[bug#30256] [PATCH 3/3] scripts: environment: Add --no-cwd.

[Mike Gerwitz]

* doc/guix.texi (Invoking guix environment): Add --no-cwd.
* guix/scripts/environment.scm (show-help, %options): Add --no-cwd.
(launch-environment/container): Add 'map-cwd?' param; only add mapping for cwd
if #t.  Only change to cwd within container if #t, otherwise home.
(guix-environment): Error if --no-cwd without --container.  Provide '(not
no-cwd?)' to launch-environment/container as 'map-cwd?'.
* tests/guix-environment.sh: Add test for no-cwd.
---
 doc/guix.texi                |  8 ++++++++
 guix/scripts/environment.scm | 33 ++++++++++++++++++++++++---------
 tests/guix-environment.sh    |  8 ++++++++
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 8218c6637..ce4545038 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7209,6 +7209,14 @@ While this will limit the leaking of user identity 
through home paths
 and each of the user fields, this is only one useful component of a
 broader privacy/anonymity solution---not one in and of itself.
 
address@hidden --no-cwd
+For containers, the default behavior is to share the current working
+directory with the isolated container and immediately change to that
+directory within the container.  If this is undesirable, @code{--no-cwd}
+will cause the current working directory to @emph{not} be automatically
+shared and will change to the user's home directory within the container
+instead.  See also @code{--user}.
+
 @item address@hidden@var{target}]
 For containers, expose the file system @var{source} from the host system
 as the read-only file system @var{target} within the container.  If
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index f50018faf..6be263a64 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -165,6 +165,9 @@ COMMAND or an interactive shell in that environment.\n"))
   -u, --user=USER        instead of copying the name and home of the current
                          user into an isolated container, use the name USER
                          with home directory /home/USER"))
+  (display (G_ "
+      --no-cwd           do not share current working directory with an
+                         isolated container"))
   (display (G_ "
       --share=SPEC       for containers, share writable host file system
                          according to SPEC"))
@@ -251,6 +254,9 @@ COMMAND or an interactive shell in that environment.\n"))
                  (lambda (opt name arg result)
                    (alist-cons 'user arg
                                (alist-delete 'user result eq?))))
+         (option '("no-cwd") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'no-cwd? #t result)))
          (option '("share") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'file-system-mapping
@@ -399,7 +405,8 @@ environment variables are cleared before setting the new 
ones."
            ((_ . status) status)))))
 
 (define* (launch-environment/container #:key command bash user user-mappings
-                                       profile paths link-profile? network?)
+                                       profile paths link-profile? network?
+                                       map-cwd?)
   "Run COMMAND within a container that features the software in PROFILE.
 Environment variables are set according to PATHS, a list of native search
 paths.  The global shell is BASH, a file name for a GNU Bash binary in the
@@ -425,11 +432,13 @@ will be used for the passwd entry.  LINK-PROFILE? creates 
a symbolic link from
              (override-user-mappings
               user home
               (append user-mappings
-                      ;; Current working directory.
-                      (list (file-system-mapping
-                             (source cwd)
-                             (target cwd)
-                             (writable? #t)))
+                      ;; Share current working directory, unless asked not to.
+                      (if map-cwd?
+                          (list (file-system-mapping
+                                 (source cwd)
+                                 (target cwd)
+                                 (writable? #t)))
+                          '())
                       ;; When in Rome, do as Nix build.cc does: Automagically
                       ;; map common network configuration files.
                       (if network?
@@ -488,8 +497,10 @@ will be used for the passwd entry.  LINK-PROFILE? creates 
a symbolic link from
                 (newline port)))
 
             ;; For convenience, start in the user's current working
-            ;; directory rather than the root directory.
-            (chdir (override-user-dir user home cwd))
+            ;; directory or, if unmapped, the home directory.
+            (chdir (if map-cwd?
+                       (override-user-dir user home cwd)
+                       home-dir))
 
             (primitive-exit/status
              ;; A container's environment is already purified, so no need to
@@ -640,6 +651,7 @@ message if any test fails."
            (container? (assoc-ref opts 'container?))
            (link-prof? (assoc-ref opts 'link-profile?))
            (network?   (assoc-ref opts 'network?))
+           (no-cwd?    (assoc-ref opts 'no-cwd?))
            (user       (assoc-ref opts 'user))
            (bootstrap? (assoc-ref opts 'bootstrap?))
            (system     (assoc-ref opts 'system))
@@ -677,6 +689,8 @@ message if any test fails."
         (leave (G_ "--link-prof cannot be used without --container~%")))
       (when (and (not container?) user)
         (leave (G_ "--user cannot be used without --container~%")))
+      (when (and (not container?) no-cwd?)
+        (leave (G_ "--no-cwd cannot be used without --container~%")))
 
       (with-store store
         (set-build-options-from-command-line store opts)
@@ -729,7 +743,8 @@ message if any test fails."
                                                   #:profile profile
                                                   #:paths paths
                                                   #:link-profile? link-prof?
-                                                  #:network? network?)))
+                                                  #:network? network?
+                                                  #:map-cwd? (not no-cwd?))))
                  (else
                   (return
                    (exit/status
diff --git a/tests/guix-environment.sh b/tests/guix-environment.sh
index a1ce96579..abb019794 100644
--- a/tests/guix-environment.sh
+++ b/tests/guix-environment.sh
@@ -84,6 +84,14 @@ HOME="$tmpdir" guix environment --bootstrap --container 
--user=foognu \
      --share="$tmpdir/umock" \
      -- guile -c "$usertest"
 
+# if not sharing CWD, chdir home
+(
+  cd "$tmpdir" \
+    && guix environment --bootstrap --container --no-cwd --user=foo  \
+            --ad-hoc guile-bootstrap --pure \
+            -- /bin/sh -c 'test $(pwd) == "/home/foo" -a ! -d '"$tmpdir"
+)
+
 # Make sure '-r' works as expected.
 rm -f "$gcroot"
 expected="`guix environment --bootstrap --ad-hoc guile-bootstrap \
-- 
2.15.1

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