forked from lix-project/lix
![Eelco Dolstra](/assets/img/avatar_default.png)
SQLite manifest cache. The DBI AutoCommit feature caused every process to have an active transaction at all times, which could indefinitely block processes wanting to update the manifest cache. * Disable fsync() in the manifest cache because we don't need integrity (the cache can always be recreated if it gets corrupted).
398 lines
12 KiB
Perl
398 lines
12 KiB
Perl
#! @perl@ -w -I@libexecdir@/nix @perlFlags@
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use strict;
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use NixManifest;
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use POSIX qw(strftime);
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use File::Temp qw(tempdir);
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my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
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STDOUT->autoflush(1);
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my $manifestDir = ($ENV{"NIX_MANIFESTS_DIR"} or "@localstatedir@/nix/manifests");
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my $logFile = "@localstatedir@/log/nix/downloads";
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# For queries, skip expensive calls to nix-hash etc. We're just
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# estimating the expected download size.
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my $fast = 1;
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# Open the manifest cache and update it if necessary.
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my $dbh = updateManifestDB();
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sub isValidPath {
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my $p = shift;
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if ($fast) {
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return -e $p;
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} else {
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return system("$binDir/nix-store --check-validity '$p' 2> /dev/null") == 0;
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}
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}
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sub parseHash {
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my $hash = shift;
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if ($hash =~ /^(.+):(.+)$/) {
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return ($1, $2);
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} else {
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return ("md5", $hash);
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}
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}
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# Compute the most efficient sequence of downloads to produce the
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# given path.
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sub computeSmallestDownload {
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my $targetPath = shift;
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# Build a graph of all store paths that might contribute to the
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# construction of $targetPath, and the special node "start". The
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# edges are either patch operations, or downloads of full NAR
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# files. The latter edges only occur between "start" and a store
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# path.
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my %graph;
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$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 addNode {
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my $graph = shift;
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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 $graph = shift;
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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 $graph, $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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push @queue, $targetPath;
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while ($queueFront < scalar @queue) {
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my $u = $queue[$queueFront++];
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next if defined $done{$u};
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$done{$u} = 1;
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addNode \%graph, $u;
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# If the path already exists, it has distance 0 from the
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# "start" node.
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if (isValidPath($u)) {
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addEdge \%graph, "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 = $dbh->selectall_arrayref(
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"select * from Patches where storePath = ?",
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{ Slice => {} }, $u);
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foreach my $patch (@{$patchList}) {
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if (isValidPath($patch->{basePath})) {
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# !!! this should be cached
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my ($baseHashAlgo, $baseHash) = parseHash $patch->{baseHash};
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my $format = "--base32";
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$format = "" if $baseHashAlgo eq "md5";
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my $hash = $fast && $baseHashAlgo eq "sha256"
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? `$binDir/nix-store -q --hash "$patch->{basePath}"`
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: `$binDir/nix-hash --type '$baseHashAlgo' $format "$patch->{basePath}"`;
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chomp $hash;
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$hash =~ s/.*://;
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next if $hash ne $baseHash;
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}
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push @queue, $patch->{basePath};
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addEdge \%graph, $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 = $dbh->selectall_arrayref(
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"select * from NARs where storePath = ?",
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{ Slice => {} }, $u);
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foreach my $narFile (@{$narFileList}) {
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# !!! how to handle files whose size is not known in advance?
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# For now, assume some arbitrary size (1 GB).
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# This has the side-effect of preferring non-Hydra downloads.
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addEdge \%graph, "start", $u, ($narFile->{size} || 1000000000), "narfile", $narFile;
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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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# $targetPath.
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my @todo = keys %graph;
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while (scalar @todo > 0) {
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# Remove the closest element from the todo list.
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# !!! inefficient, use a priority queue
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@todo = sort { -($graph{$a}->{d} <=> $graph{$b}->{d}) } @todo;
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my $u = pop @todo;
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my $u_ = $graph{$u};
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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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}
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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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return () 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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return @path;
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}
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# Parse the arguments.
