guix/gnu/build/linux-initrd.scm
Ludovic Courtès 548f7a8fa2 Move operating system helpers from (guix build …) to (gnu build …).
* guix/build/activation.scm, guix/build/install.scm,
  guix/build/linux-initrd.scm, guix/build/vm.scm: Move to...
* gnu/build: ... here.
* Makefile.am (MODULES): Remove the above guix/build/ files.
* gnu-system.am (GNU_SYSTEM_MODULES): Add the above gnu/build/ files
  here.
* gnu/services/base.scm, gnu/services/dmd.scm, gnu/system.scm,
  gnu/system/linux-initrd.scm, gnu/system/vm.scm,
  guix/scripts/system.scm: Adjust to the new module names.
2014-09-03 15:43:07 +02:00

703 lines
25 KiB
Scheme
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 linux-initrd)
#:use-module (rnrs io ports)
#:use-module (rnrs bytevectors)
#:use-module (system foreign)
#:use-module (system repl error-handling)
#:autoload (system repl repl) (start-repl)
#:autoload (system base compile) (compile-file)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 ftw)
#:use-module (guix build utils)
#:export (mount-essential-file-systems
linux-command-line
find-long-option
make-essential-device-nodes
configure-qemu-networking
disk-partitions
partition-label-predicate
find-partition-by-label
canonicalize-device-spec
mount-flags->bit-mask
check-file-system
mount-file-system
bind-mount
load-linux-module*
device-number
boot-system))
;;; Commentary:
;;;
;;; Utility procedures useful in a Linux initial RAM disk (initrd). Note that
;;; many of these use procedures not yet available in vanilla Guile (`mount',
;;; `load-linux-module', etc.); these are provided by a Guile patch used in
;;; the GNU distribution.
;;;
;;; Code:
(define* (mount-essential-file-systems #:key (root "/"))
"Mount /proc and /sys under ROOT."
(define (scope dir)
(string-append root
(if (string-suffix? "/" root)
""
"/")
dir))
(unless (file-exists? (scope "proc"))
(mkdir (scope "proc")))
(mount "none" (scope "proc") "proc")
(unless (file-exists? (scope "sys"))
(mkdir (scope "sys")))
(mount "none" (scope "sys") "sysfs"))
(define (move-essential-file-systems root)
"Move currently mounted essential file systems to ROOT."
(for-each (lambda (dir)
(let ((target (string-append root dir)))
(unless (file-exists? target)
(mkdir target))
(mount dir target "" MS_MOVE)))
'("/proc" "/sys")))
(define (linux-command-line)
"Return the Linux kernel command line as a list of strings."
(string-tokenize
(call-with-input-file "/proc/cmdline"
get-string-all)))
(define (find-long-option option arguments)
"Find OPTION among ARGUMENTS, where OPTION is something like \"--load\".
Return the value associated with OPTION, or #f on failure."
(let ((opt (string-append option "=")))
(and=> (find (cut string-prefix? opt <>)
arguments)
(lambda (arg)
(substring arg (+ 1 (string-index arg #\=)))))))
(define-syntax %ext2-endianness
;; Endianness of ext2 file systems.
(identifier-syntax (endianness little)))
;; Offset in bytes of interesting parts of an ext2 superblock. See
;; <http://www.nongnu.org/ext2-doc/ext2.html#DEF-SUPERBLOCK>.
;; TODO: Use "packed structs" from Guile-OpenGL or similar.
(define-syntax %ext2-sblock-magic (identifier-syntax 56))
(define-syntax %ext2-sblock-creator-os (identifier-syntax 72))
(define-syntax %ext2-sblock-uuid (identifier-syntax 104))
(define-syntax %ext2-sblock-volume-name (identifier-syntax 120))
(define (read-ext2-superblock device)
"Return the raw contents of DEVICE's ext2 superblock as a bytevector, or #f
if DEVICE does not contain an ext2 file system."
(define %ext2-magic
;; The magic bytes that identify an ext2 file system.
