[PATCH] add support for loading lzma compressed kernels

[Florian Fainelli]

Hello Simon,

On Monday 30 November 2009 06:51:39 Simon Horman wrote:
> On Wed, Nov 18, 2009 at 04:03:27PM -0800, Eric W. Biederman wrote:
> > Florian Fainelli <florian at openwrt.org> writes:
> > > Please find below a version which should address your comments.
> > > Thanks for reviewing the patch.
> 
> Thanks, Applied.

Oh thanks, I was about to respin with the changes Eric suggested.

> 
> > > --
> > > From: Florian Fainelli <florian at openwrt.org>
> > > Subject: [PATCH] add support for loading lzma compressed kernels
> > >
> > > This patch allows one to load a lzma compressed kernel using kexec -l.
> > > As I wanted the lzma code to be very similar to the existing
> > > zlib slurp_decompress I took lzread and associated routines
> > > from the cpio lzma support. Tested on my x86 laptop using the
> > > following commands:
> > >
> > > lzma e bzImage bzImage.lzma
> > > kexec -l bzImage.lzma
> > >
> > > Having lzma support is particularly useful on some embedded
> > > systems on which we have the kernel already lzma compressed
> > > and available on a mtd partition.
> >
> > Yes.  I don't think it is particularly useful on x86 (as we have
> > a decompressor built into the kernel) but on other arches
> > it makes a lot of sense.
> >
> > A few minor comments inline.
> >
> > > diff -urN kexec-tools-2.0.1/kexec/kexec-lzma.h
> > > kexec-tools-2.0.1.lzma/kexec/kexec-lzma.h ---
> > > kexec-tools-2.0.1/kexec/kexec-lzma.h	1970-01-01 01:00:00.000000000
> > > +0100 +++ kexec-tools-2.0.1.lzma/kexec/kexec-lzma.h	2009-11-19
> > > 00:06:24.000000000 +0100 @@ -0,0 +1,29 @@
> > > +#ifndef __KEXEC_LZMA_H
> > > +#define __KEXEC_LZMA_H
> > > +
> > > +#include <stdio.h>
> > > +#include <sys/types.h>
> > > +#include <unistd.h>
> > > +#include <inttypes.h>
> > > +#include <lzma.h>
> > > +
> > > +#include "config.h"
> > > +
> > > +#ifdef HAVE_LIBLZMA
> > > +#define kBufferSize (1 << 15)
> > > +
> > > +typedef struct lzfile {
> > > +	uint8_t buf[kBufferSize];
> > > +	lzma_stream strm;
> > > +	FILE *file;
> > > +	int encoding;
> > > +	int eof;
> > > +} LZFILE;
> > > +
> > > +LZFILE *lzopen(const char *path, const char *mode);
> > > +int lzclose(LZFILE *lzfile);
> > > +ssize_t lzread(LZFILE *lzfile, void *buf, size_t len);
> >
> > I don't think we need any of these definitions in the header file.
> >
> > > +#endif /* HAVE_LIBLZMA */
> > > +
> > > +char *lzma_decompress_file(const char *filename, off_t *r_size);
> >
> > Ideally the lzma_decompress_file stub would live here and would not
> > even compile kexec/lzma.c if we don't have lzma.
> >
> > > +#endif /* __KEXEC_LZMA_H */
> 
> I have also applied the following change
> 
> ----------------------------------------------------------------------
> 
> lzma: Move the bulk of kexec-lzma.h into lzma.c
> 
> There isn't any need for anything in kexec-lzma.h other
> than a declaration of zlib_decompress_file().
> 
> Other being cleaner it also fixes a build problem when
> lzma support isn't being compiled in.
> 
> $ make all
> i686-unknown-linux-gnu-gcc -Wall -Wextra -O2 -fomit-frame-pointer -pipe
