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git-svn: New flag to emulate empty directories
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Adds a --preserve-empty-dirs flag to the clone operation that will detect
empty directories in the remote Subversion repository and create placeholder
files in the corresponding local Git directories.  This allows "empty"
directories to exist in the history of a Git repository.

Also adds the --placeholder-file flag to control the name of any placeholder
files created.  Default value is ".gitignore".

Signed-off-by: Ray Chen <rchen@cs.umd.edu>
Acked-by: Eric Wong <normalperson@yhbt.net>
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Ray Chen authored and Eric Wong committed Sep 1, 2011
1 parent 4b5eac7 commit 40a1530
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11 changes: 11 additions & 0 deletions Documentation/git-svn.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,17 @@ Skip "branches" and "tags" of first level directories;;
affecting the working tree; and the 'rebase' command will be
able to update the working tree with the latest changes.

--preserve-empty-dirs;;
Create a placeholder file in the local Git repository for each
empty directory fetched from Subversion. This includes directories
that become empty by removing all entries in the Subversion
repository (but not the directory itself). The placeholder files
are also tracked and removed when no longer necessary.

--placeholder-filename=<filename>;;
Set the name of placeholder files created by --preserve-empty-dirs.
Default: ".gitignore"

'rebase'::
This fetches revisions from the SVN parent of the current HEAD
and rebases the current (uncommitted to SVN) work against it.
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148 changes: 144 additions & 4 deletions git-svn.perl
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@ BEGIN
$_prefix, $_no_checkout, $_url, $_verbose,
$_git_format, $_commit_url, $_tag, $_merge_info);
$Git::SVN::_follow_parent = 1;
$SVN::Git::Fetcher::_placeholder_filename = ".gitignore";
$_q ||= 0;
my %remote_opts = ( 'username=s' => \$Git::SVN::Prompt::_username,
'config-dir=s' => \$Git::SVN::Ra::config_dir,
Expand Down Expand Up @@ -139,6 +140,10 @@ BEGIN
%fc_opts } ],
clone => [ \&cmd_clone, "Initialize and fetch revisions",
{ 'revision|r=s' => \$_revision,
'preserve-empty-dirs' =>
\$SVN::Git::Fetcher::_preserve_empty_dirs,
'placeholder-filename=s' =>
\$SVN::Git::Fetcher::_placeholder_filename,
%fc_opts, %init_opts } ],
init => [ \&cmd_init, "Initialize a repo for tracking" .
" (requires URL argument)",
Expand Down Expand Up @@ -386,6 +391,12 @@ sub do_git_init_db {
my $ignore_regex = \$SVN::Git::Fetcher::_ignore_regex;
command_noisy('config', "$pfx.ignore-paths", $$ignore_regex)
if defined $$ignore_regex;

if (defined $SVN::Git::Fetcher::_preserve_empty_dirs) {
my $fname = \$SVN::Git::Fetcher::_placeholder_filename;
command_noisy('config', "$pfx.preserve-empty-dirs", 'true');
command_noisy('config', "$pfx.placeholder-filename", $$fname);
}
}

sub init_subdir {
Expand Down Expand Up @@ -4080,12 +4091,13 @@ sub _read_password {
}

package SVN::Git::Fetcher;
use vars qw/@ISA/;
use vars qw/@ISA $_ignore_regex $_preserve_empty_dirs $_placeholder_filename
@deleted_gpath %added_placeholder $repo_id/;
use strict;
use warnings;
use Carp qw/croak/;
use File::Basename qw/dirname/;
use IO::File qw//;
use vars qw/$_ignore_regex/;

# file baton members: path, mode_a, mode_b, pool, fh, blob, base
sub new {
Expand All @@ -4097,8 +4109,34 @@ sub new {
$self->{empty_symlinks} =
_mark_empty_symlinks($git_svn, $switch_path);
}
$self->{ignore_regex} = eval { command_oneline('config', '--get',
"svn-remote.$git_svn->{repo_id}.ignore-paths") };

# some options are read globally, but can be overridden locally
# per [svn-remote "..."] section. Command-line options will *NOT*
# override options set in an [svn-remote "..."] section
$repo_id = $git_svn->{repo_id};
my $k = "svn-remote.$repo_id.ignore-paths";
my $v = eval { command_oneline('config', '--get', $k) };
$self->{ignore_regex} = $v;

$k = "svn-remote.$repo_id.preserve-empty-dirs";
$v = eval { command_oneline('config', '--get', '--bool', $k) };
if ($v && $v eq 'true') {
$_preserve_empty_dirs = 1;
$k = "svn-remote.$repo_id.placeholder-filename";
$v = eval { command_oneline('config', '--get', $k) };
$_placeholder_filename = $v;
}

# Load the list of placeholder files added during previous invocations.
$k = "svn-remote.$repo_id.added-placeholder";
$v = eval { command_oneline('config', '--get-all', $k) };
if ($_preserve_empty_dirs && $v) {
# command() prints errors to stderr, so we only call it if
# command_oneline() succeeded.
my @v = command('config', '--get-all', $k);
$added_placeholder{ dirname($_) } = $_ foreach @v;
}

