588ab3c774
Add a boolean parameter to minidumpsys(), to indicate a live dump. When requested, take a snapshot of important global state, and pass this to the machine-dependent minidump function. For now this includes the kernel message buffer, and the bitset of pages to be dumped. Beyond this, we don't take much action to protect the integrity of the dump from changes in the running system. A new function msgbuf_duplicate() is added for snapshotting the message buffer. msgbuf_copy() is insufficient for this purpose since it marks any new characters it finds as read. For now, nothing can actually trigger a live minidump. A future patch will add the mechanism for this. For simplicity and safety, live dumps are disallowed for mips. Reviewed by: markj, jhb MFC after: 2 weeks Sponsored by: Juniper Networks, Inc. Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D31993
432 lines
11 KiB
C
432 lines
11 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2003 Ian Dowse. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Generic message buffer support routines.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/kernel.h>
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#include <sys/mutex.h>
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#include <sys/msgbuf.h>
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#include <sys/sysctl.h>
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/*
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* Maximum number conversion buffer length: uintmax_t in base 2, plus <>
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* around the priority, and a terminating NUL.
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*/
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#define MAXPRIBUF (sizeof(intmax_t) * NBBY + 3)
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/* Read/write sequence numbers are modulo a multiple of the buffer size. */
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#define SEQMOD(size) ((size) * 16)
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static u_int msgbuf_cksum(struct msgbuf *mbp);
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/*
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* Timestamps in msgbuf are useful when trying to diagnose when core dumps
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* or other actions occurred.
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*/
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static int msgbuf_show_timestamp = 0;
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SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RWTUN,
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&msgbuf_show_timestamp, 0, "Show timestamp in msgbuf");
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/*
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* Initialize a message buffer of the specified size at the specified
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* location. This also zeros the buffer area.
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*/
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void
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msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
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{
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mbp->msg_ptr = ptr;
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mbp->msg_size = size;
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mbp->msg_seqmod = SEQMOD(size);
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msgbuf_clear(mbp);
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mbp->msg_magic = MSG_MAGIC;
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mbp->msg_lastpri = -1;
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mbp->msg_flags = 0;
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bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
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mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
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}
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/*
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* Reinitialize a message buffer, retaining its previous contents if
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* the size and checksum are correct. If the old contents cannot be
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* recovered, the message buffer is cleared.
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*/
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void
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msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
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{
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u_int cksum;
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if (mbp->msg_magic != MSG_MAGIC || mbp->msg_size != size) {
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msgbuf_init(mbp, ptr, size);
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return;
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}
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mbp->msg_seqmod = SEQMOD(size);
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mbp->msg_wseq = MSGBUF_SEQNORM(mbp, mbp->msg_wseq);
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mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq);
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mbp->msg_ptr = ptr;
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cksum = msgbuf_cksum(mbp);
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if (cksum != mbp->msg_cksum) {
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if (bootverbose) {
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printf("msgbuf cksum mismatch (read %x, calc %x)\n",
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mbp->msg_cksum, cksum);
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printf("Old msgbuf not recovered\n");
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}
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msgbuf_clear(mbp);
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}
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mbp->msg_lastpri = -1;
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/* Assume that the old message buffer didn't end in a newline. */
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mbp->msg_flags |= MSGBUF_NEEDNL;
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bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
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mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
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}
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/*
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* Clear the message buffer.
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*/
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void
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msgbuf_clear(struct msgbuf *mbp)
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{
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bzero(mbp->msg_ptr, mbp->msg_size);
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mbp->msg_wseq = 0;
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mbp->msg_rseq = 0;
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mbp->msg_cksum = 0;
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}
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/*
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* Get a count of the number of unread characters in the message buffer.
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*/
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int
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msgbuf_getcount(struct msgbuf *mbp)
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{
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u_int len;
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len = MSGBUF_SEQSUB(mbp, mbp->msg_wseq, mbp->msg_rseq);
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if (len > mbp->msg_size)
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len = mbp->msg_size;
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return (len);
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}
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/*
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* Add a character into the message buffer, and update the checksum and
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* sequence number.
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*
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* The caller should hold the message buffer spinlock.
