Fix root channels location

.github/workflows/ci.yml

@@ -58,7 +58,7 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v19
+    - uses: cachix/install-nix-action@v20
       with:
         install_url: https://releases.nixos.org/nix/nix-2.13.3/install
     - uses: cachix/cachix-action@v12
@@ -79,7 +79,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v19
+    - uses: cachix/install-nix-action@v20
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
@@ -91,6 +91,8 @@ jobs:
     - run: exec sh -c "nix-instantiate -E 'builtins.currentTime' --eval"
     - run: exec zsh -c "nix-instantiate -E 'builtins.currentTime' --eval"
     - run: exec fish -c "nix-instantiate -E 'builtins.currentTime' --eval"
+    - run: exec bash -c "nix-channel --add https://releases.nixos.org/nixos/unstable/nixos-23.05pre466020.60c1d71f2ba nixpkgs"
+    - run: exec bash -c "nix-channel --update && nix-env -iA nixpkgs.hello && hello"
 
   docker_push_image:
     needs: [check_secrets, tests]
@@ -104,7 +106,7 @@ jobs:
     - uses: actions/checkout@v3
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v19
+    - uses: cachix/install-nix-action@v20
       with:
         install_url: https://releases.nixos.org/nix/nix-2.13.3/install
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV

src/libexpr/eval.cc

@@ -8,6 +8,7 @@
 #include "eval-inline.hh"
 #include "filetransfer.hh"
 #include "function-trace.hh"
+#include "profiles.hh"
 
 #include <algorithm>
 #include <chrono>
@@ -2491,8 +2492,8 @@ Strings EvalSettings::getDefaultNixPath()
 
     if (!evalSettings.restrictEval && !evalSettings.pureEval) {
         add(settings.useXDGBaseDirectories ? getStateDir() + "/nix/defexpr/channels" : getHome() + "/.nix-defexpr/channels");
-        add(settings.nixStateDir + "/profiles/per-user/root/channels/nixpkgs", "nixpkgs");
-        add(settings.nixStateDir + "/profiles/per-user/root/channels");
+        add(rootChannelsDir() + "/nixpkgs", "nixpkgs");
+        add(rootChannelsDir());
     }
 
     return res;

src/libstore/profiles.cc

@@ -282,28 +282,48 @@ std::string optimisticLockProfile(const Path & profile)
 
 Path profilesDir()
 {
-    auto profileRoot = createNixStateDir() + "/profiles";
+    auto profileRoot =
+        (getuid() == 0)
+        ? rootProfilesDir()
+        : createNixStateDir() + "/profiles";
     createDirs(profileRoot);
     return profileRoot;
 }
 
+Path rootProfilesDir()
+{
+    return settings.nixStateDir + "/profiles/per-user/root";
+}
+
 
 Path getDefaultProfile()
 {
     Path profileLink = settings.useXDGBaseDirectories ? createNixStateDir() + "/profile" : getHome() + "/.nix-profile";
     try {
-        auto profile =
-            getuid() == 0
-            ? settings.nixStateDir + "/profiles/default"
-            : profilesDir() + "/profile";
+        auto profile = profilesDir() + "/profile";
         if (!pathExists(profileLink)) {
             replaceSymlink(profile, profileLink);
         }
+        // Backwards compatibiliy measure: Make root's profile available as
+        // `.../default` as it's what NixOS and most of the init scripts expect
+        Path globalProfileLink = settings.nixStateDir + "/profiles/default";
+        if (getuid() == 0 && !pathExists(globalProfileLink)) {
+            replaceSymlink(profile, globalProfileLink);
+        }
         return absPath(readLink(profileLink), dirOf(profileLink));
     } catch (Error &) {
         return profileLink;
     }
 }
 
+Path defaultChannelsDir()
+{
+    return profilesDir() + "/channels";
+}
+
+Path rootChannelsDir()
+{
+    return rootProfilesDir() + "/channels";
+}
 