>  -fno-strict-aliasing -Wall -Wstrict-prototypes
>  -I/home/horms/local/opt/crosstool/i686/gcc-3.4.5-glibc-2.3.6/i686-unknown-
> linux-gnu/include -I./include -I./util_lib/include -Iinclude/
>  -I./kexec/arch/i386/include  -c -MD -o kexec/kexec.o kexec/kexec.c
> In file included from kexec/kexec.c:47:
> kexec/kexec-lzma.h:8:18: lzma.h: No such file or directory
> kexec/kexec.c: In function `locate_hole':
> kexec/kexec.c:203: warning: comparison between signed and unsigned
> 
> It ought to be possible to just provide a stub for zlib_decompress_file()
> in kexec-lzma.h and not compile lzma.c at all in the case where
> lzma support isn't being compiled in. However I see no obvious way
> to do this with the existing build system. So I'd like to deal
> with that as a separate possible change.
> 
> Changes as suggested by Eric W. Biederman.
> 
> Cc: Florian Fainelli <florian at openwrt.org>
> Cc: Eric W. Biederman <ebiederm at xmission.com>
> Signed-off-by: Simon Horman <horms at verge.net.au>
> 
> Index: kexec-tools/kexec/kexec-lzma.h
> ===================================================================
> --- kexec-tools.orig/kexec/kexec-lzma.h	2009-11-30 16:43:38.000000000 +1100
> +++ kexec-tools/kexec/kexec-lzma.h	2009-11-30 16:44:15.000000000 +1100
> @@ -1,29 +1,8 @@
>  #ifndef __KEXEC_LZMA_H
>  #define __KEXEC_LZMA_H
> 
> -#include <stdio.h>
>  #include <sys/types.h>
> -#include <unistd.h>
> -#include <inttypes.h>
> -#include <lzma.h>
> -
> -#include "config.h"
> -
> -#ifdef HAVE_LIBLZMA
> -#define kBufferSize (1 << 15)
> -
> -typedef struct lzfile {
> -	uint8_t buf[kBufferSize];
> -	lzma_stream strm;
> -	FILE *file;
> -	int encoding;
> -	int eof;
> -} LZFILE;
> -
> -LZFILE *lzopen(const char *path, const char *mode);
> -int lzclose(LZFILE *lzfile);
> -ssize_t lzread(LZFILE *lzfile, void *buf, size_t len);
> -#endif /* HAVE_LIBLZMA */
> 
>  char *lzma_decompress_file(const char *filename, off_t *r_size);
> +
>  #endif /* __KEXEC_LZMA_H */
> Index: kexec-tools/kexec/lzma.c
> ===================================================================
> --- kexec-tools.orig/kexec/lzma.c	2009-11-30 16:43:38.000000000 +1100
> +++ kexec-tools/kexec/lzma.c	2009-11-30 16:44:15.000000000 +1100
> @@ -1,4 +1,9 @@
> +#include <unistd.h>
> +#include <sys/types.h>
> +
>  #include "kexec-lzma.h"
> +#include "config.h"
> +
>  #ifdef HAVE_LIBLZMA
>  #define _GNU_SOURCE
>  #include <stdio.h>
> @@ -7,14 +12,26 @@
>  #include <stdlib.h>
>  #include <errno.h>
>  #include <limits.h>
> -#include <sys/types.h>
>  #include <sys/stat.h>
> -#include <unistd.h>
>  #include <ctype.h>
>  #include <lzma.h>
> 
>  #include "kexec.h"
> 
> +#define kBufferSize (1 << 15)
> +
> +typedef struct lzfile {
> +	uint8_t buf[kBufferSize];
> +	lzma_stream strm;
> +	FILE *file;
> +	int encoding;
> +	int eof;
> +} LZFILE;
> +
> +LZFILE *lzopen(const char *path, const char *mode);
> +int lzclose(LZFILE *lzfile);
> +ssize_t lzread(LZFILE *lzfile, void *buf, size_t len);
> +
>  static LZFILE *lzopen_internal(const char *path, const char *mode, int fd)
>  {
>  	int level = 5;
> 

-- 
WBR, Florian