/* dmesg.c -- Print out the contents of the kernel ring buffer
* Created: Sat Oct 9 16:19:47 1993
* Revised: Thu Oct 28 21:52:17 1993 by faith@cs.unc.edu
* Copyright 1993 Theodore Ts'o (tytso@athena.mit.edu)
* This program comes with ABSOLUTELY NO WARRANTY.
* Modifications by Rick Sladkey (jrs@world.std.com)
* Larger buffersize 3 June 1998 by Nicolai Langfeldt, based on a patch
* by Peeter Joot. This was also suggested by John Hudson.
* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
*
*/
#include <linux/unistd.h>
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/klog.h>
#include <ctype.h>
#include "c.h"
#include "nls.h"
#include "strutils.h"
#include "xalloc.h"
/* Close the log. Currently a NOP. */
#define SYSLOG_ACTION_CLOSE 0
/* Open the log. Currently a NOP. */
#define SYSLOG_ACTION_OPEN 1
/* Read from the log. */
#define SYSLOG_ACTION_READ 2
/* Read all messages remaining in the ring buffer. (allowed for non-root) */
#define SYSLOG_ACTION_READ_ALL 3
/* Read and clear all messages remaining in the ring buffer */
#define SYSLOG_ACTION_READ_CLEAR 4
/* Clear ring buffer. */
#define SYSLOG_ACTION_CLEAR 5
/* Disable printk's to console */
#define SYSLOG_ACTION_CONSOLE_OFF 6
/* Enable printk's to console */
#define SYSLOG_ACTION_CONSOLE_ON 7
/* Set level of messages printed to console */
#define SYSLOG_ACTION_CONSOLE_LEVEL 8
/* Return number of unread characters in the log buffer */
#define SYSLOG_ACTION_SIZE_UNREAD 9
/* Return size of the log buffer */
#define SYSLOG_ACTION_SIZE_BUFFER 10
/* dmesg flags */
#define DMESG_FL_RAW (1 << 1)
static void __attribute__((__noreturn__)) usage(FILE *out)
{
fprintf(out, _(
"\nUsage:\n"
" %s [options]\n"), program_invocation_short_name);
fprintf(out, _(
"\nOptions:\n"
" -C, --clear clear the kernel ring buffer\n"
" -c, --read-clear read and clear all messages\n"
" -d, --console-off disable printing messages to console\n"
" -e, --console-on enable printing messages to console\n"
" -h, --help display this help and exit\n"
" -n, --console-level=LEVEL set level of messages printed to console\n"
" -r, --raw print the raw message buffer\n"
" -s, --buffer-size=SIZE buffer size to query the kernel ring buffer\n"
" -V, --version output version information and exit\n\n"));
exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}
static int get_buffer_size()
{
int n = klogctl(SYSLOG_ACTION_SIZE_BUFFER, NULL, 0);
return n > 0 ? n : 0;
}
static int read_buffer(char **buf, size_t bufsize, int clear)
{
size_t sz;
int rc = -1;
int cmd = clear ? SYSLOG_ACTION_READ_CLEAR :
SYSLOG_ACTION_READ_ALL;
if (bufsize) {
sz = bufsize + 8;
*buf = xmalloc(sz * sizeof(char));
rc = klogctl(cmd, *buf, sz);
} else {
sz = 16392;
while (1) {
*buf = xmalloc(sz * sizeof(char));
rc = klogctl(SYSLOG_ACTION_READ_ALL, *buf, sz);
if (rc != sz || sz > (1 << 28))
break;
free(*buf);
*buf = NULL;
sz *= 4;
}
if (rc > 0 && clear)
rc = klogctl(SYSLOG_ACTION_READ_CLEAR, *buf, sz);
}
return rc;
}
static void print_buffer(const char *buf, size_t size, int flags)
{
int lastc = '\n';
int i;
for (i = 0; i < size; i++) {
if (!(flags & DMESG_FL_RAW) &&
(i == 0 || buf[i - 1] == '\n') && buf[i] == '<') {
i++;
while (isdigit(buf[i]))
i++;
if (buf[i] == '>')
i++;
}
lastc = buf[i];
putchar(lastc);
}
if (lastc != '\n')
putchar('\n');
}
int main(int argc, char *argv[])
{
char *buf = NULL;
int bufsize = 0;
int n;
int c;
int console_level = 0;
int cmd = -1;
int flags = 0;
static const struct option longopts[] = {
{ "clear", no_argument, NULL, 'C' },
{ "read-clear", no_argument, NULL, 'c' },
{ "raw", no_argument, NULL, 'r' },
{ "buffer-size", required_argument, NULL, 's' },
{ "console-level", required_argument, NULL, 'n' },
{ "console-off", no_argument, NULL, 'd' },
{ "console-on", no_argument, NULL, 'e' },
{ "version", no_argument, NULL, 'V' },
{ "help", no_argument, NULL, 'h' },
{ NULL, 0, NULL, 0 }
};
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
while ((c = getopt_long(argc, argv, "Ccdehrn:s:V", longopts, NULL)) != -1) {
if (cmd != -1 && strchr("Ccnde", c))
errx(EXIT_FAILURE, "%s %s",
"--{clear,read-clear,console-level,console-on,console-off}",
_("options are mutually exclusive"));
switch (c) {
case 'C':
cmd = SYSLOG_ACTION_CLEAR;
break;
case 'c':
cmd = SYSLOG_ACTION_READ_CLEAR;
break;
case 'd':
cmd = SYSLOG_ACTION_CONSOLE_OFF;
break;
case 'e':
cmd = SYSLOG_ACTION_CONSOLE_ON;
break;
case 'n':
cmd = SYSLOG_ACTION_CONSOLE_LEVEL;
console_level = strtol_or_err(optarg,
_("failed to parse level"));
break;
case 'r':
flags |= DMESG_FL_RAW;
break;
case 's':
bufsize = strtol_or_err(optarg,
_("failed to parse buffer size"));
if (bufsize < 4096)
bufsize = 4096;
break;
case 'V':
printf(_("%s from %s\n"), program_invocation_short_name,
PACKAGE_STRING);
return EXIT_SUCCESS;
case 'h':
usage(stdout);
break;
case '?':
default:
usage(stderr);
}
}
argc -= optind;
argv += optind;
if (argc > 1)
usage(stderr);
if (cmd == -1)
cmd = SYSLOG_ACTION_READ_ALL; /* default */
switch (cmd) {
case SYSLOG_ACTION_READ_ALL:
case SYSLOG_ACTION_READ_CLEAR:
if (!bufsize)
bufsize = get_buffer_size();
n = read_buffer(&buf, bufsize, cmd == SYSLOG_ACTION_READ_CLEAR);
if (n > 0)
print_buffer(buf, n, flags);
free(buf);
break;
case SYSLOG_ACTION_CLEAR:
case SYSLOG_ACTION_CONSOLE_OFF:
case SYSLOG_ACTION_CONSOLE_ON:
n = klogctl(cmd, NULL, 0);
break;
case SYSLOG_ACTION_CONSOLE_LEVEL:
n = klogctl(cmd, NULL, console_level);
break;
default:
errx(EXIT_FAILURE, _("unsupported command"));
break;
}
if (n < 0)
err(EXIT_FAILURE, _("klogctl failed"));
return EXIT_SUCCESS;
}
