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>
diff --git a/archival/tar.c b/archival/tar.c
index 7897a4a..5bd473a 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -1171,7 +1171,7 @@
}
if (opt & OPT_ANY_COMPRESS) {
- USE_FOR_MMU(IF_DESKTOP(long long) int FAST_FUNC (*xformer)(transformer_state_t *xstate, int src_fd, int dst_fd);)
+ USE_FOR_MMU(IF_DESKTOP(long long) int FAST_FUNC (*xformer)(transformer_state_t *xstate);)
USE_FOR_NOMMU(const char *xformer_prog;)
if (opt & OPT_COMPRESS)
@@ -1190,7 +1190,7 @@
USE_FOR_MMU(xformer = unpack_xz_stream;)
USE_FOR_NOMMU(xformer_prog = "unxz";)
- open_transformer_with_sig(tar_handle->src_fd, xformer, xformer_prog);
+ fork_transformer_with_sig(tar_handle->src_fd, xformer, xformer_prog);
/* Can't lseek over pipes */
tar_handle->seek = seek_by_read;
/*tar_handle->offset = 0; - already is */