6937487be7
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>
125 lines
3.4 KiB
C
125 lines
3.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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*
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* dmesg - display/control kernel ring buffer.
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*
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* Copyright 2006 Rob Landley <rob@landley.net>
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* Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//config:config DMESG
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//config: bool "dmesg (3.7 kb)"
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//config: default y
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//config: select PLATFORM_LINUX
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//config: help
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//config: dmesg is used to examine or control the kernel ring buffer. When the
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//config: Linux kernel prints messages to the system log, they are stored in
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//config: the kernel ring buffer. You can use dmesg to print the kernel's ring
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//config: buffer, clear the kernel ring buffer, change the size of the kernel
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//config: ring buffer, and change the priority level at which kernel messages
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//config: are also logged to the system console. Enable this option if you
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//config: wish to enable the 'dmesg' utility.
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//config:
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//config:config FEATURE_DMESG_PRETTY
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//config: bool "Pretty output"
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//config: default y
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//config: depends on DMESG
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//config: help
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//config: If you wish to scrub the syslog level from the output, say 'Y' here.
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//config: The syslog level is a string prefixed to every line with the form
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//config: "<#>".
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//config:
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//config: With this option you will see:
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//config: # dmesg
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//config: Linux version 2.6.17.4 .....
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//config: BIOS-provided physical RAM map:
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//config: BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
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//config:
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//config: Without this option you will see:
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//config: # dmesg
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//config: <5>Linux version 2.6.17.4 .....
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//config: <6>BIOS-provided physical RAM map:
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//config: <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
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//applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_DMESG) += dmesg.o
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//usage:#define dmesg_trivial_usage
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//usage: "[-c] [-n LEVEL] [-s SIZE]"
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//usage:#define dmesg_full_usage "\n\n"
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//usage: "Print or control the kernel ring buffer\n"
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//usage: "\n -c Clear ring buffer after printing"
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//usage: "\n -n LEVEL Set console logging level"
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//usage: "\n -s SIZE Buffer size"
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//usage: "\n -r Print raw message buffer"
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#include <sys/klog.h>
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#include "libbb.h"
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int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int dmesg_main(int argc UNUSED_PARAM, char **argv)
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{
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int len, level;
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char *buf;
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unsigned opts;
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enum {
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OPT_c = 1 << 0,
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OPT_s = 1 << 1,
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OPT_n = 1 << 2,
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OPT_r = 1 << 3
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};
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opts = getopt32(argv, "cs:+n:+r", &len, &level);
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if (opts & OPT_n) {
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if (klogctl(8, NULL, (long) level))
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bb_simple_perror_msg_and_die("klogctl");
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return EXIT_SUCCESS;
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}
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if (!(opts & OPT_s))
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len = klogctl(10, NULL, 0); /* read ring buffer size */
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if (len < 16*1024)
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len = 16*1024;
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if (len > 16*1024*1024)
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len = 16*1024*1024;
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buf = xmalloc(len);
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len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
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if (len < 0)
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bb_simple_perror_msg_and_die("klogctl");
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if (len == 0)
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return EXIT_SUCCESS;
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if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
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int last = '\n';
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int in = 0;
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/* Skip <[0-9]+> at the start of lines */
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while (1) {
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if (last == '\n' && buf[in] == '<') {
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while (buf[in++] != '>' && in < len)
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;
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} else {
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last = buf[in++];
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putchar(last);
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}
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if (in >= len)
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break;
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}
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/* Make sure we end with a newline */
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if (last != '\n')
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bb_putchar('\n');
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} else {
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full_write(STDOUT_FILENO, buf, len);
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if (buf[len-1] != '\n')
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bb_putchar('\n');
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}
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if (ENABLE_FEATURE_CLEAN_UP) free(buf);
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return EXIT_SUCCESS;
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}
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