From d266b79332ff0a4b22967a1db01c805b7c82e092 Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Wed, 2 Jul 2014 12:18:36 +0200 Subject: linux-initrd: Gracefully handle lack of or invalid ext2 superblocks. Reported by David Thompson . * 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. --- guix/build/linux-initrd.scm | 21 ++++++++++++++++----- 1 file 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 . + (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." -- cgit 1.4.1