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guix/gnu/build/file-systems.scm
Ludovic Courtès 09ce4568f2
file-systems: read-partition-{uuid,label} don't swallow ENOENT & co. 
Previously, (read-partition-uuid "/does/not/exist") would return #f.
With this change, a 'system-error exception is raised as expected.

* gnu/build/file-systems.scm (ENOENT-safe): Clarify docstring.
(partition-field-reader): Remove use of 'ENOENT-safe'.
(partition-predicate): Wrap READER in 'ENOENT-safe'.
2021-04-23 00:32:30 +02:00

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016, 2017 David Craven <david@craven.ch>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2019 Guillaume Le Vaillant <glv@posteo.net>
;;; Copyright © 2019, 2020 Tobias Geerinckx-Rice <me@tobias.gr>
;;; Copyright © 2019 David C. Trudgian <dave@trudgian.net>
;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
;;; 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 file-systems)
#:use-module (gnu system uuid)
#:use-module (gnu system file-systems)
#:use-module (guix build utils)
#:use-module (guix build bournish)
#:use-module ((guix build syscalls)
#:hide (file-system-type))
#:use-module (rnrs io ports)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (system foreign)
#:autoload (system repl repl) (start-repl)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:export (disk-partitions
partition-label-predicate
partition-uuid-predicate
partition-luks-uuid-predicate
find-partition-by-label
find-partition-by-uuid
find-partition-by-luks-uuid
canonicalize-device-spec
read-partition-label
read-partition-uuid
read-luks-partition-uuid
bind-mount
mount-flags->bit-mask
check-file-system
mount-file-system))
;;; Commentary:
;;;
;;; This modules provides tools to deal with disk partitions, and to mount and
;;; check file systems.
;;;
;;; Code:
(define (bind-mount source target)
"Bind-mount SOURCE at TARGET."
(mount source target "" MS_BIND))
(define (seek* fd/port offset whence)
"Like 'seek' but return -1 instead of throwing to 'system-error' upon
EINVAL. This makes it easier to catch cases like OFFSET being too large for
FD/PORT."
(catch 'system-error
(lambda ()
(seek fd/port offset whence))
(lambda args
(if (= EINVAL (system-error-errno args))
-1
(apply throw args)))))
(define (read-superblock device offset size magic?)
"Read a superblock of SIZE from OFFSET and DEVICE. Return the raw
superblock on success, and #f if no valid superblock was found. MAGIC?
takes a bytevector and returns #t when it's a valid superblock."
(call-with-input-file device
(lambda (port)
(and (= offset (seek* port offset SEEK_SET))
(let ((block (make-bytevector size)))
(match (get-bytevector-n! port block 0 (bytevector-length block))
((? eof-object?)
#f)
((? number? len)
(and (= len (bytevector-length block))
(and (magic? block)
block)))))))))
(define null-terminated-latin1->string
(cut latin1->string <> zero?))
(define (bytevector-utf16-length bv)
"Given a bytevector BV containing a NUL-terminated UTF16-encoded string,
determine where the NUL terminator is and return its index. If there's no
NUL terminator, return the size of the bytevector."
(let ((length (bytevector-length bv)))
(let loop ((index 0))
(if (< index length)
(if (zero? (bytevector-u16-ref bv index 'little))
index
(loop (+ index 2)))
length))))
(define* (bytevector->u16-list bv endianness #:optional (index 0))
(if (< index (bytevector-length bv))
(cons (bytevector-u16-ref bv index endianness)
(bytevector->u16-list bv endianness (+ index 2)))
'()))
;; The initrd doesn't have iconv data, so do the conversion ourselves.
(define (utf16->string bv endianness)
(list->string
(map integer->char
(reverse
(let loop ((remainder (bytevector->u16-list bv endianness))
(result '()))
(match remainder
(() result)
((a) (cons a result))
((a b x ...)
