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-rw-r--r--guix/build/linux-initrd.scm21
1 files changed, 16 insertions, 5 deletions
diff --git a/guix/build/linux-initrd.scm b/guix/build/linux-initrd.scm
index 627c55f865..7778c2ca97 100644
--- a/guix/build/linux-initrd.scm
+++ b/guix/build/linux-initrd.scm
@@ -116,14 +116,25 @@ if DEVICE does not contain an ext2 file system."
;; The magic bytes that identify an ext2 file system.
#xef53)
+ (define superblock-size
+ ;; Size of the interesting part of an ext2 superblock.
+ 264)
+
+ (define block
+ ;; The superblock contents.
+ (make-bytevector superblock-size))
+
(call-with-input-file device
(lambda (port)
(seek port 1024 SEEK_SET)
- (let* ((block (get-bytevector-n port 264))
- (magic (bytevector-u16-ref block %ext2-sblock-magic
- %ext2-endianness)))
- (and (= magic %ext2-magic)
- block)))))
+
+ ;; Note: work around <http://bugs.gnu.org/17466>.
+ (and (eqv? superblock-size (get-bytevector-n! port block 0
+ superblock-size))
+ (let ((magic (bytevector-u16-ref block %ext2-sblock-magic
+ %ext2-endianness)))
+ (and (= magic %ext2-magic)
+ block))))))
(define (ext2-superblock-uuid sblock)
"Return the UUID of ext2 superblock SBLOCK as a 16-byte bytevector."