1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #ifndef lint 9 char copyright[] = 10 "@(#) Copyright (c) 1991 The Regents of the University of California.\n\ 11 All rights reserved.\n"; 12 #endif /* not lint */ 13 14 #ifndef lint 15 static char sccsid[] = "@(#)dmesg.c 5.16 (Berkeley) 04/30/93"; 16 #endif /* not lint */ 17 18 #include <sys/cdefs.h> 19 #include <sys/msgbuf.h> 20 21 #include <fcntl.h> 22 #include <kvm.h> 23 #include <limits.h> 24 #include <nlist.h> 25 #include <stdio.h> 26 #include <stdlib.h> 27 #include <time.h> 28 #include <unistd.h> 29 #include <vis.h> 30 31 struct nlist nl[] = { 32 #define X_MSGBUF 0 33 { "_msgbufp" }, 34 { NULL }, 35 }; 36 37 void usage __P((void)); 38 39 #define KREAD(addr, var) \ 40 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 41 42 int 43 main(argc, argv) 44 int argc; 45 char *argv[]; 46 { 47 register int ch, newl, skip; 48 register char *p, *ep; 49 struct msgbuf *bufp, cur; 50 char *memf, *nlistf; 51 kvm_t *kd; 52 char buf[5]; 53 54 memf = nlistf = NULL; 55 while ((ch = getopt(argc, argv, "M:N:")) != EOF) 56 switch(ch) { 57 case 'M': 58 memf = optarg; 59 break; 60 case 'N': 61 nlistf = optarg; 62 break; 63 case '?': 64 default: 65 usage(); 66 } 67 argc -= optind; 68 argv += optind; 69 70 /* 71 * Discard setgid privileges if not the running kernel so that bad 72 * guys can't print interesting stuff from kernel memory. 73 */ 74 if (memf != NULL || nlistf != NULL) 75 setgid(getgid()); 76 77 /* Read in kernel message buffer, do sanity checks. */ 78 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == NULL) 79 exit (1); 80 if (kvm_nlist(kd, nl) == -1) 81 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 82 if (nl[X_MSGBUF].n_type == 0) 83 errx(1, "%s: msgbufp not found", nlistf ? nlistf : "namelist"); 84 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 85 errx(1, "kvm_read: %s", kvm_geterr(kd)); 86 kvm_close(kd); 87 if (cur.msg_magic != MSG_MAGIC) 88 errx(1, "magic number incorrect"); 89 if (cur.msg_bufx >= MSG_BSIZE) 90 cur.msg_bufx = 0; 91 92 /* 93 * The message buffer is circular; start at the read pointer, and 94 * go to the write pointer - 1. 95 */ 96 p = cur.msg_bufc + cur.msg_bufx; 97 ep = cur.msg_bufc + cur.msg_bufx - 1; 98 for (newl = skip = 0; p != ep; ++p) { 99 if (p == cur.msg_bufc + MSG_BSIZE) 100 p = cur.msg_bufc; 101 ch = *p; 102 /* Skip "\n<.*>" syslog sequences. */ 103 if (skip) { 104 if (ch == '>') 105 newl = skip = 0; 106 continue; 107 } 108 if (newl && ch == '<') { 109 skip = 1; 110 continue; 111 } 112 if (ch == '\0') 113 continue; 114 newl = ch == '\n'; 115 (void)vis(buf, ch, 0, 0); 116 if (buf[1] == 0) 117 (void)putchar(buf[0]); 118 else 119 (void)printf("%s", buf); 120 } 121 if (!newl) 122 (void)putchar('\n'); 123 exit(0); 124 } 125 126 void 127 usage() 128 { 129 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 130 exit(1); 131 } 132