environment: Add --link-profile.

This change is motivated by attempts to run programs (like GNU IceCat) within
containers.  The 'fontconfig' program, for example, is configured explicitly
to check ~/.guix-profile for additional fonts.

There were no existing container tests in 'tests/guix-environment.sh', but I
added one anyway for this change.

* doc/guix.texi (Invoking guix environment): Add '--link-profile'.
* guix/scripts/environment.scm (show-help): Add '--link-profile'.
(%options): Add 'link-profile' as '#\P', assigned to 'link-profile?'.
(link-environment): New procedure.
(launch-environment/container): Use it when 'link-profile?'.
[link-profile?]: New parameter.
(guix-environment): Leave when '--link-prof' but not '--container'.  Add
'#:link-profile?' argument to 'launch-environment/container' application.
* tests/guix-environment-container.sh: New '--link-profile' test.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/guix-environment-container.sh b/tests/guix-environment-container.sh
index d7c1b7057e..df40ce03e0 100644
--- a/tests/guix-environment-container.sh
+++ b/tests/guix-environment-container.sh
@@ -97,6 +97,20 @@ grep -e "$NIX_STORE_DIR/.*-bash" $tmpdir/mounts # bootstrap bash
 
 rm $tmpdir/mounts
 
+# Make sure 'GUIX_ENVIRONMENT' is linked to '~/.guix-profile' when requested
+# within a container.
+(
+  linktest='(exit (string=? (getenv "GUIX_ENVIRONMENT")
+(readlink (string-append (getenv "HOME") "/.guix-profile"))))'
+
+  cd "$tmpdir" \
+     && guix environment --bootstrap --container --link-profile \
+             --ad-hoc guile-bootstrap --pure \
+             -- guile -c "$linktest"
+)
+
+# Check the exit code.
+
 abnormal_exit_code="
 (use-modules (system foreign))
 ;; Purposely make Guile crash with a segfault. :)