#xef53)
(define superblock-size
;; Size of the interesting part of an ext2 superblock.
264)
(define block
;; The superblock contents.
(make-bytevector superblock-size))
(call-with-input-file device
(lambda (port)
(seek port 1024 SEEK_SET)
;; Note: work around <http://bugs.gnu.org/17466>.
(and (eqv? superblock-size (get-bytevector-n! port block 0
superblock-size))
(let ((magic (bytevector-u16-ref block %ext2-sblock-magic
%ext2-endianness)))
(and (= magic %ext2-magic)
block))))))
(define (ext2-superblock-uuid sblock)
"Return the UUID of ext2 superblock SBLOCK as a 16-byte bytevector."
(let ((uuid (make-bytevector 16)))
(bytevector-copy! sblock %ext2-sblock-uuid uuid 0 16)
uuid))
(define (ext2-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 16 characters, or
#f if SBLOCK has no volume name."
(let ((bv (make-bytevector 16)))
(bytevector-copy! sblock %ext2-sblock-volume-name bv 0 16)
;; This is a Latin-1, nul-terminated string.
(let ((bytes (take-while (negate zero?) (bytevector->u8-list bv))))
(if (null? bytes)
#f
(list->string (map integer->char bytes))))))
(define (disk-partitions)
"Return the list of device names corresponding to valid disk partitions."
(define (partition? major minor)
(let ((marker (format #f "/sys/dev/block/~a:~a/partition" major minor)))
(catch 'system-error
(lambda ()
(not (zero? (call-with-input-file marker read))))
(lambda args
(if (= ENOENT (system-error-errno args))
#f
(apply throw args))))))
(call-with-input-file "/proc/partitions"
(lambda (port)
;; Skip the two header lines.
(read-line port)
(read-line port)
;; Read each subsequent line, and extract the last space-separated
;; field.
(let loop ((parts '()))
(let ((line (read-line port)))
(if (eof-object? line)
(reverse parts)
(match (string-tokenize line)
(((= string->number major) (= string->number minor)
blocks name)
(if (partition? major minor)
(loop (cons name parts))
(loop parts))))))))))
(define (partition-label-predicate label)
"Return a procedure that, when applied to a partition name such as \"sda1\",
return #t if that partition's volume name is LABEL."
(lambda (part)
(let* ((device (string-append "/dev/" part))
(sblock (catch 'system-error
(lambda ()
(read-ext2-superblock device))
(lambda args
;; When running on the hand-made /dev,
;; 'disk-partitions' could return partitions for which
;; we have no /dev node. Handle that gracefully.
(if (= ENOENT (system-error-errno args))
(begin
(format (current-error-port)
"warning: device '~a' not found~%"
device)
#f)
(apply throw args))))))
(and sblock
(let ((volume (ext2-superblock-volume-name sblock)))
(and volume
(string=? volume label)))))))
(define (find-partition-by-label label)
"Return the first partition found whose volume name is LABEL, or #f if none
were found."
(and=> (find (partition-label-predicate label)
(disk-partitions))
(cut string-append "/dev/" <>)))
(define* (canonicalize-device-spec spec #:optional (title 'any))
"Return the device name corresponding to SPEC. TITLE is a symbol, one of
the following:
• 'device', in which case SPEC is known to designate a device node--e.g.,
\"/dev/sda1\";
• 'label', in which case SPEC is known to designate a partition label--e.g.,
\"my-root-part\";
• 'any', in which case SPEC can be anything.
"
(define max-trials
;; Number of times we retry partition label resolution, 1 second per
;; trial. Note: somebody reported a delay of 16 seconds (!) before their
;; USB key would be detected by the kernel, so we must wait for at least
;; this long.
20)
(define canonical-title
;; The realm of canonicalization.
(if (eq? title 'any)
(if (string-prefix? "/" spec)
'device
'label)
title))
(case canonical-title
((device)
;; Nothing to do.
spec)
((label)
;; Resolve the label.
