[Pkg-libburnia-devel] Bug#1010098: xorriso: please allow -cut-out directly from block devices

[Ivan Shmakov]

>>>>> On 2022-04-24, Thomas Schmitt wrote:
>>>>> Ivan Shmakov wrote:

 >> I’m filing this bug against versions from oldstable and stable,
 >> for that’s so far the only Debian packages’ versions I’ve tested
 >> for this issue.

 > As it is about an upstream wish:

 > The newest easily compilable and then usable version would be
 >   http://www.gnu.org/software/xorriso/xorriso-1.5.5.tar.gz

	Not under http://ftp.gnu.org/gnu/xorriso/ , though?

 > It can be compiled without much dependencies and then used without
 > installation. See "Compilation, First Glimpse, Installation" in
 >   https://www.gnu.org/software/xorriso/README_xorriso_devel

 > Said that, and now with my upstream hat on, i expect no difference
 > to versions 1.5.0 or 1.5.4 in respect to command -cut_out.

	It’d seem that I’ve missed an important detail or two in my
	original message.  The patch suggested was against the following
	Git revisions of the libisofs and libisoburn:

commit da00291519ad22c5bfa79c93ffeb04219bab0d7e
Author:     Thomas Schmitt <scdbackup at gmx.net>
AuthorDate: 2022-04-23 09:32:44 +0200
Commit:     Thomas Schmitt <scdbackup at gmx.net>
CommitDate: 2022-04-23 09:32:44 +0200

    Let the original isohybrid GPT obey system_area() option bit 17:
    GPT writable

commit 0ef65a783765dbde79242ac41d5b9f2a495de1ec
Author:     Thomas Schmitt <scdbackup at gmx.net>
AuthorDate: 2022-04-23 14:09:30 +0200
Commit:     Thomas Schmitt <scdbackup at gmx.net>
CommitDate: 2022-04-23 14:09:30 +0200

    Updated change log and web page

	I’d frankly be surprised to learn that a proper release,
	such as 1.5.5, has features which a recent revision from
	Git master branch lacks.

 > So there is no need to get xorriso-1.5.5.tar.gz unless you want
 > to test a patch proposed by me.

	I’ll be checking the master branch from time to time, and hope
	to test the patch and report the results once it lands there.

	TIA.

 > I downloaded your 114.xorriso-1.diff and will study it for the
 > goal of enabling -cut_out for more file types.

 > I already see that it makes changes about fsrc_open(), which is a
 > central facility of libisofs.  This means it will last several days
 > of study and pondering until i would be convinced of any change.

	The patch was intended, first and foremost, as a proof of
	concept; I hope I’ve identified /where/ the code needs to be
	changed, but I’m not going to claim familiarity with all the
	code paths involved, and as such cannot readily suggest
	/what/ changes are needed.  As it is, I fully expect for the
	things to break.

 > Also i need to check whether your diff interferes with the
 > ability to backup a block device file as itself and not as bearer
 > of its content:

 >   rm test.iso
 >   xorriso -outdev test.iso -map /dev/sr0 /sr0 -commit -lsdl /sr0 --

 > should produce even with a loaded BD_RE medium of 23 GiB a small ISO and
 > report a block device file in it

 >   brw-rw----    1 0        24           11,0 Apr 24 14:15 '/sr0'

	FWIW, as a user, I’d expect an additional -follow option for
	this feature, such as:

  *seekable*  If enabled, any non-regular seekable file (such as a
    block device) would be stored on image as a regular one with the
    contents taken from the original.  The default is to store special
    files as-is.  (See also the -cut_out option.)

	In the implementation, I’d rather see it not testing the
	file type specifically, aside of S_ISREG, S_ISDIR and S_ISLNK,
	but rather whether lseek (, 0, SEEK_END) gives a sane result,
	thus allowing for transparent support of novel or non-standard
	(platform-specific) file types.

-- 
FSF associate member #7257  http://am-1.org/~ivan/