$self->{empty} = {};
$self->{dir_prop} = {};
$self->{file_prop} = {};
Expand Down Expand Up @@ -4227,6 +4265,8 @@ sub delete_entry {
$self->{gii}->remove($gpath);
print "\tD\t$gpath\n" unless $::_q;
}
# Don't add to @deleted_gpath if we're deleting a placeholder file.
push @deleted_gpath, $gpath unless $added_placeholder{dirname($path)};
$self->{empty}->{$path} = 0;
undef;
}
Expand Down Expand Up @@ -4259,7 +4299,15 @@ sub add_file {
my ($dir, $file) = ($path =~ m#^(.*?)/?([^/]+)$#);
delete $self->{empty}->{$dir};
$mode = '100644';

if ($added_placeholder{$dir}) {
# Remove our placeholder file, if we created one.
delete_entry($self, $added_placeholder{$dir})
unless $path eq $added_placeholder{$dir};
delete $added_placeholder{$dir}
}
}

{ path => $path, mode_a => $mode, mode_b => $mode,
pool => SVN::Pool->new, action => 'A' };
}
Expand All @@ -4277,13 +4325,21 @@ sub add_directory {
chomp;
$self->{gii}->remove($_);
print "\tD\t$_\n" unless $::_q;
push @deleted_gpath, $gpath;
}
command_close_pipe($ls, $ctx);
$self->{empty}->{$path} = 0;
}
my ($dir, $file) = ($path =~ m#^(.*?)/?([^/]+)$#);
delete $self->{empty}->{$dir};
$self->{empty}->{$path} = 1;

if ($added_placeholder{$dir}) {
# Remove our placeholder file, if we created one.
delete_entry($self, $added_placeholder{$dir});
delete $added_placeholder{$dir}
}

out:
{ path => $path };
}
Expand Down Expand Up @@ -4447,12 +4503,96 @@ sub abort_edit {

sub close_edit {
my $self = shift;

if ($_preserve_empty_dirs) {
my @empty_dirs;

# Any entry flagged as empty that also has an associated
# dir_prop represents a newly created empty directory.
foreach my $i (keys %{$self->{empty}}) {
push @empty_dirs, $i if exists $self->{dir_prop}->{$i};
}

# Search for directories that have become empty due subsequent
# file deletes.
push @empty_dirs, $self->find_empty_directories();

# Finally, add a placeholder file to each empty directory.
$self->add_placeholder_file($_) foreach (@empty_dirs);

$self->stash_placeholder_list();
}

$self->{git_commit_ok} = 1;
$self->{nr} = $self->{gii}->{nr};
delete $self->{gii};
$self->SUPER::close_edit(@_);
}

sub find_empty_directories {
my ($self) = @_;
my @empty_dirs;
my %dirs = map { dirname($_) => 1 } @deleted_gpath;

foreach my $dir (sort keys %dirs) {
next if $dir eq ".";

# If there have been any additions to this directory, there is
# no reason to check if it is empty.
my $skip_added = 0;
foreach my $t (qw/dir_prop file_prop/) {
foreach my $path (keys %{ $self->{$t} }) {
if (exists $self->{$t}->{dirname($path)}) {
$skip_added = 1;
last;
}
}
last if $skip_added;
}
next if $skip_added;

# Use `git ls-tree` to get the filenames of this directory
# that existed prior to this particular commit.
my $ls = command('ls-tree', '-z', '--name-only',
$self->{c}, "$dir/");
my %files = map { $_ => 1 } split(/\0/, $ls);

# Remove the filenames that were deleted during this commit.
delete $files{$_} foreach (@deleted_gpath);

# Report the directory if there are no filenames left.
push @empty_dirs, $dir unless (scalar %files);
}
@empty_dirs;
}

sub add_placeholder_file {
my ($self, $dir) = @_;
my $path = "$dir/$_placeholder_filename";
my $gpath = $self->git_path($path);

my $fh = $::_repository->temp_acquire($gpath);
my $hash = $::_repository->hash_and_insert_object(Git::temp_path($fh));
Git::temp_release($fh, 1);
$self->{gii}->update('100644', $hash, $gpath) or croak $!;

# The directory should no longer be considered empty.
delete $self->{empty}->{$dir} if exists $self->{empty}->{$dir};

# Keep track of any placeholder files we create.
$added_placeholder{$dir} = $path;
}

sub stash_placeholder_list {
my ($self) = @_;
my $k = "svn-remote.$repo_id.added-placeholder";
my $v = eval { command_oneline('config', '--get-all', $k) };
command_noisy('config', '--unset-all', $k) if $v;
foreach (values %added_placeholder) {
command_noisy('config', '--add', $k, $_);
}
}

package SVN::Git::Editor;
use vars qw/@ISA $_rmdir $_cp_similarity $_find_copies_harder $_rename_limit/;
use strict;
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