busybox/console-tools/loadkmap.c
James Byrne 6937487be7 libbb: reduce the overhead of single parameter bb_error_msg() calls
Back in 2007, commit 0c97c9d437 ("'simple' error message functions by
Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower
overhead call to bb_perror_msg() when only a string was being printed
with no parameters. This saves space for some CPU architectures because
it avoids the overhead of a call to a variadic function. However there
has never been a simple version of bb_error_msg(), and since 2007 many
new calls to bb_perror_msg() have been added that only take a single
parameter and so could have been using bb_simple_perror_message().

This changeset introduces 'simple' versions of bb_info_msg(),
bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and
bb_herror_msg_and_die(), and replaces all calls that only take a
single parameter, or use something like ("%s", arg), with calls to the
corresponding 'simple' version.

Since it is likely that single parameter calls to the variadic functions
may be accidentally reintroduced in the future a new debugging config
option WARN_SIMPLE_MSG has been introduced. This uses some macro magic
which will cause any such calls to generate a warning, but this is
turned off by default to avoid use of the unpleasant macros in normal
circumstances.

This is a large changeset due to the number of calls that have been
replaced. The only files that contain changes other than simple
substitution of function calls are libbb.h, libbb/herror_msg.c,
libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c,
networking/udhcp/common.h and util-linux/mdev.c additonal macros have
been added for logging so that single parameter and multiple parameter
logging variants exist.

The amount of space saved varies considerably by architecture, and was
found to be as follows (for 'defconfig' using GCC 7.4):

Arm:     -92 bytes
MIPS:    -52 bytes
PPC:   -1836 bytes
x86_64: -938 bytes

Note that for the MIPS architecture only an exception had to be made
disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h)
because it made these files larger on MIPS.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 11:35:03 +02:00

104 lines
2.8 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini loadkmap implementation for busybox
*
* Copyright (C) 1998 Enrique Zanardi <ezanardi@ull.es>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config LOADKMAP
//config: bool "loadkmap (1.8 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: This program loads a keyboard translation table from
//config: standard input.
//applet:IF_LOADKMAP(APPLET_NOEXEC(loadkmap, loadkmap, BB_DIR_SBIN, BB_SUID_DROP, loadkmap))
//kbuild:lib-$(CONFIG_LOADKMAP) += loadkmap.o
//usage:#define loadkmap_trivial_usage
//usage: "< keymap"
//usage:#define loadkmap_full_usage "\n\n"
//usage: "Load a binary keyboard translation table from stdin"
////usage: "\n"
////usage: "\n -C TTY Affect TTY instead of /dev/tty"
//usage:
//usage:#define loadkmap_example_usage
//usage: "$ loadkmap < /etc/i18n/lang-keymap\n"
#include "libbb.h"
#define BINARY_KEYMAP_MAGIC "bkeymap"
/* From <linux/kd.h> */
struct kbentry {
unsigned char kb_table;
unsigned char kb_index;
unsigned short kb_value;
};
/* sets one entry in translation table */
#define KDSKBENT 0x4B47
/* From <linux/keyboard.h> */
#define NR_KEYS 128
#define MAX_NR_KEYMAPS 256
int loadkmap_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int loadkmap_main(int argc UNUSED_PARAM, char **argv)
{
struct kbentry ke;
int i, j, fd;
uint16_t ibuff[NR_KEYS];
/* const char *tty_name = CURRENT_TTY; */
RESERVE_CONFIG_BUFFER(flags, MAX_NR_KEYMAPS);
/* When user accidentally runs "loadkmap FILE"
* instead of "loadkmap <FILE", we end up waiting for input from tty.
* Let's prevent it: */
if (argv[1])
bb_show_usage();
/* bb_warn_ignoring_args(argv[1]); */
fd = get_console_fd_or_die();
/* or maybe:
opt = getopt32(argv, "C:", &tty_name);
fd = xopen_nonblocking(tty_name);
*/
xread(STDIN_FILENO, flags, 7);
if (!is_prefixed_with(flags, BINARY_KEYMAP_MAGIC))
bb_simple_error_msg_and_die("not a valid binary keymap");
xread(STDIN_FILENO, flags, MAX_NR_KEYMAPS);
for (i = 0; i < MAX_NR_KEYMAPS; i++) {
if (flags[i] != 1)
continue;
xread(STDIN_FILENO, ibuff, NR_KEYS * sizeof(uint16_t));
for (j = 0; j < NR_KEYS; j++) {
ke.kb_index = j;
ke.kb_table = i;
ke.kb_value = ibuff[j];
/*
* Note: table[idx:0] can contain special value
* K_ALLOCATED (marks allocated tables in kernel).
* dumpkmap saves the value as-is; but attempts
* to load it here fail, since it isn't a valid
* key value: it is K(KT_SPEC,126) == 2<<8 + 126,
* whereas last valid KT_SPEC is
* K_BARENUMLOCK == K(KT_SPEC,19).
* So far we just ignore these errors:
*/
ioctl(fd, KDSKBENT, &ke);
}
}
if (ENABLE_FEATURE_CLEAN_UP) {
close(fd);
RELEASE_CONFIG_BUFFER(flags);
}
return EXIT_SUCCESS;
}