shell: Add --cwd.

* guix/scripts/environment.scm (show-environment-options-help): Document
--cwd.
(%options): Add cwd.
(launch-environment/container): Add cwd parameter.  Implement passing it to
the container.
(guix-environment*): Reject --cwd without --container.
* doc/guix.texi (Invoking guix shell): Document it.
* tests/guix-environment-container.sh: Add tests.
* tests/guix-shell.sh: Add tests.

Fixes: guix/guix# 7825
Change-Id: Iba4ff3d2058e92f504fbcbf688346357ce913213

2 files changed, 21 insertions, 0 deletions

diff --git a/tests/guix-environment-container.sh b/tests/guix-environment-container.sh
index 5b89f8383b6..8947a4ea1ba 100644
--- a/tests/guix-environment-container.sh
+++ b/tests/guix-environment-container.sh
@@ -186,6 +186,24 @@ HOME="$tmpdir" guix environment --bootstrap --container --user=foognu \
             -- /bin/sh -c 'test $(pwd) == "/home/foo" -a ! -d '"$tmpdir"
 )
 
+# '--cwd' is independent from sharing the host current working directory.
+(
+  cd "$tmpdir" \
+    && guix environment --bootstrap --container --no-cwd --cwd=/tmp \
+            --ad-hoc guile-bootstrap --pure \
+            -- /bin/sh -c 'test $(pwd) == "/tmp" -a ! -d '"$tmpdir"
+)
+
+# Relative '--cwd' is resolved against the host CWD and still honors '--user'.
+mkdir -p "$tmpdir/home/wd"
+home_dir="$(cd "$tmpdir/home"; pwd -P)"
+(
+  cd "$tmpdir/home/wd" \
+    && HOME="$home_dir" guix environment --bootstrap --container --user=foo \
+            --cwd=. --ad-hoc guile-bootstrap --pure \
+            -- /bin/sh -c 'test "$(pwd)" = "/home/foo/wd"'
+)
+
 # Check that the root file system is read-only by default...
 guix environment --bootstrap --container --ad-hoc guile-bootstrap \
      -- guile -c '(mkdir "/whatever")' && false
diff --git a/tests/guix-shell.sh b/tests/guix-shell.sh
index b2f820bf26d..4eb4a3196cd 100644
--- a/tests/guix-shell.sh
+++ b/tests/guix-shell.sh
@@ -35,6 +35,9 @@ guix shell --bootstrap --pure guile-bootstrap -- guile --version
 # '--symlink' can only be used with --container.
 guix shell --bootstrap guile-bootstrap -S /dummy=bin/guile && false
 
+# '--cwd' can only be used with --container.
+guix shell --cwd=/tmp -n hello && false
+
 # '--ad-hoc' is a thing of the past.
 guix shell --ad-hoc guile-bootstrap && false