# Copyright © 2008 Raphaël Hertzog <hertzog@debian.org>
# Copyright © 2008-2010, 2012-2015 Guillem Jover <guillem@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

=encoding utf8

=head1 NAME

Dpkg::Source::Patch - represent a patch file

=head1 DESCRIPTION

This module provides a class to handle patch files.

B<Note>: This is a private module, its API can change at any time.

=cut

package Dpkg::Source::Patch 0.01;

use v5.36;

use POSIX qw(:errno_h :sys_wait_h);
use File::stat ();
use File::Find;
use File::Basename;
use File::Spec;
use File::Path qw(make_path);
use File::Compare;
use Fcntl qw(:mode);
use Time::HiRes;

use Dpkg;
use Dpkg::Gettext;
use Dpkg::ErrorHandling;
use Dpkg::IPC;
use Dpkg::Source::Functions qw(fs_time);

use parent qw(Dpkg::Compression::FileHandle);

sub create {
    my ($self, %opts) = @_;
    # Create the file on open.
    $self->ensure_open('w');
    *$self->{errors} = 0;
    *$self->{empty} = 1;
    if ($opts{old} and $opts{new} and $opts{filename}) {
        $opts{old} = '/dev/null' unless -e $opts{old};
        $opts{new} = '/dev/null' unless -e $opts{new};
        if (-d $opts{old} and -d $opts{new}) {
            $self->add_diff_directory($opts{old}, $opts{new}, %opts);
        } elsif (-f $opts{old} and -f $opts{new}) {
            $self->add_diff_file($opts{old}, $opts{new}, %opts);
        } else {
            $self->_fail_not_same_type($opts{old}, $opts{new}, $opts{filename});
        }
        $self->finish() unless $opts{no_finish};
    }
}

sub set_header {
    my ($self, $header) = @_;
    *$self->{header} = $header;
}

sub get_header {
    my $self = shift;

    if (ref *$self->{header} eq 'CODE') {
        return *$self->{header}->();
    } else {
        return *$self->{header};
    }
}

sub _gen_hires_diff_label($filename)
{
    # XXX: Make do without File::stat::stat as otherwise we need to use the
    # undocumented File::stat::populate() function with Time::HiRes::stat().
    my $mtime = (Time::HiRes::stat($filename))[9];
    my $t = POSIX::strftime('%Y-%m-%d %H:%M:%S', gmtime $mtime);
    return sprintf "\t%s.%09d +0000", $t, ($mtime - int $mtime) * 1_000_000_000;
}

sub add_diff_file {
    my ($self, $old, $new, %opts) = @_;
    $opts{include_timestamp} //= 0;
    my $handle_binary = $opts{handle_binary_func} // sub {
        my ($self, $old, $new, %opts) = @_;
        my $file = $opts{filename};
        $self->_fail_with_msg($file, g_('binary file contents changed'));
    };
    # Optimization to avoid forking diff if unnecessary.
    return 1 if compare($old, $new, 4096) == 0;
    # Default diff options.
    my @options;
    if ($opts{options}) {
        push @options, @{$opts{options}};
    } else {
        push @options, '-p';
    }
    # Add labels.
    if ($opts{label_old} and $opts{label_new}) {
        if ($opts{include_timestamp}) {
            $opts{label_old} .= _gen_hires_diff_label($old);
            $opts{label_new} .= _gen_hires_diff_label($new);
        } else {
            # Space in filenames need special treatment.
            $opts{label_old} .= "\t" if $opts{label_old} =~ / /;
            $opts{label_new} .= "\t" if $opts{label_new} =~ / /;
        }
        push @options, '-L', $opts{label_old},
                       '-L', $opts{label_new};
    }
    # Generate diff.
    my $diffgen;
    my $diff_pid = spawn(
        exec => [ 'diff', '-u', @options, '--', $old, $new ],
        env => {
            LC_ALL => 'C',
            TZ => 'UTC0'
        },
        to_pipe => \$diffgen,
    );
    # Check diff and write it in patch file.
    my $difflinefound = 0;
    my $binary = 0;
    local $_;

