/*
* Peek at the full contents of a message buffer without marking any
* data as read. `seqp' should point to an unsigned integer that
* msgbuf_peekbytes() can use to retain state between calls so that
* the whole message buffer can be read in multiple short reads.
* To initialise this variable to the start of the message buffer,
* call msgbuf_peekbytes() with a NULL `buf' parameter.
*
* Returns the number of characters that were placed in `buf'.
*/
int
msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp)
{
u_int len, pos, wseq;
mtx_lock_spin(&mbp->msg_lock);
if (buf == NULL) {
/* Just initialise *seqp. */
*seqp = MSGBUF_SEQNORM(mbp, mbp->msg_wseq - mbp->msg_size);
mtx_unlock_spin(&mbp->msg_lock);
return (0);
}
wseq = mbp->msg_wseq;
len = MSGBUF_SEQSUB(mbp, wseq, *seqp);
if (len == 0) {
mtx_unlock_spin(&mbp->msg_lock);
return (0);
}
if (len > mbp->msg_size) {
*seqp = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
len = mbp->msg_size;
}
pos = MSGBUF_SEQ_TO_POS(mbp, *seqp);
len = min(len, mbp->msg_size - pos);
len = min(len, (u_int)buflen);
bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len);
*seqp = MSGBUF_SEQNORM(mbp, *seqp + len);
mtx_unlock_spin(&mbp->msg_lock);
return (len);
}
/*
* Read and mark as read a number of characters from a message buffer.
* Returns the number of characters that were placed in `buf'.
*/
int
msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen)
{
u_int len, pos, wseq;
mtx_lock_spin(&mbp->msg_lock);
wseq = mbp->msg_wseq;
len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
if (len == 0) {
mtx_unlock_spin(&mbp->msg_lock);
return (0);
}
if (len > mbp->msg_size) {
mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
len = mbp->msg_size;
}
pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq);
len = min(len, mbp->msg_size - pos);
len = min(len, (u_int)buflen);
bcopy(&mbp->msg_ptr[pos], buf, len);
mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + len);
mtx_unlock_spin(&mbp->msg_lock);
return (len);
}
static void
msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, const int c)
{
u_int pos;
/* Make sure we properly wrap the sequence number. */
pos = MSGBUF_SEQ_TO_POS(mbp, *seq);
mbp->msg_cksum += (u_int)(u_char)c -
(u_int)(u_char)mbp->msg_ptr[pos];
mbp->msg_ptr[pos] = c;
*seq = MSGBUF_SEQNORM(mbp, *seq + 1);
}
/*
* Append a character to a message buffer. This function can be
* considered fully reentrant so long as the number of concurrent
* callers is less than the number of characters in the buffer.
* However, the message buffer is only guaranteed to be consistent
* for reading when there are no callers in this function.
*/
void
msgbuf_addchar(struct msgbuf *mbp, int c)
{
u_int new_seq, pos, seq;
do {
seq = mbp->msg_wseq;
new_seq = MSGBUF_SEQNORM(mbp, seq + 1);
} while (atomic_cmpset_rel_int(&mbp->msg_wseq, seq, new_seq) == 0);
pos = MSGBUF_SEQ_TO_POS(mbp, seq);
atomic_add_int(&mbp->msg_cksum, (u_int)(u_char)c -
(u_int)(u_char)mbp->msg_ptr[pos]);
mbp->msg_ptr[pos] = c;
}
void
kgdb_dmesg(void)
{
CORE_ADDR bufp;
int size, rseq, wseq;
char c;
/*
* Display the unread portion of the message buffer. This gives the
* user a some initial data to work from.
*/
if (quiet)
return;
bufp = kgdb_parse("msgbufp->msg_ptr");
size = (int)kgdb_parse("msgbufp->msg_size");
if (bufp == 0 || size == 0)
return;
rseq = (int)kgdb_parse("msgbufp->msg_rseq");
wseq = (int)kgdb_parse("msgbufp->msg_wseq");
rseq = MSGBUF_SEQ_TO_POS(size, rseq);
wseq = MSGBUF_SEQ_TO_POS(size, wseq);
if (rseq == wseq)
return;
printf("\nUnread portion of the kernel message buffer:\n");
while (rseq < wseq) {
read_memory(bufp + rseq, &c, 1);
putchar(c);
rseq++;
if (rseq == size)
rseq = 0;
}
if (c != '\n')
putchar('\n');
putchar('\n');
}
/*
* Read and mark as read a character from a message buffer.
* Returns the character, or -1 if no characters are available.
*/
int
msgbuf_getchar(struct msgbuf *mbp)
{
u_int len, wseq;
int c;
wseq = mbp->msg_wseq;
len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
if (len == 0)
return (-1);
if (len > mbp->msg_size)
mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)];
mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + 1);
return (c);
}
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.
*/
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");
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);
}
