Use the old fork() method of tar compression support, rather than
read_bz2....
- (*uncompress)(int in, int out) seems like a more natural interface
for compression code.
- it might improve performance by seperating the work into one cpu
bound and one io bound process.
- There is extra code required to do read_[gz|bunzip] since (*uncompress)(int in,
int out) will normally be used by the standalone compression applet.
There have been problems with this method so if you see a "Short read"
error let me know.
Hello Rob,
Here's a patch to your bunzip-3.c file. Nice work btw.
One minor bug fix... checking for error return when read()ing.
Some size/performance optimizations as well. One instance of
memset() seems unnecssary. You might want to take a look.
Anyway, on my machine, decompressing linux-2.6.0-test7.tar.bz2
to /dev/null gave the following times:
bunzip-3.c bzcat (system) bunzip-3.c (patched)
real 0m24.420s 0m22.725s 0m20.701s
user 0m23.930s 0m22.170s 0m20.180s
sys 0m0.070s 0m0.080s 0m0.140s
Size of the patched version is comparable (slightly larger or
smaller depending on compiler flags).
Manuel
The API for using partial writes, as described in my last message, sucked.
So here's a patch against my last patch that changes things so that
write_bunzip_data calls read_bunzip_data itself behind the scenes whenever
necessary. So usage is now just start_bunzip(), write_bunzip_data() until it
returns a negative number, and then the cleanup at the end of
uncompressStream.
It adds 32 bytes to the executable, but it should allow the caller (tar) to be
simplified enough to compensate. Total -Os stripped exe size now 6856 bytes.
Rob
P.S. I attached the whole C file so you don't have to keep incremental
patches straight if you don't want to. :)
P.S. In the version I'm banging on now, I've simplified the license to just
LGPL. I read the OSL a bit more closely and the patent termination clause
would have bit IBM in their counter-suit of SCO if the code in question had
been OSL instead of GPL, and I've decided I just don't want to beta-test
legal code right now.
