Extract creating $XDG_CACHE_HOME into its own function

share/functions/__fish_make_cache_dir.fish

@@ -0,0 +1,9 @@
+function __fish_make_cache_dir --description "Create and return XDG_CACHE_HOME"
+    set -l xdg_cache_home $XDG_CACHE_HOME
+    if test -z "$xdg_cache_home"; or string match -qv '/*' -- $xdg_cache_home; or set -q xdg_cache_home[2]
+        set xdg_cache_home $HOME/.cache
+    end
+    mkdir -m 700 -p $xdg_cache_home
+    and echo $xdg_cache_home
+end
+

share/functions/__fish_print_packages.fish

@@ -32,11 +32,8 @@ function __fish_print_packages
     and return
 
     # Set up cache directory
-    set -l xdg_cache_home $XDG_CACHE_HOME
-    if test -z "$xdg_cache_home"
-        set xdg_cache_home $HOME/.cache
-    end
-    mkdir -m 700 -p $xdg_cache_home
+    set -l xdg_cache_home (__fish_make_cache_dir)
+    or return
 
     # yum is slow, just like rpm, so go to the background
     if type -q -f /usr/share/yum-cli/completion-helper.py

share/functions/__fish_print_pacman_packages.fish

@@ -5,12 +5,9 @@ function __fish_print_pacman_packages
     argparse i/installed -- $argv
     or return 1
 
-    # Set up cache directory
-    set -l xdg_cache_home $XDG_CACHE_HOME
-    if test -z "$xdg_cache_home"
-        set xdg_cache_home $HOME/.cache
-    end
-    mkdir -m 700 -p $xdg_cache_home
+    set -l xdg_cache_home (__fish_make_cache_dir)
+    or return
+
     if not set -q only_installed
         set -l cache_file $xdg_cache_home/.pac-cache.$USER
         if test -f $cache_file

share/functions/__fish_print_zypper_packages.fish

@@ -1,11 +1,8 @@
 function __fish_print_zypper_packages
     type -q -f zypper || return 1
 
-    set -l xdg_cache_home $XDG_CACHE_HOME
-    if test -z "$xdg_cache_home"
-        set xdg_cache_home $HOME/.cache
-    end
-    mkdir -m 700 -p $xdg_cache_home
+    set -l xdg_cache_home (__fish_make_cache_dir)
+    or return
 
     # Use libzypp cache file if available
     if test -f /var/cache/zypp/solv/@System/solv.idx