NetBSD/sbin/dmesg/dmesg.c

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/* $NetBSD: dmesg.c,v 1.15 1997/09/20 09:48:35 enami Exp $ */
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/*-
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* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
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*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
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#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1991, 1993\n\
The Regents of the University of California. All rights reserved.\n");
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#endif /* not lint */
#ifndef lint
#if 0
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static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93";
#else
__RCSID("$NetBSD: dmesg.c,v 1.15 1997/09/20 09:48:35 enami Exp $");
#endif
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#endif /* not lint */
#include <sys/msgbuf.h>
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#include <err.h>
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#include <fcntl.h>
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#include <kvm.h>
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#include <limits.h>
#include <nlist.h>
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#include <stdio.h>
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#include <stdlib.h>
#include <time.h>
#include <unistd.h>
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#include <vis.h>
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struct nlist nl[] = {
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#define X_MSGBUF 0
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{ "_msgbufp" },
{ NULL },
};
int main __P((int, char *[]));
void usage __P((void));
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#define KREAD(addr, var) \
kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
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int
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main(argc, argv)
int argc;
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char *argv[];
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{
int ch, newl, skip, i;
char *p;
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struct kern_msgbuf *bufp, cur;
char *memf, *nlistf, *bufdata;
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kvm_t *kd;
char buf[5];
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memf = nlistf = NULL;
while ((ch = getopt(argc, argv, "M:N:")) != -1)
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switch(ch) {
case 'M':
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memf = optarg;
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break;
case 'N':
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nlistf = optarg;
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break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
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/*
* Discard setgid privileges if not the running kernel so that bad
* guys can't print interesting stuff from kernel memory.
*/
if (memf != NULL || nlistf != NULL)
setgid(getgid());
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/* Read in message buffer header and data, and do sanity checks. */
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if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == NULL)
exit (1);
if (kvm_nlist(kd, nl) == -1)
errx(1, "kvm_nlist: %s", kvm_geterr(kd));
if (nl[X_MSGBUF].n_type == 0)
errx(1, "%s: msgbufp not found", nlistf ? nlistf : "namelist");
if (KREAD(nl[X_MSGBUF].n_value, bufp))
errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
nl[X_MSGBUF].n_value);
if (KREAD((long)bufp, cur))
errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd),
(unsigned long)bufp);
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if (cur.msg_magic != MSG_MAGIC)
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errx(1, "magic number incorrect");
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bufdata = malloc(cur.msg_bufs);
if (bufdata == NULL)
errx(1, "couldn't allocate space for buffer data");
if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata,
cur.msg_bufs) != cur.msg_bufs)
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errx(1, "kvm_read: %s", kvm_geterr(kd));
kvm_close(kd);
if (cur.msg_bufx >= cur.msg_bufs)
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cur.msg_bufx = 0;
/*
* The message buffer is circular; start at the write pointer
* (which points the oldest character), and go to the write
* pointer - 1 (which points the newest character). I.e, loop
* over cur.msg_bufs times. Unused area is skipped since it
* contains nul.
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*/
for (newl = skip = i = 0, p = bufdata + cur.msg_bufx;
i < cur.msg_bufs; i++, p++) {
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if (p == bufdata + cur.msg_bufs)
p = bufdata;
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ch = *p;
/* Skip "\n<.*>" syslog sequences. */
if (skip) {
if (ch == '>')
newl = skip = 0;
continue;
}
if (newl && ch == '<') {
skip = 1;
continue;
}
if (ch == '\0')
continue;
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newl = ch == '\n';
(void)vis(buf, ch, 0, 0);
if (buf[1] == 0)
(void)putchar(buf[0]);
else
(void)printf("%s", buf);
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}
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if (!newl)
(void)putchar('\n');
exit(0);
}
void
usage()
{
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(void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n");
exit(1);
}