    while (<$diffgen>) {
        if (m/^(?:binary|[^-+\@ ].*\bdiffer\b)/i) {
            $binary = 1;
            $handle_binary->($self, $old, $new, %opts);
            last;
        } elsif (m/^[-+\@ ]/) {
            $difflinefound++;
        } elsif (m/^\\ /) {
            warning(g_('file %s has no final newline (either ' .
                       'original or modified version)'), $new);
        } else {
            chomp;
            error(g_("unknown line from diff -u on %s: '%s'"), $new, $_);
        }
        if (*$self->{empty} and defined(*$self->{header})) {
            $self->print($self->get_header())
                or syserr(g_('cannot write'));
            *$self->{empty} = 0;
        }
        print { $self } $_
            or syserr(g_('cannot write'));
    }
    close($diffgen) or syserr(g_('cannot close diff pipe'));
    wait_child($diff_pid,
        no_check => 1,
        cmdline => "diff -u @options -- $old $new",
    );
    # Verify diff process ended successfully.
    # Exit code of diff:
    #   0 => no difference
    #   1 => diff ok
    #   2 => error
    # Ignore error if binary content detected.
    my $exit = WEXITSTATUS($?);
    unless (WIFEXITED($?) && ($exit == 0 || $exit == 1 || $binary)) {
        subprocerr(g_('diff on %s'), $new);
    }
    return ($exit == 0 || $exit == 1);
}

sub add_diff_directory {
    my ($self, $old, $new, %opts) = @_;
    # TODO: make this function more configurable:
    # - Offer to disable some checks.
    my $basedir = $opts{basedirname} || basename($new);
    my $diff_ignore;
    if ($opts{diff_ignore_func}) {
        $diff_ignore = $opts{diff_ignore_func};
    } elsif ($opts{diff_ignore_regex}) {
        $diff_ignore = sub { return $_[0] =~ /$opts{diff_ignore_regex}/o };
    } else {
        $diff_ignore = sub { return 0 };
    }

    my @diff_files;
    my %files_in_new;
    my $add_new = sub {
        my $fn = (length > length($new)) ? substr($_, length($new) + 1) : '.';
        return if $diff_ignore->($fn);
        $files_in_new{$fn} = 1;
        my $new_st = File::stat::lstat("$new/$fn")
            or syserr(g_('cannot stat file %s'), "$new/$fn");
        my $mode = S_IMODE($new_st->mode);
        my $size = $new_st->size;
        if (-l $new_st) {
            unless (-l "$old/$fn") {
                $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
                return;
            }
            my $n = readlink("$new/$fn");
            unless (defined $n) {
                syserr(g_('cannot read symbolic link %s'), "$new/$fn");
            }
            my $n2 = readlink("$old/$fn");
            unless (defined $n2) {
                syserr(g_('cannot read symbolic link %s'), "$old/$fn");
            }
            unless ($n eq $n2) {
                $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
            }
        } elsif (-f $new_st) {
            my $old_file = "$old/$fn";
            if (not lstat("$old/$fn")) {
                if ($! != ENOENT) {
                    syserr(g_('cannot stat file %s'), "$old/$fn");
                }
                $old_file = '/dev/null';
            } elsif (not -f _) {
                $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
                return;
            }

            my $label_old = "$basedir.orig/$fn";
            if ($opts{use_dev_null}) {
                $label_old = $old_file if $old_file eq '/dev/null';
            }
            push @diff_files, [$fn, $mode, $size, $old_file, "$new/$fn",
                               $label_old, "$basedir/$fn"];
        } elsif (-p $new_st) {
            unless (-p "$old/$fn") {
                $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
            }
        } elsif (-b $new_st || -c $new_st || -S $new_st) {
            $self->_fail_with_msg("$new/$fn",
                g_('device or socket is not allowed'));
        } elsif (-d $new_st) {
            if (not lstat("$old/$fn")) {
                if ($! != ENOENT) {
                    syserr(g_('cannot stat file %s'), "$old/$fn");
                }
            } elsif (not -d _) {
                $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
            }
        } else {
            $self->_fail_with_msg("$new/$fn", g_('unknown file type'));
        }
    };
    my $add_old = sub {
        my $fn = (length > length($old)) ? substr($_, length($old) + 1) : '.';
        return if $diff_ignore->($fn);
        return if $files_in_new{$fn};
        lstat("$old/$fn") or syserr(g_('cannot stat file %s'), "$old/$fn");
        if (-f _) {
            if (not defined $opts{include_removal}) {
                warning(g_('ignoring deletion of file %s'), $fn);
            } elsif (not $opts{include_removal}) {
                warning(g_('ignoring deletion of file %s, use --include-removal to override'), $fn);
            } else {
                push @diff_files, [$fn, 0, 0, "$old/$fn", '/dev/null',
                                   "$basedir.orig/$fn", '/dev/null'];
            }
        } elsif (-d _) {
            warning(g_('ignoring deletion of directory %s'), $fn);
        } elsif (-l _) {
            warning(g_('ignoring deletion of symbolic link %s'), $fn);
        } else {
            $self->_fail_not_same_type("$old/$fn", "$new/$fn", $fn);
        }
    };

