vm: Use 'fold2' from (guix combinators).

* gnu/build/vm.scm: Use (guix combinators).
(fold2): Remove.

vm: Estimate the disk size by default.

* gnu/build/vm.scm (estimated-partition-size): New procedure.
* gnu/system/vm.scm (expression->derivation-in-linux-vm):
Change #:disk-image-size default to 'guess.
[builder]: When DISK-IMAGE-SIZE is 'guess, use
'estimated-partition-size' and compute and estimate of the image size.
(qemu-image): Likewise.
* guix/build/store-copy.scm (file-size, closure-size): New procedures.
* guix/scripts/system.scm (%default-options): Change 'image-size' to
'guess.
* doc/guix.texi (Building the Installation Image): Remove '--image-size'
flag from example.
(Invoking guix system): Document the image size estimate.

vm: Display the disk and partition sizes.

* gnu/build/vm.scm (load-in-linux-vm): Add 'format' call when
MAKE-DISK-IMAGE? is true.
(initialize-partition-table): Show the size of the partitions being
created.

vm: Fix 'load-in-linux-vm' docstring.

* gnu/build/vm.scm (load-in-linux-vm): Change default value of
  #:disk-image-size.  Update docstring to note that DISK-IMAGE-SIZE is
  in bytes.

marionette: Factorize 'wait-for-file'.

* gnu/build/marionette.scm (wait-for-file): New procedure.
* gnu/tests/base.scm (run-mcron-test)[test](wait-for-file): Remove.
Pass second argument in 'wait-for-file' calls.
* gnu/tests/ssh.scm (run-ssh-test)[test](wait-for-file): Remove.
Pass second argument in 'wait-for-file' calls.
* gnu/tests/messaging.scm (run-xmpp-test)[test](guest-wait-for-file):
Remove.
Use 'wait-for-file' instead, with second argument.

file-systems: Handle EIO error in 'ENOENT-safe' as well.

Trying to boot GuixSD when an audio CD is in the drive will die with an
"input/output error" when trying to read the superblock from the cd
drive.

This patch catches and warns in this case rather than dying.

* gnu/build/file-systems.scm (ENOENT-safe): Handle EIO.

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

file-systems: Provide string->ext*-uuid, string->btrfs-uuid.

* gnu/build/file-systems.scm (string->ext2-uuid, string->ext3-uuid,
string->ext4-uuid, string->btrfs-uuid): New variables.  Export them.

file-systems: Provide string->iso9660-uuid.

* gnu/build/file-systems.scm (string->iso9660-uuid): New variable.  Export it.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

file-systems: Use creation time if modification time is unset for ISO9660.

* gnu/build/file-systems.scm (iso9660-superblock-uuid): Modify.

file-systems: Improve error handling in the iso9660 case - fixes boot problem.

* gnu/build/file-systems.scm (read-iso9660-superblock): Modify.

file-systems: Improve error reporting.

Suggested by Chris Marusich <cmmarusich@gmail.com>.
Fixes <https://bugs.gnu.org/27143>.

* gnu/build/file-systems.scm (read-iso9660-primary-volume-descriptor):
Improve error reporting.

gnu: build: Improve comments.

* gnu/build/file-systems.scm (iso9660-superblock-volume-name):
Add clarifying comment.

activation: Change permissions on /root to #o700.

Reported by Alex Griffin <a@ajgrf.com>.
Fixes <http://bugs.gnu.org/27135>.

* gnu/build/activation.scm (add-user): When UID is zero, add 'chmod'
call.
* gnu/tests/base.scm (run-basic-test)["permissions on /root"]: New test.

Merge branch 'master' into staging

gnu: build: Improve docstrings.

* gnu/build/file-systems.scm (iso9660-superblock?,
read-iso9660-superblock, iso9660-superblock-uuid): Improve docstrings.

Merge branch 'master' into staging

vm: Add UEFI loader to disk images.

* gnu/build/vm.scm (install-efi): New procedure.
(initialize-hard-disk): Generate EFI blob when ESP is present.
* gnu/system/vm.scm (qemu-image): Append 40MiB EFI System Partition.

(cherry picked from commit ecf5d5376979fadd971559367bf553df89fcc62b)

vm: Support creating FAT partitions.

* gnu/build/vm.scm (create-ext-file-system, create-fat-file-system): New procedures.
(format-partition): Use them. Error for unknown file systems.
* gnu/system/vm.scm (qemu-image): Include DOSFSTOOLS.
* gnu/system/linux-initrd.scm (base-initrd): Always add nls_is8859-1.ko.

vm: Support arbitrary partition flags.

* gnu/build/vm.scm (<partition>): Change BOOTABLE? to FLAGS.
(initialize-partition-table): Pass each flag to parted.
(initialize-hard-disk): Locate boot partition.
* gnu/system/vm.scm (qemu-image): Adjust partition flags.

services: user-homes: Do not create home directories marked as no-create.

Fixes a bug whereby GuixSD would create the /nonexistent directory, from
user 'nobody', even though it has 'create-home-directory?' set to #f.

* gnu/build/activation.scm (activate-users+groups): Add comment for
\#:create-home?.
(activate-user-home)[ensure-user-home]: Skip when CREATE-HOME? is #f or
SYSTEM? is #t.
* gnu/tests/base.scm (run-basic-test)["no extra home directories"]: New
tests.