => 'Git::SVN::Memoize::YAML', "$path.yaml";
        } else {
                tie %$hash => 'Memoize::Storable', "$path.db", 'nstore';
        }
}

# The GIT_DIR environment variable is not always set until after the command
# line arguments are processed, so we can't memoize in a BEGIN block.
{
        my $memoized = 0;

        sub memoize_svn_mergeinfo_functions {
                return if $memoized;
                $memoized = 1;

                my $cache_path = "$ENV{GIT_DIR}/svn/.caches/";
                mkpath([$cache_path]) unless -d $cache_path;

                my %lookup_svn_merge_cache;
                my %check_cherry_pick2_cache;
                my %has_no_changes_cache;

                tie_for_persistent_memoization(\%lookup_svn_merge_cache,
                    "$cache_path/lookup_svn_merge");
                memoize 'lookup_svn_merge',
                        SCALAR_CACHE => 'FAULT',
                        LIST_CACHE => ['HASH' => \%lookup_svn_merge_cache],
                ;

                tie_for_persistent_memoization(\%check_cherry_pick2_cache,
                    "$cache_path/check_cherry_pick2");
                memoize 'check_cherry_pick2',
                        SCALAR_CACHE => 'FAULT',
                        LIST_CACHE => ['HASH' => \%check_cherry_pick2_cache],
                ;

                tie_for_persistent_memoization(\%has_no_changes_cache,
                    "$cache_path/has_no_changes");
                memoize 'has_no_changes',
                        SCALAR_CACHE => ['HASH' => \%has_no_changes_cache],
                        LIST_CACHE => 'FAULT',
                ;
        }

        sub unmemoize_svn_mergeinfo_functions {
                return if not $memoized;
                $memoized = 0;

                Memoize::unmemoize 'lookup_svn_merge';
                Memoize::unmemoize 'check_cherry_pick2';
                Memoize::unmemoize 'has_no_changes';
        }

        sub clear_memoized_mergeinfo_caches {
                die "Only call this method in non-memoized context" if ($memoized);

                my $cache_path = "$ENV{GIT_DIR}/svn/.caches/";
                return unless -d $cache_path;

                for my $cache_file (("$cache_path/lookup_svn_merge",
                                     "$cache_path/check_cherry_pick", # old
                                     "$cache_path/check_cherry_pick2",
                                     "$cache_path/has_no_changes")) {
                        for my $suffix (qw(yaml db)) {
                                my $file = "$cache_file.$suffix";
                                next unless -e $file;
                                unlink($file) or die "unlink($file) failed: $!\n";
                        }
                }
        }


        Memoize::memoize 'Git::SVN::repos_root';
}

END {
        # Force cache writeout explicitly instead of waiting for
        # global destruction to avoid segfault in Storable:
        # http://rt.cpan.org/Public/Bug/Display.html?id=36087
        unmemoize_svn_mergeinfo_functions();
}

sub parents_exclude {
        my $parents = shift;
        my @commits = @_;
        return unless @commits;

        my @excluded;
        my $excluded;
        do {
                my @cmd = ('rev-list', "-1", @commits, "--not", @$parents );
                $excluded = command_oneline(@cmd);
                if ( $excluded ) {
                        my @new;
                        my $found;
                        for my $commit ( @commits ) {
                                if ( $commit eq $excluded ) {
                                        push @excluded, $commit;
                                        $found++;
                                }
                                else {
                                        push @new, $commit;
                                }
                        }
                        die "saw commit '$excluded' in rev-list output, "
                                ."but we didn't ask for that commit (wanted: @commits --not @$parents)"
                                        unless $found;
                        @commits = @new;
                }
        }
                while ($excluded and @commits);

        return @excluded;
}

# Compute what's new in svn:mergeinfo.
sub mergeinfo_changes {
        my ($self, $old_path, $old_rev, $path, $rev, $mergeinfo_prop) = @_;
        my %minfo = map {split ":", $_ } split "\n", $mergeinfo_prop;
        my $old_minfo = {};

