quilt: Generate individual patches CHANGELOG BUG

1 files changed, 254 insertions, 8 deletions

diff --git a/dgit b/dgit
index af95766..972a839 100755
--- a/dgit
+++ b/dgit
@@ -53,6 +53,8 @@ our $rmonerror = 1;
 our $existing_package = 'dpkg';
 our $cleanmode = 'dpkg-source';
 our $changes_since_version;
+our $quilt_mode;
+our $quilt_modes_re = 'linear|smash|auto|nofix';
 our $we_are_responder;
 our $initiator_tempdir;
 
@@ -2037,6 +2039,8 @@ our $version;
 our $sourcechanges;
 our $dscfn;
 
+#----- `3.0 (quilt)' handling -----
+
 our $fakeeditorenv = 'DGIT_FAKE_EDITOR_QUILT';
 
 sub quiltify_dpkg_commit ($$$;$) {
@@ -2066,17 +2070,243 @@ END
     }
 }
 
+sub quiltify_trees_differ ($$) {
+    my ($x,$y) = @_;
+    # returns 1 iff the two tree objects differ other than in debian/
+    local $/=undef;
+    my @cmd = (@git, qw(diff-tree --name-only -z), $x, $y);
+    my $diffs= cmdoutput @cmd;
+    foreach my $f (split /\0/, $diffs) {
+	next if $f eq 'debian';
+	return 1;
+    }
+    return 0;
+}
+
+sub quiltify_tree_sentinelfiles ($) {
+    # lists the `sentinel' files present in the tree
+    my ($x) = @_;
+    my $r = cmdoutput @git, qw(ls-tree --name-only), $x,
+        qw(-- debian/rules debian/control);
+    $r =~ s/\n/,/g;
+    return $r;
+}
+
 sub quiltify ($$) {
-    my ($clogp,$headref) = @_;
+    my ($clogp,$target) = @_;
+
+    # Quilt patchification algorithm
+    #
+    # We search backwards through the history of the main tree's HEAD
+    # (T) looking for a start commit S whose tree object is identical
+    # to to the patch tip tree (ie the tree corresponding to the
+    # current dpkg-committed patch series).  For these purposes
+    # `identical' disregards anything in debian/ - this wrinkle is
+    # necessary because dpkg-source treates debian/ specially.
+    #
+    # We can only traverse edges where at most one of the ancestors'
+    # trees differs (in changes outside in debian/).  And we cannot
+    # handle edges which change .pc/ or debian/patches.  To avoid
+    # going down a rathole we avoid traversing edges which introduce
+    # debian/rules or debian/control.  And we set a limit on the
+    # number of edges we are willing to look at.
+    #
+    # If we succeed, we walk forwards again.  For each traversed edge
+    # PC (with P parent, C child) (starting with P=S and ending with
+    # C=T) to we do this:
+    #  - git checkout C
+    #  - dpkg-source --commit with a patch name and message derived from C
+    # After traversing PT, we git commit the changes which
+    # should be contained within debian/patches.
+
+    changedir '../fake';
+    mktree_in_ud_here();
+    rmtree '.pc';
+    runcmd @git, 'add', '.';
+    my $oldtiptree=git_write_tree();
+    changedir '../work';
+
+    # The search for the path S..T is breadth-first.  We maintain a
+    # todo list containing search nodes.  A search node identifies a
+    # commit, and looks something like this:
+    #  $p = {
+    #      Commit => $git_commit_id,
+    #      Child => $c,                          # or undef if P=T
+    #      Whynot => $reason_edge_PC_unsuitable, # in @nots only
+    #      Nontrivial => true iff $p..$c has relevant changes
+    #  };
+
+    my @todo;
+    my @nots;
+    my $sref_S;
+    my $max_work=100;
+    my %considered; # saves being exponential on some weird graphs
+
+    my $t_sentinels = quiltify_tree_sentinelfiles $target;
+
+    my $not = sub {
+	my ($search,$whynot) = @_;
+	printdebug " search NOT $search->{Commit} $whynot\n";
+	$search->{Whynot} = $whynot;
+	push @nots, $search;
+	no warnings qw(exiting);
+	next;
+    };
+
+    push @todo, {
+	Commit => $target,
+    };
 
