Mirror of GNU Guix
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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2017 Danny Milosavljevic <dannym@scratchpost.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
;;; 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 system uuid)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (rnrs bytevectors)
#:use-module (ice-9 match)
#:use-module (ice-9 vlist)
#:use-module (ice-9 regex)
#:use-module (ice-9 format)
#:export (uuid
;; XXX: For lack of a better place.
;;; Tools that lack a better place.
(define (sub-bytevector bv start size)
"Return a copy of the SIZE bytes of BV starting from offset START."
(let ((result (make-bytevector size)))
(bytevector-copy! bv start result 0 size)
(define (latin1->string bv terminator)
"Return a string of BV, a latin1 bytevector, or #f. TERMINATOR is a predicate
that takes a number and returns #t when a termination character is found."
(let ((bytes (take-while (negate terminator) (bytevector->u8-list bv))))
(if (null? bytes)
(list->string (map integer->char bytes)))))
;;; DCE UUIDs.
(define-syntax %network-byte-order
(identifier-syntax (endianness big)))
(define (dce-uuid->string uuid)
"Convert UUID, a 16-byte bytevector, to its string representation, something
like \"6b700d61-5550-48a1-874c-a3d86998990e\"."
;; See <https://tools.ietf.org/html/rfc4122>.
(let ((time-low (bytevector-uint-ref uuid 0 %network-byte-order 4))
(time-mid (bytevector-uint-ref uuid 4 %network-byte-order 2))
(time-hi (bytevector-uint-ref uuid 6 %network-byte-order 2))
(clock-seq (bytevector-uint-ref uuid 8 %network-byte-order 2))
(node (bytevector-uint-ref uuid 10 %network-byte-order 6)))
(format #f "~8,'0x-~4,'0x-~4,'0x-~4,'0x-~12,'0x"
time-low time-mid time-hi clock-seq node)))
(define %uuid-rx
;; The regexp of a UUID.
(make-regexp "^([[:xdigit:]]{8})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{12})$"))
(define (string->dce-uuid str)
"Parse STR as a DCE UUID (see <https://tools.ietf.org/html/rfc4122>) and
return its contents as a 16-byte bytevector. Return #f if STR is not a valid
UUID representation."
(and=> (regexp-exec %uuid-rx str)
(lambda (match)
(letrec-syntax ((hex->number
(syntax-rules ()
((_ index)
(string->number (match:substring match index)
(syntax-rules ()
((_ bv index (number len) rest ...)
(bytevector-uint-set! bv index number
(endianness big) len)
(put! bv (+ index len) rest ...)))
((_ bv index)
(let ((time-low (hex->number 1))
(time-mid (hex->number 2))
(time-hi (hex->number 3))
(clock-seq (hex->number 4))
(node (hex->number 5))
(uuid (make-bytevector 16)))
(put! uuid 0
(time-low 4) (time-mid 2) (time-hi 2)
(clock-seq 2) (node 6)))))))
;;; ISO-9660.
;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf>.
(define %iso9660-uuid-rx
;; Y m d H M S ss
(make-regexp "^([[:digit:]]{4})-([[:digit:]]{2})-([[:digit:]]{2})-([[:digit:]]{2})-([[:digit:]]{2})-([[:digit:]]{2})-([[:digit:]]{2})$"))
(define (string->iso9660-uuid str)
"Parse STR as a ISO9660 UUID (which is really a timestamp - see /dev/disk/by-uuid).
Return its contents as a 16-byte bytevector. Return #f if STR is not a valid
ISO9660 UUID representation."
(and=> (regexp-exec %iso9660-uuid-rx str)
(lambda (match)
(letrec-syntax ((match-numerals
(syntax-rules ()
((_ index (name rest ...) body)
(let ((name (match:substring match index)))
(match-numerals (+ 1 index) (rest ...) body)))
((_ index () body)
(match-numerals 1 (year month day hour minute second hundredths)
(string->utf8 (string-append year month day
hour minute second hundredths)))))))
(define (iso9660-uuid->string uuid)
"Given an UUID bytevector, return its timestamp string."
(define (digits->string bytes)
(latin1->string bytes (lambda (c) #f)))
(let* ((year (sub-bytevector uuid 0 4))
(month (sub-bytevector uuid 4 2))
(day (sub-bytevector uuid 6 2))
(hour (sub-bytevector uuid 8 2))
(minute (sub-bytevector uuid 10 2))
(second (sub-bytevector uuid 12 2))
(hundredths (sub-bytevector uuid 14 2))
(parts (list year month day hour minute second hundredths)))
(string-append (string-join (map digits->string parts) "-"))))
;;; FAT32/FAT16.