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*/
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static void
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msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, const int c)
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{
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u_int pos;
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/* Make sure we properly wrap the sequence number. */
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pos = MSGBUF_SEQ_TO_POS(mbp, *seq);
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mbp->msg_cksum += (u_int)(u_char)c -
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(u_int)(u_char)mbp->msg_ptr[pos];
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mbp->msg_ptr[pos] = c;
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*seq = MSGBUF_SEQNORM(mbp, *seq + 1);
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}
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/*
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* Append a character to a message buffer.
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*/
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void
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msgbuf_addchar(struct msgbuf *mbp, int c)
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{
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mtx_lock_spin(&mbp->msg_lock);
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msgbuf_do_addchar(mbp, &mbp->msg_wseq, c);
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mtx_unlock_spin(&mbp->msg_lock);
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}
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/*
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* Append a NUL-terminated string with a priority to a message buffer.
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* Filter carriage returns if the caller requests it.
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*
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* XXX The carriage return filtering behavior is present in the
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* msglogchar() API, however testing has shown that we don't seem to send
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* carriage returns down this path. So do we still need it?
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*/
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void
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msgbuf_addstr(struct msgbuf *mbp, int pri, const char *str, int filter_cr)
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{
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u_int seq;
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size_t len, prefix_len;
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char prefix[MAXPRIBUF];
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char buf[32];
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int i, j, needtime;
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len = strlen(str);
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prefix_len = 0;
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/* If we have a zero-length string, no need to do anything. */
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if (len == 0)
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return;
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mtx_lock_spin(&mbp->msg_lock);
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/*
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* If this is true, we may need to insert a new priority sequence,
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* so prepare the prefix.
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*/
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if (pri != -1)
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prefix_len = sprintf(prefix, "<%d>", pri);
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/*
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* Starting write sequence number.
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*/
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seq = mbp->msg_wseq;
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/*
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* Whenever there is a change in priority, we have to insert a
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* newline, and a priority prefix if the priority is not -1. Here
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* we detect whether there was a priority change, and whether we
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* did not end with a newline. If that is the case, we need to
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* insert a newline before this string.
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*/
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if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
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msgbuf_do_addchar(mbp, &seq, '\n');
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mbp->msg_flags &= ~MSGBUF_NEEDNL;
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}
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needtime = 1;
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for (i = 0; i < len; i++) {
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/*
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* If we just had a newline, and the priority is not -1
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* (and therefore prefix_len != 0), then we need a priority
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* prefix for this line.
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*/
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if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
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int j;
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for (j = 0; j < prefix_len; j++)
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msgbuf_do_addchar(mbp, &seq, prefix[j]);
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}
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if (msgbuf_show_timestamp && needtime == 1 &&
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(mbp->msg_flags & MSGBUF_NEEDNL) == 0) {
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snprintf(buf, sizeof(buf), "[%jd] ",
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(intmax_t)time_uptime);
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for (j = 0; buf[j] != '\0'; j++)
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msgbuf_do_addchar(mbp, &seq, buf[j]);
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needtime = 0;
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}
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/*
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* Don't copy carriage returns if the caller requested
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* filtering.
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*
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* XXX This matches the behavior of msglogchar(), but is it
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* necessary? Testing has shown that we don't seem to get
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* carriage returns here.
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*/
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if ((filter_cr != 0) && (str[i] == '\r'))
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continue;
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/*
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* Clear this flag if we see a newline. This affects whether
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* we need to insert a new prefix or insert a newline later.
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*/
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if (str[i] == '\n')
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mbp->msg_flags &= ~MSGBUF_NEEDNL;
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else
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mbp->msg_flags |= MSGBUF_NEEDNL;
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msgbuf_do_addchar(mbp, &seq, str[i]);
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}
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/*
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* Update the write sequence number for the actual number of
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* characters we put in the message buffer. (Depends on whether
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* carriage returns are filtered.)
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*/
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mbp->msg_wseq = seq;
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/*
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* Set the last priority.
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*/
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mbp->msg_lastpri = pri;
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mtx_unlock_spin(&mbp->msg_lock);
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}
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/*
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* Read and mark as read a character from a message buffer.
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* Returns the character, or -1 if no characters are available.
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*/
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int
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msgbuf_getchar(struct msgbuf *mbp)
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{
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u_int len, wseq;
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int c;
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mtx_lock_spin(&mbp->msg_lock);
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wseq = mbp->msg_wseq;
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len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
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if (len == 0) {
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mtx_unlock_spin(&mbp->msg_lock);
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return (-1);
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}
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if (len > mbp->msg_size)
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mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
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c = (u_char)mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq)];
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mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + 1);
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mtx_unlock_spin(&mbp->msg_lock);
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return (c);
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}
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/*
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* Read and mark as read a number of characters from a message buffer.
