;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013-2020, 2022 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
;;; Copyright © 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2024 Nicolas Graves <ngraves@ngraves.fr>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu build install)
#:use-module (guix build syscalls)
#:use-module (guix build utils)
#:use-module (guix build store-copy)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:export (install-boot-config
evaluate-populate-directive
populate-root-file-system
install-database-and-gc-roots
populate-single-profile-directory
mount-cow-store
unmount-cow-store))
;;; Commentary:
;;;
;;; This module supports the installation of the GNU system on a hard disk.
;;; It is meant to be used both in a build environment (in derivations that
;;; build VM images), and on the bare metal (when really installing the
;;; system.)
;;;
;;; Code:
(define (install-boot-config bootcfg bootcfg-location mount-point)
"Atomically copy BOOTCFG into BOOTCFG-LOCATION on the MOUNT-POINT. Note
that the caller must make sure that BOOTCFG is registered as a GC root so
that the fonts, background images, etc. referred to by BOOTCFG are not GC'd."
(let* ((target (string-append mount-point bootcfg-location))
(pivot (string-append target ".new")))
(mkdir-p (dirname target))
;; Copy BOOTCFG instead of just symlinking it, because symlinks won't
;; work when /boot is on a separate partition. Do that atomically.
(copy-file bootcfg pivot)
(rename-file pivot target)))
(define* (evaluate-populate-directive directive target
#:key
(default-gid 0)
(default-uid 0)
(error-on-dangling-symlink? #t))
"Evaluate DIRECTIVE, an sexp describing a file or directory to create under
directory TARGET. DEFAULT-UID and DEFAULT-GID are the default UID and GID in
the context of the caller. If the directive matches those defaults then,
'chown' won't be run. When ERROR-ON-DANGLING-SYMLINK? is true, abort with an
error when a dangling symlink would be created."
(define target* (if (string-suffix? "/" target)
target
(string-append target "/")))
(let loop ((directive directive))
(catch 'system-error
(lambda ()
(match directive
(('directory name)
(mkdir-p (string-append target* name)))
(('directory name uid gid)
(let ((dir (string-append target* name)))
(mkdir-p dir)
;; If called from a context without "root" permissions, "chown"
;; to root will fail. In that case, do not try to run "chown"
;; and assume that the file will be chowned elsewhere (when
;; interned in the store for instance).
(or (and (= uid default-uid) (= gid default-gid))
(chown dir uid gid))))
(('directory name uid gid mode)
(loop `(directory ,name ,uid ,gid))
(chmod (string-append target* name) mode))
(('file name)
(call-with-output-file (string-append target* name)
(const #t)))
(('file name (? string? content))
(call-with-output-file (string-append target* name)
(lambda (port)
(display content port))))
((new '-> old)
(let ((new* (string-append target* new)))
(let try ()
(catch 'system-error
(lambda ()
(when error-on-dangling-symlink?
;; When the symbolic link points to a relative path,
;; checking if its target exists must be done relatively
;; to the link location.
(unless (if (string-prefix? "/" old)
(file-exists? old)
(with-directory-excursion (dirname new*)
(file-exists? old)))
(error (format #f "symlink `~a' points to nonexistent \
file `~a'" new* old))))
(symlink old new*))
(lambda args
;; When doing 'guix system init' on the current '/', some
;; symlinks may already exists. Override them.
(if (= EEXIST (system-error-errno args))
(begin
(delete-file new*)
(try))
(apply throw args)))))))))
(lambda args
;; Usually we can only get here when installing to an existing root,
;; as with 'guix system init foo.scm /'.
(format (current-error-port)
"error: failed to evaluate directive: ~s~%"
directive)
(apply throw args)))))
(define (directives store)
"Return a list of directives to populate the root file system that will host
STORE."
`((directory ,store 0 0 #o1775)
(directory "/etc")
(directory "/var/log") ; for shepherd
(directory "/var/guix/gcroots")
(directory "/var/empty") ; for no-login accounts
(directory "/var/db") ; for dhclient, etc.
(directory "/mnt")
(directory "/var/guix/profiles/per-user/root" 0 0)
;; Link to the initial system generation.
("/var/guix/profiles/system" -> "system-1-link")
("/var/guix/gcroots/booted-system" -> "/run/booted-system")
("/var/guix/gcroots/current-system" -> "/run/current-system")
("/var/guix/gcroots/profiles" -> "/var/guix/profiles")
(directory "/bin")
(directory "/tmp" 0 0 #o1777) ; sticky bit
(directory "/var/tmp" 0 0 #o1777)
(directory "/var/lock" 0 0 #o1777)
(directory "/home" 0 0)))
(define* (populate-root-file-system system target
#:key (extras '()))
"Make the essential non-store files and directories on TARGET. This
includes /etc, /var, /run, /bin/sh, etc., and all the symlinks to SYSTEM.
EXTRAS is a list of directives appended to the built-in directives to populate
TARGET."
;; It's expected that some symbolic link targets do not exist yet, so do not
;; error on dangling links.