(if (and (>= a #xD800) (< a #xDC00) ; high surrogate
(>= b #xDC00) (< b #xE000)) ; low surrogate
(loop x (cons (+ #x10000
(* #x400 (- a #xD800))
(- b #xDC00))
result))
(loop (cons b x) (cons a result))))))))))
(define (null-terminated-utf16->string bv endianness)
(utf16->string (sub-bytevector bv 0 (bytevector-utf16-length bv))
endianness))
;;;
;;; Ext2 file systems.
;;;
;; <http://www.nongnu.org/ext2-doc/ext2.html#DEF-SUPERBLOCK>.
;; TODO: Use "packed structs" from Guile-OpenGL or similar.
(define-syntax %ext2-endianness
;; Endianness of ext2 file systems.
(identifier-syntax (endianness little)))
(define (ext2-superblock? sblock)
"Return #t when SBLOCK is an ext2 superblock."
(let ((magic (bytevector-u16-ref sblock 56 %ext2-endianness)))
(= magic #xef53)))
(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."
(read-superblock device 1024 264 ext2-superblock?))
(define (ext2-superblock-uuid sblock)
"Return the UUID of ext2 superblock SBLOCK as a 16-byte bytevector."
(sub-bytevector sblock 104 16))
(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."
(null-terminated-latin1->string (sub-bytevector sblock 120 16)))
(define (check-ext2-file-system device)
"Return the health of an ext2 file system on DEVICE."
(match (status:exit-val
(system* "e2fsck" "-v" "-p" "-C" "0" device))
(0 'pass)
(1 'errors-corrected)
(2 'reboot-required)
(_ 'fatal-error)))
;;;
;;; Linux swap.
;;;
;; Linux "swap space" is not a file system but it has a UUID and volume name,
;; like actual file systems, and we want to be able to look up swap partitions
;; by UUID and by label.
(define %linux-swap-magic
(string->utf8 "SWAPSPACE2"))
;; Like 'PAGE_SIZE' in Linux, arch/x86/include/asm/page.h.
;; XXX: This is always 4K on x86_64, i386, and ARMv7. However, on AArch64,
;; this is determined by 'CONFIG_ARM64_PAGE_SHIFT' in the kernel, which is 12
;; by default (4K) but can be 14 or 16.
(define %page-size 4096)
(define (linux-swap-superblock? sblock)
"Return #t when SBLOCK is an linux-swap superblock."
(and (= (bytevector-length sblock) %page-size)
(bytevector=? (sub-bytevector sblock (- %page-size 10) 10)
%linux-swap-magic)))
(define (read-linux-swap-superblock device)
"Return the raw contents of DEVICE's linux-swap superblock as a bytevector, or #f
if DEVICE does not contain an linux-swap file system."
(read-superblock device 0 %page-size linux-swap-superblock?))
;; See 'union swap_header' in 'include/linux/swap.h'.
(define (linux-swap-superblock-uuid sblock)
"Return the UUID of Linux-swap superblock SBLOCK as a 16-byte bytevector."
(sub-bytevector sblock (+ 1024 4 4 4) 16))
(define (linux-swap-superblock-volume-name sblock)
"Return the label of Linux-swap superblock SBLOCK as a string."
(null-terminated-latin1->string
(sub-bytevector sblock (+ 1024 4 4 4 16) 16)))
;;;
;;; Bcachefs file systems.
;;;
;; <https://evilpiepirate.org/git/bcachefs-tools.git/tree/libbcachefs/bcachefs_format.h>
(define-syntax %bcachefs-endianness
;; Endianness of bcachefs file systems.
(identifier-syntax (endianness little)))
(define (bcachefs-superblock? sblock)
"Return #t when SBLOCK is an bcachefs superblock."
(bytevector=? (sub-bytevector sblock 24 16)
#vu8(#xc6 #x85 #x73 #xf6 #x4e #x1a #x45 #xca
#x82 #x65 #xf5 #x7f #x48 #xba #x6d #x81)))
(define (read-bcachefs-superblock device)
"Return the raw contents of DEVICE's bcachefs superblock as a bytevector, or #f
if DEVICE does not contain a bcachefs file system."