 }

src/libstore/profiles.hh

@@ -68,13 +68,32 @@ void lockProfile(PathLocks & lock, const Path & profile);
    rebuilt. */
 std::string optimisticLockProfile(const Path & profile);
 
-/* Creates and returns the path to a directory suitable for storing the user’s
-   profiles. */
+/**
+ * Create and return the path to a directory suitable for storing the user’s
+ * profiles.
+ */
 Path profilesDir();
 
-/* Resolve the default profile (~/.nix-profile by default, $XDG_STATE_HOME/
-   nix/profile if XDG Base Directory Support is enabled), and create if doesn't
-   exist */
+/**
+ * Return the path to the profile directory for root (but don't try creating it)
+ */
+Path rootProfilesDir();
+
+/**
+ * Create and return the path to the file used for storing the users's channels
+ */
+Path defaultChannelsDir();
+
+/**
+ * Return the path to the channel directory for root (but don't try creating it)
+ */
+Path rootChannelsDir();
+
+/**
+ * Resolve the default profile (~/.nix-profile by default,
+ * $XDG_STATE_HOME/nix/profile if XDG Base Directory Support is enabled),
+ * and create if doesn't exist
+ */
 Path getDefaultProfile();
 
 }

src/nix-channel/nix-channel.cc

@@ -168,7 +168,8 @@ static int main_nix_channel(int argc, char ** argv)
         nixDefExpr = settings.useXDGBaseDirectories ? createNixStateDir() + "/defexpr" : home + "/.nix-defexpr";
 
         // Figure out the name of the channels profile.
-        profile = profilesDir() + "/channels";
+        profile = profilesDir() +  "/channels";
+        createDirs(dirOf(profile));
 
         enum {
             cNone,

src/nix-env/nix-env.cc

@@ -1403,11 +1403,11 @@ static int main_nix_env(int argc, char * * argv)
             try {
                 createDirs(globals.instSource.nixExprPath);
                 replaceSymlink(
-                    fmt("%s/profiles/per-user/%s/channels", settings.nixStateDir, getUserName()),
+                    defaultChannelsDir(),
                     globals.instSource.nixExprPath + "/channels");
                 if (getuid() != 0)
                     replaceSymlink(
-                        fmt("%s/profiles/per-user/root/channels", settings.nixStateDir),
+                        rootChannelsDir(),
                         globals.instSource.nixExprPath + "/channels_root");
             } catch (Error &) { }
         }

tests/installer/default.nix

@@ -30,6 +30,14 @@ let
     };
   };
 
+  mockChannel = pkgs:
+    pkgs.runCommandNoCC "mock-channel" {} ''
+      mkdir nixexprs
+      mkdir $out
+      echo -n 'someContent' > nixexprs/someFile
+      tar cvf - nixexprs | bzip2 > $out/nixexprs.tar.bz2
+    '';
+
   disableSELinux = "sudo setenforce 0";
 
   images = {
@@ -189,6 +197,9 @@ let
         echo "Running installer..."
         $ssh "set -eux; $installScript"
 
+        echo "Copying the mock channel"
+        scp -r -P 20022 $ssh_opts ${mockChannel pkgs} vagrant@localhost:channel
+
         echo "Testing Nix installation..."
         $ssh <<EOF
           set -ex
@@ -204,6 +215,17 @@ let
 
           out=\$(nix-build --no-substitute -E 'derivation { name = "foo"; system = "x86_64-linux"; builder = "/bin/sh"; args = ["-c" "echo foobar > \$out"]; }')
           [[ \$(cat \$out) = foobar ]]
+
+          if pgrep nix-daemon; then
+            MAYBESUDO="sudo"
+          else
+            MAYBESUDO=""
+          fi
+
+
+          $MAYBESUDO \$(which nix-channel) --add file://\$HOME/channel myChannel
+          $MAYBESUDO \$(which nix-channel) --update
+          [[ \$(nix-instantiate --eval --expr 'builtins.readFile <myChannel/someFile>') = '"someContent"' ]]
         EOF
 
         echo "Done!"