        my $ra = $self->ra;
        # Give up if $old_path isn't in the repo.
        # This is probably a merge on a subtree.
        if ($ra->check_path($old_path, $old_rev) != $SVN::Node::dir) {
                warn "W: ignoring svn:mergeinfo on $old_path, ",
                        "directory didn't exist in r$old_rev\n";
                return {};
        }
        my (undef, undef, $props) = $ra->get_dir($old_path, $old_rev);
        if (defined $props->{"svn:mergeinfo"}) {
                my %omi = map {split ":", $_ } split "\n",
                        $props->{"svn:mergeinfo"};
                $old_minfo = \%omi;
        }

        my %changes = ();
        foreach my $p (keys %minfo) {
                my $a = $old_minfo->{$p} || "";
                my $b = $minfo{$p};
                # Omit merged branches whose ranges lists are unchanged.
                next if $a eq $b;
                # Remove any common range list prefix.
                ($a ^ $b) =~ /^[\0]*/;
                my $common_prefix = rindex $b, ",", $+[0] - 1;
                $changes{$p} = substr $b, $common_prefix + 1;
        }
        print STDERR "Checking svn:mergeinfo changes since r$old_rev: ",
                scalar(keys %minfo), " sources, ",
                scalar(keys %changes), " changed\n";

        return \%changes;
}

# note: this function should only be called if the various dirprops
# have actually changed
sub find_extra_svn_parents {
        my ($self, $mergeinfo, $parents) = @_;
        # aha!  svk:merge property changed...

        memoize_svn_mergeinfo_functions();

        # We first search for merged tips which are not in our
        # history.  Then, we figure out which git revisions are in
        # that tip, but not this revision.  If all of those revisions
        # are now marked as merge, we can add the tip as a parent.
        my @merges = sort keys %$mergeinfo;
        my @merge_tips;
        my $url = $self->url;
        my $uuid = $self->ra_uuid;
        my @all_ranges;
        for my $merge ( @merges ) {
                my ($tip_commit, @ranges) =
                        lookup_svn_merge( $uuid, $url,
                                          $merge, $mergeinfo->{$merge} );
                unless (!$tip_commit or
                                grep { $_ eq $tip_commit } @$parents ) {
                        push @merge_tips, $tip_commit;
                        push @all_ranges, @ranges;
                } else {
                        push @merge_tips, undef;
                }
        }

        my %excluded = map { $_ => 1 }
                parents_exclude($parents, grep { defined } @merge_tips);

        # check merge tips for new parents
        my @new_parents;
        for my $merge_tip ( @merge_tips ) {
                my $merge = shift @merges;
                next unless $merge_tip and $excluded{$merge_tip};
                my $spec = "$merge:$mergeinfo->{$merge}";

                # check out 'new' tips
                my $merge_base;
                eval {
                        $merge_base = command_oneline(
                                "merge-base",
                                @$parents, $merge_tip,
                        );
                };
                if ($@) {
                        die "An error occurred during merge-base"
                                unless $@->isa("Git::Error::Command");

                        warn "W: Cannot find common ancestor between ".
                             "@$parents and $merge_tip. Ignoring merge info.\n";
                        next;
                }

                # double check that there are no missing non-merge commits
                my ($ninc, $ifirst) = check_cherry_pick2(
                        $merge_base, $merge_tip,
                        $parents,
                        @all_ranges,
                       );

                if ($ninc) {
                        warn "W: svn cherry-pick ignored ($spec) - missing " .
                                "$ninc commit(s) (eg $ifirst)\n";
                } else {
                        warn "Found merge parent ($spec): ", $merge_tip, "\n";
                        push @new_parents, $merge_tip;
                }
        }

