hush/libbb
Ron Yorston 610c4c385b 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>
2016-03-30 00:44:11 +02:00
..
appletlib.c applet_tables: save space by removing applet name offsets 2016-03-30 00:44:11 +02:00
ask_confirmation.c
auto_string.c libbb: auto_string() for efficient handling of temporary malloced stirngs 2015-10-09 17:59:56 +02:00
bb_askpass.c use auto_string() where appropriate to kill a few statics 2015-10-09 18:16:40 +02:00
bb_bswap_64.c
bb_do_delay.c
bb_pwd.c libpwdgrp: rewritten to use malloced implementation 2015-01-02 21:37:59 +01:00
bb_qsort.c
bb_strtod.c
bb_strtonum.c libbb/bb_strtonum: always set end ptr, even on error return 2011-12-22 13:00:32 +01:00
bbunit.c unit-tests: remove code depending on WANT_TIMING 2015-08-17 17:01:49 +02:00
change_identity.c libbb: Enable support for !CONFIG_MULTIUSER 2015-05-12 23:59:57 +02:00
chomp.c
compare_string_array.c libbb: another unit test for is_suffixed_with 2015-09-15 23:38:01 +02:00
concat_path_file.c
concat_subpath_file.c
Config.src lineedit: FEATURE_REVERSE_SEARCH should not depend on SAVEHISTORY 2015-10-30 21:39:19 +01:00
copy_file.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
copyfd.c libbb: use sendfile() to copy data between file descriptors 2014-11-27 23:31:58 +01:00
correct_password.c ftpd: add optional support for authentication 2014-08-05 21:57:18 +02:00
crc32.c
default_error_retval.c
device_open.c
die_if_bad_username.c
dump.c hexdump: don't unconditionally limit the usable address range 2013-03-27 15:15:33 +01:00
endofname.c move endofname() to libbb 2013-02-26 00:36:53 +01:00
executable.c libbb: rename execable -> executable. No code changes 2014-05-02 17:15:58 +02:00
fclose_nonstdin.c sed: open input files sequentially to avoid EMFILE 2013-11-28 03:14:16 +01:00
fflush_stdout_and_exit.c remove global "jmp_buf die_jmp" from !FEATURE_PREFER_APPLETS builds 2015-10-09 16:42:57 +02:00
fgets_str.c
find_mount_point.c find_mount_point: fix find_mount_point for char devices 2012-01-18 01:49:11 +01:00
find_pid_by_name.c
find_root_device.c
full_write.c
get_console.c
get_cpu_count.c
get_last_path_component.c
get_line_from_file.c
get_shell_name.c mark get_shell_name FAST_FUNC 2012-10-03 09:42:21 +02:00
get_volsize.c
getopt32.c
getpty.c script: make it work even if fd 0 is closed 2014-03-16 12:34:53 +01:00
hash_md5_sha.c md5sum: code shrink 2015-10-07 19:17:01 +02:00
hash_md5prime.c
herror_msg.c
human_readable.c du: extra compat: with -k and -m, round sizes up 2015-10-15 21:33:34 +02:00
in_ether.c Removes stray empty line from code 2015-07-13 03:25:46 +02:00
inet_cksum.c
inet_common.c libbb: make INET[6]_rresolve use sockaddr2{host,dotted}_noport 2015-02-03 12:07:40 +01:00
info_msg.c
inode_hash.c du, copy_file: fix file matching on cramfs. Closes 5456 2014-02-25 15:27:58 +01:00
isdirectory.c libbb: remove is_directory's argument which is always NULL 2011-12-18 03:27:46 +01:00
Kbuild.src randomconfig fixes 2014-12-22 19:37:05 +01:00
kernel_version.c tidy up strtok use 2015-10-23 18:43:16 +02:00
last_char_is.c
lineedit_ptr_hack.c
lineedit.c lineedit: search applets as well as PATH for tab completion 2015-10-30 19:49:33 +01:00
llist.c
logenv.c zcip: Add environment variable for overriding log functionality 2014-11-04 12:19:04 +01:00
login.c libbb: introduce and use strftime_[YYYYMMDD]HHMMSS() 2013-03-29 12:30:33 +01:00
loop.c libbb/loop: don't try to re-use existing loop device 2015-02-07 19:13:57 +01:00
make_directory.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
makedev.c
match_fstype.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
messages.c libiproute: rename invarg(a,b) to invarg_1_to_2(a,b) 2015-10-14 13:21:01 +02:00
missing_syscalls.c Resolve linker issues with Android API 21 (dprintf, tcdrain) 2015-12-17 16:42:41 +01:00
mode_string.c
mtab.c
nuke_str.c fix failures found by randomconfig builds 2013-12-31 23:22:36 +01:00
obscure.c unit-tests: implement the unit-testing framework 2014-06-22 16:30:41 +02:00
parse_config.c mdev: do not treat non-leading '#' chars as start of comment. Closes 4676 2012-01-11 00:37:17 +01:00
