From e0feac940e7af31c5ddfa3c54b54567ef6632e4f Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 7 Jan 2017 13:00:41 +0000
Subject: dgit-badcommit-fixup: New mode --check which is readonly.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 debian/changelog     |  2 +-
 dgit-badcommit-fixup | 26 +++++++++++++++++---------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index bf26827..9446c3f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,6 +1,6 @@
 dgit (2.17~) unstable; urgency=medium
 
-  * 
+  * dgit-badcommit-fixup: New mode --check which is readonly.
 
  --
 
diff --git a/dgit-badcommit-fixup b/dgit-badcommit-fixup
index c119c4a..a9a8f60 100755
--- a/dgit-badcommit-fixup
+++ b/dgit-badcommit-fixup
@@ -3,6 +3,7 @@
 # Script to help with fallout from #849041.
 #
 # usage:
+#   dgit-badcommit-fixup --check
 #   dgit-badcommit-fixup --test
 #   dgit-badcommit-fixup --real
 
@@ -34,6 +35,8 @@ foreach my $a (@ARGV) {
 	$real = 0;
     } elsif ($a eq '--real') {
 	$real = 1;
+    } elsif ($a eq '--check') {
+	$real = -1;
     } else {
 	die "$a ?";
     }
@@ -254,40 +257,45 @@ if ($bare eq 'true') {
 filter_updates();
 
 if (!@updates) {
-    print Dumper(\%count), "nothing to do\n";
+    print Dumper(\%count), "all is well - nothing to do\n";
     exit 0;
 }
 
 #print Dumper(\@updates);
 
-open U, "|git update-ref -m 'dgit bad commit fixup' --stdin" or die $!;
+open U, "|git update-ref -m 'dgit bad commit fixup' --stdin" or die $!
+    if $real >= 0;
 
 for my $up (@updates) {
     my ($ref, $old, $new, $nobackup) = @$up;
     my $otherref = $ref;
     $otherref =~ s{^refs/}{};
-    if ($real) {
+    if ($real > 0) {
 	print U <<END or die $! unless $nobackup;
 create refs/dgit-badcommit/$otherref $old
 END
 	print U <<END or die $!;
 update $ref $new $old
 END
-    } else {
+    } elsif ($real==0) {
 	print U <<END or die $!;
 update refs/dgit-badfixuptest/$otherref $new
 END
+    } else {
+	print "found trouble in history of $ref\n" or die $!;
     }
 }
 
-$?=0; $!=0;
-close U or die "$? $!";
-die $? if $?;
+if ($real >= 0) {
+    $?=0; $!=0;
+    close U or die "$? $!";
+    die $? if $?;
+}
 
 print Dumper(\%count);
 
-if ($real) {
+if ($real >= 0) {
     print "old values saved in refs/dgit-badcommit/\n" or die $!;
-} else {
+} elsif ($real == 0) {
     print "testing output saved in refs/dgit-badfixuptest/\n" or die $!;
 }
-- 
cgit v1.2.3