        # cater for merges which merge commits from multiple branches
        if ( @new_parents > 1 ) {
                for ( my $i = 0; $i <= $#new_parents; $i++ ) {
                        for ( my $j = 0; $j <= $#new_parents; $j++ ) {
                                next if $i == $j;
                                next unless $new_parents[$i];
                                next unless $new_parents[$j];
                                my $revs = command_oneline(
                                        "rev-list", "-1",
                                        "$new_parents[$i]..$new_parents[$j]",
                                       );
                                if ( !$revs ) {
                                        undef($new_parents[$j]);
                                }
                        }
                }
        }
        push @$parents, grep { defined } @new_parents;
}

sub make_log_entry {
        my ($self, $rev, $parents, $ed, $parent_rev, $parent_path) = @_;
        my $untracked = $self->get_untracked($ed);

        my @parents = @$parents;
        my $props = $ed->{dir_prop}{$self->path};
        if ( $props->{"svk:merge"} ) {
                $self->find_extra_svk_parents($props->{"svk:merge"}, \@parents);
        }
        if ( $props->{"svn:mergeinfo"} ) {
                my $mi_changes = $self->mergeinfo_changes
                        ($parent_path, $parent_rev,
                         $self->path, $rev,
                         $props->{"svn:mergeinfo"});
                $self->find_extra_svn_parents($mi_changes, \@parents);
        }

        open my $un, '>>', "$self->{dir}/unhandled.log" or croak $!;
        print $un "r$rev\n" or croak $!;
        print $un $_, "\n" foreach @$untracked;
        my %log_entry = ( parents => \@parents, revision => $rev,
                          log => '');

        my $headrev;
        my $logged = delete $self->{logged_rev_props};
        if (!$logged || $self->{-want_revprops}) {
                my $rp = $self->ra->rev_proplist($rev);
                foreach (sort keys %$rp) {
                        my $v = $rp->{$_};
                        if (/^svn:(author|date|log)$/) {
                                $log_entry{$1} = $v;
                        } elsif ($_ eq 'svm:headrev') {
                                $headrev = $v;
                        } else {
                                print $un "  rev_prop: ", uri_encode($_), ' ',
                                          uri_encode($v), "\n";
                        }
                }
        } else {
                map { $log_entry{$_} = $logged->{$_} } keys %$logged;
        }
        close $un or croak $!;

        $log_entry{date} = parse_svn_date($log_entry{date});
        $log_entry{log} .= "\n";
        my $author = $log_entry{author} = check_author($log_entry{author});
        my ($name, $email) = defined $::users{$author} ? @{$::users{$author}}
                                                       : ($author, undef);

        my ($commit_name, $commit_email) = ($name, $email);
        if ($_use_log_author) {
                my $name_field;
                if ($log_entry{log} =~ /From:\s+(.*\S)\s*\n/i) {
                        $name_field = $1;
                } elsif ($log_entry{log} =~ /Signed-off-by:\s+(.*\S)\s*\n/i) {
                        $name_field = $1;
                }
                if (!defined $name_field) {
                        if (!defined $email) {
                                $email = $name;
                        }
                } elsif ($name_field =~ /(.*?)\s+<(.*)>/) {
                        ($name, $email) = ($1, $2);
                } elsif ($name_field =~ /(.*)@/) {
                        ($name, $email) = ($1, $name_field);
                } else {
                        ($name, $email) = ($name_field, $name_field);
                }
        }
        if (defined $headrev && $self->use_svm_props) {
                if ($self->rewrite_root) {
                        die "Can't have both 'useSvmProps' and 'rewriteRoot' ",
                            "options set!\n";
                }
                if ($self->rewrite_uuid) {
                        die "Can't have both 'useSvmProps' and 'rewriteUUID' ",
                            "options set!\n";
                }
                my ($uuid, $r) = $headrev =~ m{^([a-f\d\-]{30,}):(\d+)$}i;
                # we don't want "SVM: initializing mirror for junk" ...
                return undef if $r == 0;
                my $svm = $self->svm;
                if ($uuid ne $svm->{uuid}) {
                        die "UUID mismatch on SVM path:\n",
                            "expected: $svm->{uuid}\n",
                            "     got: $uuid\n";
                }
                my $full_url = $self->full_url;
                $full_url =~ s#^\Q$svm->{replace}\E(/|$)#$svm->{source}$1# or
                             die "Failed to replace '$svm->{replace}' with ",
                                 "'$svm->{source}' in $full_url\n";
                # throw away username for storing in records
                remove_username($full_url);
                $log_entry{metadata} = "$full_url\@$r $uuid";
                $log_entry{svm_revision} = $r;
                $email ||= "$author\@$uuid";
                $commit_email ||= "$author\@$uuid";
        } elsif ($self->use_svnsync_props) {
                my $full_url = canonicalize_url(
                        add_path_to_url( $self->svnsync->{url}, $self->path )
                );
                remove_username($full_url);
                my $uuid = $self->svnsync->{uuid};
                $log_entry{metadata} = "$full_url\@$rev $uuid";
                $email ||= "$author\@$uuid";
                $commit_email ||= "$author\@$uuid";
        } else {
                my $url = $self->metadata_url;
                remove_username($url);
                my $uuid = $self->rewrite_uuid || $self->ra->get_uuid;
                $log_entry{metadata} = "$url\@$rev " . $uuid;
                $email ||= "$author\@" . $uuid;
                $commit_email ||= "$author\@" . $uuid;
        }
        $log_entry{name} = $name;
        $log_entry{email} = $email;
        $log_entry{commit_name} = $commit_name;
        $log_entry{commit_email} = $commit_email;
        \%log_entry;
}