parse_mode.c libbb: more compact API for bb_parse_mode() 2015-10-07 17:55:33 +02:00
percent_decode.c
perror_msg.c
perror_nomsg_and_die.c
perror_nomsg.c
pidfile.c
platform.c Bionic lacks ttyname_r; provide a workaround 2015-04-25 21:32:48 +02:00
print_flags.c
printable_string.c libbb: auto_string() for efficient handling of temporary malloced stirngs 2015-10-09 17:59:56 +02:00
printable.c Refactor catv. Move visible() from stty to libbb. 2013-07-30 06:29:42 +02:00
process_escape_sequence.c
procps.c pmap: fix bogus {no such process} comm field text 2015-10-24 03:45:57 +02:00
progress.c wget: if stderr is not a tty, progress bar shouldn't use tty-tricks 2015-10-23 02:01:38 +02:00
ptr_to_globals.c
pw_encrypt_des.c
pw_encrypt_md5.c fix assorted unused code and wrong format specs found by cppchekc (bug 6716) 2013-11-29 16:43:33 +01:00
pw_encrypt_sha.c
pw_encrypt.c chpasswd: support -c argument and respect DEFAULT_PASSWD_ALGO 2015-12-18 19:01:14 +01:00
read_key.c Add comments in keyboard escape sequences table 2012-06-11 14:40:17 +02:00
read_printf.c libbb: remove unnecessary argument to nonblock_immune_read 2015-04-20 13:41:32 +02:00
read.c
README
recursive_action.c
remove_file.c Add conditional support for -v / --verbose 2014-05-19 16:23:50 +02:00
replace.c xargs: add support for -I and -i. Closes 493 2014-02-27 11:17:06 +01:00
rtc.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
run_shell.c
safe_gethostname.c sendmail: use host rather than NIS domain name for HELO 2012-04-28 17:04:19 +02:00
safe_poll.c
safe_strncpy.c
safe_write.c
selinux_common.c whitespace cleanup. no code changes 2013-01-14 15:57:44 +01:00
setup_environment.c su: do not change to home dir unless -l 2012-06-12 13:21:02 +02:00
signals.c libbb: correctness/size tweaks in signal-related helpers 2012-09-27 13:20:34 +02:00
simplify_path.c
single_argv.c
skip_whitespace.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
speed_table.c libbb: FreeBSD fix for B<num> baud rate constants not fitting into a short. 2014-01-08 15:25:20 +01:00
str_tolower.c
strrstr.c unit-tests: implement the unit-testing framework 2014-06-22 16:30:41 +02:00
sysconf.c libbb: add sanity check in bb_arg_max() 2014-12-24 01:46:29 +01:00
time.c libbb: fix parsing of "10101010" date/time form 2014-01-21 07:58:18 +01:00
trim.c
u_signal_names.c
udp_io.c libbb: add setsockopt_foo helpers 2015-08-24 20:00:17 +02:00
unicode.c lineedit: improve Unicode handling (still buggy though) 2013-08-19 16:44:05 +02:00
update_passwd.c libbb: introduce and use is_prefixed_with() 2015-03-12 17:48:34 +01:00
utmp.c *: Switch to POSIX utmpx API 2015-04-02 23:03:46 +02:00
uuencode.c libbb: shrink base64 decoding a bit 2011-10-28 16:15:00 +02:00
vdprintf.c libbb.h: remove unused defines 2011-10-24 04:06:18 +02:00
verror_msg.c Fix compile failures 2014-05-02 07:18:55 +02:00
vfork_daemon_rexec.c applet_tables: save space by removing applet name offsets 2016-03-30 00:44:11 +02:00
warn_ignoring_args.c
wfopen_input.c
wfopen.c
write.c
xatonum_template.c whitespace fixes. no code changes 2013-01-15 13:58:01 +01:00
xatonum.c truncate: new applet 2015-03-22 17:56:38 +01:00
xconnect.c libbb: add setsockopt_foo helpers 2015-08-24 20:00:17 +02:00
xfunc_die.c remove global "jmp_buf die_jmp" from !FEATURE_PREFER_APPLETS builds 2015-10-09 16:42:57 +02:00
xfuncs_printf.c libbb: add a function to make a copy of a region of memory 2015-07-19 23:05:20 +02:00
xfuncs.c libbb: factor out code which queries screen width 2015-10-23 01:44:22 +02:00
xgetcwd.c
xgethostbyname.c
xreadlink.c libbb: fix a bad check for uclibc >= 0.9.31 2014-03-16 20:53:40 +01:00
xrealloc_vector.c
xregcomp.c

Please see the LICENSE file for copyright information (GPLv2)

libbb is BusyBox's utility library.  All of this stuff used to be stuffed into
a single file named utility.c.  When I split utility.c to create libbb, some of
the very oldest stuff ended up without their original copyright and licensing
information (which is now lost in the mists of time).  If you see something
that you wrote that is mis-attributed, do let me know so we can fix that up.

	Erik Andersen
	<andersen@codepoet.org>