* nix-pack-closure: store the top-level store paths in the closure.

* nix-unpack-closure: extract the top-level paths from the closure and
  print them on stdout.  This allows them to be installed, e.g.,
  "nix-env -i $(nix-unpack-closure)".  (NIX-64)

doc/manual/nix-pack-closure.xml

@@ -58,6 +58,14 @@ $ nix-pack-closure $(which azureus) | ssh scratchy nix-unpack-closure</screen>
     
 </para>
 
+<para>As a variation on the previous example, copy
+<command>azureus</command>, and also install it in the user’s profile
+on the target machine:
+
+<screen>
+$ nix-pack-closure $(which azureus) | ssh scratchy 'nix-env -i $(nix-unpack-closure)'</screen>
+ 
+
 </refsection>
 
 

doc/manual/nix-unpack-closure.xml

@@ -22,6 +22,12 @@ closure is a single file read from standard input.  See the
 description of <command>nix-pack-closure</command> for details and
 examples.</para>
 
+<para>The top-level paths in the closure (i.e., the paths passed to
+the original <command>nix-pack-closure</command> call that created the
+closure) are printed on standard output.  These paths can be passed,
+for instance, to <literal>nix-env -i</literal> to install them into a
+user environment on the target machine.</para>
+
 </refsection>
 
 

scripts/nix-pack-closure.in

@@ -21,6 +21,7 @@ mkdir "$tmpDir/contents", 0777 or die;
 mkdir "$tmpDir/references", 0777 or die;
 mkdir "$tmpDir/derivers", 0777 or die;
 
+open TOPLEVEL, ">$tmpDir/top-level" or die;
 
 
 my %storePaths;
@@ -29,6 +30,12 @@ my %storePaths;
 while (@ARGV) {
     my $storePath = shift @ARGV;
 
+    # $storePath might be a symlink to the store, so resolve it.
+    $storePath = (`$binDir/nix-store --query --resolve '$storePath'`
+        or die "cannot resolve `$storePath'");
+    chomp $storePath;
+    print TOPLEVEL $storePath, "\n";
+
     # Get the closure of this path.
     my $pid = open(READ,
         "$binDir/nix-store --query --requisites '$storePath'|") or die;

scripts/nix-unpack-closure.in

@@ -77,3 +77,12 @@ closedir(DIR) or die;
 # Register the invalid paths as valid.
 system("nix-store --register-validity <'$tmpDir/validity'") == 0
     or die "nix-store --register-validity failed";
+
+
+# Show the top-level paths so that something useful can be done with
+# them, e.g., passing them to `nix-env -i'.
+if (-e "$tmpDir/unpacked/top-level") {
+    open TOPLEVEL, "<$tmpDir/unpacked/top-level" or die;
+    while (<TOPLEVEL>) { print "$_"; }
+    close TOPLEVEL;
+}

src/nix-store/nix-store.cc

@@ -296,7 +296,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
 {
     enum { qOutputs, qRequisites, qReferences, qReferrers
          , qReferrersClosure, qDeriver, qBinding, qHash
-         , qTree, qGraph } query = qOutputs;
+         , qTree, qGraph, qResolve } query = qOutputs;
     bool useOutput = false;
     bool includeOutputs = false;
     bool forceRealise = false;
@@ -320,6 +320,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
         else if (*i == "--hash") query = qHash;
         else if (*i == "--tree") query = qTree;
         else if (*i == "--graph") query = qGraph;
+        else if (*i == "--resolve") query = qResolve;
         else if (*i == "--use-output" || *i == "-u") useOutput = true;
         else if (*i == "--force-realise" || *i == "-f") forceRealise = true;
         else if (*i == "--include-outputs") includeOutputs = true;
@@ -410,6 +411,13 @@ static void opQuery(Strings opFlags, Strings opArgs)
             break;
         }
 
+        case qResolve: {
+            for (Strings::iterator i = opArgs.begin();
+                 i != opArgs.end(); ++i)
+                cout << format("%1%\n") % fixPath(*i);
+            break;
+        }
+            
         default:
             abort();
     }