sub fetch {
        my ($self, $min_rev, $max_rev, @parents) = @_;
        my ($last_rev, $last_commit) = $self->last_rev_commit;
        my ($base, $head) = $self->get_fetch_range($min_rev, $max_rev);
        $self->ra->gs_fetch_loop_common($base, $head, [$self]);
}

sub set_tree_cb {
        my ($self, $log_entry, $tree, $rev, $date, $author) = @_;
        $self->{inject_parents} = { $rev => $tree };
        $self->fetch(undef, undef);
}

sub set_tree {
        my ($self, $tree) = (shift, shift);
        my $log_entry = ::get_commit_entry($tree);
        unless ($self->{last_rev}) {
                fatal("Must have an existing revision to commit");
        }
        my %ed_opts = ( r => $self->{last_rev},
                        log => $log_entry->{log},
                        ra => $self->ra,
                        tree_a => $self->{last_commit},
                        tree_b => $tree,
                        editor_cb => sub {
                               $self->set_tree_cb($log_entry, $tree, @_) },
                        svn_path => $self->path );
        if (!Git::SVN::Editor->new(\%ed_opts)->apply_diff) {
                print "No changes\nr$self->{last_rev} = $tree\n";
        }
}

sub rebuild_from_rev_db {
        my ($self, $path) = @_;
        my $r = -1;
        open my $fh, '<', $path or croak "open: $!";
        binmode $fh or croak "binmode: $!";
        while (<$fh>) {
                length($_) == 41 or croak "inconsistent size in ($_) != 41";
                chomp($_);
                ++$r;
                next if $_ eq ('0' x 40);
                $self->rev_map_set($r, $_);
                print "r$r = $_\n";
        }
        close $fh or croak "close: $!";
        unlink $path or croak "unlink: $!";
}

#define a global associate map to record rebuild status
my %rebuild_status;
#define a global associate map to record rebuild verify status
my %rebuild_verify_status;