-    my $time = time;
-    my $ncommits = 3;
-    my $msg = cmdoutput @git, qw(log), "-n$ncommits";
+    while (@todo) {
+	my $c = shift @todo;
+	next if $considered{$c->{Commit}}++;
+
+	$not->($c, "maximum search space exceeded") if --$max_work <= 0;
+
+	printdebug "quiltify investigate $c->{Commit}\n";
+
+	# are we done?
+	if (!quiltify_trees_differ $c->{Commit}, $oldtiptree) {
+	    printdebug " search finished hooray!\n";
+	    $sref_S = $c;
+	    last;
+	}
+
+	if ($quilt_mode eq 'nofix') {
+	    fail "quilt fixup required but quilt mode is \`nofix'\n".
+		"HEAD commit $c->{Commit} differs from tree implied by ".
+		" debian/patches (tree object $oldtiptree)";
+	}
+	if ($quilt_mode eq 'smash') {
+	    printdebug " search quitting smash\n";
+	    last;
+	}
+
+	my $c_sentinels = quiltify_tree_sentinelfiles $c->{Commit};
+	$not->($c, "has $c_sentinels not $t_sentinels")
+	    if $c_sentinels ne $t_sentinels;
+
+	my $commitdata = cmdoutput @git, qw(cat-file commit), $c->{Commit};
+	$commitdata =~ m/\n\n/;
+	$commitdata =~ $`;
+	my @parents = ($commitdata =~ m/^parent (\w+)$/gm);
+	@parents = map { { Commit => $_, Child => $c } } @parents;
+
+	$not->($c, "root commit") if !@parents;
+
+	foreach my $p (@parents) {
+	    $p->{Nontrivial}= quiltify_trees_differ $p->{Commit},$c->{Commit};
+	}
+	my $ndiffers = grep { $_->{Nontrivial} } @parents;
+	$not->($c, "merge ($ndiffers nontrivial parents)") if $ndiffers > 1;
+
+	foreach my $p (@parents) {
+	    printdebug "considering C=$c->{Commit} P=$p->{Commit}\n";
+
+	    my @cmd= (@git, qw(diff-tree -r --name-only),
+		      $p->{Commit},$c->{Commit}, qw(-- debian/patches .pc));
+	    my $patchstackchange = cmdoutput @cmd;
+	    if (length $patchstackchange) {
+		$patchstackchange =~ s/\n/,/g;
+		$not->($p, "changed $patchstackchange");
+	    }
 
