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dmesg.8
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dmesg.c
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Editing: dmesg.c
/*- * SPDX-License-Identifier: BSD-3-Clause * * 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. 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 <ctype.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 <stdbool.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <vis.h> #include <sys/syslog.h> static struct nlist nl[] = { #define X_MSGBUF 0 { "_msgbufp", 0, 0, 0, 0 }, { NULL, 0, 0, 0, 0 }, }; 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 ch, clear; bool all; all = false; clear = false; (void) setlocale(LC_CTYPE, ""); memf = nlistf = NULL; while ((ch = getopt(argc, argv, "acM:N:")) != -1) switch(ch) { case 'a': all = true; break; case 'c': clear = true; break; case 'M': memf = optarg; break; case 'N': nlistf = optarg; break; case '?': default: usage(); } argc -= optind; if (argc != 0) usage(); if (memf == NULL) { /* * Running kernel. Use sysctl. This gives an unwrapped buffer * as a side effect. Remove nulterm (if present) so the value * returned by sysctl is formatted as the rest of the code * expects (the same as the value read from a core file below). */ if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) err(1, "sysctl kern.msgbuf"); /* Allocate extra room for growth between the sysctl calls. */ buflen += buflen/8; /* Allocate more than sysctl sees, for room to append \n\0. */ if ((bp = malloc(buflen + 2)) == NULL) errx(1, "malloc failed"); if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) err(1, "sysctl kern.msgbuf"); if (buflen > 0 && bp[buflen - 1] == '\0') buflen--; if (clear) if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int))) err(1, "sysctl kern.msgbuf_clear"); } 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) != (ssize_t)(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) != (ssize_t)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); p++; } for (; p < ep; p = nextp) { nextp = memchr(p, '\n', ep - p); nextp++; /* Skip ^<[0-9]+> syslog sequences. */ if (*p == '<' && isdigit(*(p+1))) { 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) { fprintf(stderr, "usage: dmesg [-ac] [-M core [-N system]]\n"); exit(1); }
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