sub rebuild {
        my ($self) = @_;
        my $map_path = $self->map_path;
        my $partial = (-e $map_path && ! -z $map_path);
        my $verify_key = $self->refname.'^0';
        if (!$rebuild_verify_status{$verify_key}) {
                my $verify_result = ::verify_ref($verify_key);
                if ($verify_result) {
                        $rebuild_verify_status{$verify_key} = 1;
                }
        }
        if (!$rebuild_verify_status{$verify_key}) {
                return;
        }
        if (!$partial && ($self->use_svm_props || $self->no_metadata)) {
                my $rev_db = $self->rev_db_path;
                $self->rebuild_from_rev_db($rev_db);
                if ($self->use_svm_props) {
                        my $svm_rev_db = $self->rev_db_path($self->svm_uuid);
                        $self->rebuild_from_rev_db($svm_rev_db);
                }
                $self->unlink_rev_db_symlink;
                return;
        }
        print "Rebuilding $map_path ...\n" if (!$partial);
        my ($base_rev, $head) = ($partial ? $self->rev_map_max_norebuild(1) :
                (undef, undef));
        my $key_value = ($head ? "$head.." : "") . $self->refname;
        if (exists $rebuild_status{$key_value}) {
                print "Done rebuilding $map_path\n" if (!$partial || !$head);
                my $rev_db_path = $self->rev_db_path;
                if (-f $self->rev_db_path) {
                        unlink $self->rev_db_path or croak "unlink: $!";
                }
                $self->unlink_rev_db_symlink;
                return;
        }
        my ($log, $ctx) =
                command_output_pipe(qw/rev-list --pretty=raw --reverse/,
                                $key_value,
                                '--');
        $rebuild_status{$key_value} = 1;
        my $metadata_url = $self->metadata_url;
        remove_username($metadata_url);
        my $svn_uuid = $self->rewrite_uuid || $self->ra_uuid;
        my $c;
        while (<$log>) {
                if ( m{^commit ($::sha1)$} ) {
                        $c = $1;
                        next;
                }
                next unless s{^\s*(git-svn-id:)}{$1};
                my ($url, $rev, $uuid) = ::extract_metadata($_);
                remove_username($url);

                # ignore merges (from set-tree)
                next if (!defined $rev || !$uuid);

                # if we merged or otherwise started elsewhere, this is
                # how we break out of it
                if (($uuid ne $svn_uuid) ||
                    ($metadata_url && $url && ($url ne $metadata_url))) {
                        next;
                }
                if ($partial && $head) {
                        print "Partial-rebuilding $map_path ...\n";
                        print "Currently at $base_rev = $head\n";
                        $head = undef;
                }

                $self->rev_map_set($rev, $c);
                print "r$rev = $c\n";
        }
        command_close_pipe($log, $ctx);
        print "Done rebuilding $map_path\n" if (!$partial || !$head);
        my $rev_db_path = $self->rev_db_path;
        if (-f $self->rev_db_path) {
                unlink $self->rev_db_path or croak "unlink: $!";
        }
        $self->unlink_rev_db_symlink;
}

# rev_map:
# Tie::File seems to be prone to offset errors if revisions get sparse,
# it's not that fast, either.  Tie::File is also not in Perl 5.6.  So
# one of my favorite modules is out :<  Next up would be one of the DBM
# modules, but I'm not sure which is most portable...
#
# This is the replacement for the rev_db format, which was too big
# and inefficient for large repositories with a lot of sparse history
# (mainly tags)
#
# The format is this:
#   - 24 bytes for every record,
#     * 4 bytes for the integer representing an SVN revision number
#     * 20 bytes representing the sha1 of a git commit
#   - No empty padding records like the old format
#     (except the last record, which can be overwritten)
#   - new records are written append-only since SVN revision numbers
#     increase monotonically
#   - lookups on SVN revision number are done via a binary search
#   - Piping the file to xxd -c24 is a good way of dumping it for
#     viewing or editing (piped back through xxd -r), should the need
#     ever arise.
#   - The last record can be padding revision with an all-zero sha1
#     This is used to optimize fetch performance when using multiple
#     "fetch" directives in .git/config
#
# These files are disposable unless noMetadata or useSvmProps is set

sub _rev_map_set {
        my ($fh, $rev, $commit) = @_;

        binmode $fh or croak "binmode: $!";
        my $size = (stat($fh))[7];
        ($size % 24) == 0 or croak "inconsistent size: $size";

