/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2003 Ian Dowse. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
/*
* Generic message buffer support routines.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/mutex.h>
#include <sys/msgbuf.h>
#include <sys/sysctl.h>
/*
* Maximum number conversion buffer length: uintmax_t in base 2, plus <>
* around the priority, and a terminating NUL.
*/
#define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3)
/* Read/write sequence numbers are modulo a multiple of the buffer size. */
#define SEQMOD(size) ((size) * 16)
static u_int msgbuf_cksum(struct msgbuf *mbp);
/*
* Timestamps in msgbuf are useful when trying to diagnose when core dumps
* or other actions occurred.
*/
static int msgbuf_show_timestamp = 0;
SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RWTUN,
&msgbuf_show_timestamp, 0, "Show timestamp in msgbuf");
/*
* Initialize a message buffer of the specified size at the specified
* location. This also zeros the buffer area.
*/
void
msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
{
mbp->msg_ptr = ptr;
mbp->msg_size = size;
mbp->msg_seqmod = SEQMOD(size);
msgbuf_clear(mbp);
mbp->msg_magic = MSG_MAGIC;
mbp->msg_lastpri = -1;
mbp->msg_flags = 0;
bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
}
/*
* Reinitialize a message buffer, retaining its previous contents if
* the size and checksum are correct. If the old contents cannot be
* recovered, the message buffer is cleared.
*/
void
msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
{
u_int cksum;
if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) {
msgbuf_init(mbp, ptr, size);
return;
}
mbp->msg_seqmod = SEQMOD(size);
mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq);
mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq);
mbp->msg_ptr = ptr;
cksum = msgbuf_cksum(mbp);
if (cksum != mbp->msg_cksum) {
if (bootverbose) {
printf("msgbuf cksum mismatch (read %x, calc %x)\n",
mbp->msg_cksum, cksum);
printf("Old msgbuf not recovered\n");
}
msgbuf_clear(mbp);
}
mbp->msg_lastpri = -1;
/* Assume that the old message buffer didn't end in a newline. */
mbp->msg_flags |= MSGBUF_NEEDNL;
bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
}
/*
* Clear the message buffer.
*/
void
msgbuf_clear(struct msgbuf *mbp)
{
bzero(mbp->msg_ptr, mbp->msg_size);
mbp->msg_wseq = 0;
mbp->msg_rseq = 0;
mbp->msg_cksum = 0;
}
/*
* Get a count of the number of unread characters in the message buffer.
*/
int
msgbuf_getcount(struct msgbuf *mbp)
{
u_int len;
len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq);
if (len > mbp->msg_size)
len = mbp->msg_size;
return (len);
}
/*
* Add a character into the message buffer, and update the checksum and
* sequence number.
*
* The caller should hold the message buffer spinlock.
*/
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.
*/
void
msgbuf_addchar(struct msgbuf *mbp, int c)
{
mtx_lock_spin(&mbp->msg_lock);
msgbuf_do_addchar(mbp, &mbp->msg_wseq, c);
mtx_unlock_spin(&mbp->msg_lock);
}
/*
* Append a NUL-terminated string with a priority to a message buffer.
* Filter carriage returns if the caller requests it.
*
* XXX The carriage return filtering behavior is present in the
* msglogchar() API, however testing has shown that we don't seem to send
* carriage returns down this path. So do we still need it?
*/
void
msgbuf_addstr(struct msgbuf *mbp, int pri, const char *str, int filter_cr)
{
u_int seq;
size_t len, prefix_len;
char prefix[MAXPRIBUF];
char buf[32];
int i, j, needtime;
len = strlen(str);
prefix_len = 0;
/* If we have a zero-length string, no need to do anything. */
if (len == 0)
return;
mtx_lock_spin(&mbp->msg_lock);
/*
* If this is true, we may need to insert a new priority sequence,
* so prepare the prefix.
*/
if (pri != -1)
prefix_len = sprintf(prefix, "<%d>", pri);
/*
* Starting write sequence number.
*/
seq = mbp->msg_wseq;
/*
* Whenever there is a change in priority, we have to insert a
* newline, and a priority prefix if the priority is not -1. Here
* we detect whether there was a priority change, and whether we
* did not end with a newline. If that is the case, we need to
* insert a newline before this string.
*/
if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
msgbuf_do_addchar(mbp, &seq, '\n');
mbp->msg_flags &= ~MSGBUF_NEEDNL;
}
needtime = 1;
for (i = 0; i < len; i++) {
/*
* If we just had a newline, and the priority is not -1
* (and therefore prefix_len != 0), then we need a priority
* prefix for this line.
*/
if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
int j;
for (j = 0; j < prefix_len; j++)
msgbuf_do_addchar(mbp, &seq, prefix[j]);
}
if (msgbuf_show_timestamp && needtime == 1 &&
(mbp->msg_flags & MSGBUF_NEEDNL) == 0) {
snprintf(buf, sizeof(buf), "[%jd] ",
(intmax_t)time_uptime);
for (j = 0; buf[j] != '\0'; j++)
msgbuf_do_addchar(mbp, &seq, buf[j]);
needtime = 0;
}
/*
* Don't copy carriage returns if the caller requested
* filtering.
*
* XXX This matches the behavior of msglogchar(), but is it
* necessary? Testing has shown that we don't seem to get
* carriage returns here.
*/
if ((filter_cr != 0) && (str[i] == '\r'))
continue;
/*
* Clear this flag if we see a newline. This affects whether
* we need to insert a new prefix or insert a newline later.
*/
if (str[i] == '\n')
mbp->msg_flags &= ~MSGBUF_NEEDNL;
else
mbp->msg_flags |= MSGBUF_NEEDNL;
msgbuf_do_addchar(mbp, &seq, str[i]);
}
/*
* Update the write sequence number for the actual number of
* characters we put in the message buffer. (Depends on whether
* carriage returns are filtered.)
*/
mbp->msg_wseq = seq;
/*
* Set the last priority.
*/
mbp->msg_lastpri = pri;
mtx_unlock_spin(&mbp->msg_lock);
}
/*
* 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;
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 (-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);
mtx_unlock_spin(&mbp->msg_lock);
return (c);
}
/*
* 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);
}
/*
* 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);
}
/*
* Compute the checksum for the complete message buffer contents.
*/
static u_int
msgbuf_cksum(struct msgbuf *mbp)
{
u_int i, sum;
sum = 0;
for (i = 0; i < mbp->msg_size; i++)
sum += (u_char)mbp->msg_ptr[i];
return (sum);
}
/*
* Copy from one message buffer to another.
*/
void
msgbuf_copy(struct msgbuf *src, struct msgbuf *dst)
{
int c;
while ((c = msgbuf_getchar(src)) >= 0)
msgbuf_addchar(dst, c);
}