(let loop ((count 0))
(let ((device (find-partition-by-label spec)))
(or device
;; Some devices take a bit of time to appear, most notably USB
;; storage devices. Thus, wait for the device to appear.
(if (> count max-trials)
(error "failed to resolve partition label" spec)
(begin
(format #t "waiting for partition '~a' to appear...~%"
spec)
(sleep 1)
(loop (+ 1 count))))))))
;; TODO: Add support for UUIDs.
(else
(error "unknown device title" title))))
(define* (make-disk-device-nodes base major #:optional (minor 0))
"Make the block device nodes around BASE (something like \"/root/dev/sda\")
with the given MAJOR number, starting with MINOR."
(mknod base 'block-special #o644 (device-number major minor))
(let loop ((i 1))
(when (< i 6)
(mknod (string-append base (number->string i))
'block-special #o644 (device-number major (+ minor i)))
(loop (+ i 1)))))
(define* (make-essential-device-nodes #:key (root "/"))
"Make essential device nodes under ROOT/dev."
;; The hand-made udev!
(define (scope dir)
(string-append root
(if (string-suffix? "/" root)
""
"/")
dir))
(unless (file-exists? (scope "dev"))
(mkdir (scope "dev")))
;; Make the device nodes for SCSI disks.
(make-disk-device-nodes (scope "dev/sda") 8)
(make-disk-device-nodes (scope "dev/sdb") 8 16)
(make-disk-device-nodes (scope "dev/sdc") 8 32)
(make-disk-device-nodes (scope "dev/sdd") 8 48)
;; SCSI CD-ROM devices (aka. "/dev/sr0" etc.).
(mknod (scope "dev/scd0") 'block-special #o644 (device-number 11 0))
(mknod (scope "dev/scd1") 'block-special #o644 (device-number 11 1))
;; The virtio (para-virtualized) block devices, as supported by QEMU/KVM.
(make-disk-device-nodes (scope "dev/vda") 252)
;; Memory (used by Xorg's VESA driver.)
(mknod (scope "dev/mem") 'char-special #o640 (device-number 1 1))
(mknod (scope "dev/kmem") 'char-special #o640 (device-number 1 2))
;; Inputs (used by Xorg.)
(unless (file-exists? (scope "dev/input"))
(mkdir (scope "dev/input")))
(mknod (scope "dev/input/mice") 'char-special #o640 (device-number 13 63))
(mknod (scope "dev/input/mouse0") 'char-special #o640 (device-number 13 32))
(mknod (scope "dev/input/event0") 'char-special #o640 (device-number 13 64))
;; System console. This node is magically created by the kernel on the
;; initrd's root, so don't try to create it in that case.
(unless (string=? root "/")
(mknod (scope "dev/console") 'char-special #o600
(device-number 5 1)))
;; TTYs.
(mknod (scope "dev/tty") 'char-special #o600
(device-number 5 0))
(chmod (scope "dev/tty") #o666)
(let loop ((n 0))
(and (< n 50)
(let ((name (format #f "dev/tty~a" n)))
(mknod (scope name) 'char-special #o600
(device-number 4 n))
(loop (+ 1 n)))))
;; Serial line.
(mknod (scope "dev/ttyS0") 'char-special #o660
(device-number 4 64))
;; Pseudo ttys.
(mknod (scope "dev/ptmx") 'char-special #o666
(device-number 5 2))
(chmod (scope "dev/ptmx") #o666)
;; Create /dev/pts; it will be mounted later, at boot time.
(unless (file-exists? (scope "dev/pts"))
(mkdir (scope "dev/pts")))
;; Rendez-vous point for syslogd.
(mknod (scope "dev/log") 'socket #o666 0)
(mknod (scope "dev/kmsg") 'char-special #o600 (device-number 1 11))
;; Other useful nodes, notably relied on by guix-daemon.
