d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Don't print the oldest line in the message buffer if the buffer is

Browse Source 
full, since that line is almost always incomplete. Make the parsing
of <%d> lines more strict.

Also simplify the logic a little:
 - Start off by making the buffer linear so that we don't have to
   deal with it wrapping around (suggested by bde).
 - Process line by line rather than byte at a time.
This commit is contained in:
Ian Dowse 2004-02-05 21:07:50 +00:00
parent 4c3558aa82
commit 59f256ec35
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=125497
1 changed files with 56 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
sbin/dmesg/dmesg.c
View File

@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
#include <nlist.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vis.h>
#include <sys/syslog.h>
@ -74,16 +75,14 @@ void usage(void) __dead2;
int
main(int argc, char *argv[])
{
int ch, newl, skip;
char *p, *ep;
struct msgbuf *bufp, cur;
char *bp, *memf, *nlistf;
char *bp, *ep, *memf, *nextp, *nlistf, *p, *q;
kvm_t *kd;
char buf[5];
int all = 0;
int pri;
size_t buflen, bufpos;
int all, ch, pri;
char buf[5];
all = 0;
(void) setlocale(LC_CTYPE, "");
memf = nlistf = NULL;
while ((ch = getopt(argc, argv, "aM:N:")) != -1)
@ -105,15 +104,13 @@ main(int argc, char *argv[])
argv += optind;
if (memf == NULL && nlistf == NULL) {
/* Running kernel. Use sysctl. */
/* Running kernel. Use sysctl to get an unwrapped buffer. */
if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
err(1, "sysctl kern.msgbuf");
if ((bp = malloc(buflen)) == NULL)
errx(1, "malloc failed");
if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
err(1, "sysctl kern.msgbuf");
/* We get a dewrapped buffer using sysctl. */
bufpos = 0;
} else {
/* Read in kernel message buffer, do sanity checks. */
kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
@ -132,58 +129,64 @@ main(int argc, char *argv[])
bp = malloc(cur.msg_size);
if (!bp)
errx(1, "malloc failed");
if (kvm_read(kd, (long)cur.msg_ptr, bp, cur.msg_size) !=
cur.msg_size)
/* 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;
bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq);
}
/*
* The message buffer is circular. If the buffer has wrapped, the
* write pointer points to the oldest data. Otherwise, the write
* pointer points to \0's following the data. Read the entire
* buffer starting at the write pointer and ignore nulls so that
* we effectively start at the oldest data.
* 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 + bufpos;
ep = (bufpos == 0 ? bp + buflen : p);
newl = skip = 0;
do {
if (p == bp + buflen)
p = bp;
ch = *p;
/* Skip "\n<.*>" syslog sequences. */
if (skip) {
if (ch == '\n') {
skip = 0;
newl = 1;
} if (ch == '>') {
if (LOG_FAC(pri) == LOG_KERN || all)
newl = skip = 0;
} else if (ch >= '0' && ch <= '9') {
pri *= 10;
pri += ch - '0';
}
continue;
}
if (newl && ch == '<') {
pri = 0;
skip = 1;
continue;
}
if (ch == '\0')
continue;
newl = ch == '\n';
(void)vis(buf, ch, 0, 0);
if (buf[1] == 0)
(void)putchar(buf[0]);
p = bp;
ep = &bp[buflen];
if (*p == '\0') {
/* Strip leading \0's */
while (p != ep && *p == '\0')
p++;
} else if (!all) {
/* Skip the first line, since it is probably incomplete. */
p = memchr(p, '\n', ep - p);
if (p == NULL)
p = ep;
else
(void)printf("%s", buf);
} while (++p != ep);
if (!newl)
(void)putchar('\n');
p++;
}
for (; p != ep; p = nextp) {
nextp = memchr(p, '\n', ep - p);
if (nextp == NULL)
nextp = ep;
else
nextp++;
/* Skip ^<[0-9]+> syslog sequences. */
if (*p == '<') {
pri = 0;
for (q = p + 1; q != ep && *q >= '0' && *q <= '9'; q++)
pri = pri * 10 + (*q - '0');
if (q != ep && *q == '>' && q != p + 1) {
if (LOG_FAC(pri) != LOG_KERN && !all)
continue;
p = q + 1;
}
}
for (; p != nextp; p++) {
(void)vis(buf, *p, 0, 0);
if (buf[1] == 0)
(void)putchar(buf[0]);
else
(void)printf("%s", buf);
}
if (nextp == ep && ep[-1] != '\n')
(void)putchar('\n');
}
exit(0);
}