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authorLudovic Courtès <ludo@gnu.org>2015-07-14 15:06:46 +0200
committerLudovic Courtès <ludo@gnu.org>2015-07-14 15:24:20 +0200
commit661a1d7924e174a28e0e21bf516aa1a8a44dad73 (patch)
treee794ceca18881f189fa0be3a2477cf7a9ccd0182
parent0ec5ee94861980a6957d210adf1903ea96202dd9 (diff)
file-systems: Allow users to specify file system UUIDs as strings.
Fixes <http://bugs.gnu.org/19778>. Reported by Mark H Weaver <mhw@netris.org>. * gnu/system/file-systems.scm (%uuid-rx): New variable. (string->uuid): New procedure. (uuid): New macro. * tests/file-systems.scm: New file. * Makefile.am (SCM_TESTS): Add it. * doc/guix.texi (File Systems): Give an example of UUID.
-rw-r--r--Makefile.am1
-rw-r--r--doc/guix.texi18
-rw-r--r--gnu/system/file-systems.scm57
-rw-r--r--tests/file-systems.scm46
4 files changed, 121 insertions, 1 deletions
diff --git a/Makefile.am b/Makefile.am
index 7059a8f594..5cf9314014 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -203,6 +203,7 @@ SCM_TESTS = \
tests/lint.scm \
tests/publish.scm \
tests/size.scm \
+ tests/file-systems.scm \
tests/containers.scm
if HAVE_GUILE_JSON
diff --git a/doc/guix.texi b/doc/guix.texi
index 7b1d18a151..ad5b38af31 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4963,8 +4963,24 @@ interpreted as a file name; when it is @code{label}, then @code{device}
is interpreted as a partition label name; when it is @code{uuid},
@code{device} is interpreted as a partition unique identifier (UUID).
+UUIDs may be converted from their string representation (as shown by the
+@command{tune2fs -l} command) using the @code{uuid} form, like this:
+
+@example
+(file-system
+ (mount-point "/home")
+ (type "ext4")
+ (title 'uuid)
+ (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
+@end example
+
The @code{label} and @code{uuid} options offer a way to refer to disk
-partitions without having to hard-code their actual device name.
+partitions without having to hard-code their actual device
+name@footnote{Note that, while it is tempting to use
+@file{/dev/disk/by-uuid} and similar device names to achieve the same
+result, this is not recommended: These special device nodes are created
+by the udev daemon and may be unavailable at the time the device is
+mounted.}.
However, when a file system's source is a mapped device (@pxref{Mapped
Devices}), its @code{device} field @emph{must} refer to the mapped
diff --git a/gnu/system/file-systems.scm b/gnu/system/file-systems.scm
index 33926444b6..ece8fb41e6 100644
--- a/gnu/system/file-systems.scm
+++ b/gnu/system/file-systems.scm
@@ -18,9 +18,13 @@
(define-module (gnu system file-systems)
#:use-module (ice-9 match)
+ #:use-module (ice-9 regex)
#:use-module (guix gexp)
#:use-module (guix records)
#:use-module (guix store)
+ #:use-module (rnrs bytevectors)
+ #:use-module ((gnu build file-systems) #:select (uuid->string))
+ #:re-export (uuid->string)
#:export (<file-system>
file-system
file-system?
@@ -35,6 +39,8 @@
file-system-create-mount-point?
file-system->spec
+ string->uuid
+ uuid
%fuse-control-file-system
%binary-format-file-system
@@ -106,6 +112,57 @@ initrd code."
(($ <file-system> device title mount-point type flags options _ check?)
(list device title mount-point type flags options check?))))
+(define %uuid-rx
+ ;; The regexp of a UUID.
+ (make-regexp "^([[:xdigit:]]{8})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{12})$"))
+
+(define (string->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)
+ 16))))
+ (put!
+ (syntax-rules ()
+ ((_ bv index (number len) rest ...)
+ (begin
+ (bytevector-uint-set! bv index number
+ (endianness big) len)
+ (put! bv (+ index len) rest ...)))
+ ((_ bv index)
+ bv))))
+ (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)))))))
+
+(define-syntax uuid
+ (lambda (s)
+ "Return the bytevector corresponding to the given UUID representation."
+ (syntax-case s ()
+ ((_ str)
+ (string? (syntax->datum #'str))
+ ;; A literal string: do the conversion at expansion time.
+ (with-syntax ((bv (string->uuid (syntax->datum #'str))))
+ #''bv))
+ ((_ str)
+ #'(string->uuid str)))))
+
+
+;;;
+;;; Common file systems.
+;;;
+
(define %fuse-control-file-system
;; Control file system for Linux' file systems in user-space (FUSE).
(file-system
diff --git a/tests/file-systems.scm b/tests/file-systems.scm
new file mode 100644
index 0000000000..d445b4971f
--- /dev/null
+++ b/tests/file-systems.scm
@@ -0,0 +1,46 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 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 (test-file-systems)
+ #:use-module (gnu system file-systems)
+ #:use-module (srfi srfi-64)
+ #:use-module (rnrs bytevectors))
+
+;; Test the (gnu system file-systems) module.
+
+(test-begin "file-systems")
+
+(test-equal "uuid->string"
+ "c5307e6b-d1ba-499d-89c5-cb0b143577c4"
+ (uuid->string
+ #vu8(197 48 126 107 209 186 73 157 137 197 203 11 20 53 119 196)))
+
+(test-equal "string->uuid"
+ '(16 "4dab5feb-d176-45de-b287-9b0a6e4c01cb")
+ (let ((uuid (string->uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
+ (list (bytevector-length uuid) (uuid->string uuid))))
+
+(test-assert "uuid"
+ (let ((str "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))
+ (bytevector=? (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")
+ (string->uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))))
+
+(test-end)
+
+
+(exit (= (test-runner-fail-count (test-runner-current)) 0))