-    quiltify_dpkg_commit "auto-$version-$headref-$time",
-        (getfield $clogp, 'Maintainer'),
-        "Automatically generated patch ($clogp->{Version})\n".
-        "Last (up to) $ncommits git changes, FYI:\n\n". $msg;
+	    printdebug " search queue P=$p->{Commit} ",
+	        ($p->{Nontrivial} ? "NT" : "triv"),"\n";
+	    push @todo, $p;
+	}
+    }
+
+    if (!$sref_S) {
+	printdebug "quiltify want to smash\n";
+
+	my $abbrev = sub {
+	    my $x = $_[0]{Commit};
+	    $x =~ s/(.*?[0-9a-z]{8})[0-9a-z]*$/$1/;
+	    return $;
+	};
+	my $reportnot = sub {
+	    my ($notp) = @_;
+	    my $s = $abbrev->($notp);
+	    my $c = $notp->{Child};
+	    $s .= "..".$abbrev->($c) if $c;
+	    $s .= ": ".$c->{Whynot};
+	    return $s;
+	};
+	if ($quilt_mode eq 'linear') {
+	    print STDERR "$us: quilt fixup cannot be linear.  Stopped at:\n";
+	    foreach my $notp (@nots) {
+		print STDERR "$us:  ", $reportnot->($notp), "\n";
+	    }
+	    fail "quilt fixup naive history linearisation failed.\n".
+ "Use dpkg-source --commit by hand; or, --quilt=smash for one ugly patch";
+	} elsif ($quilt_mode eq 'smash') {
+	} elsif ($quilt_mode eq 'auto') {
+	    progress "quilt fixup cannot be linear, smashing...";
+	} else {
+	    die "$quilt_mode ?";
+	}
+
+	my $time = time;
+	my $ncommits = 3;
+	my $msg = cmdoutput @git, qw(log), "-n$ncommits";
+
+	quiltify_dpkg_commit "auto-$version-$target-$time",
+	    (getfield $clogp, 'Maintainer'),
+	    "Automatically generated patch ($clogp->{Version})\n".
+	    "Last (up to) $ncommits git changes, FYI:\n\n". $msg;
+	return;
+    }
+
+    progress "quiltify linearisation planning successful, executing...";
+
+    for (my $p = $sref_S;
+	 my $c = $p->{Child};
+	 $p = $p->{Child}) {
+	printdebug "quiltify traverse $p->{Commit}..$c->{Commit}\n";
+	next unless $p->{Nontrivial};
+
+	my $cc = $c->{Commit};
+
+	my $commitdata = cmdoutput @git, qw(cat-file commit), $cc;
+	$commitdata =~ m/\n\n/ or die "$c ?";
+	$commitdata = $`;
+	my $msg = $'; #';
+	$commitdata =~ m/^author (.*) \d+ [-+0-9]+$/m or die "$cc ?";
+	my $author = $1;
+
+	$msg =~ s/^(.*)\n*/$1\n/ or die "$cc $msg ?";
+
+	my $title = $1;
+	my $patchname = $title;
+	$patchname =~ s/[.:]$//;
+	$patchname =~ y/ A-Z/-a-z/;
+	$patchname =~ y/-a-z0-9_.+=~//cd;
+	$patchname =~ s/^\W/x-$&/;
+	$patchname = substr($patchname,0,40);
+	my $index;
+	for ($index='';
+	     stat "debian/patches/$patchname$index";
+	     $index++) { }
+	$!==ENOENT or die "$patchname$index $!";
+
+	runcmd @git, qw(checkout -q), $cc;
+
+	# We use the tip's changelog so that dpkg-source doesn't
+	# produce complaining messages from dpkg-parsechangelog.  None
+	# of the information dpkg-source gets from the changelog is
+	# actually relevant - it gets put into the original message
+	# which dpkg-source provides our stunt editor, and then
+	# overwritten.
+	runcmd @git, qw(checkout -q), $target, qw(debian/changelog);
+
+	quiltify_dpkg_commit "$patchname$index", $author, $msg,
+	    "X-Dgit-Generated: $clogp->{Version} $cc\n";
+
+	runcmd @git, qw(checkout -q), $cc, qw(debian/changelog);
+    }
+
+    runcmd @git, qw(checkout -q master);
 }
 
 sub build_maybe_quilt_fixup () {
@@ -2235,6 +2465,8 @@ sub quilt_fixup_editor () {
     exit 0;
 }
 
+#----- other building -----
+
 sub clean_tree () {
     if ($cleanmode eq 'dpkg-source') {
 	runcmd_ordryrun_local @dpkgbuildpackage, qw(-T clean);
@@ -2441,6 +2673,11 @@ sub parseopts () {
 		$cleanmode = $1;
 	    } elsif (m/^--clean=(.*)$/s) {
 		badusage "unknown cleaning mode \`$1'";
+	    } elsif (m/^--quilt=($quilt_modes_re)$/s) {
+		push @ropts, $_;
+		$quilt_mode = $1;
+	    } elsif (m/^--quilt=(.*)$/s) {
+		badusage "unknown quilt fixup mode \`$1'";
 	    } elsif (m/^--ignore-dirty$/s) {
 		push @ropts, $_;
 		$ignoredirty = 1;
@@ -2524,6 +2761,15 @@ if (!@ARGV) {
 my $cmd = shift @ARGV;
 $cmd =~ y/-/_/;
 
+if (!defined $quilt_mode) {
+    $quilt_mode = cfg('dgit.force.quilt-mode', 'RETURN-UNDEF')
+	// access_cfg('quilt-mode', 'RETURN-UNDEF')
+	// 'linear';
+    $quilt_mode =~ m/^($quilt_modes_re)$/ 
+	or badcfg "unknown quilt-mode \`$quilt_mode'";
+    $quilt_mode = $1;
+}
+
 my $fn = ${*::}{"cmd_$cmd"};
 $fn or badusage "unknown operation $cmd";
 $fn->();