[scripts] add branch/tree filter to ignore changes outside a given DIR over a sequence of commits

2 files changed, 189 insertions, 0 deletions

diff --git a/scripts/git/branch-filter/tree-filter/directory_change_restrict.pl b/scripts/git/branch-filter/tree-filter/directory_change_restrict.pl
new file mode 100644
index 000000000..c1107cc73
--- /dev/null
+++ b/scripts/git/branch-filter/tree-filter/directory_change_restrict.pl
@@ -0,0 +1,146 @@
+#!/usr/bin/env perl
+
+use v5.12;
+use strict;
+use warnings;
+
+# FILENAME: directory_change_restrict.pl
+# CREATED: 06/11/12 08:04:15 by Kent Fredric (kentnl) <kentfredric@gmail.com>
+# ABSTRACT: Restrict changes to happen in a single dir
+#
+#
+
+sub USAGE {
+  return <<"EOT";
+
+  $0
+
+  $0 PRESERVEPATH COMMIT
+
+  GIVEN: a path in git you wish to keep the history of, and to ignore changes outside of
+
+         a commit to ignore changes beyond
+
+
+  git
+    filter-branch
+      --prune-empty
+      --tree-filter 'perl path/to/$0 PRESERVEPATH COMMIT'
+      range_start..range_end
+
+ABOUT
+
+  If you have a series of commits crossing multiple directories, but you're only
+  interested in *changes* that occurred for certain specific directories for certain specific commit ranges, ie:
+
+  ~9000 previous commits
+
+  COMMIT9000:
+    +- dir/a
+    +- dir/b
+    +- dir/c
+
+  COMMIT9001:
+    +- dir/b
+    +- dir/c
+
+  COMMIT9002:
+    +- dir/a
+
+  COMMIT9003:
+    +- dir/a
+    +- dir/c
+
+
+  You don't want to *delete* paths b & c just to isolate changes to a after commit 9000
+
+  So you create a branch,
+
+    git checkout -b selective-a master
+
+  And filter chanegs only to a
+
+    git filter-branch
+      --prune-empty
+      --tree-filter 'perl path/to/$0 dir/a COMMIT8999'
+      COMMIT9000..COMMIT9003
+
+  The resulting branch 'selective-a' should look like:
+
+  COMMIT9000:
+    +- dir/a
+
+  COMMIT9002:
+    +- dir/a
+
+  COMMIT9003:
+    +- dir/a
+
+
+  But changes to dir/b and dir/c prior to COMMIT9000 are preserved in this branches history.
+
+  This is a useful tool to exercise to split commits pertaining to multiple ebuilds into per-package histories
+  instead of shared history commits.
+
+
+EOT
+}
+
+use Git::Wrapper;
+use Path::Class qw( dir file );
+use File::Temp qw();
+
+my ( $path, $commit ) = @ARGV;
+
+if ( $ENV{DIRECTORY_CHANGE_RESTRICT_path} ) {
+  $path   = $ENV{DIRECTORY_CHANGE_RESTRICT_path};
+  $commit = @ARGV;
+}
+if ( $ENV{DIRECTORY_CHANGE_RESTRICT_commit} ) {
+  $commit = $ENV{DIRECTORY_CHANGE_RESTRICT_commit};
+}
+
+if ( not $path or not $commit ) {
+  die USAGE();
+}
+
+my $git = Git::Wrapper->new('.');
+
+if ( not -e $path ) {
+  revert_tree($commit);
+  exit 0;
+}
+
+my $preserve = ( -f $path ? file($path) : dir($path) );
+
+my $tempfile = File::Temp->new( 'git-filter-branch.XXXXX', SUFFIX => '.tar', TMPDIR => 1, UNLINK => 1 );
+
+tar( '-cf', $tempfile->filename, $preserve );
+revert_tree($commit);
+if ( -f $preserve ) {
+  $preserve->remove();
+}
+else {
+  $preserve->rmtree();
+}
+tar( '-xf', $tempfile->filename );
+
+sub revert_tree {
+  my ($commit) = @_;
+  $git->reset( qw( --hard ), $commit, '--' );
+  $git->reset(qw( --soft  ORIG_HEAD -- ));
+}
+
+sub tar {
+  my (@args) = @_;
+  open my $fh, '-|', 'tar', @args or do {
+    die "Error calling tar: $? $! $@";
+  };
+  while ( my $line = <$fh> ) {
+    chomp $line;
+    print "\e[39m$line\e[0m\n";
+  }
+  $fh->close or do {
+    warn "Error closing tar: $? $! $@";
+  };
+}
diff --git a/scripts/git/directory_changes_to_branch.pl b/scripts/git/directory_changes_to_branch.pl
new file mode 100644
index 000000000..b88147f68
--- /dev/null
+++ b/scripts/git/directory_changes_to_branch.pl
@@ -0,0 +1,43 @@
+#!/usr/bin/env perl
+eval 'echo "Called with something not perl"' && exit 1    # Non-Perl protection.
+  if 0;
+
+use 5.14.2;
+use strict;
+use warnings;
+
+use FindBin;
+use lib "$FindBin::Bin/../lib";
+
+use env::gentoo::perl_experimental;
+
+
+
+# FILENAME: directory_changes_to_branch.pl
+# CREATED: 06/11/12 08:45:40 by Kent Fredric (kentnl) <kentfredric@gmail.com>
+# ABSTRACT: convert a history of changes to a given path to a dedicated branch
+
+my ( $branchname, $path, $branch_base , $branch_tip ) = @ARGV;
+my ( $env ) = env::gentoo::perl_experimental->new();
+
+use Git::Wrapper;
+use Git::Repository;
+use File::Temp;
+
+my $git = Git::Repository->new( work_tree => $env->root );
+
+say "Creating branch $branchname based on changes in $path since $branch_base";
+
+my $filter = $env->root->subdir('scripts')->subdir('git')->subdir('branch-filter')->subdir('tree-filter')->file('directory_change_restrict.pl');
+
+$ENV{DIRECTORY_CHANGE_RESTRICT_path} = $path;
+$ENV{DIRECTORY_CHANGE_RESTRICT_commit} = $branch_base;
+
+use File::pushd;
+
+my $cwd = pushd( $env->root->stringify );
+
+$git->run('checkout','-b',$branchname , $branch_tip );
+$git->run( 'filter-branch', '-f', qw( --prune-empty  --tree-filter ),"$^X $filter", $branch_base . '..' . $branchname );
+
+