From 2baa64c36aedd47d06aa853ef780dbcffa7131bb Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 12 Sep 2013 00:10:50 +0100
Subject: More comprehensive warnings in many cases of archive skew.

---
 debian/changelog |  1 +
 dgit             | 38 ++++++++++++++++++++++++++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index 507d2c1..89b5c1f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,7 @@ dgit (0.15) unstable; urgency=low
   * Provide `dgit version' and `--version'.  Closes: #721654.
   * Better handling of packages pushed using dgit and stuck in NEW.
     (And, use of `--new' is not needed with fetch.)  Closes: #722199.
+  * More comprehensive warnings in many cases of archive skew.
 
  --
 
diff --git a/dgit b/dgit
index 123c2d5..1838f2f 100755
--- a/dgit
+++ b/dgit
@@ -131,7 +131,7 @@ sub url_get {
     return $r->decoded_content();
 }
 
-our ($dscdata,$dscurl,$dsc);
+our ($dscdata,$dscurl,$dsc,$skew_warning_vsn);
 
 sub printcmd {
     my $fh = shift @_;
@@ -450,7 +450,10 @@ sub get_archive_dsc () {
 	my ($vsn,$subpath) = @$vinfo;
 	$dscurl = access_cfg('mirror').$subpath;
 	$dscdata = url_get($dscurl);
-	next unless defined $dscdata;
+	if (!$dscdata) {
+	    $skew_warning_vsn = $vsn if !defined $skew_warning_vsn;
+	    next;
+	}
 	my $dscfh = new IO::File \$dscdata, '<' or die $!;
 	print DEBUG Dumper($dscdata) if $debug>1;
 	$dsc = parsecontrolfh($dscfh,$dscurl, allow_pgp=>1);
@@ -750,12 +753,20 @@ END
 	$hash = $lastpush_hash;
 	print STDERR <<END or die $!;
 
-Package not found in the archive, but has allegedly been
-pushed/uploaded using dgit.
+Package not found in the archive, but has allegedly been pushed using dgit.
 $later_warning_msg
 END
     } else {
 	print DEBUG "nothing found!\n";
+	if (defined $skew_warning_vsn) {
+	    print STDERR <<END or die $!;
+
+Warning: relevant archive skew detected.
+Archive allegedly contains $skew_warning_vsn
+But we were not able to obtain any version from the archive or git.
+
+END
+	}
 	return 0;
     }
     print DEBUG "current hash=$hash\n";
@@ -764,6 +775,25 @@ END
 	    " (archive's version left in DGIT_ARCHIVE)"
 	    unless is_fast_fwd($lastpush_hash, $hash);
     }
+    if (defined $skew_warning_vsn) {
+	mkpath '.git/dgit';
+	print DEBUG "SKEW CHECK WANT $skew_warning_vsn\n";
+	my $clogf = ".git/dgit/changelog.tmp";
+	runcmd shell_cmd "exec >$clogf",
+	    @git, qw(cat-file blob), "$hash:debian/changelog";
+	my $gotclogp = parsechangelog("-l$clogf");
+	my $got_vsn = getfield $gotclogp, 'Version';
+	print DEBUG "SKEW CHECK GOT $got_vsn\n";
+	if (version_compare_string($got_vsn, $skew_warning_vsn) < 0) {
+	    print STDERR <<END or die $!;
+
+Warning: archive skew detected.  Using the available version:
+Archive allegedly contains    $skew_warning_vsn
+We were able to obtain only   $got_vsn
+
+END
+	}
+    }
     if ($lastpush_hash ne $hash) {
 	my @upd_cmd = (@git, qw(update-ref -m), 'dgit fetch', lrref(), $hash);
 	if (!$dryrun) {
-- 
cgit v1.2.3