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if ($ARGV[0] eq "--query") {
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while (<STDIN>) {
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my $cmd = $_; chomp $cmd;
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if ($cmd eq "have") {
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my $storePath = <STDIN>; chomp $storePath;
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print STDOUT (
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scalar @{$dbh->selectcol_arrayref("select 1 from NARs where storePath = ?", {}, $storePath)} > 0
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? "1\n" : "0\n");
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}
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elsif ($cmd eq "info") {
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my $storePath = <STDIN>; chomp $storePath;
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my $infos = $dbh->selectall_arrayref(
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"select * from NARs where storePath = ?",
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{ Slice => {} }, $storePath);
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my $info;
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if (scalar @{$infos} > 0) {
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$info = @{$infos}[0];
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}
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else {
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print "0\n";
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next; # not an error
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}
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print "1\n";
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print "$info->{deriver}\n";
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my @references = split " ", $info->{refs};
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print scalar @references, "\n";
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print "$_\n" foreach @references;
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my @path = computeSmallestDownload $storePath;
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my $downloadSize = 0;
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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 = $edge->{end};
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if ($edge->{type} eq "patch") {
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$downloadSize += $edge->{info}->{size} || 0;
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}
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elsif ($edge->{type} eq "narfile") {
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$downloadSize += $edge->{info}->{size} || 0;
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}
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}
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print "$downloadSize\n";
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my $narSize = $info->{narSize} || 0;
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print "$narSize\n";
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}
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else { die "unknown command `$cmd'"; }
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}
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exit 0;
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}
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elsif ($ARGV[0] ne "--substitute") {
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die;
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}
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die unless scalar @ARGV == 2;
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my $targetPath = $ARGV[1];
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$fast = 0;
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# Create a temporary directory.
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my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
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or die "cannot create a temporary directory";
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my $tmpNar = "$tmpDir/nar";
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my $tmpNar2 = "$tmpDir/nar2";
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open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
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my $date = strftime ("%F %H:%M:%S UTC", gmtime (time));
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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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# Compute the shortest path.
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my @path = computeSmallestDownload $targetPath;
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die "don't know how to produce $targetPath\n" if scalar @path == 0;
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# We don't need the manifest anymore, so close it as an optimisation:
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# if we still have SQLite locks blocking other processes (we
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# shouldn't), this gets rid of them.
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$dbh->disconnect;
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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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$ENV{"PRINT_PATH"} = 1;
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$ENV{"QUIET"} = 1;
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my ($hash, $path) = `$binDir/nix-prefetch-url '$url'`;
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die "download of `$url' failed" . ($! ? ": $!" : "") unless $? == 0;
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chomp $path;
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return $path;
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}
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my $finalNarHash;
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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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if ($edge->{type} eq "present") {
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print "using already present path `$v'\n";
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print LOGFILE "$$ present $v\n";
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if ($curStep < $maxStep) {
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# Since this is not the last step, the path will be used
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# as a base to one or more patches. So turn the base path
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# into a NAR archive, to which we can apply the patch.
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print " packing base path...\n";
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system("$binDir/nix-store --dump $v > $tmpNar") == 0
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or die "cannot dump `$v'";
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}
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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}";
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# Apply the patch to the NAR archive produced in step 1 (for
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# the already present path) or a later step (for patch sequences).
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print " applying patch...\n";
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system("@libexecdir@/bspatch $tmpNar $tmpNar2 $patchPath") == 0
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or die "cannot apply patch `$patchPath' to $tmpNar";
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if ($curStep < $maxStep) {
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# The archive will be used as the base of the next patch.
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rename "$tmpNar2", "$tmpNar" or die "cannot rename NAR archive: $!";
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} else {
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# This was the last patch. Unpack the final NAR archive
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# into the target path.
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print " unpacking patched archive...\n";
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system("$binDir/nix-store --restore $v < $tmpNar2") == 0
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or die "cannot unpack $tmpNar2 into `$v'";
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}
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$finalNarHash = $patch->{narHash};
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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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my $size = $narFile->{size} || -1;
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print LOGFILE "$$ narfile $narFile->{url} $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}";
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if ($curStep < $maxStep) {
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# The archive will be used a base to a patch.
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system("@bunzip2@ < '$narFilePath' > $tmpNar") == 0
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or die "cannot unpack `$narFilePath' into `$v'";
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} else {
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# Unpack the archive into the target path.
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print " unpacking archive...\n";
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system("@bunzip2@ < '$narFilePath' | $binDir/nix-store --restore '$v'") == 0
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or die "cannot unpack `$narFilePath' into `$v'";
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}
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$finalNarHash = $narFile->{narHash};
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}
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$curStep++;
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}
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# Make sure that the hash declared in the manifest matches what we
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# downloaded and unpacked.
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if (defined $finalNarHash) {
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my ($hashAlgo, $hash) = parseHash $finalNarHash;
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# The hash in the manifest can be either in base-16 or base-32.
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# Handle both.
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my $extraFlag =
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($hashAlgo eq "sha256" && length($hash) != 64)
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? "--base32" : "";
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my $hash2 = `@bindir@/nix-hash --type $hashAlgo $extraFlag $targetPath`
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or die "cannot compute hash of path `$targetPath'";
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chomp $hash2;
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die "hash mismatch in downloaded path $targetPath; expected $hash, got $hash2"
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if $hash ne $hash2;
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} else {
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die "cannot check integrity of the downloaded path since its hash is not known";
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}
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print LOGFILE "$$ success\n";
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close LOGFILE;
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