home-manager: handle missing per-user profiles directory

Specifically, if the global per-user profiles path do not exist and we
cannot create it during the activation, then place our profile in the
Home Manager data directory. We prefer to use the global location,
though, since it makes it visible to `nix-collect-garbage`.

This is intended to improve compatibility with Nix version 2.14 and
later, which no longer creates the per-user directories.

Also, use the Home Manager data directory to manage the gcroot for the
current generation. It does not have to sit in the global per-user
gcroots directory since it should never be eligible for GC.

home-manager/home-manager

@@ -19,7 +19,7 @@ function removeByName() {
 }
 
 function setNixProfileCommands() {
-    if [[ -e ~/.nix-profile/manifest.json ]] ; then
+    if [[ -e $HOME/.nix-profile/manifest.json ]] ; then
         LIST_OUTPATH_CMD="nix profile list"
         REMOVE_CMD="removeByName"
     else
@@ -93,6 +93,23 @@ function setHomeManagerNixPath() {
     done
 }
 
+# Sets some useful Home Manager related paths as global read-only variables.
+function setHomeManagerPathVariables() {
+    declare -r nixStateDir="${NIX_STATE_DIR:-/nix/var/nix}"
+    declare -r globalProfilesDir="$nixStateDir/profiles/per-user/$USER"
+    declare -r globalGcrootsDir="$nixStateDir/gcroots/per-user/$USER"
+
+    declare -gr HM_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}/home-manager"
+    declare -gr HM_STATE_DIR="${XDG_STATE_HOME:-$HOME/.local/state}/home-manager"
+    declare -gr HM_GCROOT_LEGACY_PATH="$globalGcrootsDir/current-home"
+
+    if [[ -d "$globalProfilesDir" ]]; then
+        declare -gr HM_PROFILE_DIR="$globalProfilesDir"
+    else
+        declare -gr HM_PROFILE_DIR="$HM_STATE_DIR/profiles"
+    fi
+}
+
 function setFlakeAttribute() {
     local configFlake="${XDG_CONFIG_HOME:-$HOME/.config}/nixpkgs/flake.nix"
     if [[ -z $FLAKE_ARG && ! -v HOME_MANAGER_CONFIG && -e "$configFlake" ]]; then
@@ -339,7 +356,7 @@ function doListGens() {
         color="always"
     fi
 
-    pushd "$NIX_STATE_DIR/profiles/per-user/$USER" > /dev/null
+    pushd "$HM_PROFILE_DIR" > /dev/null
     # shellcheck disable=2012
     ls --color=$color -gG --time-style=long-iso --sort time home-manager-*-link \
         | cut -d' ' -f 4- \
@@ -352,7 +369,7 @@ function doListGens() {
 function doRmGenerations() {
     setVerboseAndDryRun
 
-    pushd "$NIX_STATE_DIR/profiles/per-user/$USER" > /dev/null
+    pushd "$HM_PROFILE_DIR" > /dev/null
 
     for generationId in "$@"; do
         local linkName="home-manager-$generationId-link"
@@ -370,17 +387,10 @@ function doRmGenerations() {
     popd > /dev/null
 }
 
-function doRmAllGenerations() {
-    $DRY_RUN_CMD rm $VERBOSE_ARG \
-        "$NIX_STATE_DIR/profiles/per-user/$USER/home-manager"*
-}
-
 function doExpireGenerations() {
-    local profileDir="$NIX_STATE_DIR/profiles/per-user/$USER"
-
     local generations
     generations="$( \
-        find "$profileDir" -name 'home-manager-*-link' -not -newermt "$1" \
+        find "$HM_PROFILE_DIR" -name 'home-manager-*-link' -not -newermt "$1" \
         | sed 's/^.*-\([0-9]*\)-link$/\1/' \
     )"
 
@@ -482,6 +492,7 @@ function doUninstall() {
     read -r -n 1 -p "$(_i 'Really uninstall Home Manager?') [y/n] " confirmation
     echo
 
