+sub maybe_split_brain_save ($$$) {
+ my ($headref, $dgitview, $msg) = @_;
+ # => message fragment "$saved" describing disposition of $dgitview
+ return "commit id $dgitview" unless defined $split_brain_save;
+ my @cmd = (shell_cmd "cd ../../../..",
+ @git, qw(update-ref -m),
+ "dgit --dgit-view-save $msg HEAD=$headref",
+ $split_brain_save, $dgitview);
+ runcmd @cmd;
+ return "and left in $split_brain_save";
+}
+
+# An "infopair" is a tuple [ $thing, $what ]
+# (often $thing is a commit hash; $what is a description)
+
+sub infopair_cond_equal ($$) {
+ my ($x,$y) = @_;
+ $x->[0] eq $y->[0] or fail <<END;
+$x->[1] ($x->[0]) not equal to $y->[1] ($y->[0])
+END
+};
+
+sub infopair_lrf_tag_lookup ($$) {
+ my ($tagnames, $what) = @_;
+ # $tagname may be an array ref
+ my @tagnames = ref $tagnames ? @$tagnames : ($tagnames);
+ printdebug "infopair_lrfetchref_tag_lookup $what @tagnames\n";
+ foreach my $tagname (@tagnames) {
+ my $lrefname = lrfetchrefs."/tags/$tagname";
+ my $tagobj = $lrfetchrefs_f{$lrefname};
+ next unless defined $tagobj;
+ printdebug "infopair_lrfetchref_tag_lookup $tagobj $tagname $what\n";
+ return [ git_rev_parse($tagobj), $what ];
+ }
+ fail @tagnames==1 ? <<END : <<END;
+Wanted tag $what (@tagnames) on dgit server, but not found
+END
+Wanted tag $what (one of: @tagnames) on dgit server, but not found
+END
+}
+
+sub infopair_cond_ff ($$) {
+ my ($anc,$desc) = @_;
+ is_fast_fwd($anc->[0], $desc->[0]) or fail <<END;
+$anc->[1] ($anc->[0]) .. $desc->[1] ($desc->[0]) is not fast forward
+END
+};
+
+sub pseudomerge_version_check ($$) {
+ my ($clogp, $archive_hash) = @_;
+
+ my $arch_clogp = commit_getclogp $archive_hash;
+ my $i_arch_v = [ (getfield $arch_clogp, 'Version'),
+ 'version currently in archive' ];
+ if (defined $overwrite_version) {
+ if (length $overwrite_version) {
+ infopair_cond_equal([ $overwrite_version,
+ '--overwrite= version' ],
+ $i_arch_v);
+ } else {
+ my $v = $i_arch_v->[0];
+ progress "Checking package changelog for archive version $v ...";
+ eval {
+ my @xa = ("-f$v", "-t$v");
+ my $vclogp = parsechangelog @xa;
+ my $cv = [ (getfield $vclogp, 'Version'),
+ "Version field from dpkg-parsechangelog @xa" ];
+ infopair_cond_equal($i_arch_v, $cv);
+ };
+ if ($@) {
+ $@ =~ s/^dgit: //gm;
+ fail "$@".
