From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 17 Feb 2018 11:47:19 +0000 (+0000)
Subject: git-debrebase: provide breakwater command
X-Git-Tag: archive/debian/5.0~187
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=dgit.git;a=commitdiff_plain;h=7ec74423668f93db5107faaae4314f79a2d9d2f0

git-debrebase: provide breakwater command

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/git-debrebase b/git-debrebase
index 32737269..1a62852e 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -28,6 +28,7 @@
 #
 #    git-debrebase [<options> --] [<git-rebase options...>]
 #    git-debrebase [<options>] analyse
+#    git-debrebase [<options>] breakwater      # prints breakwater tip only
 #    git-debrebase [<options>] launder         # prints breakwater tip etc.
 #    git-debrebase [<options>] stitch [--prose=<for commit message>]
 #    git-debrebase [<options>] downstream-rebase-launder-v0  # experimental
@@ -508,6 +509,42 @@ sub classify ($) {
     return $unknown->("complex merge");
 }
 
+sub breakwater_of ($) {
+    my ($head) = @_; # must be laundered
+    my $breakwater;
+    my $unclean = sub {
+	my ($why) = @_;
+	fail "branch needs laundering (run git-debrebase): $why";
+    };
+    for (;;) {
+	my $cl = classify $head;
+	my $ty = $cl->{Type};
+	if ($ty eq 'Packaging' or
+	    $ty eq 'Changelog') {
+	    $breakwater //= $head;
+	} elsif ($ty eq 'BreakwaterUpstreamMerge' or
+		 $ty eq 'BreakwaterStart') {
+	    $breakwater //= $head;
+	    last;
+	} elsif ($ty eq 'Upstream') {
+	    $unclean->("packaging change ($breakwater)".
+		       " follows upstream change (eg $head)")
+		if defined $breakwater;
+	} elsif ($ty eq 'Mixed') {
+	    $unclean->('found mixed upstream/packaging commit ($head)');
+	} elsif ($ty eq 'Pseudomerge' or
+		 $ty eq 'AddPatches') {
+	    $unclean->("found interchange conversion commit ($ty, $head)");
+	} elsif ($ty eq 'DgitImportUnpatched') {
+	    $unclean->("found dgit dsc import ($head)");
+	} else {
+	    fail "found unprocessable commit, cannot cope: $head; $cl->{Why}";
+	}
+	$head = $cl->{Parents}[0]{CommitId};
+    }
+    return $breakwater;
+}
+
 sub walk ($;$$);
 sub walk ($;$$) {
     my ($input,
@@ -1133,6 +1170,12 @@ sub cmd_record_ffq_prev () {
     }
 }
 
+sub cmd_breakwater () {
+    badusage "no arguments allowed" if @ARGV;
+    my $bw = breakwater_of git_rev_parse 'HEAD';
+    print "$bw\n" or die $!;
+}
+
 sub cmd_stitch () {
     my $prose = '';
     GetOptions('prose=s', \$prose) or die badusage("bad options to stitch");