* New kind of manifest object: "localPath", which denotes that a store

path can be created by copying it from another location in the file
  system.  This is useful in the NixOS installation.

scripts/download-using-manifests.pl.in

@@ -34,17 +34,31 @@ print "\n*** Trying to download/patch `$targetPath'\n";
 
 # Load all manifests.
 my %narFiles;
+my %localPaths;
 my %patches;
 
 for my $manifest (glob "$manifestDir/*.nixmanifest") {
 #    print STDERR "reading $manifest\n";
-    if (readManifest($manifest, \%narFiles, \%patches) < 3) {
+    if (readManifest($manifest, \%narFiles, \%localPaths, \%patches) < 3) {
         print STDERR "you have an old-style manifest `$manifest'; please delete it\n";
         exit 1;
     }
 }
 
 
+# If we can copy from a local path, do that.
+my $localPathList = $localPaths{$targetPath};
+foreach my $localPath (@{$localPathList}) {
+    my $sourcePath = $localPath->{copyFrom};
+    if (-e $sourcePath) {
+        print "\n*** Step 1/1: copying from $sourcePath\n";
+        system("@bindir@/nix-store --dump $sourcePath | @bindir@/nix-store --restore $targetPath") == 0
+            or die "cannot copy `$sourcePath' to `$targetPath'";
+        exit 0;
+    }
+}
+
+
 # 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.

scripts/generate-patches.pl.in

@@ -28,16 +28,18 @@ print "TEMP = $tmpDir\n";
 #END { rmdir $tmpDir; }
 
 my %srcNarFiles;
+my %srcLocalPaths;
 my %srcPatches;
 
 my %dstNarFiles;
+my %dstLocalPaths;
 my %dstPatches;
 
 readManifest "$srcDir/MANIFEST",
-    \%srcNarFiles, \%srcPatches;
+    \%srcNarFiles, \%srcLocalPaths, \%srcPatches;
 
 readManifest "$dstDir/MANIFEST",
-    \%dstNarFiles, \%dstPatches;
+    \%dstNarFiles, \%dstLocalPaths, \%dstPatches;
 
 
 sub findOutputPaths {

scripts/maintenance/gc-releases.pl

@@ -7,11 +7,12 @@ use readcache;
 
 # Read the manifests.
 my %narFiles;
+my %localPaths;
 my %patches;
 
 foreach my $manifest (@ARGV) {
     print STDERR "loading $manifest\n";
-    if (readManifest($manifest, \%narFiles, \%patches, 1) < 3) {
+    if (readManifest($manifest, \%narFiles, \%localPaths, \%patches, 1) < 3) {
 #        die "manifest `$manifest' is too old (i.e., for Nix <= 0.7)\n";
     }
 }

scripts/maintenance/shrink-manifest.pl

@@ -6,11 +6,12 @@ use readcache;
 
 
 my %allNarFiles;
+my %allLocalPaths;
 my %allPatches;
 
 foreach my $manifest (glob "/data/webserver/dist/*/*/MANIFEST") {
     print STDERR "loading $manifest\n";
-    readManifest($manifest, \%allNarFiles, \%allPatches, 1);
+    readManifest($manifest, \%allNarFiles, \%allLocalPaths, \%allPatches, 1);
 }
 
 

scripts/nix-pull.in

@@ -28,6 +28,7 @@ umask 0022;
 
 # Process the URLs specified on the command line.
 my %narFiles;
+my %localPaths;
 my %patches;
 
 my $skipWrongStore = 0;
@@ -42,7 +43,7 @@ sub processURL {
            "'$url' > '$manifest'") == 0
            or die "curl failed: $?";
 
-    if (readManifest($manifest, \%narFiles, \%patches) < 3) {
+    if (readManifest($manifest, \%narFiles, \%localPaths, \%patches) < 3) {
         die "manifest `$url' is too old (i.e., for Nix <= 0.7)\n";
     }
 
@@ -80,7 +81,7 @@ while (@ARGV) {
 }
 
 
-my $size = scalar (keys %narFiles);
+my $size = scalar (keys %narFiles) + scalar (keys %localPaths);
 print "$size store paths in manifest\n";
 