        my $wr_offset = 0;
        if ($size > 0) {
                sysseek($fh, -24, SEEK_END) or croak "seek: $!";
                my $read = sysread($fh, my $buf, 24) or croak "read: $!";
                $read == 24 or croak "read only $read bytes (!= 24)";
                my ($last_rev, $last_commit) = unpack(rev_map_fmt, $buf);
                if ($last_commit eq ('0' x40)) {
                        if ($size >= 48) {
                                sysseek($fh, -48, SEEK_END) or croak "seek: $!";
                                $read = sysread($fh, $buf, 24) or
                                    croak "read: $!";
                                $read == 24 or
                                    croak "read only $read bytes (!= 24)";
                                ($last_rev, $last_commit) =
                                    unpack(rev_map_fmt, $buf);
                                if ($last_commit eq ('0' x40)) {
                                        croak "inconsistent .rev_map\n";
                                }
                        }
                        if ($last_rev >= $rev) {
                                croak "last_rev is higher!: $last_rev >= $rev";
                        }
                        $wr_offset = -24;
                }
        }
        sysseek($fh, $wr_offset, SEEK_END) or croak "seek: $!";
        syswrite($fh, pack(rev_map_fmt, $rev, $commit), 24) == 24 or
          croak "write: $!";
}

sub _rev_map_reset {
        my ($fh, $rev, $commit) = @_;
        my $c = _rev_map_get($fh, $rev);
        $c eq $commit or die "_rev_map_reset(@_) commit $c does not match!\n";
        my $offset = sysseek($fh, 0, SEEK_CUR) or croak "seek: $!";
        truncate $fh, $offset or croak "truncate: $!";
}

sub mkfile {
        my ($path) = @_;
        unless (-e $path) {
                my ($dir, $base) = ($path =~ m#^(.*?)/?([^/]+)$#);
                mkpath([$dir]) unless -d $dir;
                open my $fh, '>>', $path or die "Couldn't create $path: $!\n";
                close $fh or die "Couldn't close (create) $path: $!\n";
        }
}

sub rev_map_set {
        my ($self, $rev, $commit, $update_ref, $uuid) = @_;
        defined $commit or die "missing arg3\n";
        length $commit == 40 or die "arg3 must be a full SHA1 hexsum\n";
        my $db = $self->map_path($uuid);
        my $db_lock = "$db.lock";
        my $sigmask;
        $update_ref ||= 0;
        if ($update_ref) {
                $sigmask = POSIX::SigSet->new();
                my $signew = POSIX::SigSet->new(SIGINT, SIGHUP, SIGTERM,
                        SIGALRM, SIGUSR1, SIGUSR2);
                sigprocmask(SIG_BLOCK, $signew, $sigmask) or
                        croak "Can't block signals: $!";
        }
        mkfile($db);

        $LOCKFILES{$db_lock} = 1;
        my $sync;
        # both of these options make our .rev_db file very, very important
        # and we can't afford to lose it because rebuild() won't work
        if ($self->use_svm_props || $self->no_metadata) {
                require File::Copy;
                $sync = 1;
                File::Copy::copy($db, $db_lock) or die "rev_map_set(@_): ",
                                           "Failed to copy: ",
                                           "$db => $db_lock ($!)\n";
        } else {
                rename $db, $db_lock or die "rev_map_set(@_): ",
                                            "Failed to rename: ",
                                            "$db => $db_lock ($!)\n";
        }

        sysopen(my $fh, $db_lock, O_RDWR | O_CREAT)
             or croak "Couldn't open $db_lock: $!\n";
        if ($update_ref eq 'reset') {
                clear_memoized_mergeinfo_caches();
                _rev_map_reset($fh, $rev, $commit);
        } else {
                _rev_map_set($fh, $rev, $commit);
        }

        if ($sync) {
                $fh->flush or die "Couldn't flush $db_lock: $!\n";
                $fh->sync or die "Couldn't sync $db_lock: $!\n";
        }
        close $fh or croak $!;
        if ($update_ref) {
                $_head = $self;
                my $note = "";
                $note = " ($update_ref)" if ($update_ref !~ /^\d*$/);
                command_noisy('update-ref', '-m', "r$rev$note",
                              $self->refname, $commit);
        }
        rename $db_lock, $db or die "rev_map_set(@_): ", "Failed to rename: ",
                                    "$db_lock => $db ($!)\n";
        delete $LOCKFILES{$db_lock};
        if ($update_ref) {
                sigprocmask(SIG_SETMASK, $sigmask) or
                        croak "Can't restore signal mask: $!";
        }
}

