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Further simplify the code for printing the message buffer:

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- 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
This commit is contained in:
Ian Dowse 2004-02-08 23:08:53 +00:00
parent dc894e1a6c
commit ccdb237094
1 changed files with 36 additions and 33 deletions
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69
sbin/dmesg/dmesg.c
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@ -50,8 +50,10 @@ __FBSDID("$FreeBSD$");
#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>
@ -76,11 +78,11 @@ int
main(int argc, char *argv[])
{
struct msgbuf *bufp, cur;
char *bp, *ep, *memf, *nextp, *nlistf, *p, *q;
char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp;
kvm_t *kd;
size_t buflen, bufpos;
int all, ch, pri;
char buf[5];
long pri;
int all, ch;
all = 0;
(void) setlocale(LC_CTYPE, "");
@ -104,15 +106,18 @@ main(int argc, char *argv[])
argv += optind;
if (memf == NULL && nlistf == NULL) {
/* Running kernel. Use sysctl to get an unwrapped buffer. */
/*
* 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)) == NULL)
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, do sanity checks. */
/* Read in kernel message buffer and do sanity checks. */
kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
if (kd == NULL)
exit (1);
@ -126,9 +131,9 @@ main(int argc, char *argv[])
if (cur.msg_magic != MSG_MAGIC)
errx(1, "kernel message buffer has different magic "
"number");
bp = malloc(cur.msg_size);
if (!bp)
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,
@ -141,6 +146,17 @@ main(int argc, char *argv[])
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
@ -150,42 +166,29 @@ main(int argc, char *argv[])
ep = &bp[buflen];
if (*p == '\0') {
/* Strip leading \0's */
while (p != ep && *p == '\0')
while (*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
p++;
p = memchr(p, '\n', ep - p) + 1;
}
for (; p != ep; p = nextp) {
nextp = memchr(p, '\n', ep - p);
if (nextp == NULL)
nextp = ep;
else
nextp++;
for (; p < ep; p = nextp) {
nextp = memchr(p, '\n', ep - p) + 1;
/* 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) {
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;
}
}
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');
(void)strvisx(visbp, p, nextp - p, 0);
(void)printf("%s", visbp);
}
exit(0);
}