From: ludo@gnu.org (Ludovic Courtès)
To: Danny Milosavljevic <dannym@scratchpost.org>
Cc: guix-devel@gnu.org
Subject: Re: GuixSD bootable ISO-9669 image
Date: Tue, 02 May 2017 14:37:04 +0200 [thread overview]
Message-ID: <87efw7igen.fsf@gnu.org> (raw)
In-Reply-To: <20170428101844.540ce399@scratchpost.org> (Danny Milosavljevic's message of "Fri, 28 Apr 2017 10:18:44 +0200")
[-- Attachment #1: Type: text/plain, Size: 1721 bytes --]
Hi!
I just tested your patch, Danny (last version attached): I took the
image at
<http://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-8.7.1-amd64-netinst.iso>
and then did:
--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,m (gnu build file-systems)
scheme@(gnu build file-systems)> (define sb (read-iso9660-superblock "/tmp/debian-8.7.1-amd64-netinst.iso.part"))
scheme@(gnu build file-systems)> (iso9660-superblock-volume-name sb)
$2 = "Debian 8.7.1 amd64 1"
scheme@(gnu build file-systems)> (iso9660-superblock-uuid sb)
$3 = #vu8(50 48 49 55 48 49 49 54 49 49 48 49 48 49 48 48 0)
scheme@(gnu build file-systems)> (bytevector-length $3)
$4 = 17
scheme@(gnu build file-systems)> (uuid->string $3)
$5 = "32303137-3031-3136-3131-303130313030"
--8<---------------cut here---------------end--------------->8---
Seems to work!
Could you clarify the two “See grub” in here:
--8<---------------cut here---------------start------------->8---
(define (iso9660-superblock-uuid sblock)
"Return the Volume ID of a iso9660 superblock SBLOCK as a 4-byte bytevector."
;; Note: The field is the volume creation time.
;; FIXME Use only certain parts (See grub).
;; FIXME treat "all 0" as invalid.
(sub-bytevector sblock 813 17))
;; FIXME make result human-readable (See grub).
;(define (iso9660-uuid->string uuid)
--8<---------------cut here---------------end--------------->8---
Should ‘iso9660-uuid->string’ be different from ‘uuid->string’?
Anyway, I think we should polish and commit real soon. :-) Perhaps we
can add a note about endianness and assume little endian for now.
Thank you Danny!
Ludo’.
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Type: text/x-patch, Size: 3381 bytes --]
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index 0cb84b8aa..4c826830d 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -230,6 +230,55 @@ Trailing spaces are trimmed."
\f
;;;
+;;; ISO9660 file systems.
+;;;
+
+;; <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf>.
+
+;(define-syntax %iso9660-endianness
+; ;; Endianness of iso9660 file systems that we use.
+; ;; Actually, iso9660 has redundant data (i.e. data for both endiannesses).
+; (identifier-syntax (endianness little)))
+
+(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 Volume ID of a iso9660 superblock SBLOCK as a 4-byte bytevector."
+ ;; Note: The field is the volume creation time.
+ ;; FIXME Use only certain parts (See grub).
+ ;; FIXME treat "all 0" as invalid.
+ (sub-bytevector sblock 813 17))
+
+;; FIXME make result human-readable (See grub).
+;(define (iso9660-uuid->string uuid)
+
+(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))
+
+\f
+;;;
;;; LUKS encrypted devices.
;;;
@@ -340,7 +389,9 @@ 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 +399,9 @@ 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)
next prev parent reply other threads:[~2017-05-02 12:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 14:17 GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements] ng0
2017-04-18 15:16 ` Chris Marusich
2017-04-19 20:59 ` Ludovic Courtès
2017-04-23 4:52 ` Chris Marusich
2017-04-24 5:11 ` GuixSD bootable ISO-9669 image (was: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements]) Chris Marusich
2017-04-27 13:42 ` GuixSD bootable ISO-9669 image Ludovic Courtès
2017-04-27 17:08 ` GuixSD bootable ISO-9669 image (was: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements]) Danny Milosavljevic
2017-04-27 20:00 ` Danny Milosavljevic
2017-04-28 8:18 ` Danny Milosavljevic
2017-05-02 12:37 ` Ludovic Courtès [this message]
2017-05-02 12:53 ` GuixSD bootable ISO-9669 image ng0
2017-05-03 6:26 ` Mark H Weaver
2017-05-02 20:09 ` Danny Milosavljevic
2017-05-02 21:11 ` Ludovic Courtès
2017-05-07 19:37 ` Danny Milosavljevic
2017-05-08 14:14 ` Ludovic Courtès
2017-05-11 23:30 ` Danny Milosavljevic
2017-05-12 15:33 ` Ludovic Courtès
2017-05-14 21:25 ` Danny Milosavljevic
2017-05-16 8:31 ` Ludovic Courtès
2017-06-06 9:35 ` Danny Milosavljevic
2017-06-08 12:25 ` Ludovic Courtès
2017-05-02 20:12 ` Danny Milosavljevic
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87efw7igen.fsf@gnu.org \
--to=ludo@gnu.org \
--cc=dannym@scratchpost.org \
--cc=guix-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/guix.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.