[bug#56050] [PATCH] home: services: environment-variables: Fix XDG base directories.

[Philip McGrath]

When the environment initialization script is run, XDG_DATA_DIRS and/or
XDG_CONFIG_DIRS may be empty or unset, in which case we must use their
respective defaults from the specification, rather than ending the value
with a trailing ":". For further discussion, see
<https://lists.gnu.org/archive/html/help-guix/2022-05/msg00147.html>.

* gnu/home/services.scm
(environment-variables->setup-environment-script): Use conditional
parameter expansion for XDG_DATA_DIRS and XDG_CONFIG_DIRS.
---

MANPATH and INFOPATH don't have this problem because they have
well-defined behavior for a trailing ":".

XCURSOR_PATH, on the other hand, does seem to have a similar problem. In
my KDE Plasma Wayland session, at least, omiting the default caused the
cursor to disappear when hovering over the border of a window. I could
fix this on my Debian-based distribution by putting:

    export XCURSOR_PATH="${XCURSOR_PATH:-/usr/share/icons:/usr/share/pixmaps}"

in a file under "/etc/profile.d", but I'm not sure if that default is
truly portable even among FHS-based distros. For example, it sounds like
Gentoo uses "/usr/share/cursors/xorg-x11". So I haven't tried to address
XCURSOR_PATH for now.

  -Philip

 gnu/home/services.scm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gnu/home/services.scm b/gnu/home/services.scm
index 5ee3357792..ba14d8a119 100644
--- a/gnu/home/services.scm
+++ b/gnu/home/services.scm
@@ -208,7 +208,7 @@ (define (environment-variables->setup-environment-script 
vars)
 
 case $XDG_DATA_DIRS in
   *$HOME_ENVIRONMENT/profile/share*) ;;
-  *) export XDG_DATA_DIRS=$HOME_ENVIRONMENT/profile/share:$XDG_DATA_DIRS ;;
+  *) export 
XDG_DATA_DIRS=$HOME_ENVIRONMENT/profile/share:${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/}
 ;;
 esac
 case $MANPATH in
   *$HOME_ENVIRONMENT/profile/share/man*) ;;
@@ -220,7 +220,7 @@ (define (environment-variables->setup-environment-script 
vars)
 esac
 case $XDG_CONFIG_DIRS in
   *$HOME_ENVIRONMENT/profile/etc/xdg*) ;;
-  *) export XDG_CONFIG_DIRS=$HOME_ENVIRONMENT/profile/etc/xdg:$XDG_CONFIG_DIRS 
;;
+  *) export 
XDG_CONFIG_DIRS=$HOME_ENVIRONMENT/profile/etc/xdg:${XDG_CONFIG_DIRS:-/etc/xdg} 
;;
 esac
 case $XCURSOR_PATH in
   *$HOME_ENVIRONMENT/profile/share/icons*) ;;

base-commit: 3154b582567539d8d607344fbd03a3d8456f66cb
-- 
2.32.0