(for-each (match-lambda
((file major minor)
(mknod (scope file) 'char-special #o666
(device-number major minor))
(chmod (scope file) #o666)))
'(("dev/null" 1 3)
("dev/zero" 1 5)
("dev/full" 1 7)
("dev/random" 1 8)
("dev/urandom" 1 9)))
(symlink "/proc/self/fd" (scope "dev/fd"))
(symlink "/proc/self/fd/0" (scope "dev/stdin"))
(symlink "/proc/self/fd/1" (scope "dev/stdout"))
(symlink "/proc/self/fd/2" (scope "dev/stderr"))
;; Loopback devices.
(let loop ((i 0))
(when (< i 8)
(mknod (scope (string-append "dev/loop" (number->string i)))
'block-special #o660
(device-number 7 i))
(loop (+ 1 i))))
;; File systems in user space (FUSE).
(mknod (scope "dev/fuse") 'char-special #o666 (device-number 10 229)))
(define %host-qemu-ipv4-address
(inet-pton AF_INET "10.0.2.10"))
(define* (configure-qemu-networking #:optional (interface "eth0"))
"Setup the INTERFACE network interface and /etc/resolv.conf according to
QEMU's default networking settings (see net/slirp.c in QEMU for default
networking values.) Return #t if INTERFACE is up, #f otherwise."
(display "configuring QEMU networking...\n")
(let* ((sock (socket AF_INET SOCK_STREAM 0))
(address (make-socket-address AF_INET %host-qemu-ipv4-address 0))
(flags (network-interface-flags sock interface)))
(set-network-interface-address sock interface address)
(set-network-interface-flags sock interface (logior flags IFF_UP))
;; Hello! We used to create /etc/resolv.conf here, with "nameserver
;; 10.0.2.3\n". However, with Linux-libre 3.16, we're getting ENOSPC.
;; And since it's actually unnecessary, it's gone.
(logand (network-interface-flags sock interface) IFF_UP)))
;; Linux mount flags, from libc's <sys/mount.h>.
(define MS_RDONLY 1)
(define MS_NOSUID 2)
(define MS_NODEV 4)
(define MS_NOEXEC 8)
(define MS_BIND 4096)
(define MS_MOVE 8192)
(define (bind-mount source target)
"Bind-mount SOURCE at TARGET."
(mount source target "" MS_BIND))
(define (load-linux-module* file)
"Load Linux module from FILE, the name of a `.ko' file."
(define (slurp module)
(call-with-input-file file get-bytevector-all))
(load-linux-module (slurp file)))
(define (device-number major minor)
"Return the device number for the device with MAJOR and MINOR, for use as
the last argument of `mknod'."
(+ (* major 256) minor))
(define (pidof program)
"Return the PID of the first presumed instance of PROGRAM."
(let ((program (basename program)))
(find (lambda (pid)
(let ((exe (format #f "/proc/~a/exe" pid)))
(and=> (false-if-exception (readlink exe))
(compose (cut string=? program <>) basename))))
(filter-map string->number (scandir "/proc")))))
(define* (mount-root-file-system root type
#:key volatile-root? (unionfs "unionfs"))
"Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT?
is true, mount ROOT read-only and make it a union with a writable tmpfs using
UNIONFS."
(define (mark-as-not-killable pid)
;; Tell the 'user-processes' dmd service that PID must be kept alive when
;; shutting down.
(mkdir-p "/root/etc/dmd")
(let ((port (open-file "/root/etc/dmd/do-not-kill" "a")))
(chmod port #o600)
(write pid port)
(newline port)
(close-port port)))
(catch #t
(lambda ()
(if volatile-root?
(begin
(mkdir-p "/real-root")
(mount root "/real-root" type MS_RDONLY)
(mkdir-p "/rw-root")
(mount "none" "/rw-root" "tmpfs")
;; We want read-write /dev nodes.
(make-essential-device-nodes #:root "/rw-root")
;; Make /root a union of the tmpfs and the actual root. Use
;; 'max_files' to set a high RLIMIT_NOFILE for the unionfs process
;; itself. Failing to do that, we quickly run out of file
;; descriptors; see <http://bugs.gnu.org/17827>.
