Syslinux - Apr 2014 - Issues with syslinux_run_command(str) and parameters

Apologies for how that formatted. Also on pastebin: http://pastebin.com/EXSq75yX
--Ian
> From: ian at internals.io
> To: ady-sf at hotmail.com; syslinux at zytor.com
> Date: Tue, 29 Apr 2014 19:09:09 -0500
> Subject: Re: [syslinux] Issues with syslinux_run_command(str) and
parameters
> 
> I don't think that's it, but fair enough, try this sample config:
> ************************************************# Test File: isolinux.cfg
> default vesamenu.c32
> ALLOWOPTIONS 0
> LABEL Test	kernel whichsys.c32	append -iso- memdisk initrd=fdboot.img -sys-
initrd=fdboot.img
> MENU END************************************************
> 
> I am using binaries from 6.03-pre11 from kernel.org. I used vesamenu.c32
and fdboot.img (FreeDOS) for the example but they are not required.
> Accepting that this is a silly use of whichsys.c32, running the same thing
in both cases, it does illustrate the issue. When ALLOWEDOPTIONS is set to 0,
memdisk errors "No ramdisk image specified!" as it does not receive
the additional parameter. If you comment out ALLOWEDOPTIONS 0, then memdisk
loads the image without any trouble.
> Similarly, if I use a config that only has the ALLOWOPTIONS 0 line (no
vesamenu, etc.), "memdisk initrd=fdboot.img" will error "No
ramdisk image specified!". Again commenting out ALLOWOPTIONS 0 resolves
this.
> 
> My apologies for not providing the sample config previously!
> --Ian
> 
> > From: ady-sf at hotmail.com
> > To: syslinux at zytor.com
> > Date: Wed, 30 Apr 2014 02:32:05 +0300
> > Subject: Re: [syslinux] Issues with syslinux_run_command(str) and
parameters
> > 
> > 
> > > 
> > > Thanks Ady, you were spot on, and I should have tested that
scenario!
> > > I narrowed the issue down to a line in my config: 
> > > 
> > > 
> > > ALLOWEDOPTIONS 0
> > > 
> > > 
> > > The comment next to it in my config indicates this was added to 
> > > disallow users dropping to the console with Escape or Tab, a 
> > > restriction I would like to keep. BUT, when this is set whichsys 
> > > fails to function in the manner I described. And similarly if I
end
> > > up at the console prompt for any other reason and try to run 
> > > something, no parameters make it through).
> > > 
> > > 
> > > Is this expected? Seems a bit odd. 
> > > 
> > > Thank you very much!
> > > 
> > > --Ian
> > 
> > The directive you are referring to is "ALLOWOPTIONS 0" (no
"ED"),
> > which prevents users from editing commands. In other words, the user 
> > can only execute LABELs "as-is". Yet, I doubt this is the
(only)
> > problem.
> > 
> > My guess is that you are using another directive, "NOESCAPE
1",
> > which, when combined with additional directives ("PROMPT 0"
and/or
> > "UI"), prevents the possibility of "forcing" the
"boot:" prompt (with
> > either SHIFT / ALT / CAPS LOCK / NUM LOCK) at boot time.
> > 
> > In practice, "NOESCAPE 1" forces either the DEFAULT command
or the UI
> > directive (the latter takes precedence), thus preventing the 
> > possibility of using the CLI at *any* time, even after executing some 
> > other command.
> > 
> > So, take for example "ls.c32". Normally, after executing
"ls.c32" you
> > would end (back) at the CLI. But with "NOESCAPE 1", you jump
> > immediately to the UI directive (or, if UI is not used, to the 
> > DEFAULT command); the CLI is not allowed.
> > 
> > My guess is that something in your cfg is being (automatically) 
> > executed and then it is exiting (whether after failure or success) 
> > back to Syslinux. Since the CLI is not allowed (by "NOESCAPE
1"), the
> > Syslinux menu is seen again. Once the menu is loaded, the same entry 
> > is again automatically executed... producing a loop.
> > 
> > I don't really know yet whether you are actually using
"NOESCAPE 1".
> > Whichever the case, I would repeat my suggestion to post the content 
> > of your cfg file, so we might find out which command is failing (and 
> > therefore sending you to a loop).
> > 
> > Additionally, it could be helpful to double check the paths to your 
> > images. For instance, if you have "APPEND initrd=/myimage",
is
> > "myimage" really located in "/"?
> > 
> > Regards,
> > Ady.
> > 
> > _______________________________________________
> > Syslinux mailing list
> > Submissions to Syslinux at zytor.com
> > Unsubscribe or set options at:
> > http://www.zytor.com/mailman/listinfo/syslinux
>  		 	   		  
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Try the following and let us know. If it doesn't work, we'll try 
other alternatives.

 ***
 
 DEFAULT vesamenu.c32
 ALLOWOPTIONS 0
 
 LABEL test
 COM32 whichsys.c32
 APPEND -iso- iso -sys- sys
 
 LABEL iso
 LINUX memdisk
 APPEND initrd=fdboot.img
 
 LABEL sys
 LINUX memdisk
 APPEND initrd=fdboot.img
 
 ***

Regards,
Ady.

I did confirm earlier that this does work, and combined with a MENU HIDDEN to
hide it from the visible menu it is a possible solution. I originally assumed
that this was due to that going down a different code path and did not mention
it, apologies. The scale of my menu makes doubling/tripling menu entries less
ideal, though.

Do we consider it intended functionality that modules such as whichsys will not
work under ALLOWOPTIONS 0? A strict reading of the wiki would allow for this, as
the subsequently loaded module does not have parameters in an append label:
http://www.syslinux.org/wiki/index.php/SYSLINUX#ALLOWOPTIONS_flag_val

Naturally given my situation here, I think it would be ideal if we could
separate disabling user edits & commands from blocking modules loading other
modules, etc. :)
--Ian
> From: ady-sf at hotmail.com
> To: syslinux at zytor.com
> Date: Wed, 30 Apr 2014 03:36:35 +0300
> Subject: Re: [syslinux] Issues with syslinux_run_command(str) and
parameters
> 
> Try the following and let us know. If it doesn't work, we'll try 
> other alternatives.
> 
>  ***
>  
>  DEFAULT vesamenu.c32
>  ALLOWOPTIONS 0
>  
>  LABEL test
>  COM32 whichsys.c32
>  APPEND -iso- iso -sys- sys
>  
>  LABEL iso
>  LINUX memdisk
>  APPEND initrd=fdboot.img
>  
>  LABEL sys
>  LINUX memdisk
>  APPEND initrd=fdboot.img
>  
>  ***
> 
> Regards,
> Ady.
> _______________________________________________
> Syslinux mailing list
> Submissions to Syslinux at zytor.com
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