git-branchmove: code to attempt to detach the head

1 files changed, 49 insertions, 4 deletions

diff --git a/bin/git-branchmove b/bin/git-branchmove
index fed28766..c59d936a 100755
--- a/bin/git-branchmove
+++ b/bin/git-branchmove
@@ -20,7 +20,7 @@
 # This script is based on Ian Jackson's git-branchmove script, in the
 # chiark-utils Debian source package.  Ian's script assumes throughout
 # that it is possible to have unrestricted shell access to the remote,
-# however, while this script avoids that assumption.
+# however, while this script avoids that global assumption.
 #
 # As much as possible we treat the remote argument as opaque, i.e., we
 # don't distinguish between git URIs and named remotes.  That means
@@ -94,6 +94,34 @@ die "git-branchmove: unknown operation\n"
 # is this a named remote or a git URL?
 my $named_remote = $remote =~ m|:| or $remote =~ m|^[/.]|;
 
+# Attempt to determine how we might be able to run commands in the
+# remote repo.  This will only be used if we need to try to detach the
+# remote HEAD.  These regexps are lifted from Ian's script
+my $rurl, my $rrune, my $rdir;
+if ($named_remote) {
+    $rurl = `git remote get-url --push $remote`;
+} else {
+    $rurl = $remote;
+}
+if ($rurl =~ m#^ssh://([^:/]+)(?:\:(\w+))?#) {
+    $rdir = "$'\''";
+    $rrune = "ssh ";
+    if ($2) {
+        $rrune .= " -p $3";
+    }
+    $rrune .= "$1";
+} elsif ($rurl =~ m#^([-+_.0-9a-zA-Z\@]+):(?!//|:)#) {
+    $rdir = "$'\''";
+    $rrune = "ssh $1";
+} elsif ($rurl =~ m#^[/.]#) {
+    $rdir = $rurl;
+    $rrune = undef;
+}
+
+# DEBUG
+print "dir is $rdir and rune is $rrune\n";
+exit 0;
+
 # If we don't prefix the patterns, we might match branches the user
 # doesn't intend.  E.g. 'foo' would match 'wip/foo'
 my @branch_pats = map { $_ =~ s|^|[r]efs/heads/|; $_ } @patterns;
@@ -134,9 +162,26 @@ if ($op eq "put") {
         $source_head = (split /\s/, $lines[0])[1];
     }
 }
-die "git-branchmove: would delete checked-out branch $source_head"
-  if (defined $source_head and
-      grep /^$source_head$/, map {$_->{ref}} @source_branches);
+if (defined $source_head and
+    grep /^$source_head$/, map {$_->{ref}} @source_branches) {
+    if ($attempt_detach) {
+        if ($op eq 'put') {
+            $git->checkout('--detach');
+        } elsif ($op eq 'get') {
+            if (defined $rrune and defined $rdir) {
+                system "$rrune \"set -e; cd $rdir; git checkout --detach\""
+                  or die "failed to detach remote HEAD";
+            } elsif (!defined $rrune and defined $rdir) {
+                my $dest_git = Git::Wrapper->new($rdir);
+                $dest_git->checkout('--detach');
+            } else {
+                die "git-branchmove: don't know how to detach remote HEAD";
+            }
+        }
+    } else {
+        die "git-branchmove: would delete checked-out branch $source_head";
+    }
+}
 
 # check whether we would overwrite anything
 foreach my $source_branch (@source_branches) {