+sub server_branch ($) { return "$branchprefix/$_[0]"; }
+sub server_ref ($) { return "refs/".server_branch($_[0]); }
+
+sub stat_exists ($) {
+ my ($f) = @_;
+ return 1 if stat $f;
+ return 0 if $!==&ENOENT;
+ die "stat $f: $!";
+}
+
+sub git_for_each_ref ($$) {
+ my ($pattern,$func) = @_;
+ # calls $func->($objid,$objtype,$fullrefname,$reftail);
+ # $reftail is RHS of ref after refs/\w+/
+ # breaks if $pattern matches any ref `refs/blah' where blah has no `/'
+ my $fh = new IO::File "-|", qw(git for-each-ref), $pattern or die $!;
+ while (<$fh>) {
+ m#^(\w+)\s+(\w+)\s+(refs/\w+/(\S+))\s# or die "$_ ?";
+ $func->($1,$2,$3,$4);
+ }
+ $!=0; $?=0; close $fh or die "$pattern $? $!";
+}
+
+sub git_for_each_tag_referring ($$) {
+ my ($objreferring, $func) = @_;
+ # calls $func->($objid,$fullrefname,$tagname);
+ git_for_each_ref('refs/tags', sub {
+ my ($objid,$objtype,$fullrefname,$tagname) = @_;
+ next unless $objtype eq 'tag';
+ next if defined $objreferring and $objid ne $objreferring;
+ $func->($objid,$fullrefname,$tagname);
+ });
+}
+