;; We completely ignore the back-up superblock & any checksum errors.
;; Superblock field names, with offset & length respectively, in bytes:
;; 0 16 bch_csum
;; 16 8 version
;; 24 16 magic
;; 40 16 uuid ← ‘internal UUID’, you probably don't want this
;; 56 16 user_uuid ← ‘external UUID’, the one by which to mount
;; 72 32 label
;; … there are more & the superblock is extensible, but we don't care yet.
(read-superblock device 4096 104 bcachefs-superblock?))
(define (bcachefs-superblock-external-uuid sblock)
"Return the external UUID of bcachefs superblock SBLOCK as a 16-byte
bytevector."
(sub-bytevector sblock 56 16))
(define (bcachefs-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 32 characters, or
#f if SBLOCK has no volume name."
(null-terminated-latin1->string (sub-bytevector sblock 72 32)))
(define (check-bcachefs-file-system device)
"Return the health of a bcachefs file system on DEVICE."
(let ((ignored-bits (logior 2)) ; DEVICE was mounted read-only
(status
(status:exit-val
(apply system* "bcachefs" "fsck" "-p" "-v"
;; Make each multi-device member a separate argument.
(string-split device #\:)))))
(match (logand (lognot ignored-bits) status)
(0 'pass)
(1 'errors-corrected)
(_ 'fatal-error))))
;;;
;;; Btrfs file systems.
;;;
;; <https://btrfs.wiki.kernel.org/index.php/On-disk_Format#Superblock>.
(define-syntax %btrfs-endianness
;; Endianness of btrfs file systems.
(identifier-syntax (endianness little)))
(define (btrfs-superblock? sblock)
"Return #t when SBLOCK is a btrfs superblock."
(bytevector=? (sub-bytevector sblock 64 8)
(string->utf8 "_BHRfS_M")))
(define (read-btrfs-superblock device)
"Return the raw contents of DEVICE's btrfs superblock as a bytevector, or #f
if DEVICE does not contain a btrfs file system."
(read-superblock device 65536 4096 btrfs-superblock?))
(define (btrfs-superblock-uuid sblock)
"Return the UUID of a btrfs superblock SBLOCK as a 16-byte bytevector."
(sub-bytevector sblock 32 16))
(define (btrfs-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 256 characters, or
#f if SBLOCK has no volume name."
(null-terminated-latin1->string (sub-bytevector sblock 299 256)))
(define (check-btrfs-file-system device)
"Return the health of a btrfs file system on DEVICE."
(match (status:exit-val
(system* "btrfs" "device" "scan"))
(0 'pass)
(_ 'fatal-error)))
;;;
;;; FAT32 file systems.
;;;
;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-107.pdf>.
(define (fat32-superblock? sblock)
"Return #t when SBLOCK is a fat32 superblock."
(bytevector=? (sub-bytevector sblock 82 8)
(string->utf8 "FAT32 ")))
(define (read-fat32-superblock device)
"Return the raw contents of DEVICE's fat32 superblock as a bytevector, or
#f if DEVICE does not contain a fat32 file system."
(read-superblock device 0 90 fat32-superblock?))
(define (fat32-superblock-uuid sblock)
"Return the Volume ID of a fat superblock SBLOCK as a 4-byte bytevector."
(sub-bytevector sblock 67 4))
(define (fat32-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 11 characters, or
#f if SBLOCK has no volume name. The volume name is a latin1 string.
Trailing spaces are trimmed."
(string-trim-right (latin1->string (sub-bytevector sblock 71 11) (lambda (c) #f)) #\space))
(define (check-fat-file-system device)
"Return the health of a fat file system on DEVICE."
(match (status:exit-val
(system* "fsck.vfat" "-v" "-a" device))
(0 'pass)
(1 'errors-corrected)
(_ 'fatal-error)))
;;;
;;; FAT16 file systems.
;;;
(define (fat16-superblock? sblock)
"Return #t when SBLOCK is a fat16 boot record."
