From c67e1d4470f98bb98365e54c9e872b05b7da6b45 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 9 Feb 2017 00:11:51 +0000
Subject: [PATCH] git-debrebase: avoid rewrite better

---
 git-debrebase | 51 +++++++++++++++++++++++++++++----------------------
 1 file changed, 29 insertions(+), 22 deletions(-)

diff --git a/git-debrebase b/git-debrebase
index e231b512..6542c65c 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -222,7 +222,7 @@ sub launder ($$$) {
     my ($input, $pseudos_must_overwrite_this, $wantdebonly) = @_;
     # go through commits backwards
     # we generate two lists of commits to apply
-    my (@deb_cl, @ups_cl);
+    my (@deb_cl, @ups_cl, @processed);
     my %found;
     my @pseudomerges;
 
@@ -234,6 +234,9 @@ sub launder ($$$) {
 	$ms .= "\n\n[git-debrebase $appendinfo]\n";
 	return (Msg => $ms);
     };
+    my $rewrite_from_here = sub {
+	push @processed, { SpecialMethod => 'StartRewrite' };
+    };
 
     my $cur = $input;
 
@@ -245,13 +248,16 @@ sub launder ($$$) {
 	my $p0 = $cl->{Parents}[0]{CommitId};
 	if ($ty eq 'AddPatches') {
 	    $cur = $p0;
+	    $rewrite_from_here->();
 	    next;
 	} elsif ($ty eq 'Packaging') {
 	    push @deb_cl, $cl;
+	    push @processed, $cl;
 	    $cur = $p0;
 	    next;
 	} elsif ($ty eq 'Upstream') {
 	    push @ups_cl, $cl;
+	    push @processed, $cl;
 	    $cur = $p0;
 	    next;
 	} elsif ($ty eq 'Mixed') {
@@ -262,12 +268,14 @@ sub launder ($$$) {
 	    };
 	    $queue->(\@deb_cl, "debian");
 	    $queue->(\@ups_cl, "upstream");
+	    $rewrite_from_here->();
 	    next;
 	} elsif ($ty eq 'Pseudomerge') {
 	    if (defined $pseudos_must_overwrite_this) {
 		confess 'xxx actually check this';
 	    }
 	    push @pseudomerges, $cl;
+	    $rewrite_from_here->();
 	    $cur = $ty->{Contributor};
 	    next;
 	} elsif ($ty eq 'BreakwaterUpstreamMerge') {
@@ -299,6 +307,7 @@ sub launder ($$$) {
 	    };
 	    my $differs = get_differs $previous_breakwater, $cl->{Tree};
 	    $basis = launder $pseudomerges[0]{Overwritten}, undef, 1;
+	    $rewrite_from_here->();
 	    last;
 	} else {
 	    die "Reached difficult commit $cur: ".Dumper($cl);
@@ -309,6 +318,8 @@ sub launder ($$$) {
     workarea_fresh();
     in_workarea sub { xxx attributes xxx };
 
+    my $rewriting = 1;
+
     my $build = $basis;
 
     my $rm_tree_cached = sub {
@@ -328,8 +339,6 @@ sub launder ($$$) {
  
     my $committer_authline = calculate_committer_authline();
 
-    my $need_rewrite = 0;
-
     in_workarea sub {
 	mkdir $rd or $!==EEXIST or die $!;
 	my $current_method;
@@ -346,17 +355,19 @@ sub launder ($$$) {
 		$read_tree_debian->($cltree);
 	    } elsif ($method eq 'Upstream') {
 		$read_tree_upstream->($cltree);
+	    } elsif ($method eq 'StartRewrite') {
+		$rewriting = 1;
+		next;
 	    } elsif ($method eq 'DgitImportDebianUpdate') {
 		$read_tree_debian->($cltree);
 		$rm_tree_cached(qw(debian/patches));
-		$need_rewrite = 1;
 	    } elsif ($method eq 'DgitImportUpstreamUpdate') {
 		$read_tree_upstream->($cltree);
 		push @parents, map { $_->{CommitId} } @{ $cl->{OrigParents} };
-		$need_rewrite = 1;
 	    } else {
 		confess "$method ?";
 	    }
+	    $rewriting ||= $cl ne pop @processed;
 	    my $newtree = cmdoutput @git, qw(write-tree);
 	    my $ch = $cl->{Hdr};
 	    $ch =~ s{^tree .*}{tree $newtree}m or confess "$ch ?";
@@ -364,24 +375,20 @@ sub launder ($$$) {
 	    $ch =~ s{(?=^author}{
 		map { "parent $_\n" } @parents
 	    }me or confess "$ch ?";
-	    foreach my $rewrite ($need_rewrite ? 1 : qw(0 1)) {
-		if ($rewrite) {
-		    $ch =~ s{^committer .*$}{$committer_authline}m
-			or confess "$ch ?";
-		    $need_rewrite = 1;
-		}
-		my $cf = "$rd/m$rewrite"
-		open CD, ">", $cf or die $!;
-		print CD $ch, "\n", $cl->{Msg}; or die $!;
-		close CD or die $!;
-		my @cmd = (@git, qw(hash-object));
-		push @cmd, qw(-w) if $rewrite;
-		push @cmd, qw(-t commit), $cf;
-		my $newcommit = cmdoutput @cmd;
-		next unless $rewrite or $newcommit eq $cl->{CommitId};
-		$build = $newcommit;
-		last;
+	    if ($rewrite) {
+		$ch =~ s{^committer .*$}{$committer_authline}m
+		    or confess "$ch ?";
 	    }
+	    my $cf = "$rd/m$rewrite"
+		open CD, ">", $cf or die $!;
+	    print CD $ch, "\n", $cl->{Msg}; or die $!;
+	    close CD or die $!;
+	    my @cmd = (@git, qw(hash-object));
+	    push @cmd, qw(-w) if $rewrite;
+	    push @cmd, qw(-t commit), $cf;
+	    my $newcommit = cmdoutput @cmd;
+	    confess "$ch ?" unless $rewrite or $newcommit eq $cl->{CommitId};
+	    $build = $newcommit;
 	}
     };
 
-- 
2.30.2