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610c4c385b
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>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#ifndef BUSYBOX_H
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#define BUSYBOX_H 1
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#include "libbb.h"
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/* BB_DIR_foo and BB_SUID_bar constants: */
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#include "applet_metadata.h"
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PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
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/* Defined in appletlib.c (by including generated applet_tables.h) */
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/* Keep in sync with applets/applet_tables.c! */
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extern const char applet_names[] ALIGN1;
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extern int (*const applet_main[])(int argc, char **argv);
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extern const uint8_t applet_flags[] ALIGN1;
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extern const uint8_t applet_suid[] ALIGN1;
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extern const uint8_t applet_install_loc[] ALIGN1;
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#if ENABLE_FEATURE_PREFER_APPLETS
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# define APPLET_IS_NOFORK(i) (applet_flags[(i)/4] & (1 << (2 * ((i)%4))))
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# define APPLET_IS_NOEXEC(i) (applet_flags[(i)/4] & (1 << ((2 * ((i)%4))+1)))
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#else
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# define APPLET_IS_NOFORK(i) 0
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# define APPLET_IS_NOEXEC(i) 0
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#endif
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#if ENABLE_FEATURE_SUID
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# define APPLET_SUID(i) ((applet_suid[(i)/4] >> (2 * ((i)%4)) & 3))
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#endif
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#if ENABLE_FEATURE_INSTALLER
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#define APPLET_INSTALL_LOC(i) ({ \
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unsigned v = (i); \
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if (v & 1) v = applet_install_loc[v/2] >> 4; \
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else v = applet_install_loc[v/2] & 0xf; \
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v; })
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#endif
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/* Length of these names has effect on size of libbusybox
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* and "individual" binaries. Keep them short.
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*/
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#if ENABLE_BUILD_LIBBUSYBOX
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#if ENABLE_FEATURE_SHARED_BUSYBOX
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int lbb_main(char **argv) EXTERNALLY_VISIBLE;
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#else
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int lbb_main(char **argv);
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#endif
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#endif
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POP_SAVED_FUNCTION_VISIBILITY
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#endif
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