 
@@ -90,19 +91,32 @@ print STDERR "registering substitutes...\n";
 my $pid = open(WRITE, "|$binDir/nix-store --register-substitutes")
     or die "cannot run nix-store";
 
-foreach my $storePath (keys %narFiles) {
-    my $narFileList = $narFiles{$storePath};
-    foreach my $narFile (@{$narFileList}) {
+sub writeRegistration {
+    my $storePath = shift;
+    my $object = shift;
     print WRITE "$storePath\n";
-        print WRITE "$narFile->{deriver}\n";
+    print WRITE "$object->{deriver}\n";
     print WRITE "$libexecDir/nix/download-using-manifests.pl\n";
     print WRITE "0\n";
-        my @references = split " ", $narFile->{references};
+    my @references = split " ", $object->{references};
     my $count = scalar @references;
     print WRITE "$count\n";
     foreach my $reference (@references) {
         print WRITE "$reference\n";
     }
+}
+
+foreach my $storePath (keys %narFiles) {
+    my $narFileList = $narFiles{$storePath};
+    foreach my $narFile (@{$narFileList}) {
+        writeRegistration $storePath, $narFile;
+    }
+}
+
+foreach my $storePath (keys %localPaths) {
+    my $localPathList = $localPaths{$storePath};
+    foreach my $localPath (@{$localPathList}) {
+        writeRegistration $storePath, $localPath;
     }
 }
 

scripts/readmanifest.pm.in

@@ -34,6 +34,7 @@ sub addPatch {
 sub readManifest {
     my $manifest = shift;
     my $narFiles = shift;
+    my $localPaths = shift;
     my $patches = shift;
     my $allowConflicts = shift;
     $allowConflicts = 0 unless defined $allowConflicts;
@@ -57,6 +58,7 @@ sub readManifest {
     my $references;
     my $deriver;
     my $hashAlgo;
+    my $copyFrom;
 
     while (<MANIFEST>) {
         chomp;
@@ -125,9 +127,25 @@ sub readManifest {
                         }, $allowConflicts;
                 }
 
+                elsif ($type eq "localPath") {
+
+                    $$localPaths{$storePath} = []
+                        unless defined $$localPaths{$storePath};
+
+                    my $localPathsList = $$localPaths{$storePath};
+
+                    # !!! remove duplicates
+                    
+                    push @{$localPathsList},
+                        { copyFrom => $copyFrom, references => $references
+                        , deriver => ""
+                        };
+                }
+
             }
             
             elsif (/^\s*StorePath:\s*(\/\S+)\s*$/) { $storePath = $1; }
+            elsif (/^\s*CopyFrom:\s*(\/\S+)\s*$/) { $copyFrom = $1; }
             elsif (/^\s*Hash:\s*(\S+)\s*$/) { $hash = $1; }
             elsif (/^\s*URL:\s*(\S+)\s*$/) { $url = $1; }
             elsif (/^\s*Size:\s*(\d+)\s*$/) { $size = $1; }
@@ -158,6 +176,7 @@ sub writeManifest
     my $manifest = shift;
     my $narFiles = shift;
     my $patches = shift;
+    my $copySources = shift;
 
     open MANIFEST, ">$manifest.tmp"; # !!! check exclusive
 

scripts/remove-patches.pl

@@ -6,13 +6,12 @@ use readmanifest;
 for my $p (@ARGV) {
 
     my %narFiles;
+    my %localPaths;
     my %patches;
 
-    readManifest $p,
-        \%narFiles, \%patches;
+    readManifest $p, \%narFiles, \%localPaths, \%patches;
 
     %patches = ();
     
-    writeManifest $p,
-        \%narFiles, \%patches;
+    writeManifest $p, \%narFiles, \%patches;
 }

scripts/update-manifest.pl

@@ -8,9 +8,10 @@ die unless scalar @ARGV == 2;
 my $cache = $ARGV[0];
 my $manifest = $ARGV[1];
 my %narFiles;
+my %localPaths;
 my %patches;
 
-readManifest $manifest, \%narFiles, \%patches;
+readManifest $manifest, \%narFiles, \%localPaths, \%patches;
 
 foreach my $storePath (keys %narFiles) {
     my $narFileList = $narFiles{$storePath};