(bytevector=? (sub-bytevector sblock 54 8)
(string->utf8 "FAT16 ")))
(define (read-fat16-superblock device)
"Return the raw contents of DEVICE's fat16 superblock as a bytevector, or
#f if DEVICE does not contain a fat16 file system."
(read-superblock device 0 62 fat16-superblock?))
(define (fat16-superblock-uuid sblock)
"Return the Volume ID of a fat superblock SBLOCK as a 4-byte bytevector."
(sub-bytevector sblock 39 4))
(define (fat16-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 11 characters, or
#f if SBLOCK has no volume name. The volume name is a latin1 string.
Trailing spaces are trimmed."
(string-trim-right (latin1->string (sub-bytevector sblock 43 11)
(lambda (c) #f))
#\space))
;;;
;;; ISO9660 file systems.
;;;
;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf>.
(define (iso9660-superblock? sblock)
"Return #t when SBLOCK is an iso9660 volume descriptor."
(bytevector=? (sub-bytevector sblock 1 6)
;; Note: "\x01" is the volume descriptor format version
(string->utf8 "CD001\x01")))
(define (read-iso9660-primary-volume-descriptor device offset)
"Find and read the first primary volume descriptor, starting at OFFSET.
Return #f if not found."
(let* ((sblock (read-superblock device offset 2048 iso9660-superblock?))
(type-code (if sblock
(bytevector-u8-ref sblock 0)
(error (format #f
"Could not read ISO9660 primary
volume descriptor from ~s"
device)))))
(match type-code
(255 #f) ; Volume Descriptor Set Terminator.
(1 sblock) ; Primary Volume Descriptor
(_ (read-iso9660-primary-volume-descriptor device (+ offset 2048))))))
(define (read-iso9660-superblock device)
"Return the raw contents of DEVICE's iso9660 primary volume descriptor
as a bytevector, or #f if DEVICE does not contain an iso9660 file system."
;; Start reading at sector 16.
;; Since we are not sure that the device contains an ISO9660 file system,
;; we have to find that out first.
(if (read-superblock device (* 2048 16) 2048 iso9660-superblock?)
(read-iso9660-primary-volume-descriptor device (* 2048 16))
#f)) ; Device does not contain an iso9660 file system.
(define (iso9660-superblock-uuid sblock)
"Return the modification time of an iso9660 primary volume descriptor
SBLOCK as a bytevector. If that's not set, returns the creation time."
;; Drops GMT offset for compatibility with Grub, blkid and /dev/disk/by-uuid.
;; Compare Grub: "2014-12-02-19-30-23-00".
;; Compare blkid result: "2014-12-02-19-30-23-00".
;; Compare /dev/disk/by-uuid entry: "2014-12-02-19-30-23-00".
(let* ((creation-time (sub-bytevector sblock 813 17))
(modification-time (sub-bytevector sblock 830 17))
(unset-time (make-bytevector 17 0))
(time (if (bytevector=? unset-time modification-time)
creation-time
modification-time)))
(sub-bytevector time 0 16))) ; strips GMT offset.
(define (iso9660-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string. The volume name is an ASCII
string. Trailing spaces are trimmed."
;; Note: Valid characters are of the set "[0-9][A-Z]_" (ECMA-119 Appendix A)
(string-trim-right (latin1->string (sub-bytevector sblock 40 32)
(lambda (c) #f)) #\space))
;;;
;;; JFS file systems.
;;;
;; Taken from <linux-libre>/fs/jfs/jfs_superblock.h.
(define-syntax %jfs-endianness
;; Endianness of JFS file systems.
(identifier-syntax (endianness little)))
(define (jfs-superblock? sblock)
"Return #t when SBLOCK is a JFS superblock."
(bytevector=? (sub-bytevector sblock 0 4)
(string->utf8 "JFS1")))
(define (read-jfs-superblock device)
"Return the raw contents of DEVICE's JFS superblock as a bytevector, or #f
if DEVICE does not contain a JFS file system."
