hexdump.c revision 13563
197318Sphk/*-
297318Sphk * Copyright (c) 1986, 1988, 1991, 1993
397318Sphk *	The Regents of the University of California.  All rights reserved.
497318Sphk * (c) UNIX System Laboratories, Inc.
597318Sphk * All or some portions of this file are derived from material licensed
697318Sphk * to the University of California by American Telephone and Telegraph
797318Sphk * Co. or Unix System Laboratories, Inc. and are reproduced herein with
897318Sphk * the permission of UNIX System Laboratories, Inc.
997318Sphk *
1097318Sphk * Redistribution and use in source and binary forms, with or without
1197318Sphk * modification, are permitted provided that the following conditions
1297318Sphk * are met:
1397318Sphk * 1. Redistributions of source code must retain the above copyright
1497318Sphk *    notice, this list of conditions and the following disclaimer.
1597318Sphk * 2. Redistributions in binary form must reproduce the above copyright
1697318Sphk *    notice, this list of conditions and the following disclaimer in the
1797318Sphk *    documentation and/or other materials provided with the distribution.
1897318Sphk * 3. All advertising materials mentioning features or use of this software
1997318Sphk *    must display the following acknowledgement:
2097318Sphk *	This product includes software developed by the University of
2197318Sphk *	California, Berkeley and its contributors.
2297318Sphk * 4. Neither the name of the University nor the names of its contributors
2397318Sphk *    may be used to endorse or promote products derived from this software
2497318Sphk *    without specific prior written permission.
2597318Sphk *
2697318Sphk * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
2797318Sphk * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
2897318Sphk * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
2997318Sphk * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
3097318Sphk * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
3197318Sphk * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
3297318Sphk * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
3397318Sphk * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34139778Simp * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35139778Simp * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36139778Simp * SUCH DAMAGE.
3797318Sphk *
3897318Sphk *	@(#)subr_prf.c	8.3 (Berkeley) 1/21/94
3997318Sphk * $Id: subr_prf.c,v 1.25 1996/01/19 21:05:52 phk Exp $
4097318Sphk */
4197318Sphk
4297318Sphk#include "opt_ddb.h"
43116196Sobrien
44116196Sobrien#include <sys/param.h>
45116196Sobrien#include <sys/systm.h>
4697318Sphk#include <sys/reboot.h>
4797318Sphk#include <sys/msgbuf.h>
4897318Sphk#include <sys/proc.h>
4997318Sphk#include <sys/vnode.h>
5097318Sphk#include <sys/tty.h>
5197318Sphk#include <sys/tprintf.h>
5297318Sphk#include <sys/syslog.h>
5397318Sphk#include <sys/malloc.h>
5498987Sphk#include <machine/cons.h>
55104087Sphk
5698987Sphk/*
5797318Sphk * Note that stdarg.h and the ANSI style va_start macro is used for both
5897318Sphk * ANSI and traditional C compilers.
5997318Sphk */
60143418Sume#include <machine/stdarg.h>
6197318Sphk
6297318Sphk#ifdef KADB
6397318Sphk#include <machine/kdbparam.h>
6498987Sphk#endif
6598987Sphk
66107953Sphk
67107953Sphk#define TOCONS	0x01
68107953Sphk#define TOTTY	0x02
6997318Sphk#define TOLOG	0x04
7097318Sphk
7197318Sphkstruct	tty *constty;			/* pointer to console "window" tty */
7298987Sphk
7398987Sphkstatic void (*v_putc)(int) = cnputc;	/* routine to putc on virtual console */
7498987Sphk
7598987Sphkstatic void  logpri __P((int level));
7698987Sphkstatic void  msglogchar(int c, void *dummyarg);
7797318Sphkstruct putchar_arg {int flags; struct tty *tty; };
7897318Sphkstatic void  putchar __P((int ch, void *arg));
7997318Sphkstatic char *ksprintn __P((u_long num, int base, int *len));
8098987Sphk
8197318Sphkstatic int consintr = 1;		/* Ok to handle console interrupts? */
8297318Sphk
8398987Sphk/*
8498987Sphk * Variable panicstr contains argument to first call to panic; used as flag
8598987Sphk * to indicate that the kernel has already called panic.
8698987Sphk */
8798987Sphkconst char *panicstr;
8898987Sphk
8998987Sphk/*
9098987Sphk * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
9198987Sphk * and then reboots.  If we are called twice, then we avoid trying to sync
9298987Sphk * the disks as this often leads to recursive panics.
