Re: [PATCH] parser: Remove escape from the state transitions

[Daniel Kiper]

On Fri, Oct 13, 2017 at 08:53:23AM -0600, Eric Snowberg wrote:
> > On Oct 13, 2017, at 3:36 AM, Daniel Kiper <address@hidden> wrote:
> > On Thu, Oct 12, 2017 at 08:38:51AM -0600, Eric Snowberg wrote:
> >>> On Oct 12, 2017, at 5:43 AM, Daniel Kiper <address@hidden> wrote:
> >>> On Mon, Oct 09, 2017 at 09:23:44AM -0600, Eric Snowberg wrote:
> >>>>> On Oct 9, 2017, at 5:48 AM, Daniel Kiper <address@hidden> wrote:
> >>>>> On Fri, Oct 06, 2017 at 09:37:54AM -0600, Eric Snowberg wrote:
> >>>>>>> On Oct 6, 2017, at 8:47 AM, Daniel Kiper <address@hidden> wrote:
> >>>>>>> On Tue, May 30, 2017 at 04:07:52PM -0600, Eric Snowberg wrote:
> >>>>>>>> Remove GRUB_PARSER_STATE_ESC with state GRUB_PARSER_STATE_TEXT from
> >>>>>>>> the list of not allowed characters.
> >>>>>>>
> >>>>>>> Once again, NACK for this patch. I explained why earlier but...
> >>>>>>>
> >>>>>>>> This fixes a problem where a properly escaped comma is in the disk 
> >>>>>>>> path.
> >>>>>>>>
> >>>>>>>> For example: 
> >>>>>>>> /address@hidden/address@hidden/LSI,address@hidden/address@hidden:a
> >>>>>>>>
> >>>>>>>> During grub install, the search.fs_uuid is correctly stored in the
> >>>>>>>> core.img.
> >>>>>>>>
> >>>>>>>> As seen here:
> >>>>>>>>
> >>>>>>>> 001e380: 7365 6172 6368 2e66 735f 7575 6964 2039  search.fs_uuid 9
> >>>>>>>> 001e390: 6462 6137 6333 362d 6431 6432 2d34 6163  dba7c36-d1d2-4ac
> >>>>>>>> 001e3a0: 642d 6135 3037 2d30 3634 6132 3462 3538  d-a507-064a24b58
> >>>>>>>> 001e3b0: 3666 3420 726f 6f74 2069 6565 6531 3237  6f4 root ieee127
> >>>>>>>> 001e3c0: 352f 2f70 6369 4033 3036 2f70 6369 4031  
> >>>>>>>> 5//address@hidden/address@hidden
> >>>>>>>> 001e3d0: 2f4c 5349 5c2c 6d72 7361 7340 302f 6469  
> >>>>>>>> /LSI\,address@hidden/di
> >>>>>>>> 001e3e0: 736b 4030 3a61 200a 7365 7420 7072 6566  address@hidden:a 
> >>>>>>>> .set pref
> >>>>>>>> 001e3f0: 6978 3d28 2472 6f6f 7429 272f 6772 7562  ix=($root)'/grub
> >>>>>>>> 001e400: 3227 0a00 0000 0000 0000 0003 0000 0010  2'..............
> >>>>>>>> 001e410: 2f67 7275 6232 0000                      /grub2..
> >>>>>>>>
> >>>>>>>> Before this change the following args would be sent to
> >>>>>>>> grub_cmd_do_search:
> >>>>>>>>
> >>>>>>>> key: 9dba7c36-d1d2-4acd-a507-064a24b586f4
> >>>>>>>> var: root
> >>>>>>>> hint: 
> >>>>>>>> ieee1275//address@hidden/address@hidden/LSI,address@hidden/address@hidden:a
> >>>>>>>
> >>>>>>> ...because hint should be quoted in core.img using double quotes or 
> >>>>>>> even single quotes...
> >>>>>>> Or every control char should be escaped. Normal shell rules apply 
> >>>>>>> here.
> >>>>>>
> >>>>>> Hints are written during the install into the core.img. Once the system
> >>>>>> boots, the parser is used to retrieve information from the core.img.
> >>>>>> Currently the parser will strip double quotes, single quotes and 
> >>>>>> escapes.
> >>>>>> So I don’t understand how you recommend fixing this then.
> >>>>>
> >>>>> Could you send me or point a script which creates embedded config for 
> >>>>> you?
> >>>>
> >>>> There is no script.
> >>>>
> >>>> As I explained in the patch.  If your boot device name has a comma, which
> >>>> it does with a Megaraid, you can not boot GRUB.
> >>>>
> >>>> Install as follows:
> >>>>
> >>>> $ grub-install —force /dev/sda1
> >>>>
> >>>> By default it creates a core.img with what I provided in the git comment:
> >>>>
> >>>> 001e380: 7365 6172 6368 2e66 735f 7575 6964 2039  search.fs_uuid 9
> >>>> 001e390: 6462 6137 6333 362d 6431 6432 2d34 6163  dba7c36-d1d2-4ac
> >>>> 001e3a0: 642d 6135 3037 2d30 3634 6132 3462 3538  d-a507-064a24b58
> >>>> 001e3b0: 3666 3420 726f 6f74 2069 6565 6531 3237  6f4 root ieee127