# If want_commit, this will return an array of (rev, commit) where
# commit _must_ be a valid commit in the archive.
# Otherwise, it'll return the max revision (whether or not the
# commit is valid or just a 0x40 placeholder).
sub rev_map_max {
        my ($self, $want_commit) = @_;
        $self->rebuild;
        my ($r, $c) = $self->rev_map_max_norebuild($want_commit);
        $want_commit ? ($r, $c) : $r;
}

sub rev_map_max_norebuild {
        my ($self, $want_commit) = @_;
        my $map_path = $self->map_path;
        stat $map_path or return $want_commit ? (0, undef) : 0;
        sysopen(my $fh, $map_path, O_RDONLY) or croak "open: $!";
        binmode $fh or croak "binmode: $!";
        my $size = (stat($fh))[7];
        ($size % 24) == 0 or croak "inconsistent size: $size";

        if ($size == 0) {
                close $fh or croak "close: $!";
                return $want_commit ? (0, undef) : 0;
        }

        sysseek($fh, -24, SEEK_END) or croak "seek: $!";
        sysread($fh, my $buf, 24) == 24 or croak "read: $!";
        my ($r, $c) = unpack(rev_map_fmt, $buf);
        if ($want_commit && $c eq ('0' x40)) {
                if ($size < 48) {
                        return $want_commit ? (0, undef) : 0;
                }
                sysseek($fh, -48, SEEK_END) or croak "seek: $!";
                sysread($fh, $buf, 24) == 24 or croak "read: $!";
                ($r, $c) = unpack(rev_map_fmt, $buf);
                if ($c eq ('0'x40)) {
                        croak "Penultimate record is all-zeroes in $map_path";
                }
        }
        close $fh or croak "close: $!";
        $want_commit ? ($r, $c) : $r;
}

sub rev_map_get {
        my ($self, $rev, $uuid) = @_;
        my $map_path = $self->map_path($uuid);
        return undef unless -e $map_path;

        sysopen(my $fh, $map_path, O_RDONLY) or croak "open: $!";
        my $c = _rev_map_get($fh, $rev);
        close($fh) or croak "close: $!";
        $c
}

sub _rev_map_get {
        my ($fh, $rev) = @_;

        binmode $fh or croak "binmode: $!";
        my $size = (stat($fh))[7];
        ($size % 24) == 0 or croak "inconsistent size: $size";

        if ($size == 0) {
                return undef;
        }

        my ($l, $u) = (0, $size - 24);
        my ($r, $c, $buf);

        while ($l <= $u) {
                my $i = int(($l/24 + $u/24) / 2) * 24;
                sysseek($fh, $i, SEEK_SET) or croak "seek: $!";
                sysread($fh, my $buf, 24) == 24 or croak "read: $!";
                my ($r, $c) = unpack(rev_map_fmt, $buf);

                if ($r < $rev) {
                        $l = $i + 24;
                } elsif ($r > $rev) {
                        $u = $i - 24;
                } else { # $r == $rev
                        return $c eq ('0' x 40) ? undef : $c;
                }
        }
        undef;
}

# Finds the first svn revision that exists on (if $eq_ok is true) or
# before $rev for the current branch.  It will not search any lower
# than $min_rev.  Returns the git commit hash and svn revision number
# if found, else (undef, undef).
sub find_rev_before {
        my ($self, $rev, $eq_ok, $min_rev) = @_;
        --$rev unless $eq_ok;
        $min_rev ||= 1;
        my $max_rev = $self->rev_map_max;
        $rev = $max_rev if ($rev > $max_rev);
        while ($rev >= $min_rev) {
                if (my $c = $self->rev_map_get($rev)) {
                        return ($rev, $c);
                }
                --$rev;
        }
        return (undef, undef);
}