+ "Perhaps debian/changelog does not mention $v ?";
+ }
+ }
+ }
+
+ printdebug "pseudomerge_version_check i_arch_v @$i_arch_v\n";
+ return $i_arch_v;
+}
+
+sub pseudomerge_make_commit ($$$$ $$) {
+ my ($clogp, $dgitview, $archive_hash, $i_arch_v,
+ $msg_cmd, $msg_msg) = @_;
+ progress "Declaring that HEAD inciudes all changes in $i_arch_v->[0]...";
+
+ my $tree = cmdoutput qw(git rev-parse), "${dgitview}:";
+ my $authline = clogp_authline $clogp;
+
+ chomp $msg_msg;
+ $msg_cmd .=
+ !defined $overwrite_version ? ""
+ : !length $overwrite_version ? " --overwrite"
+ : " --overwrite=".$overwrite_version;
+
+ mkpath '.git/dgit';
+ my $pmf = ".git/dgit/pseudomerge";
+ open MC, ">", $pmf or die "$pmf $!";
+ print MC <<END or die $!;
+tree $tree
+parent $dgitview
+parent $archive_hash
+author $authline
+commiter $authline
+
+$msg_msg
+
+[$msg_cmd]
+END
+ close MC or die $!;
+
+ return make_commit($pmf);
+}
+
+sub splitbrain_pseudomerge ($$$$) {
+ my ($clogp, $maintview, $dgitview, $archive_hash) = @_;
+ # => $merged_dgitview
+ printdebug "splitbrain_pseudomerge...\n";
+ #
+ # We: debian/PREVIOUS HEAD($maintview)
+ # expect: o ----------------- o
+ # \ \
+ # o o
+ # a/d/PREVIOUS $dgitview
+ # $archive_hash \
+ # If so, \ \
+ # we do: `------------------ o
+ # this: $dgitview'
+ #
+
+ return $dgitview unless defined $archive_hash;
+
+ printdebug "splitbrain_pseudomerge...\n";
+
+ my $i_arch_v = pseudomerge_version_check($clogp, $archive_hash);
+
+ if (!defined $overwrite_version) {
+ progress "Checking that HEAD inciudes all changes in archive...";
+ }
+
+ return $dgitview if is_fast_fwd $archive_hash, $dgitview;
+
+ if (defined $overwrite_version) {
+ } elsif (!eval {
+ my $t_dep14 = debiantag_maintview $i_arch_v->[0], access_nomdistro;
+ my $i_dep14 = infopair_lrf_tag_lookup($t_dep14, "maintainer view tag");
+ my $t_dgit = debiantag_new $i_arch_v->[0], access_nomdistro;
+ my $i_dgit = infopair_lrf_tag_lookup($t_dgit, "dgit view tag");
+ my $i_archive = [ $archive_hash, "current archive contents" ];
+
+ printdebug "splitbrain_pseudomerge i_archive @$i_archive\n";
+
+ infopair_cond_equal($i_dgit, $i_archive);
+ infopair_cond_ff($i_dep14, $i_dgit);
+ infopair_cond_ff($i_dep14, [ $maintview, 'HEAD' ]);
+ 1;
+ }) {
+ print STDERR <<END;
+$us: check failed (maybe --overwrite is needed, consult documentation)
+END
+ die "$@";
+ }
+
+ my $r = pseudomerge_make_commit
+ $clogp, $dgitview, $archive_hash, $i_arch_v,
+ "dgit --quilt=$quilt_mode",
+ (defined $overwrite_version ? <<END_OVERWR : <<END_MAKEFF);
+Declare fast forward from $i_arch_v->[0]
+END_OVERWR
+Make fast forward from $i_arch_v->[0]
+END_MAKEFF
+
+ maybe_split_brain_save $maintview, $r, "pseudomerge";
+
+ progress "Made pseudo-merge of $i_arch_v->[0] into dgit view.";
+ return $r;
+}
+
+sub plain_overwrite_pseudomerge ($$$) {
+ my ($clogp, $head, $archive_hash) = @_;
+
+ printdebug "plain_overwrite_pseudomerge...";
+
+ my $i_arch_v = pseudomerge_version_check($clogp, $archive_hash);
+
+ return $head if is_fast_fwd $archive_hash, $head;
+
+ my $m = "Declare fast forward from $i_arch_v->[0]";
+
+ my $r = pseudomerge_make_commit
+ $clogp, $head, $archive_hash, $i_arch_v,
+ "dgit", $m;
+
+ runcmd @git, qw(update-ref -m), $m, 'HEAD', $r, $head;
+
+ progress "Make pseudo-merge of $i_arch_v->[0] into your HEAD.";
+ return $r;
+}
+