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* Returns the number of characters that were placed in `buf'.
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*/
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int
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msgbuf_getbytes(struct msgbuf *mbp, char *buf, int buflen)
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{
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u_int len, pos, wseq;
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mtx_lock_spin(&mbp->msg_lock);
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wseq = mbp->msg_wseq;
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len = MSGBUF_SEQSUB(mbp, wseq, mbp->msg_rseq);
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if (len == 0) {
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mtx_unlock_spin(&mbp->msg_lock);
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return (0);
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}
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if (len > mbp->msg_size) {
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mbp->msg_rseq = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
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len = mbp->msg_size;
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}
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pos = MSGBUF_SEQ_TO_POS(mbp, mbp->msg_rseq);
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len = min(len, mbp->msg_size - pos);
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len = min(len, (u_int)buflen);
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bcopy(&mbp->msg_ptr[pos], buf, len);
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mbp->msg_rseq = MSGBUF_SEQNORM(mbp, mbp->msg_rseq + len);
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mtx_unlock_spin(&mbp->msg_lock);
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return (len);
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}
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/*
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* Peek at the full contents of a message buffer without marking any
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* data as read. `seqp' should point to an unsigned integer that
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* msgbuf_peekbytes() can use to retain state between calls so that
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* the whole message buffer can be read in multiple short reads.
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* To initialise this variable to the start of the message buffer,
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* call msgbuf_peekbytes() with a NULL `buf' parameter.
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*
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* Returns the number of characters that were placed in `buf'.
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*/
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int
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msgbuf_peekbytes(struct msgbuf *mbp, char *buf, int buflen, u_int *seqp)
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{
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u_int len, pos, wseq;
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mtx_lock_spin(&mbp->msg_lock);
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if (buf == NULL) {
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/* Just initialise *seqp. */
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*seqp = MSGBUF_SEQNORM(mbp, mbp->msg_wseq - mbp->msg_size);
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mtx_unlock_spin(&mbp->msg_lock);
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return (0);
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}
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wseq = mbp->msg_wseq;
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len = MSGBUF_SEQSUB(mbp, wseq, *seqp);
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if (len == 0) {
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mtx_unlock_spin(&mbp->msg_lock);
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return (0);
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}
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if (len > mbp->msg_size) {
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*seqp = MSGBUF_SEQNORM(mbp, wseq - mbp->msg_size);
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len = mbp->msg_size;
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}
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pos = MSGBUF_SEQ_TO_POS(mbp, *seqp);
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len = min(len, mbp->msg_size - pos);
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len = min(len, (u_int)buflen);
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bcopy(&mbp->msg_ptr[MSGBUF_SEQ_TO_POS(mbp, *seqp)], buf, len);
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*seqp = MSGBUF_SEQNORM(mbp, *seqp + len);
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mtx_unlock_spin(&mbp->msg_lock);
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return (len);
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}
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/*
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* Compute the checksum for the complete message buffer contents.
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*/
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static u_int
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msgbuf_cksum(struct msgbuf *mbp)
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{
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u_int i, sum;
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sum = 0;
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for (i = 0; i < mbp->msg_size; i++)
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sum += (u_char)mbp->msg_ptr[i];
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return (sum);
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}
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/*
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* Copy from one message buffer to another.
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*/
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void
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msgbuf_copy(struct msgbuf *src, struct msgbuf *dst)
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{
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int c;
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while ((c = msgbuf_getchar(src)) >= 0)
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msgbuf_addchar(dst, c);
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}
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/*
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* Get a snapshot of the message buffer, without modifying its internal state
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* (i.e. don't mark any new characters as read).
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*/
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void
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msgbuf_duplicate(struct msgbuf *src, struct msgbuf *dst, char *dst_msgptr)
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{
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mtx_lock_spin(&src->msg_lock);
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bcopy(src, dst, sizeof(struct msgbuf));
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dst->msg_ptr = dst_msgptr;
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bcopy(src->msg_ptr, dst->msg_ptr, src->msg_size);
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mtx_unlock_spin(&src->msg_lock);
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}
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