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authorLudovic Courtès <ludo@gnu.org>2014-07-02 12:18:36 +0200
committerLudovic Courtès <ludo@gnu.org>2014-07-02 12:18:36 +0200
commitd266b79332ff0a4b22967a1db01c805b7c82e092 (patch)
treeefc1f80370a4af3275f6a893339c11d5e3985267 /guix
parent0f28ee348778379bfa81094491b73479f1113f84 (diff)
downloadgnu-guix-d266b79332ff0a4b22967a1db01c805b7c82e092.tar
gnu-guix-d266b79332ff0a4b22967a1db01c805b7c82e092.tar.gz
linux-initrd: Gracefully handle lack of or invalid ext2 superblocks.
Reported by David Thompson <dthompson2@worcester.edu>. * guix/build/linux-initrd.scm (read-ext2-superblock): Add 'superblock-size' variable. Read with 'get-bytevector-n!' instead of 'getbytevector-n', and make sure we read exactly SUPERBLOCK-SIZE bytes.
Diffstat (limited to 'guix')
-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."