[linux-audio-user] audio cdrom permissions

Paul Perkins speaker-to-vegetables at pobox.com
Wed May 21 08:11:01 EDT 2003


I don't see any more permissions problems here. I have seen a particular
drive/motherboard combo where reading the Table of Contents (TOC) of an
audio CD would not work. I swapped drives (different brands of el cheapo
CDRW) between two machines, after which both systems could read & rip
audio! You might have a similar situation, not a software configuration
problem but an incompatibility among the drive, the motherboard, and the
device driver software. There could be a work-around, but I have no idea
what it would be. For what it's worth, the machine where the problem
showed up identifies its IDE interface (via lspci -v) as a "VIA
Technologies, Inc. VT82C586B".

Good luck.

Paul

On Mon, 2003-05-19 at 16:56, derek holzer wrote:
> hi gang,
> 
> still tracking this problem, so let me reply to the two kind people that 
> have written so far. to clarify, i am trying to RIP audio, not BURN it. 
> it seems both folks started thinking about write permissions and not 
> necessarily read permissions.
> 
> devdsp at mail2.inform.dk wrote:
> 
> >>The easiest way is to chmod all of these entries to 777. You need to be able to
> >>write to your CD-ROM drive as a regular user, after all :)
> >>    
> >>
> 
> i have done this, and it makes no difference. also, being a member of 
> group "cdrom" and "disk" doesn't make much diff, so i can't imagine that 
> being in "cdromwriter", as you suggest elsewhere, would change this..... 
> funny thing is that it ACTS like i haven't changed these permissions! as 
> you can see below, when i try chmod 777, it doesn't affect it, even 
> though i am 'su'... what am i doing wrong here?
> 
> debian:/home/derek# chmod 777 /dev/sg0
> debian:/home/derek# ls -al /dev/sg0
> lr-xr-xr-x    1 root     root           36 May 19 22:15 /dev/sg0 -> 
> scsi/host0/bus0/target0/lun0/generic
> 
> 
> Paul Perkins wrote:
> 
> >Under 2.4.x kernel (or earlier), burning CDs (and possibly ripping audio
> >CDs too) needs access to the "generic scsi" device for the drive (don't
> >you love those violent terms for copying data?). Conventionally called
> >/dev/sg0, device (21,0). The "0" may be another number if you have
> >multiple real or emulated SCSI devices. I'm not sure, but I think this
> >may change in the 2.6 kernel series.
> >
> 
> i do have a /dev/sr0
> lr-xr-xr-x    1 root     root           36 May 19 22:15 /dev/sg0 -> 
> scsi/host0/bus0/target0/lun0/generic
> 
> and the new permissions for its target are as follows:
> 
> debian:/# ls -al /dev/scsi/host1/bus0/target0/lun0/
> total 0
> drwxrwxrwx    1 root     root            0 Jan  1  1970 .
> drwxr-xr-x    1 root     root            0 Jan  1  1970 ..
> brwxrwxrwx    1 root     cdrom     11,   0 Jan  1  1970 cd
> crwxrwxrwx    1 root     root      21,   1 Jan  1  1970 generic
> 
> once i changed the permissions sucessfully to those above, cdparanoia 
> gives me this when i try to Query an audio CD:
> 
> --------------begin
> debian:/home/derek# cdparanoia -vQ
> cdparanoia III release 9.8 (March 23, 2001)
> (C) 2001 Monty <monty at xiph.org> and Xiphophorus
> 
> Report bugs to paranoia at xiph.org
> http://www.xiph.org/paranoia/
> 
> Checking /dev/cdrom for cdrom...
>     Testing /dev/cdrom for cooked ioctl() interface
>         /dev/scsi/host1/bus0/target0/lun0/cd is not a cooked ioctl CDROM.
>     Testing /dev/cdrom for SCSI interface