    my $scan_new = {
        wanted => $add_new,
        no_chdir => 1,
    };
    find($scan_new, $new);
    my $scan_old = {
        wanted => $add_old,
        no_chdir => 1,
    };
    find($scan_old, $old);

    if ($opts{order_from} and -e $opts{order_from}) {
        my $order_from = Dpkg::Source::Patch->new(
            filename => $opts{order_from},
        );
        my $analysis = $order_from->analyze($basedir, verbose => 0);
        my %patchorder;
        my $i = 0;
        foreach my $fn (@{$analysis->{patchorder}}) {
            $fn =~ s{^[^/]+/}{};
            $patchorder{$fn} = $i++;
        }
        # 'quilt refresh' sorts files as follows:
        #   - Any files in the existing patch come first, in the order in
        #     which they appear in the existing patch.
        #   - New files follow, sorted lexicographically.
        # This seems a reasonable policy to follow, and avoids autopatches
        # being shuffled when they are regenerated.
        foreach my $diff_file (sort { $a->[0] cmp $b->[0] } @diff_files) {
            my $fn = $diff_file->[0];
            $patchorder{$fn} //= $i++;
        }
        @diff_files = sort { $patchorder{$a->[0]} <=> $patchorder{$b->[0]} }
                      @diff_files;
    } else {
        @diff_files = sort { $a->[0] cmp $b->[0] } @diff_files;
    }

    foreach my $diff_file (@diff_files) {
        my ($fn, $mode, $size,
            $old_file, $new_file, $label_old, $label_new) = @$diff_file;
        my $success = $self->add_diff_file($old_file, $new_file,
            filename => $fn,
            label_old => $label_old,
            label_new => $label_new,
            %opts,
        );
        if ($success and
            $old_file eq '/dev/null' and $new_file ne '/dev/null') {
            if (not $size) {
                warning(g_("newly created empty file '%s' will not " .
                           'be represented in diff'), $fn);
            } else {
                if ($mode & (S_IXUSR | S_IXGRP | S_IXOTH)) {
                    warning(g_("executable mode %04o of '%s' will " .
                               'not be represented in diff'), $mode, $fn)
                        unless $fn eq 'debian/rules';
                }
                if ($mode & (S_ISUID | S_ISGID | S_ISVTX)) {
                    warning(g_("special mode %04o of '%s' will not " .
                               'be represented in diff'), $mode, $fn);
                }
            }
        }
    }
}

sub finish {
    my $self = shift;
    close($self) or syserr(g_('cannot close %s'), $self->get_filename());
    return not *$self->{errors};
}

sub has_errors($self)
{
    return *$self->{errors};
}

sub register_error {
    my $self = shift;
    *$self->{errors}++;
}
sub _fail_with_msg {
    my ($self, $file, $msg) = @_;
    errormsg(g_('cannot represent changes to %s: %s'), $file, $msg);
    $self->register_error();
}
sub _fail_not_same_type {
    my ($self, $old, $new, $file) = @_;
    my $old_type = get_type($old);
    my $new_type = get_type($new);
    errormsg(g_('cannot represent changes to %s using GNU diff:'), $file);
    errormsg(g_('  new version is %s'), $new_type);
    errormsg(g_('  old version is %s'), $old_type);
    hint(g_('you can use a git formatted patch to represent these changes:'));
    hint(g_('  with "git format-patch" or "git diff --no-index a/ b/"'));
    $self->register_error();
}

sub _getline {
    my $handle = shift;

    my $line = <$handle>;
    if (defined $line) {
        # Strip end-of-line chars.
        chomp($line);
        $line =~ s/\r$//;
    }
    return $line;
}

