busybox/util-linux/dmesg.c

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/* vi: set sw=4 ts=4: */
/*
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*
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* dmesg - display/control kernel ring buffer.
*
* Copyright 2006 Rob Landley <rob@landley.net>
* Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
//usage:#define dmesg_trivial_usage
//usage: "[-c] [-n LEVEL] [-s SIZE]"
//usage:#define dmesg_full_usage "\n\n"
//usage: "Print or control the kernel ring buffer\n"
//usage: "\n -c Clear ring buffer after printing"
//usage: "\n -n LEVEL Set console logging level"
//usage: "\n -s SIZE Buffer size"
//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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{
int len, level;
char *buf;
unsigned opts;
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enum {
OPT_c = 1 << 0,
OPT_s = 1 << 1,
OPT_n = 1 << 2,
OPT_r = 1 << 3
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};
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opt_complementary = "s+:n+"; /* numeric */
opts = getopt32(argv, "cs:n:r", &len, &level);
if (opts & OPT_n) {
if (klogctl(8, NULL, (long) level))
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bb_perror_msg_and_die("klogctl");
return EXIT_SUCCESS;
}
if (!(opts & OPT_s))
len = klogctl(10, NULL, 0); /* read ring buffer size */
if (len < 16*1024)
len = 16*1024;
if (len > 16*1024*1024)
len = 16*1024*1024;
buf = xmalloc(len);
len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
if (len < 0)
bb_perror_msg_and_die("klogctl");
if (len == 0)
return EXIT_SUCCESS;
if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
int last = '\n';
int in = 0;
/* Skip <[0-9]+> at the start of lines */
while (1) {
if (last == '\n' && buf[in] == '<') {
while (buf[in++] != '>' && in < len)
;
} else {
last = buf[in++];
putchar(last);
}
if (in >= len)
break;
}
/* Make sure we end with a newline */
if (last != '\n')
bb_putchar('\n');
} else {
full_write(STDOUT_FILENO, buf, len);
if (buf[len-1] != '\n')
bb_putchar('\n');
}
if (ENABLE_FEATURE_CLEAN_UP) free(buf);
return EXIT_SUCCESS;
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}