* Make nix-env --dry-run print the paths to be substituted correctly

  again.  (After the previous substituter mechanism refactoring I
  didn't update the code that obtains the references of substitutable
  paths.)  This required some refactoring: the substituter programs
  are now kept running and receive/respond to info requests via
  stdin/stdout.

2 files changed, 81 insertions, 67 deletions

diff --git a/scripts/copy-from-other-stores.pl.in b/scripts/copy-from-other-stores.pl.in
index 74efbd7459e6..00de3ff9991e 100644
--- a/scripts/copy-from-other-stores.pl.in
+++ b/scripts/copy-from-other-stores.pl.in
@@ -2,6 +2,9 @@
 
 use strict;
 use File::Basename;
+use IO::Handle;
+
+STDOUT->autoflush(1);
 
 my @remoteStoresAll = split ':', ($ENV{"NIX_OTHER_STORES"} or "");
 
@@ -33,42 +36,46 @@ sub findStorePath {
 }
 
 
-if ($ARGV[0] eq "--query-paths") {
-    foreach my $store (@remoteStores) {
-        opendir DIR, "$store/var/nix/db/info" or next;
-        print "@storedir@/$_\n" foreach readdir DIR;
-        closedir DIR;
-    }
-}
+if ($ARGV[0] eq "--query") {
 
+    while (<STDIN>) {
+        my $cmd = $_; chomp $cmd;
 
-elsif ($ARGV[0] eq "--query-info") {
-    shift @ARGV;
-    
-    foreach my $storePath (@ARGV) {
-
-        (my $infoFile) = findStorePath $storePath;
-        next unless $infoFile;
-        
-        my $deriver = "";
-        my @references = ();
-
-        open INFO, "<$infoFile" or die "cannot read info file $infoFile\n";
-        while (<INFO>) {
-            chomp;
-            #print STDERR "GOT $_\n";
-            /^([\w-]+): (.*)$/ or die "bad info file";
-            my $key = $1;
-            my $value = $2;
-            if ($key eq "Deriver") { $deriver = $value; }
-            elsif ($key eq "References") { @references = split ' ', $value; }
+        if ($cmd eq "have") {
+            my $storePath = <STDIN>; chomp $storePath;
+            (my $infoFile) = findStorePath $storePath;
+            print STDOUT ($infoFile ? "1\n" : "0\n");
+        }
+
+        elsif ($cmd eq "info") {
+            my $storePath = <STDIN>; chomp $storePath;
+            (my $infoFile) = findStorePath $storePath;
+            if (!$infoFile) {
+                print "0\n";
+                next; # not an error
+            }
+            print "1\n";
+
+            my $deriver = "";
+            my @references = ();
+
+            open INFO, "<$infoFile" or die "cannot read info file $infoFile\n";
+            while (<INFO>) {
+                chomp;
+                /^([\w-]+): (.*)$/ or die "bad info file";
+                my $key = $1;
+                my $value = $2;
+                if ($key eq "Deriver") { $deriver = $value; }
+                elsif ($key eq "References") { @references = split ' ', $value; }
+            }
+            close INFO;
+
+            print "$deriver\n";
+            print scalar @references, "\n";
+            print "$_\n" foreach @references;
         }
-        close INFO;
 
-        print "$storePath\n";
-        print "$deriver\n";
-        print scalar @references, "\n";
-        print "$_\n" foreach @references;
+        else { die "unknown command `$cmd'"; }
     }
 }
 
diff --git a/scripts/download-using-manifests.pl.in b/scripts/download-using-manifests.pl.in
index c0b822b912e4..e862a2d9fb1b 100644
--- a/scripts/download-using-manifests.pl.in
+++ b/scripts/download-using-manifests.pl.in
@@ -5,27 +5,18 @@ use readmanifest;
 use POSIX qw(strftime);
 use File::Temp qw(tempdir);
 
+STDOUT->autoflush(1);
+
 my $manifestDir = "@localstatedir@/nix/manifests";
 my $logFile = "@localstatedir@/log/nix/downloads";
 
 
-# Create a temporary directory.
-my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
-    or die "cannot create a temporary directory";
-
-chdir $tmpDir or die "cannot change to `$tmpDir': $!";
-
-my $tmpNar = "$tmpDir/nar";
-my $tmpNar2 = "$tmpDir/nar2";
-
-
 # Load all manifests.
 my %narFiles;
 my %localPaths;
 my %patches;
 
 for my $manifest (glob "$manifestDir/*.nixmanifest") {
-#    print STDERR "reading $manifest\n";
     if (readManifest($manifest, \%narFiles, \%localPaths, \%patches) < 3) {
         print STDERR "you have an old-style manifest `$manifest'; please delete it\n";
         exit 1;
@@ -35,34 +26,40 @@ for my $manifest (glob "$manifestDir/*.nixmanifest") {
 
 # Parse the arguments.
 
-if ($ARGV[0] eq "--query-paths") {
-    foreach my $storePath (keys %narFiles) { print "$storePath\n"; }
-    foreach my $storePath (keys %localPaths) { print "$storePath\n"; }
-    exit 0;
-}
+if ($ARGV[0] eq "--query") {
 
-elsif ($ARGV[0] eq "--query-info") {
-    shift @ARGV;
-    foreach my $storePath (@ARGV) {
-        my $info;
-        if (defined $narFiles{$storePath}) {
-            $info = @{$narFiles{$storePath}}[0];
-        }
-        elsif (defined $localPaths{$storePath}) {
-            $info = @{$localPaths{$storePath}}[0];
-        }
-        else {
-            next; # not an error
+    while (<STDIN>) {
+        my $cmd = $_; chomp $cmd;
+
+        if ($cmd eq "have") {
+            my $storePath = <STDIN>; chomp $storePath;
+            print STDOUT ((defined $narFiles{$storePath} or defined $localPaths{$storePath})
+                ? "1\n" : "0\n");
         }
-        print "$storePath\n";
-        print "$info->{deriver}\n";
-        my @references = split " ", $info->{references};
-        my $count = scalar @references;
-        print "$count\n";
-        foreach my $reference (@references) {
-            print "$reference\n";
+
+        elsif ($cmd eq "info") {
+            my $storePath = <STDIN>; chomp $storePath;
+            my $info;
+            if (defined $narFiles{$storePath}) {
+                $info = @{$narFiles{$storePath}}[0];
+            }
+            elsif (defined $localPaths{$storePath}) {
+                $info = @{$localPaths{$storePath}}[0];
+            }
+            else {
+                print "0\n";
+                next; # not an error
+            }
+            print "1\n";
+            print "$info->{deriver}\n";
+            my @references = split " ", $info->{references};
+            print scalar @references, "\n";
+            print "$_\n" foreach @references;
         }
+        
+        else { die "unknown command `$cmd'"; }
     }
+
     exit 0;
 }
 
@@ -75,6 +72,16 @@ die unless scalar @ARGV == 2;
 my $targetPath = $ARGV[1];
 
 
+# Create a temporary directory.
+my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
+    or die "cannot create a temporary directory";
+
+chdir $tmpDir or die "cannot change to `$tmpDir': $!";
+
+my $tmpNar = "$tmpDir/nar";
+my $tmpNar2 = "$tmpDir/nar2";
+
+
 open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
 
 my $date = strftime ("%F %H:%M:%S UTC", gmtime (time));