# Fetch the header filename ignoring the optional timestamp.
sub _fetch_filename {
    my ($diff, $header) = @_;

    # Strip any leading spaces.
    $header =~ s/^\s+//;

    # Is it a C-style string?
    if ($header =~ m/^"/) {
        error(g_('diff %s patches file with C-style encoded filename'), $diff);
    } else {
        # Tab is the official separator, it is always used when filename
        # contain spaces. Try it first, otherwise strip on space if there
        # is no tab.
        $header =~ s/\s.*// unless $header =~ s/\t.*//;
    }

    return $header;
}

sub _intuit_file_patched {
    my ($old, $new) = @_;

    return $new unless defined $old;
    return $old unless defined $new;
    return $new if -e $new and not -e $old;
    return $old if -e $old and not -e $new;

    # We do not consider the case where both files are non-existent and
    # where patch picks the one with the fewest directories to create
    # since dpkg-source will pre-create the required directories.

    # Pre-calculate metrics used by patch.
    my ($tmp_o, $tmp_n) = ($old, $new);
    my ($len_o, $len_n) = (length($old), length($new));
    $tmp_o =~ tr{/\\}{/}s;
    $tmp_n =~ tr{/\\}{/}s;
    # Count the number of / in the strings.
    my $nb_comp_o = ($tmp_o =~ tr{/}{/});
    my $nb_comp_n = ($tmp_n =~ tr{/}{/});
    $tmp_o =~ s{^.*/}{};
    $tmp_n =~ s{^.*/}{};
    my ($blen_o, $blen_n) = (length($tmp_o), length($tmp_n));

    # Decide like patch would.
    if ($nb_comp_o != $nb_comp_n) {
        return ($nb_comp_o < $nb_comp_n) ? $old : $new;
    } elsif ($blen_o != $blen_n) {
        return ($blen_o < $blen_n) ? $old : $new;
    } elsif ($len_o != $len_n) {
        return ($len_o < $len_n) ? $old : $new;
    }
    return $old;
}

# Check diff for sanity, find directories to create as a side effect.
sub analyze {
    my ($self, $destdir, %opts) = @_;

    $opts{verbose} //= 1;
    my $diff = $self->get_filename();
    my %filepatched;
    my %dirtocreate;
    my @patchorder;
    my $patch_header = '';
    my $diff_count = 0;

    my $line = _getline($self);

    HUNK: while (defined $line or not eof $self) {
        my (%path, %fn);

        # Skip comments leading up to the patch (if any). Although we do not
        # look for an Index: pseudo-header in the comments, because we would
        # not use it anyway, as we require both ---/+++ filename headers.
        while (1) {
            if ($line =~ /^(?:--- |\+\+\+ |@@ -)/) {
                last;
            } else {
                $patch_header .= "$line\n";
            }
            $line = _getline($self);
            last HUNK if not defined $line;
        }
        $diff_count++;
        # Read file header (---/+++ pair).
        unless ($line =~ s/^--- //) {
            error(g_("expected ^--- in line %d of diff '%s'"), $., $diff);
        }
        $path{old} = $line = _fetch_filename($diff, $line);
        if ($line ne '/dev/null' and $line =~ s{^[^/]*/+}{$destdir/}) {
            $fn{old} = $line;
        }
        if ($line =~ /\.dpkg-orig$/) {
            error(g_("diff '%s' patches file with name ending in .dpkg-orig"),
                  $diff);
        }

        $line = _getline($self);
        unless (defined $line) {
            error(g_("diff '%s' finishes in middle of ---/+++ (line %d)"),
                  $diff, $.);
        }
        unless ($line =~ s/^\+\+\+ //) {
            error(g_("line after --- is not as expected in diff '%s' (line %d)"),
                  $diff, $.);
        }
        $path{new} = $line = _fetch_filename($diff, $line);
        if ($line ne '/dev/null' and $line =~ s{^[^/]*/+}{$destdir/}) {
            $fn{new} = $line;
        }

        unless (defined $fn{old} or defined $fn{new}) {
            error(g_("none of the filenames in ---/+++ are valid in diff '%s' (line %d)"),
                  $diff, $.);
        }