(unless (zero? (system* unionfs "-o"
"cow,allow_other,use_ino,suid,dev,max_files=65536"
"/rw-root=RW:/real-root=RO"
"/root"))
(error "unionfs failed"))
;; Make sure unionfs remains alive till the end. Because
;; 'fuse_daemonize' doesn't tell the PID of the forked daemon, we
;; have to resort to 'pidof' here.
(mark-as-not-killable (pidof unionfs)))
(begin
(check-file-system root type)
(mount root "/root" type))))
(lambda args
(format (current-error-port) "exception while mounting '~a': ~s~%"
root args)
(start-repl)))
(copy-file "/proc/mounts" "/root/etc/mtab"))
(define (check-file-system device type)
"Run a file system check of TYPE on DEVICE."
(define fsck
(string-append "fsck." type))
(let ((status (system* fsck "-v" "-p" device)))
(match (status:exit-val status)
(0
#t)
(1
(format (current-error-port) "'~a' corrected errors on ~a; continuing~%"
fsck device))
(2
(format (current-error-port) "'~a' corrected errors on ~a; rebooting~%"
fsck device)
(sleep 3)
(reboot))
(code
(format (current-error-port) "'~a' exited with code ~a on ~a; spawning REPL~%"
fsck code device)
(start-repl)))))
(define (mount-flags->bit-mask flags)
"Return the number suitable for the 'flags' argument of 'mount' that
corresponds to the symbols listed in FLAGS."
(let loop ((flags flags))
(match flags
(('read-only rest ...)
(logior MS_RDONLY (loop rest)))
(('bind-mount rest ...)
(logior MS_BIND (loop rest)))
(('no-suid rest ...)
(logior MS_NOSUID (loop rest)))
(('no-dev rest ...)
(logior MS_NODEV (loop rest)))
(('no-exec rest ...)
(logior MS_NOEXEC (loop rest)))
(()
0))))
(define* (mount-file-system spec #:key (root "/root"))
"Mount the file system described by SPEC under ROOT. SPEC must have the
form:
(DEVICE TITLE MOUNT-POINT TYPE (FLAGS ...) OPTIONS CHECK?)
DEVICE, MOUNT-POINT, and TYPE must be strings; OPTIONS can be a string or #f;
FLAGS must be a list of symbols. CHECK? is a Boolean indicating whether to
run a file system check."
(match spec
((source title mount-point type (flags ...) options check?)
(let ((source (canonicalize-device-spec source title))
(mount-point (string-append root "/" mount-point)))
(when check?
(check-file-system source type))
(mkdir-p mount-point)
(mount source mount-point type (mount-flags->bit-mask flags)
(if options
(string->pointer options)
%null-pointer))
;; Update /etc/mtab.
(mkdir-p (string-append root "/etc"))
(let ((port (open-file (string-append root "/etc/mtab") "a")))
(format port "~a ~a ~a ~a 0 0~%"
source mount-point type (or options ""))
(close-port port))))))
(define (switch-root root)
"Switch to ROOT as the root file system, in a way similar to what
util-linux' switch_root(8) does."
(move-essential-file-systems root)
(chdir root)
;; Since we're about to 'rm -rf /', try to make sure we're on an initrd.
;; TODO: Use 'statfs' to check the fs type, like klibc does.
(when (or (not (file-exists? "/init")) (directory-exists? "/home"))
(format (current-error-port)
"The root file system is probably not an initrd; \
bailing out.~%root contents: ~s~%" (scandir "/"))
(force-output (current-error-port))
(exit 1))
;; Delete files from the old root, without crossing mount points (assuming
;; there are no mount points in sub-directories.) That means we're leaving
;; the empty ROOT directory behind us, but that's OK.
(let ((root-device (stat:dev (stat "/"))))
(for-each (lambda (file)
(unless (member file '("." ".."))