(read-superblock device 32768 184 jfs-superblock?))
(define (jfs-superblock-uuid sblock)
"Return the UUID of JFS superblock SBLOCK as a 16-byte bytevector."
(sub-bytevector sblock 136 16))
(define (jfs-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."
(null-terminated-latin1->string (sub-bytevector sblock 152 16)))
(define (check-jfs-file-system device)
"Return the health of a JFS file system on DEVICE."
(match (status:exit-val
(system* "jfs_fsck" "-p" "-v" device))
(0 'pass)
(1 'errors-corrected)
(2 'reboot-required)
(_ 'fatal-error)))
;;;
;;; F2FS (Flash-Friendly File System)
;;;
;;; https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/tree/include/linux/f2fs_fs.h
;;; (but using xxd proved to be simpler)
(define-syntax %f2fs-endianness
;; Endianness of F2FS file systems
(identifier-syntax (endianness little)))
;; F2FS actually stores two adjacent copies of the superblock.
;; should we read both?
(define (f2fs-superblock? sblock)
"Return #t when SBLOCK is an F2FS superblock."
(let ((magic (bytevector-u32-ref sblock 0 %f2fs-endianness)))
(= magic #xF2F52010)))
(define (read-f2fs-superblock device)
"Return the raw contents of DEVICE's F2FS superblock as a bytevector, or #f
if DEVICE does not contain an F2FS file system."
(read-superblock device
;; offset of magic in first copy
#x400
;; difference between magic of second
;; and first copies
(- #x1400 #x400)
f2fs-superblock?))
(define (f2fs-superblock-uuid sblock)
"Return the UUID of F2FS superblock SBLOCK as a 16-byte bytevector."
(sub-bytevector sblock
(- (+ #x460 12)
;; subtract superblock offset
#x400)
16))
(define (f2fs-superblock-volume-name sblock)
"Return the volume name of SBLOCK as a string of at most 512 characters, or
#f if SBLOCK has no volume name."
(null-terminated-utf16->string
(sub-bytevector sblock (- (+ #x470 12) #x400) 512)
%f2fs-endianness))
(define (check-f2fs-file-system device)
"Return the health of a F2FS file system on DEVICE."
(match (status:exit-val
(system* "fsck.f2fs" "-p" device))
;; 0 and -1 are the only two possibilities
;; (according to the manpage)
(0 'pass)
(_ 'fatal-error)))
;;;
;;; LUKS encrypted devices.
;;;
;; The LUKS header format is described in "LUKS On-Disk Format Specification":
;; <https://gitlab.com/cryptsetup/cryptsetup/wikis/Specification>. We follow
;; version 1.2.1 of this document.
;; The LUKS2 header format is described in "LUKS2 On-Disk Format Specification":
;; <https://gitlab.com/cryptsetup/LUKS2-docs/blob/master/luks2_doc_wip.pdf>.
;; It is a WIP document.
(define-syntax %luks-endianness
;; Endianness of LUKS headers.
(identifier-syntax (endianness big)))
(define (luks-superblock? sblock)
"Return #t when SBLOCK is a luks superblock."
(define %luks-magic
;; The 'LUKS_MAGIC' constant.
(u8-list->bytevector (append (map char->integer (string->list "LUKS"))
(list #xba #xbe))))
(let ((magic (sub-bytevector sblock 0 6))
(version (bytevector-u16-ref sblock 6 %luks-endianness)))
(and (bytevector=? magic %luks-magic)
(or (= version 1) (= version 2)))))
(define (read-luks-header file)
"Read a LUKS header from FILE. Return the raw header on success, and #f if
not valid header was found."
;; Size in bytes of the LUKS binary header, which includes key slots in
;; LUKS1. In LUKS2 the binary header is partially backward compatible, so
;; that UUID can be extracted as for LUKS1. Keyslots and other metadata are
;; not part of this header in LUKS2, but are included in the JSON metadata
;; area that follows.