+    # shellcheck disable=2086
     case $confirmation in
         y|Y)
             _i "Switching to empty Home Manager configuration..."
@@ -493,10 +504,22 @@ function doUninstall() {
             doSwitch
             $DRY_RUN_CMD $REMOVE_CMD home-manager-path || true
             rm "$HOME_MANAGER_CONFIG"
-            $DRY_RUN_CMD rm $VERBOSE_ARG -r \
+
-                "${XDG_DATA_HOME:-$HOME/.local/share}/home-manager"
+            if [[ -e $HM_DATA_HOME ]]; then
-            $DRY_RUN_CMD rm $VERBOSE_ARG \
+                $DRY_RUN_CMD rm $VERBOSE_ARG -r "$HM_DATA_HOME"
-                "$NIX_STATE_DIR/gcroots/per-user/$USER/current-home"
+            fi
+
+            if [[ -e $HM_PROFILE_DIR ]]; then
+                $DRY_RUN_CMD rm $VERBOSE_ARG "$HM_PROFILE_DIR/home-manager"*
+            fi
+
+            if [[ -e $HM_GCROOT_LEGACY_PATH ]]; then
+                $DRY_RUN_CMD rm $VERBOSE_ARG "$HM_GCROOT_LEGACY_PATH"
+            fi
+
+            if [[ -e $HM_STATE_DIR ]]; then
+                $DRY_RUN_CMD rm $VERBOSE_ARG -r "$HM_STATE_DIR"
+            fi
             ;;
         *)
             _i "Yay!"
@@ -504,22 +527,6 @@ function doUninstall() {
             ;;
     esac
 
-    local deleteProfiles
-    read -r -n 1 \
-         -p "$(_i 'Remove all Home Manager generations?') [y/n] " \
-         deleteProfiles
-    echo
-
-    case $deleteProfiles in
-        y|Y)
-            doRmAllGenerations
-            _i 'All generations are now eligible for garbage collection.'
-            ;;
-        *)
-            _i 'Leaving generations but they may still be garbage collected.'
-            ;;
-    esac
-
     _i "Home Manager is uninstalled but your home.nix is left untouched."
 }
 
@@ -591,8 +598,6 @@ function doHelp() {
     echo "  uninstall    Remove Home Manager"
 }
 
-readonly NIX_STATE_DIR="${NIX_STATE_DIR:-/nix/var/nix}"
-
 EXTRA_NIX_PATH=()
 HOME_MANAGER_CONFIG_ATTRIBUTE=""
 PASSTHROUGH_OPTS=()
@@ -601,6 +606,7 @@ COMMAND_ARGS=()
 FLAKE_ARG=""
 
 setHomeManagerNixPath
+setHomeManagerPathVariables
 
 while [[ $# -gt 0 ]]; do
     opt="$1"

home-manager/po/home-manager.pot

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Home Manager\n"
 "Report-Msgid-Bugs-To: https://github.com/nix-community/home-manager/issues\n"
-"POT-Creation-Date: 2022-03-26 15:08+0100\n"
+"POT-Creation-Date: 2023-03-07 23:36+0100\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -26,15 +26,15 @@ msgstr ""
 msgid "No configuration file found. Please create one at %s"
 msgstr ""
 
-#: home-manager/home-manager:122
+#: home-manager/home-manager:146
 msgid "Can't inspect options of a flake configuration"
 msgstr ""
 
-#: home-manager/home-manager:162
+#: home-manager/home-manager:185
 msgid "Can't instantiate a flake configuration"
 msgstr ""
 
-#: home-manager/home-manager:237
+#: home-manager/home-manager:258
 msgid ""
 "There is %d unread and relevant news item.\n"
 "Read it by running the command \"%s news\"."
@@ -44,92 +44,80 @@ msgid_plural ""
 msgstr[0] ""
 msgstr[1] ""
 
-#: home-manager/home-manager:251
+#: home-manager/home-manager:272
 msgid "Unknown \"news.display\" setting \"%s\"."
 msgstr ""
 
-#: home-manager/home-manager:258
+#: home-manager/home-manager:279
 #, sh-format
 msgid "Please set the $EDITOR environment variable"
 msgstr ""
 
-#: home-manager/home-manager:273
+#: home-manager/home-manager:294
 msgid "Cannot run build in read-only directory"
 msgstr ""
 
-#: home-manager/home-manager:355
+#: home-manager/home-manager:378
 msgid "No generation with ID %s"
 msgstr ""
 
