diff options
| -rw-r--r-- | gnu/build/file-systems.scm | 65 |
1 files changed, 63 insertions, 2 deletions
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm index 0cb84b8aad..47aa77dd3e 100644 --- a/gnu/build/file-systems.scm +++ b/gnu/build/file-systems.scm @@ -230,6 +230,63 @@ Trailing spaces are trimmed." ;;; +;;; ISO9660 file systems. +;;; + +;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf>. + +(define (iso9660-superblock? sblock) + "Return #t when SBLOCK is a iso9660 superblock." + (bytevector=? (sub-bytevector sblock 1 6) + ;; Note: "\x01" is the volume descriptor format version + (string->utf8 "CD001\x01"))) + +(define (read-iso9660-primary-volume-descriptor device offset) + "Find and read the first primary volume descriptor, starting at OFFSET. + Return #f if not found." + (let* ((sblock (read-superblock device offset 2048 iso9660-superblock?)) + (type-code (if sblock (array-ref sblock 0) 255))) + (match type-code + (255 #f) ; Volume Descriptor Set Terminator. + (1 sblock) ; Primary Volume Descriptor + (_ (read-iso9660-primary-volume-descriptor device (+ offset 2048)))))) + +(define (read-iso9660-superblock device) + "Return the raw contents of DEVICE's iso9660 superblock as a bytevector, or +#f if DEVICE does not contain a iso9660 file system." + ;; Start reading at sector 16. + (read-iso9660-primary-volume-descriptor device (* 2048 16))) + +(define (iso9660-superblock-uuid sblock) + "Return the modification time of a iso9660 superblock SBLOCK as a bytevector." + ;; Drops GMT offset for compatibility with Grub, blkid and /dev/disk/by-uuid. + ;; Compare Grub: "2014-12-02-19-30-23-00". + ;; Compare blkid result: "2014-12-02-19-30-23-00". + ;; Compare /dev/disk/by-uuid entry: "2014-12-02-19-30-23-00". + (sub-bytevector sblock 830 16)) + +(define (iso9660-uuid->string uuid) + "Given an UUID bytevector, return its timestamp string." + (define (digits->string bytes) + (latin1->string bytes (lambda (c) #f))) + (let* ((year (sub-bytevector uuid 0 4)) + (month (sub-bytevector uuid 4 2)) + (day (sub-bytevector uuid 6 2)) + (hour (sub-bytevector uuid 8 2)) + (minute (sub-bytevector uuid 10 2)) + (second (sub-bytevector uuid 12 2)) + (hundredths (sub-bytevector uuid 14 2)) + (parts (list year month day hour minute second hundredths))) + (string-append (string-join (map digits->string parts))))) + +(define (iso9660-superblock-volume-name sblock) + "Return the volume name of SBLOCK as a string. The volume name is an ASCII +string. Trailing spaces are trimmed." + (string-trim-right (latin1->string (sub-bytevector sblock 40 32) + (lambda (c) #f)) #\space)) + + +;;; ;;; LUKS encrypted devices. ;;; @@ -340,7 +397,9 @@ partition field reader that returned a value." (_ #f))) (define %partition-label-readers - (list (partition-field-reader read-ext2-superblock + (list (partition-field-reader read-iso9660-superblock + iso9660-superblock-volume-name) + (partition-field-reader read-ext2-superblock ext2-superblock-volume-name) (partition-field-reader read-btrfs-superblock btrfs-superblock-volume-name) @@ -348,7 +407,9 @@ partition field reader that returned a value." fat32-superblock-volume-name))) (define %partition-uuid-readers - (list (partition-field-reader read-ext2-superblock + (list (partition-field-reader read-iso9660-superblock + iso9660-superblock-uuid) + (partition-field-reader read-ext2-superblock ext2-superblock-uuid) (partition-field-reader read-btrfs-superblock btrfs-superblock-uuid) |