(let* ((file (string-append "/" file))
(device (stat:dev (lstat file))))
(when (= device root-device)
(delete-file-recursively file)))))
(scandir "/")))
;; Make ROOT the new root.
(mount root "/" "" MS_MOVE)
(chroot ".")
(chdir "/")
(when (file-exists? "/dev/console")
;; Close the standard file descriptors since they refer to the old
;; /dev/console, and reopen them.
(let ((console (open-file "/dev/console" "r+b0")))
(for-each close-fdes '(0 1 2))
(dup2 (fileno console) 0)
(dup2 (fileno console) 1)
(dup2 (fileno console) 2)
(close-port console))))
(define* (boot-system #:key
(linux-modules '())
qemu-guest-networking?
guile-modules-in-chroot?
volatile-root?
(mounts '()))
"This procedure is meant to be called from an initrd. Boot a system by
first loading LINUX-MODULES, then setting up QEMU guest networking if
QEMU-GUEST-NETWORKING? is true, mounting the file systems specified in MOUNTS,
and finally booting into the new root if any. The initrd supports kernel
command-line options '--load', '--root', and '--repl'.
Mount the root file system, specified by the '--root' command-line argument,
if any.
MOUNTS must be a list suitable for 'mount-file-system'.
When GUILE-MODULES-IN-CHROOT? is true, make core Guile modules available in
the new root.
When VOLATILE-ROOT? is true, the root file system is writable but any changes
to it are lost."
(define root-mount-point?
(match-lambda
((device _ "/" _ ...) #t)
(_ #f)))
(define root-fs-type
(or (any (match-lambda
((device _ "/" type _ ...) type)
(_ #f))
mounts)
"ext4"))
(display "Welcome, this is GNU's early boot Guile.\n")
(display "Use '--repl' for an initrd REPL.\n\n")
(call-with-error-handling
(lambda ()
(mount-essential-file-systems)
(let* ((args (linux-command-line))
(to-load (find-long-option "--load" args))
(root (find-long-option "--root" args)))
(when (member "--repl" args)
(start-repl))
(display "loading kernel modules...\n")
(for-each (compose load-linux-module*
(cut string-append "/modules/" <>))
linux-modules)
(when qemu-guest-networking?
(unless (configure-qemu-networking)
(display "network interface is DOWN\n")))
;; Make /dev nodes.
(make-essential-device-nodes)
;; Prepare the real root file system under /root.
(unless (file-exists? "/root")
(mkdir "/root"))
(if root
(mount-root-file-system (canonicalize-device-spec root)
root-fs-type
#:volatile-root? volatile-root?)
(mount "none" "/root" "tmpfs"))
(unless (file-exists? "/root/dev")
(mkdir "/root/dev")
(make-essential-device-nodes #:root "/root"))
;; Mount the specified file systems.
(for-each mount-file-system
(remove root-mount-point? mounts))
(when guile-modules-in-chroot?
;; Copy the directories that contain .scm and .go files so that the
;; child process in the chroot can load modules (we would bind-mount
;; them but for some reason that fails with EINVAL -- XXX).
(mkdir-p "/root/share")
(mkdir-p "/root/lib")
(mount "none" "/root/share" "tmpfs")
(mount "none" "/root/lib" "tmpfs")
(copy-recursively "/share" "/root/share"
#:log (%make-void-port "w"))
(copy-recursively "/lib" "/root/lib"
#:log (%make-void-port "w")))
(if to-load
(begin
(switch-root "/root")
(format #t "loading '~a'...\n" to-load)
;; TODO: Remove /lib, /share, and /loader.go.
(primitive-load to-load)
(format (current-error-port)
"boot program '~a' terminated, rebooting~%"
to-load)
(sleep 2)
(reboot))
(begin
(display "no boot file passed via '--load'\n")
(display "entering a warm and cozy REPL\n")
(start-repl)))))))
;;; linux-initrd.scm ends here