>         generic device: /dev/scsi/host1/bus0/target0/lun0/generic
>         ioctl device: /dev/scsi/host1/bus0/target0/lun0/cd
> 
> Found an accessible SCSI CDROM drive.
> Looking at revision of the SG interface in use...
>     SG interface version 3.1.24; OK.
> 
> CDROM model sensed sensed: TOSHIBA DVD-ROM SD-C2502 1711
> 
> 
> Checking for SCSI emulation...
>     Drive is ATAPI (using SCSI host adaptor emulation)
> 
> Checking for MMC style command set...
>     Drive is MMC style
> 004: Unable to read table of contents header
> 
> Unable to open disc.  Is there an audio CD in the drive?
> -----------------end
> 
> so i am still not sure what the problem is....
> 
> >If some of the applications you are using are installed with set-uid,
> >(perhaps on a helper program rather than the main one), that would
> >explain why similar actions may only work as user root in one
> >application, but work as a normal user in another application.
> >
> 
> none of the apps were knowingly installed set-uid... they all came from 
> deb packages, though, so i know of no way to tell for certain. how to 
> find out? how to change?
> 
> it's stuff like this that makes me think my laptop is haunted ;-)
> 
> thanks for your suggestions,
> derek
> 
> >On Sun, 2003-05-18 at 13:03, derek holzer wrote:
> >  
> >
> >>> i've been having a bit of trouble with playing and ripping CDs, maybe 
> >>> someone here can help?
> >>> 
> >>> i'm running Debian on a laptop, and as root i don't have any serious 
> >>> problems doing either, but as a user it becomes a bit wierd... let me 
> >>> explain...
> >>> 
> >>> as user, i am in groups cdrom and disk. i have set permissions as follows:
> >>> 
> >>> in /dev:
> >>> lr-xr-xr-x    1 root     root           13 May 18 17:31 cdrom -> 
> >>> cdroms/cdrom0
> >>> drwxr-xr-x    1 root     root            0 Jan  1  1970 cdroms
> >>> 
> >>> in /dev/cdroms
> >>> lr-xr-xr-x    1 root     root           34 Jan  1  1970 cdrom0 -> 
> >>> ../scsi/host1/bus0/target0/lun0/cd
> >>> 
> >>> in /dev/scsi/host1/bus0/target0/lun0/
> >>> brw-rw-rw-    1 root     cdrom     11,   0 Jan  1  1970 cd
> >>> 
> >>> i have none of these other cdrom devices listed in /dev:
> >>> /dev/hdc
> >>> /dev/sr0
> >>> /dec/scd0
> >>> but my drive appears to be ATAPI with SCSI emulation. i have added the 
> >>> following to my /etc/lilo.conf to reflect this:
> >>> append="hdc=ide-scsi"
> >>> although commenting this out doesn't seem to do much.
> >>> 
> >>> i can rip CDs as a user with Grip, but RipperX tells me i need 
> >>> permission to access the CD drive [cannot open cdrom drive]. i can play 
> >>> CD audio with Alsaplayer, but not with XMMS.  likewise, xfreecd doesn't 
> >>> find the drive, but workman does. very inconsistant! running cdparanoia 
> >>> -vQ as user gives the following:
> >>> 
> >>> Checking /dev/cdrom for cdrom...
> >>>     Testing /dev/cdrom for cooked ioctl() interface
> >>>         /dev/scsi/host1/bus0/target0/lun0/cd is not a cooked ioctl CDROM.
> >>>     Testing /dev/cdrom for SCSI interface
> >>>         No generic SCSI device found to match CDROM device 
> >>> /dev/scsi/host1/bus0/target0/lun0/cd
> >>> 
> >>> it seems that there are still some permissions to change somewhere, but 
> >>> i can't for the life of me figure out where!
> >>> 
> >>> what have i missed?
> >>> 
> >>> thanks,
> >>> derek
> >>    
> >>
> 
> 

-- 
sigmotto: Liberty is theft.




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