# Finds the first svn revision that exists on (if $eq_ok is true) or
# after $rev for the current branch.  It will not search any higher
# than $max_rev.  Returns the git commit hash and svn revision number
# if found, else (undef, undef).
sub find_rev_after {
        my ($self, $rev, $eq_ok, $max_rev) = @_;
        ++$rev unless $eq_ok;
        $max_rev ||= $self->rev_map_max;
        while ($rev <= $max_rev) {
                if (my $c = $self->rev_map_get($rev)) {
                        return ($rev, $c);
                }
                ++$rev;
        }
        return (undef, undef);
}

sub _new {
        my ($class, $repo_id, $ref_id, $path) = @_;
        unless (defined $repo_id && length $repo_id) {
                $repo_id = $default_repo_id;
        }
        unless (defined $ref_id && length $ref_id) {
                # Access the prefix option from the git-svn main program if it's loaded.
                my $prefix = defined &::opt_prefix ? ::opt_prefix() : "";
                $_[2] = $ref_id =
                             "refs/remotes/$prefix$default_ref_id";
        }
        $_[1] = $repo_id;
        my $dir = "$ENV{GIT_DIR}/svn/$ref_id";

        # Older repos imported by us used $GIT_DIR/svn/foo instead of
        # $GIT_DIR/svn/refs/remotes/foo when tracking refs/remotes/foo
        if ($ref_id =~ m{^refs/remotes/(.+)}) {
                my $old_dir = "$ENV{GIT_DIR}/svn/$1";
                if (-d $old_dir && ! -d $dir) {
                        $dir = $old_dir;
                }
        }

        $_[3] = $path = '' unless (defined $path);
        mkpath([$dir]);
        my $obj = bless {
                ref_id => $ref_id, dir => $dir, index => "$dir/index",
                config => "$ENV{GIT_DIR}/svn/config",
                map_root => "$dir/.rev_map", repo_id => $repo_id }, $class;

        # Ensure it gets canonicalized
        $obj->path($path);

        return $obj;
}

sub path {
        my $self = shift;

        if (@_) {
                my $path = shift;
                $self->{_path} = canonicalize_path($path);
                return;
        }

        return $self->{_path};
}

sub url {
        my $self = shift;

        if (@_) {
                my $url = shift;
                $self->{url} = canonicalize_url($url);
                return;
        }

        return $self->{url};
}

# for read-only access of old .rev_db formats
sub unlink_rev_db_symlink {
        my ($self) = @_;
        my $link = $self->rev_db_path;
        $link =~ s/\.[\w-]+$// or croak "missing UUID at the end of $link";
        if (-l $link) {
                unlink $link or croak "unlink: $link failed!";
        }
}

sub rev_db_path {
        my ($self, $uuid) = @_;
        my $db_path = $self->map_path($uuid);
        $db_path =~ s{/\.rev_map\.}{/\.rev_db\.}
            or croak "map_path: $db_path does not contain '/.rev_map.' !";
        $db_path;
}

# the new replacement for .rev_db
sub map_path {
        my ($self, $uuid) = @_;
        $uuid ||= $self->ra_uuid;
        "$self->{map_root}.$uuid";
}

sub uri_encode {
        my ($f) = @_;
        $f =~ s#([^a-zA-Z0-9\*!\:_\./\-])#sprintf("%%%02X",ord($1))#eg;
        $f
}

sub uri_decode {
        my ($f) = @_;
        $f =~ s#%([0-9a-fA-F]{2})#chr(hex($1))#eg;
        $f
}

sub remove_username {
        $_[0] =~ s{^([^:]*://)[^@]+@}{$1};
}

1;