#!/usr/bin/perl

use strict;
use warnings;

die "Arguments missing: $0 [-c] <chroot> <spec>\n" unless @ARGV;
my $clear;
if ( $ARGV[0] eq "-c" ) {
	$clear = 1;
	shift @ARGV;
}
my $chroot = shift @ARGV or die "chroot directory not specified\n";
my $spec = shift @ARGV or die "Spec file not specified\n";

-d $chroot or die "chroot '$chroot' is not a directory\n";
-r $spec or die "spec file '$spec' is not readable\n";

my @rpms;
open F_IN, "<", $spec or die "Cannot open '$spec'\n";
while ( <F_IN> ) {
	if ( /^\s*(?:%\{.*)?BuildRequires:\s*(\S+)/i ) {
		local $_ = $1;
		s/}$//;
		push @rpms, $_;
	} elsif ( /^%(prep|build|changelog)/ ) {
		last;
	}
}
close F_IN;

sub clear_files
{
	my $rpm = shift;
	my $files = shift;
	foreach my $file ( @$files ) {
		chop $file;
		my $f = $chroot.$file;

		local $_;
		while ( $_ = readlink $f and m#^/# ) {
			 $f = $chroot.$_;
		}

		# skip missing files, like "%_excludedocs 0" being active
		next unless stat $f;

		# XXX: this truncates mtime to its low resolution value
		my $mtime = (stat $f)[9];
		warn "Mtime failed on $f" unless $mtime;
		utime 0, $mtime, $f;
	}
}

sub check_files
{
	my $rpm = shift;
	my $files = shift;
	#my $used = 0;
	foreach my $file ( @$files ) {
		chop $file;
		my $f = $chroot.$file;

		local $_;
		while ( $_ = readlink $f and m#^/# ) {
			 $f = $chroot.$_;
		}

		my $atime = (stat $f)[8];
		if ( not defined $atime ) {
			print "$rpm: $f no atime\n";
		} elsif ( $atime > 0 ) {
			#print "$rpm: $file accessed\n";
			#$used = 1;
			return;
		} else {
			#print "$rpm: $file NOT accessed !\n";
		}
	}
	print "$rpm may be superfluous !\n";# unless $used;
}

sub rpm {
	my @cmd = ("rpm", "--root=$chroot", @_);
	open my $fh, '-|', @cmd or die "$!: @cmd";
	my @data = <$fh>;
	close $fh;
	warn $! if $!;
	return @data;
}

foreach my $rpm ( @rpms ) {
	my @files = rpm("-ql", "--what-provides", "$rpm");
	next if $files[0] =~ /^no package provides/;
	#print "*** $rpm ***\n";
	if ( $clear ) {
		clear_files( $rpm, \@files );
	} else {
		check_files( $rpm, \@files );
	}
	#print "\n\n";
}