freebsd-dev/sbin/dmesg/dmesg.c
Ian Dowse ccdb237094 Further simplify the code for printing the message buffer:
- Ensure that the buffer ends with "\n\0" to avoid special cases
   and allow the use of strtol().
 - Use strvisx() on each complete line instead of character by
   character.

Submitted by:	bde
MFC after:	1 week
2004-02-08 23:08:53 +00:00

202 lines
5.7 KiB
C

/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
*/
#if 0
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1991, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static const char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/msgbuf.h>
#include <sys/sysctl.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <locale.h>
#include <nlist.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vis.h>
#include <sys/syslog.h>
struct nlist nl[] = {
#define X_MSGBUF 0
{ "_msgbufp" },
{ NULL },
};
void usage(void) __dead2;
#define KREAD(addr, var) \
kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
int
main(int argc, char *argv[])
{
struct msgbuf *bufp, cur;
char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp;
kvm_t *kd;
size_t buflen, bufpos;
long pri;
int all, ch;
all = 0;
(void) setlocale(LC_CTYPE, "");
memf = nlistf = NULL;
while ((ch = getopt(argc, argv, "aM:N:")) != -1)
switch(ch) {
case 'a':
all++;
break;
case 'M':
memf = optarg;
break;
case 'N':
nlistf = optarg;
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
if (memf == NULL && nlistf == NULL) {
/*
* Running kernel. Use sysctl. This gives an unwrapped
* buffer as a side effect.
*/
if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
err(1, "sysctl kern.msgbuf");
if ((bp = malloc(buflen + 2)) == NULL)
errx(1, "malloc failed");
if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
err(1, "sysctl kern.msgbuf");
} else {
/* Read in kernel message buffer and do sanity checks. */
kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
if (kd == 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) || KREAD((long)bufp, cur))
errx(1, "kvm_read: %s", kvm_geterr(kd));
if (cur.msg_magic != MSG_MAGIC)
errx(1, "kernel message buffer has different magic "
"number");
if ((bp = malloc(cur.msg_size + 2)) == NULL)
errx(1, "malloc failed");
/* Unwrap the circular buffer to start from the oldest data. */
bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq);
if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp,
cur.msg_size - bufpos) != cur.msg_size - bufpos)
errx(1, "kvm_read: %s", kvm_geterr(kd));
if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr,
&bp[cur.msg_size - bufpos], bufpos) != bufpos)
errx(1, "kvm_read: %s", kvm_geterr(kd));
kvm_close(kd);
buflen = cur.msg_size;
}
/*
* Ensure that the buffer ends with a newline and a \0 to avoid
* complications below. We left space above.
*/
if (buflen == 0 || bp[buflen - 1] != '\n')
bp[buflen++] = '\n';
bp[buflen] = '\0';
if ((visbp = malloc(4 * buflen + 1)) == NULL)
errx(1, "malloc failed");
/*
* The message buffer is circular, but has been unwrapped so that
* the oldest data comes first. The data will be preceded by \0's
* if the message buffer was not full.
*/
p = bp;
ep = &bp[buflen];
if (*p == '\0') {
/* Strip leading \0's */
while (*p == '\0')
p++;
} else if (!all) {
/* Skip the first line, since it is probably incomplete. */
p = memchr(p, '\n', ep - p) + 1;
}
for (; p < ep; p = nextp) {
nextp = memchr(p, '\n', ep - p) + 1;
/* Skip ^<[0-9]+> syslog sequences. */
if (*p == '<') {
errno = 0;
pri = strtol(p + 1, &q, 10);
if (*q == '>' && pri >= 0 && pri < INT_MAX &&
errno == 0) {
if (LOG_FAC(pri) != LOG_KERN && !all)
continue;
p = q + 1;
}
}
(void)strvisx(visbp, p, nextp - p, 0);
(void)printf("%s", visbp);
}
exit(0);
}
void
usage(void)
{
(void)fprintf(stderr, "usage: dmesg [-a] [-M core] [-N system]\n");
exit(1);
}