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