(define-syntax %fat-endianness
;; Endianness of FAT32/FAT16 file systems.
(identifier-syntax (endianness little)))
(define (fat-uuid->string uuid)
"Convert FAT32/FAT16 UUID, a 4-byte bytevector, to its string representation."
(let ((high (bytevector-uint-ref uuid 0 %fat-endianness 2))
(low (bytevector-uint-ref uuid 2 %fat-endianness 2)))
(format #f "~:@(~x-~x~)" low high)))
(define %fat-uuid-rx
(make-regexp "^([[:xdigit:]]{4})-([[:xdigit:]]{4})$"))
(define (string->fat-uuid str)
"Parse STR, which is in FAT32/FAT16 format, and return a bytevector or #f."
(match (regexp-exec %fat-uuid-rx str)
(uint-list->bytevector (list (string->number
(match:substring rx-match 2) 16)
(match:substring rx-match 1) 16))
;;; Generic interface.
(define string->ext2-uuid string->dce-uuid)
(define string->ext3-uuid string->dce-uuid)
(define string->ext4-uuid string->dce-uuid)
(define string->btrfs-uuid string->dce-uuid)
(define-syntax vhashq
(syntax-rules (=>)
((_ (key others ... => value) rest ...)
(vhash-consq key value
(vhashq (others ... => value) rest ...)))
((_ (=> value) rest ...)
(vhashq rest ...))))
(define %uuid-parsers
('dce 'ext2 'ext3 'ext4 'btrfs 'luks => string->dce-uuid)
('fat32 'fat16 'fat => string->fat-uuid)
('iso9660 => string->iso9660-uuid)))
(define %uuid-printers
('dce 'ext2 'ext3 'ext4 'btrfs 'luks => dce-uuid->string)
('iso9660 => iso9660-uuid->string)
('fat32 'fat16 'fat => fat-uuid->string)))
(define* (string->uuid str #:optional (type 'dce))
"Parse STR as a UUID of the given TYPE. On success, return the
corresponding bytevector; otherwise return #f."
(match (vhash-assq type %uuid-parsers)
(#f #f)
((_ . (? procedure? parse)) (parse str))))
;; High-level UUID representation that carries its type with it.
;; This is necessary to serialize bytevectors with the right printer in some
;; circumstances. For instance, GRUB "search --fs-uuid" command compares the
;; string representation of UUIDs, not the raw bytes; thus, when emitting a
;; GRUB 'search' command, we need to produce the right string representation
;; (see <https://debbugs.gnu.org/cgi/bugreport.cgi?msg=52;att=0;bug=27735>).
(define-record-type <uuid>
(make-uuid type bv)
(type uuid-type) ;'dce | 'iso9660 | ...
(bv uuid-bytevector))
(define* (bytevector->uuid bv #:optional (type 'dce))
"Return a UUID object make of BV and TYPE."
(make-uuid type bv))
(define-syntax uuid
(lambda (s)
"Return the UUID object corresponding to the given UUID representation or
#f if the string could not be parsed."
(syntax-case s (quote)
((_ str (quote type))
(and (string? (syntax->datum #'str))
(identifier? #'type))
;; A literal string: do the conversion at expansion time.
(let ((bv (string->uuid (syntax->datum #'str)
(syntax->datum #'type))))
(unless bv
(syntax-violation 'uuid "invalid UUID" s))
#`(make-uuid 'type #,(datum->syntax s bv))))
((_ str)
(string? (syntax->datum #'str))
#'(uuid str 'dce))
((_ str)
#'(let ((bv (string->uuid str 'dce)))
(and bv (make-uuid 'dce bv))))
((_ str type)
#'(let ((bv (string->uuid str type)))
(and bv (make-uuid type bv)))))))
(define uuid->string
;; Convert the given bytevector or UUID object, to the corresponding UUID
;; string representation.
(((? bytevector? bv))
(uuid->string bv 'dce))
(((? bytevector? bv) type)
(match (vhash-assq type %uuid-printers)
(#f #f)
((_ . (? procedure? unparse)) (unparse bv))))
(((? uuid? uuid))
(uuid->string (uuid-bytevector uuid) (uuid-type uuid)))))
(define uuid=?
;; Return true if A is equal to B, comparing only the actual bits.
(((? bytevector? a) (? bytevector? b))
(bytevector=? a b))
(((? uuid? a) (? bytevector? b))
(bytevector=? (uuid-bytevector a) b))
(((? uuid? a) (? uuid? b))
(bytevector=? (uuid-bytevector a) (uuid-bytevector b)))
((a b)
(uuid=? b a))))