Restore system-install profile files from the previous installer

These files are required to get Nix in PATH in existing multi-user installs using
the legacy installer. We really could use some tests.

Cc: https://git.lix.systems/lix-project/lix/issues/33

This partially reverts commit 93cc063344323a8b0d630d0a67acd121cdc3f86a.

Fixes: https://git.lix.systems/lix-project/lix/issues/173

Change-Id: Iafb55280596732670a432f604b897f48562868e4

3 files changed, 131 insertions, 0 deletions

diff --git a/scripts/local.mk b/scripts/local.mk
index cf2288bb6..46255e432 100644
--- a/scripts/local.mk
+++ b/scripts/local.mk
@@ -7,5 +7,7 @@ profiledir = $(sysconfdir)/profile.d
 
 $(eval $(call install-file-as, $(d)/nix-profile.sh, $(profiledir)/nix.sh, 0644))
 $(eval $(call install-file-as, $(d)/nix-profile.fish, $(profiledir)/nix.fish, 0644))
+$(eval $(call install-file-as, $(d)/nix-profile-daemon.sh, $(profiledir)/nix-daemon.sh, 0644))
+$(eval $(call install-file-as, $(d)/nix-profile-daemon.fish, $(profiledir)/nix-daemon.fish, 0644))
 
 clean-files += $(nix_noinst_scripts)
diff --git a/scripts/nix-profile-daemon.fish.in b/scripts/nix-profile-daemon.fish.in
new file mode 100644
index 000000000..c23aa64f0
--- /dev/null
+++ b/scripts/nix-profile-daemon.fish.in
@@ -0,0 +1,57 @@
+function add_path --argument-names new_path
+    if type -q fish_add_path
+        # fish 3.2.0 or newer
+	fish_add_path --prepend --global $new_path
+    else
+        # older versions of fish
+        if not contains $new_path $fish_user_paths
+            set --global fish_user_paths $new_path $fish_user_paths
+        end
+    end
+end
+
+# Only execute this file once per shell.
+if test -n "$__ETC_PROFILE_NIX_SOURCED"
+  exit
+end
+
+set __ETC_PROFILE_NIX_SOURCED 1
+
+set --export NIX_PROFILES "@localstatedir@/nix/profiles/default $HOME/.nix-profile"
+
+# Populate bash completions, .desktop files, etc
+if test -z "$XDG_DATA_DIRS"
+    # According to XDG spec the default is /usr/local/share:/usr/share, don't set something that prevents that default
+    set --export XDG_DATA_DIRS "/usr/local/share:/usr/share:/nix/var/nix/profiles/default/share"
+else
+    set --export XDG_DATA_DIRS "$XDG_DATA_DIRS:/nix/var/nix/profiles/default/share"
+end
+
+# Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
+if test -n "$NIX_SSH_CERT_FILE"
+  : # Allow users to override the NIX_SSL_CERT_FILE
+else if test -e /etc/ssl/certs/ca-certificates.crt # NixOS, Ubuntu, Debian, Gentoo, Arch
+  set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-certificates.crt
+else if test -e /etc/ssl/ca-bundle.pem # openSUSE Tumbleweed
+  set --export NIX_SSL_CERT_FILE /etc/ssl/ca-bundle.pem
+else if test -e /etc/ssl/certs/ca-bundle.crt # Old NixOS
+  set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-bundle.crt
+else if test -e /etc/pki/tls/certs/ca-bundle.crt # Fedora, CentOS
+  set --export NIX_SSL_CERT_FILE /etc/pki/tls/certs/ca-bundle.crt
+else if test -e "$NIX_LINK/etc/ssl/certs/ca-bundle.crt" # fall back to cacert in Nix profile
+  set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ssl/certs/ca-bundle.crt"
+else if test -e "$NIX_LINK/etc/ca-bundle.crt" # old cacert in Nix profile
+  set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ca-bundle.crt"
+else
+  # Fall back to what is in the nix profiles, favouring whatever is defined last.
+  for i in $NIX_PROFILES
+    if test -e "$i/etc/ssl/certs/ca-bundle.crt"
+      set --export NIX_SSL_CERT_FILE "$i/etc/ssl/certs/ca-bundle.crt"
+    end
+  end
+end
+
+add_path "@localstatedir@/nix/profiles/default/bin"