-#: home-manager/home-manager:357
+#: home-manager/home-manager:380
 msgid "Cannot remove the current generation %s"
 msgstr ""
 
-#: home-manager/home-manager:359
+#: home-manager/home-manager:382
 msgid "Removing generation %s"
 msgstr ""
 
-#: home-manager/home-manager:385
+#: home-manager/home-manager:401
 msgid "No generations to expire"
 msgstr ""
 
-#: home-manager/home-manager:396
+#: home-manager/home-manager:412
 msgid "No home-manager packages seem to be installed."
 msgstr ""
 
-#: home-manager/home-manager:453
+#: home-manager/home-manager:469
 msgid "Unknown argument %s"
 msgstr ""
 
-#: home-manager/home-manager:469
+#: home-manager/home-manager:485
 msgid "This will remove Home Manager from your system."
 msgstr ""
 
-#: home-manager/home-manager:472
+#: home-manager/home-manager:488
 msgid "This is a dry run, nothing will actually be uninstalled."
 msgstr ""
 
-#: home-manager/home-manager:476
+#: home-manager/home-manager:492
 msgid "Really uninstall Home Manager?"
 msgstr ""
 
-#: home-manager/home-manager:481
+#: home-manager/home-manager:498
 msgid "Switching to empty Home Manager configuration..."
 msgstr ""
 
-#: home-manager/home-manager:493
+#: home-manager/home-manager:525
 msgid "Yay!"
 msgstr ""
 
-#: home-manager/home-manager:500
+#: home-manager/home-manager:530
-msgid "Remove all Home Manager generations?"
-msgstr ""
-
-#: home-manager/home-manager:507
-msgid "All generations are now eligible for garbage collection."
-msgstr ""
-
-#: home-manager/home-manager:510
-msgid "Leaving generations but they may still be garbage collected."
-msgstr ""
-
-#: home-manager/home-manager:514
 msgid "Home Manager is uninstalled but your home.nix is left untouched."
 msgstr ""
 
-#: home-manager/home-manager:673
+#: home-manager/home-manager:695
 msgid "%s: unknown option '%s'"
 msgstr ""
 
-#: home-manager/home-manager:674
+#: home-manager/home-manager:696
 msgid "Run '%s --help' for usage help"
 msgstr ""
 
-#: home-manager/home-manager:708
+#: home-manager/home-manager:730
 msgid "expire-generations expects one argument, got %d."
 msgstr ""
 
-#: home-manager/home-manager:730
+#: home-manager/home-manager:752
 msgid "Unknown command: %s"
 msgstr ""
 

modules/files.nix

@@ -272,7 +272,10 @@ in
               $DRY_RUN_CMD nix-env $VERBOSE_ARG --profile "$genProfilePath" --set "$newGenPath"
             fi
 
-            $DRY_RUN_CMD ln -Tsf $VERBOSE_ARG "$newGenPath" "$newGenGcPath"
+            $DRY_RUN_CMD nix-store --realise "$newGenPath" --add-root "$newGenGcPath" > "$DRY_RUN_NULL"
+            if [[ -e "$legacyGenGcPath" ]]; then
+              $DRY_RUN_CMD rm $VERBOSE_ARG "$legacyGenGcPath"
+            fi
           else
             _i "No change so reusing latest profile generation %s" "$oldGenNum"
           fi

modules/home-environment.nix

@@ -584,7 +584,7 @@ in
       if config.submoduleSupport.externalPackageInstall
       then
         ''
-          if [[ -e "$nixProfilePath"/manifest.json ]] ; then
+          if [[ -e $HOME/.nix-profile/manifest.json ]] ; then
             nix profile list \
               | { grep 'home-manager-path$' || test $? = 1; } \
               | cut -d ' ' -f 4 \
@@ -608,7 +608,7 @@ in
             $DRY_RUN_CMD $oldNix profile install $1
           }
 
