busybox/archival/libarchive/get_header_tar_lzma.c
Denys Vlasenko b4c11c1397 libarchive: add capability to unpack to mem.buffer
The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a code path without fork,
benefiting all users of xmalloc_open_zipped_read_close.

"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster.

Heavily based on a patch by Lauri Kasanen <curaga@operamail.com>

function                                             old     new   delta
setup_transformer_on_fd                                -     159    +159
transformer_write                                      -     122    +122
fork_transformer                                       -     112    +112
xmalloc_open_zipped_read_close                        63     118     +55
read_bunzip                                         1866    1896     +30
xtransformer_write                                     -      19     +19
unzip_main                                          2449    2462     +13
bbunpack                                             755     766     +11
unpack_lzma_stream                                  2717    2723      +6
unpack_xz_stream                                    2393    2397      +4
unpack_Z_stream                                     1173    1175      +2
inflate_unzip                                        111     105      -6
check_signature16                                     70      63      -7
unpack_bz2_stream                                    359     349     -10
unpack_unxz                                           12       -     -12
unpack_unlzma                                         12       -     -12
unpack_uncompress                                     12       -     -12
unpack_gunzip                                         12       -     -12
unpack_bunzip2                                        12       -     -12
open_transformer                                     106      92     -14
inflate_unzip_internal                              1945    1916     -29
unpack_gz_stream                                     693     655     -38
open_zipped                                           89      47     -42
setup_unzip_on_fd                                    142      53     -89
------------------------------------------------------------------------------
(add/remove: 4/5 grow/shrink: 7/8 up/down: 533/-295)          Total: 238 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2014-12-07 00:44:00 +01:00

25 lines
621 B
C

/* vi: set sw=4 ts=4: */
/*
* Small lzma deflate implementation.
* Copyright (C) 2006 Aurelien Jacobs <aurel@gnuage.org>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
#include "bb_archive.h"
char FAST_FUNC get_header_tar_lzma(archive_handle_t *archive_handle)
{
/* Can't lseek over pipes */
archive_handle->seek = seek_by_read;
fork_transformer_with_sig(archive_handle->src_fd, unpack_lzma_stream, "unlzma");
archive_handle->offset = 0;
while (get_header_tar(archive_handle) == EXIT_SUCCESS)
continue;
/* Can only do one file at a time */
return EXIT_FAILURE;
}