        # Safety checks on both filenames that patch could use.
        foreach my $key ('old', 'new') {
            next unless defined $fn{$key};
            if ($path{$key} =~ m{/\.\./}) {
                error(g_('%s contains an insecure path: %s'), $diff, $path{$key});
            }
            my $path = $fn{$key};
            while (1) {
                last unless $path =~ s{/+[^/]*$}{};
                # $destdir is assumed safe.
                last if length($path) <= length($destdir);
            }
        }

        if ($path{old} eq '/dev/null' and $path{new} eq '/dev/null') {
            error(g_("original and modified files are /dev/null in diff '%s' (line %d)"),
                  $diff, $.);
        } elsif ($path{new} eq '/dev/null') {
            error(g_("file removal without proper filename in diff '%s' (line %d)"),
                  $diff, $. - 1) unless defined $fn{old};
            if ($opts{verbose}) {
                warning(g_('diff %s removes a non-existing file %s (line %d)'),
                        $diff, $fn{old}, $.) unless -e $fn{old};
            }
        }
        my $fn = _intuit_file_patched($fn{old}, $fn{new});

        my $dirname = $fn;
        if ($dirname =~ s{/[^/]+$}{} and not -d $dirname) {
            $dirtocreate{$dirname} = 1;
        }

        my $st = File::stat::stat($fn);
        if (defined $st) {
            if (not -f $st) {
                error(g_("diff '%s' patches something which is not a plain file"),
                      $diff);
            }
            if ($st->nlink > 1) {
                warning(g_("diff '%s' patches hard link %s which can have " .
                           'unintended consequences'), $diff, $fn);
            }
        }

        if ($filepatched{$fn}) {
            $filepatched{$fn}++;

            if ($opts{fatal_dupes}) {
                error(g_("diff '%s' patches files multiple times; split the " .
                         'diff in multiple files or merge the hunks into a ' .
                         'single one'), $diff);
            } elsif ($opts{verbose} and $filepatched{$fn} == 2) {
                warning(g_("diff '%s' patches file %s more than once"), $diff, $fn)
            }
        } else {
            $filepatched{$fn} = 1;
            push @patchorder, $fn;
        }

        # Read hunks.
        my $hunk = 0;
        while (defined($line = _getline($self))) {
            # Read hunk header (@@).
            next if $line =~ /^\\ /;
            last unless $line =~ /^@@ -\d+(,(\d+))? \+\d+(,(\d+))? @\@(?: .*)?$/;
            my ($olines, $nlines) = ($1 ? $2 : 1, $3 ? $4 : 1);
            # Read hunk.
            while ($olines || $nlines) {
                unless (defined($line = _getline($self))) {
                    if (($olines == $nlines) and ($olines < 3)) {
                        warning(g_("unexpected end of diff '%s'"), $diff)
                            if $opts{verbose};
                        last;
                    } else {
                        error(g_("unexpected end of diff '%s'"), $diff);
                    }
                }
                next if $line =~ /^\\ /;
                # Check stats.
                if ($line =~ /^ / or length $line == 0) {
                    --$olines;
                    --$nlines;
                } elsif ($line =~ /^-/) {
                    --$olines;
                } elsif ($line =~ /^\+/) {
                    --$nlines;
                } else {
                    error(g_("expected [ +-] at start of line %d of diff '%s'"),
                          $., $diff);
                }
            }
            $hunk++;
        }
        unless ($hunk) {
            error(g_("expected ^\@\@ at line %d of diff '%s'"), $., $diff);
        }
    }
    close($self);
    unless ($diff_count) {
        warning(g_("diff '%s' does not contain any patch"), $diff)
            if $opts{verbose};
    }
    *$self->{analysis}{$destdir}{dirtocreate} = \%dirtocreate;
    *$self->{analysis}{$destdir}{filepatched} = \%filepatched;
    *$self->{analysis}{$destdir}{patchorder} = \@patchorder;
    *$self->{analysis}{$destdir}{patchheader} = $patch_header;
    return *$self->{analysis}{$destdir};
}

sub prepare_apply {
    my ($self, $analysis, %opts) = @_;
    if ($opts{create_dirs}) {
        foreach my $dir (keys %{$analysis->{dirtocreate}}) {
            eval { make_path($dir, { mode => 0o777 }) };
            syserr(g_('cannot create directory %s'), $dir) if $@;
        }
    }
}

