From 227ffc6c34c7bef29a39b2745865ac25c28a7e74 Mon Sep 17 00:00:00 2001
From: Chris Marusich <address@hidden>
Date: Mon, 1 Aug 2016 08:46:48 -0700
Subject: [PATCH 5/9] Factor out procedure: device->title

---
 gnu/build/file-systems.scm | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index f1fccbd..4a8acd5 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -38,6 +38,7 @@
             find-partition-by-uuid
             find-partition-by-luks-uuid
             canonicalize-device-spec
+            device->title
 
             uuid->string
             string->uuid
@@ -364,19 +365,6 @@ the following:
     ;; this long.
     20)
 
-  (define canonical-title
-    ;; The realm of canonicalization.
-    (if (eq? title 'any)
-        (if (string? spec)
-            ;; The "--root=SPEC" kernel command-line option always provides a
-            ;; string, but the string can represent a device, a UUID, or a
-            ;; label.  So check for all three.
-            (cond ((string-prefix? "/" spec) 'device)
-                  ((string->uuid spec) 'uuid)
-                  (else 'label))
-            'uuid)
-        title))
-
   (define (resolve find-partition spec fmt)
     (let loop ((count 0))
       (let ((device (find-partition spec)))
@@ -391,6 +379,10 @@ the following:
                   (sleep 1)
                   (loop (+ 1 count))))))))
 
+  (define canonical-title (if (eq? title 'any)
+                              (device->title spec)
+                              title))
+
   (case canonical-title
     ((device)
      ;; Nothing to do.
@@ -407,6 +399,19 @@ the following:
     (else
      (error "unknown device title" title))))
 
+(define (device->title device)
+  "Guess the title for the given DEVICE, which must be a device parameter from
+a <file-system> object.  As a special case, when the DEVICE is a UUID, it may
+be specified as a string."
+  (if (string? device)
+      ;; The "--root=SPEC" kernel command-line option always provides a
+      ;; string, but the string can represent a device, a UUID, or a
+      ;; label.  So check for all three.
+      (cond ((string-prefix? "/" device) 'device)
+            ((string->uuid device) 'uuid)
+            (else 'label))
+      'uuid))
+
 (define (check-file-system device type)
   "Run a file system check of TYPE on DEVICE."
   (define fsck
-- 
2.9.2