(for-each (cut evaluate-populate-directive <> target
#:error-on-dangling-symlink? #f)
(append (directives (%store-directory)) extras))
;; Add system generation 1.
(let ((generation-1 (string-append target
"/var/guix/profiles/system-1-link")))
(let try ()
(catch 'system-error
(lambda ()
(symlink system generation-1))
(lambda args
;; If GENERATION-1 already exists, overwrite it.
(if (= EEXIST (system-error-errno args))
(begin
(delete-file generation-1)
(try))
(apply throw args)))))))
(define %root-profile
"/var/guix/profiles/per-user/root")
(define* (install-database-and-gc-roots root database profile
#:key (profile-name "guix-profile"))
"Install DATABASE, the store database, under directory ROOT. Create
PROFILE-NAME and have it link to PROFILE, a store item."
(define (scope file)
(string-append root "/" file))
(define (mkdir-p* dir)
(mkdir-p (scope dir)))
(define (symlink* old new)
(symlink old (scope new)))
(install-file database (scope "/var/guix/db/"))
(chmod (scope "/var/guix/db/db.sqlite") #o644)
(mkdir-p* "/var/guix/profiles")
(mkdir-p* "/var/guix/gcroots")
(symlink* "/var/guix/profiles" "/var/guix/gcroots/profiles")
;; Make root's profile, which makes it a GC root.
(mkdir-p* %root-profile)
(symlink* profile
(string-append %root-profile "/" profile-name "-1-link"))
(symlink* (string-append profile-name "-1-link")
(string-append %root-profile "/" profile-name)))
(define* (populate-single-profile-directory directory
#:key profile closure
(profile-name "guix-profile")
database)
"Populate DIRECTORY with a store containing PROFILE, whose closure is given
in the file called CLOSURE (as generated by #:references-graphs.) DIRECTORY
is initialized to contain a single profile under /root pointing to PROFILE.
When DATABASE is true, copy it to DIRECTORY/var/guix/db and create
DIRECTORY/var/guix/gcroots and friends.
PROFILE-NAME is the name of the profile being created under
/var/guix/profiles, typically either \"guix-profile\" or \"current-guix\".
This is used to create the self-contained tarballs with 'guix pack'."
(define (scope file)
(string-append directory "/" file))
(define (mkdir-p* dir)
(mkdir-p (scope dir)))
(define (symlink* old new)
(symlink old (scope new)))
;; Populate the store.
(populate-store (list closure) directory
#:deduplicate? #f)
(when database
(install-database-and-gc-roots directory database profile
#:profile-name profile-name))
(match profile-name
("guix-profile"
(mkdir-p* "/root")
(symlink* (string-append %root-profile "/guix-profile")
"/root/.guix-profile"))
("current-guix"
(mkdir-p* "/root/.config/guix")
(symlink* (string-append %root-profile "/current-guix")
"/root/.config/guix/current"))
(_
#t)))
(define (mount-cow-store target backing-directory)
"Make the store copy-on-write, using TARGET as the backing store. This is
useful when TARGET is on a hard disk, whereas the current store is on a RAM
disk."
(define (set-store-permissions directory)
"Set the right perms on DIRECTORY to use it as the store."
(chown directory 0 30000) ;use the fixed 'guixbuild' GID
(chmod directory #o1775))
(let ((tmpdir (string-append target "/tmp")))
(mkdir-p tmpdir)
(mount tmpdir "/tmp" "none" MS_BIND))
(let* ((rw-dir (string-append target backing-directory))
(work-dir (string-append rw-dir "/../.overlayfs-workdir")))
(mkdir-p rw-dir)
(mkdir-p work-dir)
(mkdir-p "/.rw-store")
(set-store-permissions rw-dir)
(set-store-permissions "/.rw-store")
;; Mount the overlay, then atomically make it the store.
(mount "none" "/.rw-store" "overlay" 0
(string-append "lowerdir=" (%store-directory) ","
"upperdir=" rw-dir ","
"workdir=" work-dir))
(mount "/.rw-store" (%store-directory) "" MS_MOVE)
(rmdir "/.rw-store")))
(define (umount* directory)
"Unmount DIRECTORY, but retry a few times upon EBUSY."
(let loop ((attempts 5))
(catch 'system-error
(lambda ()
(umount directory))
(lambda args
(if (and (= EBUSY (system-error-errno args))
(> attempts 0))
(begin
(sleep 1)
(loop (- attempts 1)))
(apply throw args))))))
(define (unmount-cow-store target backing-directory)
"Unmount copy-on-write store."
(let ((tmp-dir "/remove"))
(mkdir-p tmp-dir)
(mount (%store-directory) tmp-dir "" MS_MOVE)
;; We might get EBUSY at this point, possibly because of lingering
;; processes with open file descriptors. Use 'umount*' to retry upon
;; EBUSY, leaving a bit of time. See <https://issues.guix.gnu.org/59884>.
(umount* tmp-dir)
(rmdir tmp-dir)
(delete-file-recursively
(string-append target backing-directory))))
;;; install.scm ends here
