From 9aec5c491b959a70d1485149fd9e5babc97adeec Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Fri, 6 Jan 2017 16:36:06 +0000
Subject: dgit-badcommit-fixup: Implement dgit-rewrite-map

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 dgit-badcommit-fixup | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/dgit-badcommit-fixup b/dgit-badcommit-fixup
index 4663789..cd62e68 100755
--- a/dgit-badcommit-fixup
+++ b/dgit-badcommit-fixup
@@ -129,16 +129,77 @@ sub rewrite_tag ($) {
     return hashobj $_, 'tag';
 }
 
+sub rewrite_rewrite_map ($) {
+    my ($old) = @_;
+
+    my $td = 'dgit-broken-fixup.tmp';
+    runcmd qw(rm -rf), $td;
+    mkdir $td, 0700 or die "$td $!";
+    chdir $td or die $!;
+    runcmd qw(git init -q);
+    runcmd qw(git config gc.auto 0);
+    runcmd qw(rm -rf .git/objects);
+    symlink "../../objects", ".git/objects" or die $!;
+
+    my %map;
+
+    if ($old) {
+	runcmd qw(git checkout -q), $old;
+	open M, "map" or die $!;
+	while (<M>) {
+	    m/^(\w+)(?:\s+(\w+))?$/ or die;
+	    $map{$1} = $2;
+	    $count{rewrite_map_previous}++;
+	}
+	M->error and die $!;
+	close M or die $!;
+    }
+
+    filter_updates();
+    foreach my $up (@updates) {
+	$map{ $_->[1] } = $_->[2];
+    }
+
+    open M, ">", "map" or die $!;
+    print M "%s%s\n",
+	$_, (defined $map{$_} ? " $map{$_}" : "")
+	or die $!;
+	foreach keys %map;
+    close M or die $!;
+
+    runcmd qw(git commit -q), 
+	qw(-m), 'dgit-badcommit-fixup',
+	qw(map);
+
+    $!=0; $?=0;
+    my $new = `git rev-parse HEAD`;
+    die "$? $!" if $?;
+    chomp $new or die;
+
+    chdir '..' or die $!;
+    runcmd qw(rm -rf), $td;
+
+    $count{rewrite_map_updated}++;
+
+    return $new;
+}
+
 $!=0; $?=0;
 my $refs=`git for-each-ref`;
 die "$? $!" if $?;
 
 chomp $refs;
 
+our $org_rewrite_map;
+
 foreach my $rline (split /\n/, $refs) {
     my ($obj, $type, $refname) = 
 	$rline =~ m/^(\w+)\s+(\w+)\s+(\S.*)/
 	or die "$_ ?";
+    if ($refname eq 'refs/dgit-rewrite-map') {
+	$org_rewrite_map = $obj;
+	continue;
+    }
     my $rewrite;
     if ($type eq 'commit') {
 	$rewrite = rewrite_commit($obj);
@@ -151,6 +212,13 @@ foreach my $rline (split /\n/, $refs) {
     push @updates, [ $refname, $obj, $rewrite ];
 }
 
+if ($bare eq 'true') {
+    my $new_rewrite_map = edit_rewrite_map($org_rewrite_map);
+    push @updates, [ 'refs/dgit-rewrite-map',
+		     ($org_rewrite_map // '0'x40),
+		     $new_rewrite_map ];
+}
+
 filter_updates();
 
 #print Dumper(\@updates);
-- 
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