diff options
| author | Ron Yorston <rmy@pobox.com> | 2016-03-30 00:42:05 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2016-03-30 00:44:11 +0200 |
| commit | 610c4c385b38280c7bde7a48d95ec019cbfe1ab4 (patch) | |
| tree | 82ad4366ce9e927f64efa89d178c4dd2bfea1435 /libbb/vfork_daemon_rexec.c | |
| parent | 9844d7e830a2c55421e27e8828d2067c50f57c23 (diff) | |
| download | busybox-610c4c385b38280c7bde7a48d95ec019cbfe1ab4.tar.gz | |
applet_tables: save space by removing applet name offsets
The array applet_nameofs consumes two bytes per applet. It encodes
nofork/noexec flags
suid flags
the offset of the applet name in the applet_name string
Change the applet_table build tool to store the flags in two separate
arrays (applet_flags and applet_suid). Replace applet_nameofs[] with a
smaller version that only stores a limited number of offsets.
This requires changes to the macros APPLET_IS_NOFORK, APPLET_IS_NOEXEC
and APPLET_SUID.
According to Valgrind the original find_applet_by_name required
353 cycles per call, averaged over all names. Adjusting the number
of known offsets allows space to be traded off against execution time:
KNOWN_OFFSETS cycles bytes (wrt KNOWN_OFFSETS = 0)
0 9057 -
2 4604 32
4 2407 75
8 1342 98
16 908 130
32 884 194
This patch uses KNOWN_OFFSETS = 8.
v2:
Remove some dead code from the applet_table tool;
Treat the applet in the middle of the table as a special case.
v3:
Use the middle applet to adjust the start of the linear search as
well as the last applet found.
v4:
Use an augmented linear search in find_applet_by_name.
Drop the special treatment of the middle name from get_applet_name:
most of the advantage now derives from the last stored value.
v5:
Don't store index in applet_nameofs, it can be calculated.
v6:
Tweaks by Denys
function old new delta
find_applet_by_name 25 125 +100
applet_suid - 92 +92
run_applet_no_and_exit 452 460 +8
run_applet_and_exit 695 697 +2
applet_name_compare 31 - -31
applet_nameofs 734 14 -720
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 3/1 up/down: 202/-751) Total: -549 bytes
text data bss dec hex filename
925464 906 17160 943530 e65aa busybox_old
924915 906 17160 942981 e6385 busybox_unstripped
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'libbb/vfork_daemon_rexec.c')
| -rw-r--r-- | libbb/vfork_daemon_rexec.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c index d6ca7b263..1adb5b3c4 100644 --- a/libbb/vfork_daemon_rexec.c +++ b/libbb/vfork_daemon_rexec.c @@ -116,8 +116,6 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv) save_nofork_data(&old); - applet_name = APPLET_NAME(applet_no); - xfunc_error_retval = EXIT_FAILURE; /* In case getopt() or getopt32() was already called: @@ -157,6 +155,7 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv) * need argv untouched because they free argv[i]! */ char *tmp_argv[argc+1]; memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0])); + applet_name = tmp_argv[0]; /* Finally we can call NOFORK applet's main() */ rc = applet_main[applet_no](argc, tmp_argv); } else { |