-          if [[ -e "$nixProfilePath"/manifest.json ]] ; then
+          if [[ -e $HOME/.nix-profile/manifest.json ]] ; then
             INSTALL_CMD="nix profile install"
             INSTALL_CMD_ACTUAL="nixReplaceProfile"
             LIST_CMD="nix profile list"

modules/lib-bash/activation-init.sh

@@ -1,14 +1,60 @@
+# Moves the existing profile from /nix to ~ to match changed behavior in Nix
+# 2.14. See https://github.com/NixOS/nix/pull/5226.
+#
+# Note, this function is intentionally unused for now. There remains a few open
+# questions about backwards compatibility and support from
+# `nix-collect-garbage`.
+function migrateProfile() {
+    declare -r stateHome="${XDG_STATE_HOME:-$HOME/.local/state}"
+    declare -r hmStateDir="$stateHome/home-manager"
+    declare -r nixStateDir="${NIX_STATE_DIR:-/nix/var/nix}"
+
+    declare -r newProfilesDir="$hmStateDir/profiles"
+    declare -r oldProfilesDir="$nixStateDir/profiles/per-user/$USER"
+
+    if [[ ! -d $newProfilesDir ]]; then
+        _i 'Migrating profiles from %s to %s' "$oldProfilesDir" "$newProfilesDir"
+        mkdir -p "$newProfilesDir"
+        for p in "$oldProfilesDir"/home-manager-*; do
+            declare -r name="${p##*/}"
+            nix-store --realise "$p" --add-root "$newProfilesDir/$name" > /dev/null
+        done
+        cp -P "$oldProfilesDir/home-manager" "$newProfilesDir"
+    fi
+
+    rm "$oldProfilesDir"/home-manager-*
+}
+
 function setupVars() {
-    local nixStateDir="${NIX_STATE_DIR:-/nix/var/nix}"
+    declare -r nixStateDir="${NIX_STATE_DIR:-/nix/var/nix}"
-    local profilesPath="$nixStateDir/profiles/per-user/$USER"
+    declare -r globalProfilesDir="$nixStateDir/profiles/per-user/$USER"
-    local gcPath="$nixStateDir/gcroots/per-user/$USER"
+    declare -r globalGcrootsDir="$nixStateDir/gcroots/per-user/$USER"
 
-    declare -gr nixProfilePath="$profilesPath/profile"
+    declare -r stateHome="${XDG_STATE_HOME:-$HOME/.local/state}"
-    declare -gr genProfilePath="$profilesPath/home-manager"
+    declare -r hmStateDir="$stateHome/home-manager"
+    declare -r hmGcrootsDir="$hmStateDir/gcroots"
+
+    # If the global profiles path exists or we can create it, then place the HM
+    # profile there. Otherwise place it in the HM data directory. We prefer to
+    # use the global location since it makes it visible to
+    # `nix-collect-garbage`.
+    #
+    # In the future we may perform a one-shot migration to the new location.
+    #
+    # shellcheck disable=2174
+    if [[ -d "$globalProfilesDir" ]] || mkdir -m 0755 -p "$globalProfilesDir"; then
+        declare -r hmProfilesDir="$globalProfilesDir"
+    else
+        declare -r hmProfilesDir="$hmStateDir/profiles"
+        mkdir -m 0755 -p "$hmProfilesDir"
+    fi
+
+    declare -gr genProfilePath="$hmProfilesDir/home-manager"
     declare -gr newGenPath="@GENERATION_DIR@";
-    declare -gr newGenGcPath="$gcPath/current-home"
+    declare -gr newGenGcPath="$hmGcrootsDir/current-home"
+    declare -gr legacyGenGcPath="$globalGcrootsDir/current-home"
 
-    local greatestGenNum
+    declare greatestGenNum
     greatestGenNum=$( \
         nix-env --list-generations --profile "$genProfilePath" \
             | tail -1 \
@@ -21,9 +67,9 @@ function setupVars() {
         declare -gr newGenNum=1
     fi
 
-    if [[ -e $profilesPath/home-manager ]] ; then
+    if [[ -e $genProfilePath ]] ; then
-        oldGenPath="$(readlink -e "$profilesPath/home-manager")"
+        declare -g oldGenPath
-        declare -gr oldGenPath
+        oldGenPath="$(readlink -e "$genProfilePath")"
     fi
 
