fink-dpkg-status-cleanup.in

#!/usr/bin/perl
# -*- mode: Perl; tab-width: 4; -*-
# vim: ts=4 sw=4 noet

use warnings;
use strict;

use Fcntl qw(:DEFAULT :seek);
use POSIX qw(:errno_h);

my $dryrun = 0;
if (@ARGV == 1 && $ARGV[0] eq '--dry-run') {
	$dryrun = 1;
} elsif (@ARGV) {
	die "Usage: $0 [--dry-run]\n";
}

if ($> != 0 && !$dryrun) {
	die "$0 can only be run as root, except in --dry-run mode.\n";
}

### KEEP THIS IN SYNC WITH lockwait.in !!! ###

my $basepath = "@PREFIX@";		# Path prefix for dpkg
my $timeout = 5 * 60;			# Seconds to wait before failing
my $debug = 0;					# Print nice debug messages?

if ($> == 0 && !$dryrun) {
	print STDERR "We're root, gonna pre-lock\n" if $debug;

	print STDERR "Opening the lockfile\n" if $debug;
	my $lockfile = "$basepath/var/lib/dpkg/lock";
	open LOCK, ">$lockfile" or die "lockwait: Can't open: $!";
	
	print STDERR "Locking it\n" if $debug;
	### Note this pack() is specific to macOS and Darwin!!!
	# fcntl.h declares:
	#   struct flock {
	#       off_t   l_start;    /* starting offset */
	#       off_t   l_len;      /* len = 0 means until end of file */
	#       pid_t   l_pid;      /* lock owner */
	#       short   l_type;     /* lock type: read/write, etc. */
	#       short   l_whence;   /* type of l_start */
	#   };
	my $struct_flock = pack("lllliss", (0, 0), (0, 0), 0, F_WRLCK, SEEK_SET);
	my $lock_ok = fcntl(LOCK, F_SETLK, $struct_flock);
	unless ($lock_ok || $! == EOPNOTSUPP || $! == ENOLCK) {
		die "lockwait: Can't get lock: $!" unless $! == EAGAIN || $! == EACCES;
		
		my $msg = $timeout ? "up to $timeout seconds " : "";
		print STDERR "Waiting ${msg}for access to the dpkg database... ";
		eval {
			local $SIG{ALRM} = sub { die "alarm\n" };
			alarm $timeout if $timeout;
			print STDERR "Waiting for lock, timeout = $timeout\n" if $debug;
			($lock_ok = fcntl(LOCK, F_SETLKW, $struct_flock)) or
				die "lockwait: Can't get lock or wait: $!";
			alarm 0;
		};
		if ($@) {
			die unless $@ eq "alarm\n";
			print STDERR "\nTimed out, cancelling operation!\n";
			exit(1);
		}
		print STDERR "done.\n";
	}
	print STDERR "Got the lock\n" if $debug && $lock_ok;
	print STDERR "WARNING: No locking is available on this filesystem.\n" .
		"To ensure safety, do not run multiple instances simultaneously.\n"
		if !$lock_ok;
}

### END OF lockwait.in INCLUDED CODE ###

my $status_file = $basepath . '/var/lib/dpkg/status';
my $status_back = $status_file . '.' . time . '.' . $$;
my $status_temp = $status_file . '.new';

umask 0022;

open my $status_old, '<', $status_file or die "Couldn't read $status_file: $!\n";

my $status_new;  # filehandle
if (!$dryrun) {
	open $status_new, '>', $status_temp or die "Couldn't write $status_temp: $!\n";

	$debug && print "processing $status_file -> $status_temp\n";
}

my $para = '';
my $omit = 0;
my ($cnt_omit, $cnt_keep) = (0,0);
while (defined(my $line = <$status_old>)) {
    $para .= $line;
    if ($line =~ /\As*\Z/ or eof($status_old)) {
		# end of paragraph...store if not flagged to omit
		if ($omit) {
			$cnt_omit++;
			$debug && print "=====\nomit:\n-----\n$para";
		} else {
			$cnt_keep++;
			$debug && print "=====\nkeep:\n-----\n$para";
			print $status_new $para if !$dryrun;  # write to new database
		}
		$omit = 0;
		$para = '';
    } else {
		# some random paragraph line...
		if ($line eq "Status: purge ok not-installed\n") {
			$omit = 1;  # package is purged...flag to omit it
		}
    }
}

close $status_old;

if (!$dryrun) {
	close $status_new;

	$debug && print "=====\nrename $status_file -> $status_back\n";
	rename $status_file, $status_back or die "Couldn't rename $status_file to $status_back\n";

	$debug && print "rename $status_temp -> $status_file\n";
	rename $status_temp, $status_file or die "Couldn't install $status_temp as $status_file\n";
}

print "$status_file cleanup:\n\tkeep $cnt_keep\n\tomit $cnt_omit\n";

if (!$dryrun) {
}

exit 0;