(read-superblock file 0 592 luks-superblock?))
(define (luks-header-uuid header)
"Return the LUKS UUID from HEADER, as a 16-byte bytevector."
;; 40 bytes are reserved for the UUID, but in practice, it contains the 36
;; bytes of its ASCII representation.
(let ((uuid (sub-bytevector header 168 36)))
(string->uuid (utf8->string uuid))))
;;;
;;; NTFS file systems.
;;;
;; Taken from <linux-libre>/fs/ntfs/layout.h
(define-syntax %ntfs-endianness
;; Endianness of NTFS file systems.
(identifier-syntax (endianness little)))
(define (ntfs-superblock? sblock)
"Return #t when SBLOCK is a NTFS superblock."
(bytevector=? (sub-bytevector sblock 3 8)
(string->utf8 "NTFS ")))
(define (read-ntfs-superblock device)
"Return the raw contents of DEVICE's NTFS superblock as a bytevector, or #f
if DEVICE does not contain a NTFS file system."
(read-superblock device 0 511 ntfs-superblock?))
(define (ntfs-superblock-uuid sblock)
"Return the UUID of NTFS superblock SBLOCK as a 8-byte bytevector."
(sub-bytevector sblock 72 8))
;; TODO: Add ntfs-superblock-volume-name. The partition label is not stored
;; in the BOOT SECTOR like the UUID, but in the MASTER FILE TABLE, which seems
;; way harder to access.
(define (check-ntfs-file-system device)
"Return the health of a NTFS file system on DEVICE."
(match (status:exit-val
(system* "ntfsfix" device))
(0 'pass)
(_ 'fatal-error)))
;;;
;;; Partition lookup.
;;;
(define (disk-partitions)
"Return the list of device names corresponding to valid disk partitions."
(define (partition? name major minor)
;; grub-mkrescue does some funny things for EFI support which
;; makes it a lot more difficult than one would expect to support
;; booting an ISO-9660 image from an USB flash drive.
;; For example there's a buggy (too small) hidden partition in it
;; which Linux mounts and then proceeds to fail while trying to
;; fall off the edge.
;; In any case, partition tables are supposed to be optional so
;; here we allow checking entire disks for file systems, too.
(> major 2)) ;ignore RAM disks and floppy disks
(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? name major minor)
(loop (cons name parts))
(loop parts))))))))))
(define (ENOENT-safe proc)
"Wrap the one-argument PROC such that ENOENT, EIO, and ENOMEDIUM errors are
caught and lead to a warning and #f as the result."
(lambda (device)
(catch 'system-error
(lambda ()
(proc device))
(lambda args
(let ((errno (system-error-errno args)))
(cond ((= ENOENT errno)
(format (current-error-port)
"warning: device '~a' not found~%" device)
#f)
((= ENOMEDIUM errno) ;for removable media
#f)
((= EIO errno) ;unreadable hardware like audio CDs
(format (current-error-port)
"warning: failed to read from device '~a'~%" device)
#f)
(else
(apply throw args))))))))
(define (partition-field-reader read field)
"Return a procedure that takes a device and returns the value of a FIELD in
the partition superblock or #f."
(lambda (device)
(let ((sblock (read device)))
(and sblock
(field sblock)))))
(define (read-partition-field device partition-field-readers)
"Returns the value of a FIELD in the partition superblock of DEVICE or #f. It
takes a list of PARTITION-FIELD-READERS and returns the result of the first
partition field reader that returned a value."
