+sub link_ltarget ($$) {
+ my ($old,$new) = @_;
+ lstat $old or return undef;
+ if (-l _) {
+ $old = cmdoutput qw(realpath --), $old;
+ }
+ my $r = link $old, $new;
+ $r = symlink $old, $new if !$r && $!==EXDEV;
+ $r or die "(sym)link $old $new: $!";
+}
+
+sub hashfile ($) {
+ my ($fn) = @_;
+ my $h = Digest::SHA->new(256);
+ $h->addfile($fn);
+ return $h->hexdigest();
+}
+
+sub git_rev_parse ($) {
+ return cmdoutput qw(git rev-parse), "$_[0]~0";
+}
+
+sub git_cat_file ($) {
+ my ($objname) = @_;
+ # => ($type, $data) or ('missing', undef)
+ # in scalar context, just the data
+ our ($gcf_pid, $gcf_i, $gcf_o);
+ if (!$gcf_pid) {
+ my @cmd = qw(git cat-file --batch);
+ debugcmd "GCF|", @cmd;
+ $gcf_pid = open2 $gcf_o, $gcf_i, @cmd or die $!;
+ }
+ printdebug "GCF>| ", $objname, "\n";
+ print $gcf_i $objname, "\n" or die $!;
+ my $x = <$gcf_o>;
+ printdebug "GCF<| ", $x;
+ if ($x =~ m/ (missing)$/) { return ($1, undef); }
+ my ($type, $size) = $x =~ m/^.* (\w+) (\d+)\n/ or die "$objname ?";
+ my $data;
+ (read $gcf_o, $data, $size) == $size or die "$objname $!";
+ $x = <$gcf_o>;
+ $x eq "\n" or die "$objname ($_) $!";
+ return ($type, $data);
+}
+
+sub git_for_each_ref ($$;$) {
+ my ($pattern,$func,$gitdir) = @_;