Re: [BUG] GRUBs option parsing needs fixing

[Lennart Sorensen]

On Thu, Mar 08, 2012 at 02:12:30PM +0100, Andreas Vogel wrote:
> I start a new thread with this mail in order to have a thread on its own
> for this subject.

Actually you did not, you hijacked an existing thread by replying to it
and changing the subject.  Anyone with a threaded mail client now sees
your messages attached to the thread you hijacked.

> In another thread we've already had some discussion about GRUBs option
> parsing. I wanna summarize and describe here about the issue.
> 
> Right now I see 2 problems with GRUBs argument parsing:
> 
> 1) GRUBs argument parsing is not POSIX compliant.
> 
> Problem:
> POSIX (and GNU too) recommends (see
> http://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html):
> 
> "An option and its argument may or may not appear as separate tokens.
> (In other words, the whitespace separating them is optional.) Thus, ‘-o
> foo’ and ‘-ofoo’ are equivalent."
> 
> This is doesn't hold for GRUB.
> When I try
>     load_env -fenv
> an error message
>     error: unknown argument '-e'.
> is returned.
> 
> Solution:
> The GRUB argument parser needs to be fixed so that short options are
> parsed according to POSIX/GNU standards.
> 
> 2) Optional option argument is not handled correctly (and not according
> to POSIX/GNU standard)
> 
> Problem:
> Right now the GRUB argument parser doesn't handle optional arguments
> properly and it doesn't comply to POSIX/GNU standards.
> 
> For short options parsing fails for the reason described above and
> because the parser allows that the option and its (optional) argument
> might be separated with whitespace.
> 
> For long options parsing fails too because the parser allows that the
> option and its (optional) argument might be separated with whitespace.
> Example:
>     OK: search  --file  --set  --nofloppy  /boot/grub/grub.cfg
>     OK: search  --file  --set  --  /boot/grub/grub.cfg
>     ERROR: search  --file  --set  /boot/grub/grub.cfg
> 
> Solution:
> This solution follows just the POSIX/GNU standards for argument syntax
> as stated in the above mentioned HTML document.
> In order to be able to handle optional arguments for options the GRUB
> argument parser needs to implement parsing according to the following
> syntax:
> 
> a) Short option: e.g. option name 'x' taking an optional argument '<arg>'
>      Possible options: "-x"   or   "-x<arg>"
> 
> b) Long option: e.g. option name 'xlong' taking an optional argument '<arg>'
>      Possible options: "--xlong"   or   "--xlong=<arg>"  or  "--xlong="
>      For the third form the upcoming implementation is somehow free to
> decide how to interpret that option. Regarding to GNUs getopt() man
> page, this form will be interpreted by getopt() as if the option isn't
> specified at all (due to a bug). Because that interpretation is based on
> a bug and because it might make more sense the third form could/should
> be interpreted as if "--xlong" has been specified (meaning: options is
> present but without value).
> 
> So for both, short and long options taking an optional value, no
> whitespace between option and its value (if the value is present) is
> allowed.
> 
> IMHO the option parsing code in GRUB2 should be fixed as soon as
> possible. The later it will be done the more we'll have to fight with
> compatibility issues.
> 
> Any comments?

Well as a user I had never noticed.  I suppose I am used to many programs
requireing spaces around arguments, so I consider those that don't odd,
and those that don't allow spaces to be annoying.

Doesn't mean it wouldn't be nice if grub was consistent with other
GNU things.

-- 
Len Sorensen