     $VERBOSE_RUN _i "Sanity checking oldGenNum and oldGenPath"
@@ -31,7 +77,7 @@ function setupVars() {
             || ! -v oldGenNum && -v oldGenPath ]]; then
         _i $'The previous generation number and path are in conflict! These\nmust be either both empty or both set but are now set to\n\n    \'%s\' and \'%s\'\n\nIf you don\'t mind losing previous profile generations then\nthe easiest solution is probably to run\n\n   rm %s/home-manager*\n   rm %s/current-home\n\nand trying home-manager switch again. Good luck!' \
            "${oldGenNum:-}" "${oldGenPath:-}" \
-           "$profilesPath" "$gcPath"
+           "$hmProfilesDir" "$hmGcrootsDir"
         exit 1
     fi
 }
@@ -58,9 +104,12 @@ setupVars
 if [[ -v DRY_RUN ]] ; then
     _i "This is a dry run"
     export DRY_RUN_CMD=echo
+    export DRY_RUN_NULL=/dev/stdout
 else
     $VERBOSE_RUN _i "This is a live run"
     export DRY_RUN_CMD=""
+    export DRY_RUN_NULL=/dev/null
+
 fi
 
 if [[ -v VERBOSE ]]; then
@@ -77,5 +126,6 @@ else
 fi
 $VERBOSE_ECHO "  newGenPath=$newGenPath"
 $VERBOSE_ECHO "  newGenNum=$newGenNum"
-$VERBOSE_ECHO "  newGenGcPath=$newGenGcPath"
 $VERBOSE_ECHO "  genProfilePath=$genProfilePath"
+$VERBOSE_ECHO "  newGenGcPath=$newGenGcPath"
+$VERBOSE_ECHO "  legacyGenGcPath=$legacyGenGcPath"

modules/po/hm-modules.pot

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Home Manager Modules\n"
 "Report-Msgid-Bugs-To: https://github.com/nix-community/home-manager/issues\n"
-"POT-Creation-Date: 2022-03-26 15:08+0100\n"
+"POT-Creation-Date: 2023-03-07 23:36+0100\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -17,23 +17,23 @@ msgstr ""
 "Content-Type: text/plain; charset=CHARSET\n"
 "Content-Transfer-Encoding: 8bit\n"
 
-#: modules/files.nix:233
+#: modules/files.nix:234
 msgid "Creating home file links in %s"
 msgstr ""
 
-#: modules/files.nix:246
+#: modules/files.nix:247
 msgid "Cleaning up orphan links from %s"
 msgstr ""
 
-#: modules/files.nix:262
+#: modules/files.nix:263
 msgid "Creating profile generation %s"
 msgstr ""
 
-#: modules/files.nix:276
+#: modules/files.nix:280
 msgid "No change so reusing latest profile generation %s"
 msgstr ""
 
-#: modules/home-environment.nix:607
+#: modules/home-environment.nix:625
 msgid ""
 "Oops, Nix failed to install your new Home Manager profile!\n"
 "\n"
@@ -49,15 +49,19 @@ msgid ""
 "Then try activating your Home Manager configuration again."
 msgstr ""
 
-#: modules/home-environment.nix:639
+#: modules/home-environment.nix:658
 msgid "Activating %s"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:31
+#: modules/lib-bash/activation-init.sh:18
+msgid "Migrating profiles from %s to %s"
+msgstr ""
+
+#: modules/lib-bash/activation-init.sh:77
 msgid "Sanity checking oldGenNum and oldGenPath"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:34
+#: modules/lib-bash/activation-init.sh:80
 msgid ""
 "The previous generation number and path are in conflict! These\n"
 "must be either both empty or both set but are now set to\n"
@@ -73,26 +77,26 @@ msgid ""
 "and trying home-manager switch again. Good luck!"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:51
+#: modules/lib-bash/activation-init.sh:97
 msgid "Starting Home Manager activation"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:55
+#: modules/lib-bash/activation-init.sh:101
 msgid "Sanity checking Nix"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:61
+#: modules/lib-bash/activation-init.sh:107
 msgid "This is a dry run"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:64
+#: modules/lib-bash/activation-init.sh:111
 msgid "This is a live run"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:69
+#: modules/lib-bash/activation-init.sh:118
 msgid "Using Nix version: %s"
 msgstr ""
 
-#: modules/lib-bash/activation-init.sh:72
+#: modules/lib-bash/activation-init.sh:121
 msgid "Activation variables:"
 msgstr ""