+add_path "$HOME/.nix-profile/bin"
+
+functions -e add_path
diff --git a/scripts/nix-profile-daemon.sh.in b/scripts/nix-profile-daemon.sh.in
new file mode 100644
index 000000000..d256b24ed
--- /dev/null
+++ b/scripts/nix-profile-daemon.sh.in
@@ -0,0 +1,72 @@
+# Only execute this file once per shell.
+if [ -n "${__ETC_PROFILE_NIX_SOURCED:-}" ]; then return; fi
+__ETC_PROFILE_NIX_SOURCED=1
+
+NIX_LINK=$HOME/.nix-profile
+if [ -n "${XDG_STATE_HOME-}" ]; then
+    NIX_LINK_NEW="$XDG_STATE_HOME/nix/profile"
+else
+    NIX_LINK_NEW=$HOME/.local/state/nix/profile
+fi
+if [ -e "$NIX_LINK_NEW" ]; then
+    NIX_LINK="$NIX_LINK_NEW"
+else
+    if [ -t 2 ] && [ -e "$NIX_LINK_NEW" ]; then
+        warning="\033[1;35mwarning:\033[0m"
+        printf "$warning Both %s and legacy %s exist; using the latter.\n" "$NIX_LINK_NEW" "$NIX_LINK" 1>&2
+        if [ "$(realpath "$NIX_LINK")" = "$(realpath "$NIX_LINK_NEW")" ]; then
+            printf "         Since the profiles match, you can safely delete either of them.\n" 1>&2
+        else
+            # This should be an exceptionally rare occasion: the only way to get it would be to
+            # 1. Update to newer Nix;
+            # 2. Remove .nix-profile;
+            # 3. Set the $NIX_LINK_NEW to something other than the default user profile;
+            # 4. Roll back to older Nix.
+            # If someone did all that, they can probably figure out how to migrate the profile.
+            printf "$warning Profiles do not match. You should manually migrate from %s to %s.\n" "$NIX_LINK" "$NIX_LINK_NEW" 1>&2
+        fi
+    fi
+fi
+
+export NIX_PROFILES="@localstatedir@/nix/profiles/default $NIX_LINK"
+
+# Populate bash completions, .desktop files, etc
+if [ -z "${XDG_DATA_DIRS-}" ]; then
+    # According to XDG spec the default is /usr/local/share:/usr/share, don't set something that prevents that default
+    export XDG_DATA_DIRS="/usr/local/share:/usr/share:$NIX_LINK/share:/nix/var/nix/profiles/default/share"
+else
+    export XDG_DATA_DIRS="$XDG_DATA_DIRS:$NIX_LINK/share:/nix/var/nix/profiles/default/share"
+fi
+
+# Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
+if [ -n "${NIX_SSL_CERT_FILE:-}" ]; then
+    : # Allow users to override the NIX_SSL_CERT_FILE
+elif [ -e /etc/ssl/certs/ca-certificates.crt ]; then # NixOS, Ubuntu, Debian, Gentoo, Arch
+    export NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
+elif [ -e /etc/ssl/ca-bundle.pem ]; then # openSUSE Tumbleweed
+    export NIX_SSL_CERT_FILE=/etc/ssl/ca-bundle.pem
+elif [ -e /etc/ssl/certs/ca-bundle.crt ]; then # Old NixOS
+    export NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt
+elif [ -e /etc/pki/tls/certs/ca-bundle.crt ]; then # Fedora, CentOS
+    export NIX_SSL_CERT_FILE=/etc/pki/tls/certs/ca-bundle.crt
+else
+  # Fall back to what is in the nix profiles, favouring whatever is defined last.
+  check_nix_profiles() {
+    if [ -n "$ZSH_VERSION" ]; then
+      # Zsh by default doesn't split words in unquoted parameter expansion.
+      # Set local_options for these options to be reverted at the end of the function
+      # and shwordsplit to force splitting words in $NIX_PROFILES below.
+      setopt local_options shwordsplit
+    fi
+    for i in $NIX_PROFILES; do
+      if [ -e "$i/etc/ssl/certs/ca-bundle.crt" ]; then
+        export NIX_SSL_CERT_FILE=$i/etc/ssl/certs/ca-bundle.crt
+      fi
+    done
+  }
+  check_nix_profiles
+  unset -f check_nix_profiles
+fi
+
+export PATH="$NIX_LINK/bin:@localstatedir@/nix/profiles/default/bin:$PATH"
+unset NIX_LINK