LZMA magic number

[Myles Watson]

Is there a magic number for LZMA?  Should there be?

I accidentally used an uncompressed payload with v2 when it expected a
compressed payload, and it gave me the message:

       Decoder scratchpad too small!!
       Decoding error = 1

I think it would be nicer to have an error like:

       Payload not compressed with lzma!

Myles

[Peter Stuge]

On Fri, Jan 25, 2008 at 10:55:24AM -0700, Myles Watson wrote:
  I accidentally used an uncompressed payload with v2
when it
 expected a compressed payload, and it gave me the message:
 
        Decoder scratchpad too small!!
        Decoding error = 1
I got this too.


  I think it would be nicer to have an error like:
 
        Payload not compressed with lzma!
And we can check it already at build time.


//Peter

[Carl-Daniel Hailfinger]

On 25.01.2008 18:58, Peter Stuge wrote:
  On Fri, Jan 25, 2008 at 10:55:24AM -0700, Myles Watson
wrote:
   
  I accidentally used an uncompressed payload with
v2 when it
 expected a compressed payload, and it gave me the message:

        Decoder scratchpad too small!!
        Decoding error = 1
 I got this too.


   
  I think it would be nicer to have an error like:

        Payload not compressed with lzma!
 And we can check it already at build time.
LZMA compressed payloads to not have a magic number, all you can do is
check if the header parameters are in a reasonable range. Sorry.
This problem fortunately does not exist in v3 because LAR does the
compression itself and notes the compression type in th header.

Regards,
Carl-Daniel

[PATCH] Re: LZMA magic number

[Ward Vandewege]

On Sat, Jan 26, 2008 at 02:18:39AM +0100, Carl-Daniel Hailfinger wrote:
  On 25.01.2008 18:58, Peter Stuge wrote:
  On Fri, Jan 25, 2008 at 10:55:24AM -0700, Myles
Watson wrote:
   
  I accidentally used an uncompressed payload with
v2 when it
 expected a compressed payload, and it gave me the message:

        Decoder scratchpad too small!!
        Decoding error = 1
 I got this too.
   
  I think it would be nicer to have an error like:

        Payload not compressed with lzma!
 And we can check it already at build time.
 
 LZMA compressed payloads to not have a magic number, all you can do is
 check if the header parameters are in a reasonable range. Sorry.
 This problem fortunately does not exist in v3 because LAR does the
 compression itself and notes the compression type in th header.
I ran into this runtime error as well today.

Please find a patch attached that makes coreboot a bit smarter in dealing
with this situation, and avoids the fatal runtime error.

Thanks,
Ward.

-- 
Ward Vandewege <ward(a)fsf.org>
Free Software Foundation - Senior Systems Administrator

[PATCH] Re: LZMA magic number

[Myles Watson]

  -----Original Message-----
 From: coreboot-bounces(a)coreboot.org [mailto:[e-mail]]
 On Behalf Of Ward Vandewege
 Sent: Wednesday, August 27, 2008 3:02 PM
 To: Carl-Daniel Hailfinger
 Cc: coreboot(a)coreboot.org
 Subject: [coreboot] [PATCH] Re: LZMA magic number
 
 On Sat, Jan 26, 2008 at 02:18:39AM +0100, Carl-Daniel Hailfinger wrote:
  On 25.01.2008 18:58, Peter Stuge wrote:
  On Fri, Jan 25, 2008 at 10:55:24AM -0700, Myles
Watson wrote:

  I accidentally used an uncompressed payload with
v2 when it
 expected a compressed payload, and it gave me the message:

        Decoder scratchpad too small!!
        Decoding error = 1
 I got this too.

  I think it would be nicer to have an error like:

        Payload not compressed with lzma!
 And we can check it already at build time.
 LZMA compressed payloads to not have a magic number, all you can do is
 check if the header parameters are in a reasonable range. Sorry.
 This problem fortunately does not exist in v3 because LAR does the
 compression itself and notes the compression type in th header.
 
 I ran into this runtime error as well today.
 
 Please find a patch attached that makes coreboot a bit smarter in dealing
 with this situation, and avoids the fatal runtime error.
Ward,

I like the idea of assuming no compression if uncompressing it fails.  I
wonder if it would be better to copy it to dest instead of running it in
place.

Thanks,
Myles

[PATCH] Re: LZMA magic number

[Ward Vandewege]

On Wed, Aug 27, 2008 at 03:22:38PM -0600, Myles Watson wrote:
  I like the idea of assuming no compression if
uncompressing it fails.  I
 wonder if it would be better to copy it to dest instead of running it in
 place.
If compression is disabled in Config.lb the current code runs it in place as
well. So I guess it's no problem?

Thanks,
Ward.

-- 
Ward Vandewege <ward(a)fsf.org>
Free Software Foundation - Senior Systems Administrator

[PATCH] Re: LZMA magic number

[Myles Watson]

  -----Original Message-----
 From: Ward Vandewege [mailto:[e-mail]]
 Sent: Wednesday, August 27, 2008 3:31 PM
 To: Myles Watson
 Cc: 'Carl-Daniel Hailfinger'; coreboot(a)coreboot.org
 Subject: Re: [coreboot] [PATCH] Re: LZMA magic number
 
 On Wed, Aug 27, 2008 at 03:22:38PM -0600, Myles Watson wrote:
  I like the idea of assuming no compression if
uncompressing it fails.  I
 wonder if it would be better to copy it to dest instead of running it in
 place.
 
 If compression is disabled in Config.lb the current code runs it in place
 as
 well. So I guess it's no problem?
Ward,

I should have checked that.

Acked-by: Myles Watson <mylesgw(a)gmail.com>

Thanks,
Myles

  
 Thanks,
 Ward.
 
 --
 Ward Vandewege <ward(a)fsf.org>
 Free Software Foundation - Senior Systems Administrator

[PATCH] Re: LZMA magic number

[Carl-Daniel Hailfinger]

On 27.08.2008 23:39, Myles Watson wrote:
  -----Original
Message-----
 From: Ward Vandewege [mailto:[e-mail]]
 Sent: Wednesday, August 27, 2008 3:31 PM
 To: Myles Watson
 Cc: 'Carl-Daniel Hailfinger'; coreboot(a)coreboot.org
 Subject: Re: [coreboot] [PATCH] Re: LZMA magic number

 On Wed, Aug 27, 2008 at 03:22:38PM -0600, Myles Watson wrote:
     
  I like the idea of assuming no compression if
uncompressing it fails.  I
 wonder if it would be better to copy it to dest instead of running it in
 place.
 If compression is disabled in Config.lb the current code runs it in place
 as
 well. So I guess it's no problem?
 Ward,

 I should have checked that.

 Acked-by: Myles Watson <mylesgw(a)gmail.com>
The change looks sensible to me. Since it is tested, here is my ack.
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006(a)gmx.net>

Regards,
Carl-Daniel

-- 
http://www.hailfinger.org/

[PATCH] Re: LZMA magic number

[Ward Vandewege]

On Wed, Aug 27, 2008 at 11:48:26PM +0200, Carl-Daniel Hailfinger wrote:
  Acked-by:
Myles Watson <mylesgw(a)gmail.com>
 
 The change looks sensible to me. Since it is tested, here is my ack.
 Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006(a)gmx.net>
r3542.

Thanks,
Ward.

-- 
Ward Vandewege <ward(a)fsf.org>
Free Software Foundation - Senior Systems Administrator

[PATCH] Re: LZMA magic number

[Peter Stuge]

Ward Vandewege wrote:
  r3542.
Fantastic improvement. Thank you so much Ward.


//Peter