(match (filter-map (cut apply <> (list device)) partition-field-readers)
((field . _) field)
(_ #f)))
(define %partition-label-readers
(list (partition-field-reader read-iso9660-superblock
iso9660-superblock-volume-name)
(partition-field-reader read-ext2-superblock
ext2-superblock-volume-name)
(partition-field-reader read-linux-swap-superblock
linux-swap-superblock-volume-name)
(partition-field-reader read-bcachefs-superblock
bcachefs-superblock-volume-name)
(partition-field-reader read-btrfs-superblock
btrfs-superblock-volume-name)
(partition-field-reader read-fat32-superblock
fat32-superblock-volume-name)
(partition-field-reader read-fat16-superblock
fat16-superblock-volume-name)
(partition-field-reader read-jfs-superblock
jfs-superblock-volume-name)
(partition-field-reader read-f2fs-superblock
f2fs-superblock-volume-name)))
(define %partition-uuid-readers
(list (partition-field-reader read-iso9660-superblock
iso9660-superblock-uuid)
(partition-field-reader read-ext2-superblock
ext2-superblock-uuid)
(partition-field-reader read-linux-swap-superblock
linux-swap-superblock-uuid)
(partition-field-reader read-bcachefs-superblock
bcachefs-superblock-external-uuid)
(partition-field-reader read-btrfs-superblock
btrfs-superblock-uuid)
(partition-field-reader read-fat32-superblock
fat32-superblock-uuid)
(partition-field-reader read-fat16-superblock
fat16-superblock-uuid)
(partition-field-reader read-jfs-superblock
jfs-superblock-uuid)
(partition-field-reader read-f2fs-superblock
f2fs-superblock-uuid)
(partition-field-reader read-ntfs-superblock
ntfs-superblock-uuid)))
(define read-partition-label
(cut read-partition-field <> %partition-label-readers))
(define read-partition-uuid
(cut read-partition-field <> %partition-uuid-readers))
(define luks-partition-field-reader
(partition-field-reader read-luks-header luks-header-uuid))
(define read-luks-partition-uuid
(cut read-partition-field <> (list luks-partition-field-reader)))
(define (partition-predicate reader =)
"Return a predicate that returns true if the FIELD of partition header that
was READ is = to the given value."
;; When running on the hand-made /dev, 'disk-partitions' could return
;; partitions for which we have no /dev node. Handle that gracefully.
(let ((reader (ENOENT-safe reader)))
(lambda (expected)
(lambda (device)
(let ((actual (reader device)))
(and actual
(= actual expected)))))))
(define partition-label-predicate
(partition-predicate read-partition-label string=?))
(define partition-uuid-predicate
(partition-predicate read-partition-uuid uuid=?))
(define luks-partition-uuid-predicate
(partition-predicate luks-partition-field-reader uuid=?))
(define (find-partition predicate)
"Return the first partition found that matches PREDICATE, or #f if none
were found."
(lambda (expected)
(find (predicate expected)
(map (cut string-append "/dev/" <>)
(disk-partitions)))))
(define find-partition-by-label
(find-partition partition-label-predicate))
(define find-partition-by-uuid
(find-partition partition-uuid-predicate))
(define find-partition-by-luks-uuid
(find-partition luks-partition-uuid-predicate))
(define (canonicalize-device-spec spec)
"Return the device name corresponding to SPEC, which can be a <uuid>, a
<file-system-label>, or a string (typically a /dev file name or an nfs-root
containing ':/')."
(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 (resolve find-partition spec fmt)
(let loop ((count 0))
(let ((device (find-partition 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" (fmt spec))
(begin
(format #t "waiting for partition '~a' to appear...~%"
(fmt spec))
(sleep 1)
(loop (+ 1 count))))))))
(match spec
((? string?)
(if (string-contains spec ":/")
spec ; do not resolve NFS devices
;; Nothing to do, but wait until SPEC shows up.
(resolve identity spec identity)))
((? file-system-label?)
;; Resolve the label.
(resolve find-partition-by-label
(file-system-label->string spec)
identity))
((? uuid?)
(resolve find-partition-by-uuid
(uuid-bytevector spec)
uuid->string))))
(define (check-file-system device type)
"Run a file system check of TYPE on DEVICE."