> >>>> 001e3c0: 352f 2f70 6369 4033 3036 2f70 6369 4031  
> >>>> 5//address@hidden/address@hidden
> >>>> 001e3d0: 2f4c 5349 5c2c 6d72 7361 7340 302f 6469  /LSI\,address@hidden/di
> >>>> 001e3e0: 736b 4030 3a61 200a 7365 7420 7072 6566  address@hidden:a .set 
> >>>> pref
> >>>> 001e3f0: 6978 3d28 2472 6f6f 7429 272f 6772 7562  ix=($root)'/grub
> >>>> 001e400: 3227 0a00 0000 0000 0000 0003 0000 0010  2'..............
> >>>> 001e410: 2f67 7275 6232 0000                      /grub2..
> >>>>
> >>>> As you can see, everything is escaped as GRUB expects.
> >>>>
> >>>> Now during boot, the parser is used.  Without my patch, it will strip 
> >>>> the \,.
> >>>
> >>> AIUI you mean it strips '\'. If yes then it is correct behavior. And it
> >>> should stay as is. If you wish to leave '\' you have to quote hint.
> >>> Hence probably you have to fiddle with grub-install code or whatever
> >>> creates the hint.Or the hint consumer code to properly consume ',' alone.
> >>>
> >>>> So it changes the hint from:
> >>>>
> >>>> ieee1275//address@hidden/address@hidden/LSI,address@hidden/address@hidden:a
> >>>> to
> >>>> ieee1275//address@hidden/address@hidden/LSI\,address@hidden/address@hidden:a
> >>>>
> >>>> Later on, when it tries to use this disk, it incorrectly truncates
> >>>> the device name since the comma isn’t escaped and tries to do the
> >>>> grub_disk_open with ieee1275//address@hidden/address@hidden/LSI.
> >>>
> >>> I am not sure who strips everything after the ','. Whoever it is it is
> >>> not the parser for sure. There is a chance that you should look for
> >>> problem here.
> >>
> >> As I pointed out in the past, this is what strips everything after the
> >> ‘,’ during boot. This is called after the parser has stripped the ‘\’.
> >>
> >> grub-core/kern/disk.c
> >>
> >> /* Return the location of the first ',', if any, which is not
> >>  escaped by a '\'.  */
> >> static const char *
> >> find_part_sep (const char *name)
> >>
> >> Changing this would impact every platform. Also, it was my understanding
> >> that disks were to follow this encoding style for commas.  Since it is
> >> an easy way to find the disk partition. Your recommending this be changed 
> >> now?
> >> And you would approve such a patch?
> >
> > Nope, I told you that you should check where it happens. And if it is done 
> > by
> > purpose then you should not touch it. And it looks that it is. So, as I told
> > you earlier you have to quote the hint. Otherwise, '\' will be always 
> > stripped
> > by the parser. This is its normal behavior if string is not quoted.
>
> It seems like there are two parts of GRUB that are not compatible with one

I do not think so.

> another if a disk name contains a comma.  There is a parser which strips
> the escaped commas and there is the base disk driver that expects them.

It does this because string is not quoted. I am not sure why are you
surprised here. Once again: just quote the string properly and your
problem is gone.

> If you do not believe this is the case, please provide an example of how

I have never ever said that I do not believe this is the case. I say
that your fix is unacceptable and you should find other way to fix
the issue. Even I said how to fix it.

> this disk can be quoted properly to work with both the parser and the
> disk driver during boot:
>
> /address@hidden/address@hidden/LSI,address@hidden/address@hidden,0

I am a bit surprised that you are not able to quote a string but I will
give you some examples:

"/address@hidden/address@hidden/LSI\,address@hidden/address@hidden,0"
'/address@hidden/address@hidden/LSI\,address@hidden/address@hidden,0'
/address@hidden/address@hidden/LSI\\,address@hidden/address@hidden,0

Daniel