sub apply {
    my ($self, $destdir, %opts) = @_;
    # Set default values to options.
    $opts{force_timestamp} //= 1;
    $opts{remove_backup} //= 1;
    $opts{create_dirs} //= 1;
    $opts{options} ||= [
        '-t',
        '-F', '0',
        '-N',
        '-p1',
        '-u',
        '-V', 'never',
        '-b',
        '-z', '.dpkg-orig',
    ];
    $opts{add_options} //= [];
    push @{$opts{options}}, @{$opts{add_options}};
    # Check the diff and create missing directories.
    my $analysis = $self->analyze($destdir, %opts);
    $self->prepare_apply($analysis, %opts);
    # Apply the patch.
    $self->ensure_open('r');
    my ($stdout, $stderr) = ('', '');
    spawn(
        exec => [ $Dpkg::PROGPATCH, @{$opts{options}} ],
        chdir => $destdir,
        env => {
            LC_ALL => 'C',
            PATCH_GET => '0',
        },
        delete_env => [
            # Ensure expected patch(1) behavior.
            'POSIXLY_CORRECT',
        ],
        wait_child => 1,
        no_check => 1,
        from_handle => $self->get_filehandle(),
        to_string => \$stdout,
        error_to_string => \$stderr,
    );
    if ($?) {
        print { *STDOUT } $stdout;
        print { *STDERR } $stderr;
        subprocerr("LC_ALL=C $Dpkg::PROGPATCH " . join(' ', @{$opts{options}}) .
                   ' < ' . $self->get_filename());
    }
    $self->close();
    # Reset the timestamp of all the patched files and remove .dpkg-orig files.
    my @files = keys %{$analysis->{filepatched}};
    my $now = $opts{timestamp};
    $now //= fs_time($files[0]) if $opts{force_timestamp} && scalar @files;
    foreach my $fn (@files) {
        if ($opts{force_timestamp}) {
            utime($now, $now, $fn) or $! == ENOENT
                or syserr(g_('cannot change timestamp for %s'), $fn);
        }
        if ($opts{remove_backup}) {
            $fn .= '.dpkg-orig';
            unlink($fn)
                or syserr(g_('cannot remove patch backup file %s'), $fn);
        }
    }
    return $analysis;
}

# Verify if check will work...
sub check_apply {
    my ($self, $destdir, %opts) = @_;
    # Set default values to options.
    $opts{create_dirs} //= 1;
    $opts{options} ||= [
        '--dry-run',
        '-s',
        '-t',
        '-F', '0',
        '-N',
        '-p1',
        '-u',
        '-V', 'never',
        '-b',
        '-z', '.dpkg-orig',
    ];
    $opts{add_options} //= [];
    push @{$opts{options}}, @{$opts{add_options}};
    # Check the diff and create missing directories.
    my $analysis = $self->analyze($destdir, %opts);
    $self->prepare_apply($analysis, %opts);
    # Apply the patch.
    $self->ensure_open('r');
    my $patch_pid = spawn(
        exec => [ $Dpkg::PROGPATCH, @{$opts{options}} ],
        chdir => $destdir,
        env => {
            LC_ALL => 'C',
            PATCH_GET => '0',
        },
        delete_env => [
            # Ensure expected patch(1) behavior.
            'POSIXLY_CORRECT',
        ],
        from_handle => $self->get_filehandle(),
        to_file => '/dev/null',
        error_to_file => '/dev/null',
    );
    wait_child($patch_pid, no_check => 1);
    my $exit = WEXITSTATUS($?);
    subprocerr("$Dpkg::PROGPATCH --dry-run") unless WIFEXITED($?);
    $self->close();
    return ($exit == 0);
}

# Helper functions.
sub get_type {
    my $file = shift;
    if (not lstat($file)) {
        return g_('nonexistent')
            if $! == ENOENT;
        syserr(g_('cannot stat %s'), $file);
    } else {
        return g_('plain file')
            if -f _ ;
        return g_('directory')
            if -d _;
        return sprintf(g_('symbolic link to %s'), readlink($file))
            if -l _;
        return g_('block device')
            if -b _;
        return g_('character device')
            if -c _;
        return g_('named pipe')
            if -p _;
        return g_('named socket')
            if -S _;
    }
}

=head1 CHANGES

=head2 Version 0.xx

This is a private module.

=cut

1;