(define check-procedure
(cond
((string-prefix? "ext" type) check-ext2-file-system)
((string-prefix? "bcachefs" type) check-bcachefs-file-system)
((string-prefix? "btrfs" type) check-btrfs-file-system)
((string-suffix? "fat" type) check-fat-file-system)
((string-prefix? "jfs" type) check-jfs-file-system)
((string-prefix? "f2fs" type) check-f2fs-file-system)
((string-prefix? "ntfs" type) check-ntfs-file-system)
((string-prefix? "nfs" type) (const 'pass))
(else #f)))
(if check-procedure
(match (check-procedure device)
('pass
#t)
('errors-corrected
(format (current-error-port)
"File system check corrected errors on ~a; continuing~%"
device))
('reboot-required
(format (current-error-port)
"File system check corrected errors on ~a; rebooting~%"
device)
(sleep 3)
(reboot))
('fatal-error
(format (current-error-port) "File system check on ~a failed~%"
device)
;; Spawn a REPL only if someone would be able to interact with it.
(when (isatty? (current-input-port))
(format (current-error-port) "Spawning Bourne-like REPL.~%")
;; 'current-output-port' is typically connected to /dev/klog (in
;; PID 1), but here we want to make sure we talk directly to the
;; user.
(with-output-to-file "/dev/console"
(lambda ()
(start-repl %bournish-language))))))
(format (current-error-port)
"No file system check procedure for ~a; skipping~%"
device)))
(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)))
(('no-atime rest ...)
(logior MS_NOATIME (loop rest)))
(('strict-atime rest ...)
(logior MS_STRICTATIME (loop rest)))
(('lazy-time rest ...)
(logior MS_LAZYTIME (loop rest)))
(()
0))))
(define* (mount-file-system fs #:key (root "/root"))
"Mount the file system described by FS, a <file-system> object, under ROOT."
(define (mount-nfs source mount-point type flags options)
(let* ((idx (string-rindex source #\:))
(host-part (string-take source idx))
;; Strip [] from around host if present
(host (match (string-split host-part (string->char-set "[]"))
(("" h "") h)
((h) h)))
(aa (match (getaddrinfo host "nfs") ((x . _) x)))
(sa (addrinfo:addr aa))
(inet-addr (inet-ntop (sockaddr:fam sa)
(sockaddr:addr sa))))
;; Mounting an NFS file system requires passing the address
;; of the server in the addr= option
(mount source mount-point type flags
(string-append "addr="
inet-addr
(if options
(string-append "," options)
"")))))
(let* ((type (file-system-type fs))
(source (canonicalize-device-spec (file-system-device fs)))
(target (string-append root "/"
(file-system-mount-point fs)))
(flags (logior (mount-flags->bit-mask (file-system-flags fs))
;; For bind mounts, preserve the original flags such
;; as MS_NOSUID, etc. Failing to do that, the
;; MS_REMOUNT call below fails with EPERM.
;; See <https://bugs.gnu.org/46292>
(if (memq 'bind-mount (file-system-flags fs))
(statfs-flags->mount-flags
(file-system-mount-flags (statfs source)))
0)))
(options (file-system-options fs)))
(when (file-system-check? fs)
(check-file-system source type))
(catch 'system-error
(lambda ()
;; Create the mount point. Most of the time this is a directory, but
;; in the case of a bind mount, a regular file or socket may be
;; needed.
(if (and (= MS_BIND (logand flags MS_BIND))
(not (file-is-directory? source)))
(unless (file-exists? target)
(mkdir-p (dirname target))
(call-with-output-file target (const #t)))
(mkdir-p target))
(cond
((string-prefix? "nfs" type)
(mount-nfs source target type flags options))
(else
(mount source target type flags options)))
;; For read-only bind mounts, an extra remount is needed, as per
;; <http://lwn.net/Articles/281157/>, which still applies to Linux
;; 4.0.
(when (and (= MS_BIND (logand flags MS_BIND))
(= MS_RDONLY (logand flags MS_RDONLY)))
(let ((flags (logior MS_REMOUNT flags)))
(mount source target type flags options))))
(lambda args
(or (file-system-mount-may-fail? fs)
(apply throw args))))))
;;; file-systems.scm ends here
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