* Place manifests in /nix/var/nix/manifests.

* Use the new patch downloader.

1 files changed, 218 insertions, 0 deletions

diff --git a/scripts/download-using-manifests.pl.in b/scripts/download-using-manifests.pl.in
new file mode 100644
index 000000000..058fa9965
--- /dev/null
+++ b/scripts/download-using-manifests.pl.in
@@ -0,0 +1,218 @@
+#! @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);
+    }
+}