This works around guix/guix#7690 whereby calling ‘primitive-fork’ from a child
process created with ‘safe-clone’ causes said child process to hang.

* tests/containers.scm ("call-with-container, pid namespace")
("container-excursion")
("container-excursion, same namespaces")
("container-excursion*")
("container-excursion*, /proc"): Skip.

Change-Id: Ieb49a5c5e3e92cff40f6dd2472d0cb177680d9f4
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Merges: #9085

This reverts commit e0e64be8de3d220a12612b3a2e4aee428277d865.

This reverts commits 437bb9ece55f37d4b5a62cafc98c0c3b848a53ce and
a57ed987ffd1452ba5a4d70feb54893e99b8e076, which were reported in
guix/guix#1169 to occasionally cause errors like:

  guix shell: error: unshare : 268566528: Invalid argument

This makes it impossible to unmount or remount things from within
‘call-with-container’.

* gnu/build/linux-container.scm (initialize-user-namespace):
Add #:host-uid and #:host-gid. and honor them.
(run-container): Add #:lock-mounts?.  Honor it by calling ‘unshare’
followed by ‘initialize-user-namespace’.
(call-with-container): Add #:lock-mounts? and pass it down.
(container-excursion): Get the user namespace owning the PID namespace
and join it, then join the remaining namespaces.
* tests/containers.scm ("call-with-container, mnt namespace, locked mounts"):
New test.
("container-excursion"): Pass #:lock-mounts? #f.

Change-Id: I13be982aef99e68a653d472f0e595c81cfcfa392

Until now, the read-only file system set up by ‘call-with-container’
would always be writable.  With this change, it can be made read-only.
With this patch, only ‘least-authority-wrapper’ switches to a read-only
root file system.

* gnu/build/linux-container.scm (remount-read-only): New procedure.
(mount-file-systems): Add #:writable-root? and #:populate-file-system
and honor them.
(run-container): Likewise.
(call-with-container): Likewise.
* gnu/system/linux-container.scm (container-script): Pass #:writable-root?
to ‘call-with-container’.
(eval/container): Add #:populate-file-system and #:writable-root? and
honor them.
* guix/scripts/environment.scm (launch-environment/container):
Pass #:writable-root? to ‘call-with-container’.
* guix/scripts/home.scm (spawn-home-container): Likewise.
* tests/containers.scm ("call-with-container, mnt namespace, read-only root")
("call-with-container, mnt namespace, writable root"): New tests.

Change-Id: I603e2fd08851338b737bb16c8af3f765e2538906

Fixes <https://issues.guix.gnu.org/61156>.

* gnu/build/linux-container.scm (container-excursion): Add extra call to
'primitive-fork' and invoke THUNK in the child process.
* tests/containers.scm ("container-excursion"): Remove extra
'primitive-fork' call, now unnecessary.
("container-excursion*, /proc"): New test.

* gnu/build/linux-container.scm (container-excursion): Return the raw
status value.
* tests/containers.scm ("container-excursion, same namespaces"): Add
'status:exit-val' call.
* guix/scripts/container/exec.scm (guix-container-exec): Correctly
handle the different cases.

* gnu/build/linux-container.scm (mount-file-systems): Add 'chmod' call.
* tests/containers.scm
("call-with-container, mnt namespace, root permissions"): New test.

This is a followup to 96b35998e610c7fc37bf87bf9e07e63d3bebd0a3.

* tests/containers.scm ("eval/container, non-empty load path"): Add
missing 'skip-if-unsupported' call.

This fixes a type error.

* gnu/system/linux-container.scm (eval/container): Use 'append-map', not
'map'.
* tests/containers.scm ("eval/container, non-empty load path"): New test.