247 lines
6.6 KiB
Perl
247 lines
6.6 KiB
Perl
#! @perl@ -w -I@libexecdir@/nix
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use strict;
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use readmanifest;
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my $manifestDir = "@localstatedir@/nix/manifests";
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my $logFile = "@localstatedir@/log/nix/downloads";
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open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
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# Check the arguments.
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die unless scalar @ARGV == 1;
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my $targetPath = $ARGV[0];
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my $date = `date`;
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chomp $date;
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print LOGFILE "$$ get $targetPath $date\n";
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print "\n*** Trying to download/patch `$targetPath'\n";
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# Load all manifests.
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my %narFiles;
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my %patches;
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my %successors;
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for my $manifest (glob "$manifestDir/*.nixmanifest") {
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# print STDERR "reading $manifest\n";
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readManifest $manifest, \%narFiles, \%patches, \%successors;
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}
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# Build a graph of all store paths that might contribute to the
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# construction of $targetPath, and the special node "start". The
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# edges are either patch operations, or downloads of full NAR files.
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# The latter edges only occur between "start" and a store path.
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my %graph;
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$graph{"start"} = {d => 0, pred => undef, edges => []};
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my @queue = ();
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my $queueFront = 0;
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my %done;
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sub addToQueue {
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my $v = shift;
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return if defined $done{$v};
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$done{$v} = 1;
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push @queue, $v;
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}
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sub addNode {
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my $u = shift;
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$graph{$u} = {d => 999999999999, pred => undef, edges => []}
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unless defined $graph{$u};
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}
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sub addEdge {
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my $u = shift;
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my $v = shift;
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my $w = shift;
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my $type = shift;
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my $info = shift;
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addNode $u;
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push @{$graph{$u}->{edges}},
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{weight => $w, start => $u, end => $v, type => $type, info => $info};
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my $n = scalar @{$graph{$u}->{edges}};
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}
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addToQueue $targetPath;
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sub isValidPath {
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my $p = shift;
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system "nix-store --isvalid '$p' 2> /dev/null";
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return $? == 0;
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}
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while ($queueFront < scalar @queue) {
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my $u = $queue[$queueFront++];
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# print "$u\n";
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addNode $u;
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# If the path already exists, it has distance 0 from the "start"
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# node.
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if (isValidPath($u)) {
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addEdge "start", $u, 0, "present", undef;
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}
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else {
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# Add patch edges.
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my $patchList = $patches{$u};
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foreach my $patch (@{$patchList}) {
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if (isValidPath($patch->{basePath})) {
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# !!! this should be cached
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my $hash = `nix-hash "$patch->{basePath}"`;
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chomp $hash;
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# print " MY HASH is $hash\n";
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if ($hash ne $patch->{baseHash}) {
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print LOGFILE "$$ rejecting $patch->{basePath}\n";
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next;
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}
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}
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# print " PATCH from $patch->{basePath}\n";
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addToQueue $patch->{basePath};
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addEdge $patch->{basePath}, $u, $patch->{size}, "patch", $patch;
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}
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# Add NAR file edges to the start node.
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my $narFileList = $narFiles{$u};
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foreach my $narFile (@{$narFileList}) {
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# print " NAR from $narFile->{url}\n";
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addEdge "start", $u, $narFile->{size}, "narfile", $narFile;
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if ($u eq $targetPath) {
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print LOGFILE "$$ full-download-would-be $narFile->{size}\n";
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}
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}
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}
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}
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# Run Dijkstra's shortest path algorithm to determine the shortest
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# sequence of download and/or patch actions that will produce
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# $targetPath.
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sub byDistance { # sort by distance, reversed
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return -($graph{$a}->{d} <=> $graph{$b}->{d});
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}
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my @todo = keys %graph;
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while (scalar @todo > 0) {
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# Remove the closest element from the todo list.
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@todo = sort byDistance @todo;
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my $u = pop @todo;
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my $u_ = $graph{$u};
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# print "IN $u $u_->{d}\n";
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foreach my $edge (@{$u_->{edges}}) {
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my $v_ = $graph{$edge->{end}};
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if ($v_->{d} > $u_->{d} + $edge->{weight}) {
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$v_->{d} = $u_->{d} + $edge->{weight};
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# Store the edge; to edge->start is actually the
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# predecessor.
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$v_->{pred} = $edge;
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# print " RELAX $edge->{end} $v_->{d}\n";
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}
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}
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}
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# Retrieve the shortest path from "start" to $targetPath.
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my @path = ();
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my $cur = $targetPath;
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die "don't know how to produce $targetPath\n"
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unless defined $graph{$targetPath}->{pred};
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while ($cur ne "start") {
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push @path, $graph{$cur}->{pred};
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$cur = $graph{$cur}->{pred}->{start};
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}
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# Traverse the shortest path, perform the actions described by the
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# edges.
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my $curStep = 1;
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my $maxStep = scalar @path;
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sub downloadFile {
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my $url = shift;
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my $hash = shift;
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$ENV{"PRINT_PATH"} = 1;
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$ENV{"QUIET"} = 1;
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my ($hash2, $path) = `nix-prefetch-url '$url' '$hash'`;
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chomp $hash2;
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chomp $path;
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die "hash mismatch" if $hash ne $hash2;
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return $path;
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}
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while (scalar @path > 0) {
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my $edge = pop @path;
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my $u = $edge->{start};
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my $v = $edge->{end};
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print "\n*** Step $curStep/$maxStep: ";
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$curStep++;
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if ($edge->{type} eq "present") {
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print "using already present path `$v'\n";
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print LOGFILE "$$ present $v\n";
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}
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elsif ($edge->{type} eq "patch") {
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my $patch = $edge->{info};
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print "applying patch `$patch->{url}' to `$u' to create `$v'\n";
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print LOGFILE "$$ patch $patch->{url} $patch->{size} $patch->{baseHash} $u $v\n";
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# Download the patch.
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print " downloading patch...\n";
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my $patchPath = downloadFile "$patch->{url}", "$patch->{hash}";
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# Turn the base path into a NAR archive, to which we can
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# actually apply the patch.
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print " packing base path...\n";
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system "nix-store --dump $patch->{basePath} > /tmp/nar";
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die "cannot dump `$patch->{basePath}'" if ($? != 0);
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# Apply the patch.
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print " applying patch...\n";
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system "@libexecdir@/bspatch /tmp/nar /tmp/nar2 $patchPath";
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die "cannot apply patch `$patchPath' to /tmp/nar" if ($? != 0);
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# Unpack the resulting NAR archive into the target path.
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print " unpacking patched archive...\n";
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system "nix-store --restore $v < /tmp/nar2";
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die "cannot unpack /tmp/nar2 into `$v'" if ($? != 0);
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}
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elsif ($edge->{type} eq "narfile") {
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my $narFile = $edge->{info};
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print "downloading `$narFile->{url}' into `$v'\n";
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print LOGFILE "$$ narfile $narFile->{url} $narFile->{size} $v\n";
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# Download the archive.
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print " downloading archive...\n";
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my $narFilePath = downloadFile "$narFile->{url}", "$narFile->{hash}";
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# Unpack the archive into the target path.
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print " unpacking archive...\n";
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system "bunzip2 < '$narFilePath' | nix-store --restore '$v'";
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die "cannot unpack `$narFilePath' into `$v'" if ($? != 0);
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}
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}
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print LOGFILE "$$ success\n";
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close LOGFILE;
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