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