Compression for bbconfig applet

[Denys Vlasenko]

On Sunday 29 August 2010 13:43, Denys Vlasenko wrote:
> > Looking for the best place to store the configuration files of different
> > busybox installations, I take a look on the bbconfig applet. Nice idea
> > to store the configuration in the binary itself, at least on machines,
> > where the size doesn't that matter, but ... bbconfig stores the
> > configuration data in an uncompressed string :-( ...so I did some quick
> > hacking ... now the configuration could be stored compressed in
> > bbconfig, using either gzip, bzip2, lzma or xz.
> > 
> > scripts/bbzconfig -g .config >include/bbconfigopts.h
> > ( use -g for gzip, -b for bzip2, -l for lzma, -x for xz )
> > 
> > This creates the compressed configuration data to be included in busybox.
> > 
> > busybox bbconfig | scripts/bbzconfig >.config
> > 
> > Restores the configuration from busybox binary.
> > 
> > Saves me about 20k on my i686 machine.
> > 
> > But it's not perfect ...
> 
> Can you make it work similarly to FEATURE_COMPRESS_USAGE?
> 
> That is, make it a config option which depents on BBCONFIG,
> and then conditionally include decompress_bunzip2.o
> if this options is selected. See below how it is done
> for FEATURE_COMPRESS_USAGE in ./archival/libunarchive/Kbuild.src:
> 
> $ grep -r FEATURE_COMPRESS_USAGE .
> ./libbb/appletlib.c:#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
> ./libbb/appletlib.c:#if ENABLE_FEATURE_COMPRESS_USAGE
> ./libbb/appletlib.c:#endif /* FEATURE_COMPRESS_USAGE */
> ./scripts/Makefile.IMA:ifdef CONFIG_FEATURE_COMPRESS_USAGE
> ./TEST_config_rh9:CONFIG_FEATURE_COMPRESS_USAGE=y
> ./archival/libunarchive/Kbuild.src:lib-$(CONFIG_FEATURE_COMPRESS_USAGE)    += decompress_bunzip2.o
> ./Config.in:config FEATURE_COMPRESS_USAGE
> ./TEST_config_nommu:CONFIG_FEATURE_COMPRESS_USAGE=y
> ./TEST_config_noprintf:# CONFIG_FEATURE_COMPRESS_USAGE is not set
> 
> 
> Generation of compressed version of bbconfigopts.h
> should probably be added to scripts/mkconfigs. Currently
> it is used like this (see top-level Makefile):
> 
> $(srctree)/scripts/mkconfigs > include/bbconfigopts.h
> 
> By changing it so that it takes parameters
> instead of spewing data to stdout:
> 
> $(srctree)/scripts/mkconfigs include/bbconfigopts.h include/bbconfigopts_compressed.h
> 
> you can generate both uncompressed and compressed versions
> (see applets/usage_compressed for an example).
> 
> Then just use one or the other from bbconfig.c depending
> on the selected bbconfig methd (uncompressed or compressed).

Done, please try current git.
-- 
vda