Move all of NixOS to nixos/ in preparation of the repository merge

nixos/modules/system/etc/etc.nix

@@ -0,0 +1,117 @@
+# Management of static files in /etc.
+
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  etc' = filter (f: f.enable) (attrValues config.environment.etc);
+
+  etc = pkgs.stdenv.mkDerivation {
+    name = "etc";
+
+    builder = ./make-etc.sh;
+
+    preferLocalBuild = true;
+
+    /* !!! Use toXML. */
+    sources = map (x: x.source) etc';
+    targets = map (x: x.target) etc';
+    modes = map (x: x.mode) etc';
+  };
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    environment.etc = mkOption {
+      type = types.loaOf types.optionSet;
+      default = {};
+      example =
+        { hosts =
+            { source = "/nix/store/.../etc/dir/file.conf.example";
+              mode = "0440";
+            };
+          "default/useradd".text = "GROUP=100 ...";
+        };
+      description = ''
+        Set of files that have to be linked in <filename>/etc</filename>.
+      '';
+
+      options = singleton ({ name, config, ... }:
+        { options = {
+
+            enable = mkOption {
+              type = types.bool;
+              default = true;
+              description = ''
+                Whether this /etc file should be generated.  This
+                option allows specific /etc files to be disabled.
+              '';
+            };
+
+            target = mkOption {
+              description = ''
+                Name of symlink (relative to
+                <filename>/etc</filename>).  Defaults to the attribute
+                name.
+              '';
+            };
+
+            text = mkOption {
+              default = null;
+              type = types.nullOr types.string;
+              description = "Text of the file.";
+            };
+
+            source = mkOption {
+              types = types.path;
+              description = "Path of the source file.";
+            };
+
+            mode = mkOption {
+              default = "symlink";
+              example = "0600";
+              description = ''
+                If set to something else than <literal>symlink</literal>,
+                the file is copied instead of symlinked, with the given
+                file mode.
+              '';
+            };
+
+          };
+
+          config = {
+            target = mkDefault name;
+            source = mkIf (config.text != null)
+              (mkDefault (pkgs.writeText "etc-file" config.text));
+          };
+
+        });
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    system.build.etc = etc;
+
+    system.activationScripts.etc = stringAfter [ "stdio" ]
+      ''
+        # Set up the statically computed bits of /etc.
+        echo "setting up /etc..."
+        ${pkgs.perl}/bin/perl ${./setup-etc.pl} ${etc}/etc
+      '';
+
+  };
+
+}

nixos/modules/system/etc/make-etc.sh

@@ -0,0 +1,42 @@
+source $stdenv/setup
+
+mkdir -p $out/etc
+
+set -f
+sources_=($sources)
+targets_=($targets)
+modes_=($modes)
+set +f
+
+for ((i = 0; i < ${#targets_[@]}; i++)); do
+    source="${sources_[$i]}"
+    target="${targets_[$i]}"
+
+    if [[ "$source" =~ '*' ]]; then
+
+        # If the source name contains '*', perform globbing.
+        mkdir -p $out/etc/$target
+        for fn in $source; do
+            ln -s "$fn" $out/etc/$target/
+        done
+
+    else
+        
+        mkdir -p $out/etc/$(dirname $target)
+        if ! [ -e $out/etc/$target ]; then
+            ln -s $source $out/etc/$target
+        else
+            echo "duplicate entry $target -> $source"
+            if test "$(readlink $out/etc/$target)" != "$source"; then
+                echo "mismatched duplicate entry $(readlink $out/etc/$target) <-> $source"
+                exit 1
+            fi
+        fi
+        
+        if test "${modes_[$i]}" != symlink; then
+            echo "${modes_[$i]}" > $out/etc/$target.mode
+        fi
+        
+    fi
+done
+

nixos/modules/system/etc/setup-etc.pl

@@ -0,0 +1,68 @@
+use strict;
+use File::Find;
+use File::Copy;
+use File::Path;
+use File::Basename;
+
+my $etc = $ARGV[0] or die;
+my $static = "/etc/static";
+
+sub atomicSymlink {
+    my ($source, $target) = @_;
+    my $tmp = "$target.tmp";
+    unlink $tmp;
+    symlink $source, $tmp or return 1;
+    rename $tmp, $target or return 1;
+    return 1;
+}
+
+
+# Atomically update /etc/static to point at the etc files of the
+# current configuration.
+atomicSymlink $etc, $static or die;
+
+
+# Remove dangling symlinks that point to /etc/static.  These are
+# configuration files that existed in a previous configuration but not
+# in the current one.  For efficiency, don't look under /etc/nixos
+# (where all the NixOS sources live).
+sub cleanup {
+    if ($File::Find::name eq "/etc/nixos") {
+        $File::Find::prune = 1;
+        return;
+    }
+    if (-l $_) {
+        my $target = readlink $_;
+        if (substr($target, 0, length $static) eq $static) {
+            my $x = "/etc/static/" . substr($File::Find::name, length "/etc/");
+            unless (-l $x) {
+                print STDERR "removing obsolete symlink ‘$File::Find::name’...\n";
+                unlink "$_";
+            }
+        }
+    }
+}
+
+find(\&cleanup, "/etc");
+
+
+# For every file in the etc tree, create a corresponding symlink in
+# /etc to /etc/static.  The indirection through /etc/static is to make
+# switching to a new configuration somewhat more atomic.
+sub link {
+    my $fn = substr $File::Find::name, length($etc) + 1 or next;
+    my $target = "/etc/$fn";
+    File::Path::make_path(dirname $target);
+    if (-e "$_.mode") {
+        open MODE, "<$_.mode";
+        my $mode = <MODE>; chomp $mode;
+        close MODE;
+        copy "$static/$fn", "$target.tmp" or warn;
+        chmod oct($mode), "$target.tmp" or warn;
+        rename "$target.tmp", $target or warn;
+    } elsif (-l "$_") {
+        atomicSymlink "$static/$fn", $target or warn;
+    }
+}
+
+find(\&link, $etc);