GNU bug report logs - #26751
[PATCH] gnu: build: file-systems: Add ISO-9660.

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 26751 in the body.
You can then email your comments to 26751 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Danny Milosavljevic <dannym <at> scratchpost.org>
To: guix-patches <at> gnu.org
Cc: Danny Milosavljevic <dannym <at> scratchpost.org>
Subject: [PATCH] gnu: build: file-systems: Add ISO-9660.
Date: Tue,  2 May 2017 22:04:36 +0200

* gnu/build/file-systems.scm (iso9660-superblock?,
read-iso9660-primary-volume-descriptor, read-iso9660-superblock,
iso9660-superblock-uuid, iso9660-uuid->string,
iso9660-superblock-volume-name): New variables.
(%partition-label-readers): Add iso9660.
(%partition-uuid-readers): Add iso9660.
---
 gnu/build/file-systems.scm | 67 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index 0cb84b8aa..e2a6cd626 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -230,6 +230,65 @@ 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 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))
+
+(define (iso9660-uuid->string uuid)
+  ;; 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".
+  (define digits->string latin1->string)
+  (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))
+         (hundreths (sub-bytevector uuid 14 2))
+         ;; offset: In 15 min intervals, two's complement, from GMT.
+         (offset (bytevector-u8-ref uuid 16))
+         (parts (list year month day hour minute second hundreths)))
+    (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 +399,9 @@ 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 +409,9 @@ 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)

Message #8 received at 26751 <at> debbugs.gnu.org (full text, mbox):

From: Danny Milosavljevic <dannym <at> scratchpost.org>
To: 26751 <at> debbugs.gnu.org
Cc: Danny Milosavljevic <dannym <at> scratchpost.org>
Subject: [PATCH v2] gnu: build: file-systems: Add ISO-9660.
Date: Tue,  2 May 2017 22:32:09 +0200

* gnu/build/file-systems.scm (iso9660-superblock?,
read-iso9660-primary-volume-descriptor, read-iso9660-superblock,
iso9660-superblock-uuid, iso9660-uuid->string,
iso9660-superblock-volume-name): New variables.
(%partition-label-readers): Add iso9660.
(%partition-uuid-readers): Add iso9660.
---
 gnu/build/file-systems.scm | 64 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index 0cb84b8aa..3e702cc8d 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -230,6 +230,62 @@ 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."
+  ;; FIXME Use only certain parts (See grub).
+  ;; FIXME treat "all 0" as invalid.
+  ;; 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)
+  (define digits->string latin1->string)
+  (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))
+         (hundreths (sub-bytevector uuid 14 2))
+         (parts (list year month day hour minute second hundreths)))
+    (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 +396,9 @@ 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 +406,9 @@ 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)

Message #11 received at 26751 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Danny Milosavljevic <dannym <at> scratchpost.org>
Cc: 26751 <at> debbugs.gnu.org
Subject: Re: bug#26751: [PATCH v2] gnu: build: file-systems: Add ISO-9660.
Date: Tue, 02 May 2017 23:32:13 +0200

Danny Milosavljevic <dannym <at> scratchpost.org> skribis:

> * gnu/build/file-systems.scm (iso9660-superblock?,
> read-iso9660-primary-volume-descriptor, read-iso9660-superblock,
> iso9660-superblock-uuid, iso9660-uuid->string,
> iso9660-superblock-volume-name): New variables.
> (%partition-label-readers): Add iso9660.
> (%partition-uuid-readers): Add iso9660.

[...]

> +(define (iso9660-superblock-uuid sblock)
> +  "Return the modification time of a iso9660 superblock SBLOCK as a bytevector."
> +  ;; FIXME Use only certain parts (See grub).
> +  ;; FIXME treat "all 0" as invalid.

Please expound these two comments, as discussed on guix-devel.

> +  ;; 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)
> +  (define digits->string latin1->string)
> +  (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))
> +         (hundreths (sub-bytevector uuid 14 2))
> +         (parts (list year month day hour minute second hundreths)))
> +    (string-append (string-join (map digits->string parts)))))

Neat!  Please add a docstring.

> +(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))

Please trim to 80 columns.  :-)

OK with these changes, thank you!

Ludo’.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.