9398987Sphk */
9498987Sphk#ifdef __GNUC__
9598987Sphk__dead			/* panic() does not return */
9698987Sphk#endif
9797318Sphkvoid
9898987Sphkpanic(const char *fmt, ...)
9998987Sphk{
10098987Sphk	int bootopt;
10198987Sphk	va_list ap;
10298987Sphk
10398987Sphk	bootopt = RB_AUTOBOOT | RB_DUMP;
10498987Sphk	if (panicstr)
10598987Sphk		bootopt |= RB_NOSYNC;
10698987Sphk	else
10798987Sphk		panicstr = fmt;
10898987Sphk
10998987Sphk	va_start(ap, fmt);
11098987Sphk	printf("panic: %r\n", fmt, ap);
11198987Sphk	va_end(ap);
11298987Sphk
11398987Sphk#ifdef KGDB
11498987Sphk	kgdb_panic();
11598987Sphk#endif
11698987Sphk#ifdef KADB
11798987Sphk	if (boothowto & RB_KDB)
11898987Sphk		kdbpanic();
11998987Sphk#endif
12098987Sphk#ifdef DDB
12198987Sphk	Debugger ("panic");
12298987Sphk#endif
12398987Sphk	boot(bootopt);
12498987Sphk}
12598987Sphk
12698987Sphk/*
12798987Sphk * Warn that a system table is full.
12898987Sphk */
12998987Sphkvoid
13098987Sphktablefull(tab)
13198987Sphk	const char *tab;
13298987Sphk{
13398987Sphk
13497318Sphk	log(LOG_ERR, "%s: table is full\n", tab);
13597318Sphk}
13697318Sphk
13797318Sphk/*
13897318Sphk * Uprintf prints to the controlling terminal for the current process.
13998987Sphk * It may block if the tty queue is overfull.  No message is printed if
14098987Sphk * the queue does not clear in a reasonable time.
14197318Sphk */
14297318Sphkvoid
14397318Sphkuprintf(const char *fmt, ...)
144111119Simp{
14597318Sphk	struct proc *p = curproc;
14697318Sphk	va_list ap;
14797318Sphk	struct putchar_arg pca;
14898987Sphk
14997318Sphk	if (p->p_flag & P_CONTROLT && p->p_session->s_ttyvp) {
15098987Sphk		va_start(ap, fmt);
15198987Sphk		pca.tty = p->p_session->s_ttyp;
15297318Sphk		pca.flags = TOTTY;
15398987Sphk		kvprintf(fmt, putchar, &pca, 10, ap);
15497318Sphk		va_end(ap);
15598987Sphk	}
15698987Sphk}
15798987Sphk
15897318Sphktpr_t
15997318Sphktprintf_open(p)
16097318Sphk	register struct proc *p;
16197318Sphk{
16297318Sphk
16397318Sphk	if (p->p_flag & P_CONTROLT && p->p_session->s_ttyvp) {
16497318Sphk		SESSHOLD(p->p_session);
16598987Sphk		return ((tpr_t) p->p_session);
16697318Sphk	}
16797318Sphk	return ((tpr_t) NULL);
16897318Sphk}
16997318Sphk
17097318Sphkvoid
17197318Sphktprintf_close(sess)
17297318Sphk	tpr_t sess;
17397318Sphk{
17497318Sphk
17597318Sphk	if (sess)
17697318Sphk		SESSRELE((struct session *) sess);
17797318Sphk}
17898987Sphk
17998987Sphk/*
18097318Sphk * tprintf prints on the controlling terminal associated
18197318Sphk * with the given session.
18297318Sphk */
18397318Sphkvoid
18497318Sphktprintf(tpr_t tpr, const char *fmt, ...)
18597318Sphk{
18697318Sphk	register struct session *sess = (struct session *)tpr;
187104057Sphk	struct tty *tp = NULL;
188104195Sphk	int flags = TOLOG;
189104057Sphk	va_list ap;
190104057Sphk	struct putchar_arg pca;
19197318Sphk
19297318Sphk	logpri(LOG_INFO);
19397318Sphk	if (sess && sess->s_ttyvp && ttycheckoutq(sess->s_ttyp, 0)) {
19497318Sphk		flags |= TOTTY;
19597318Sphk		tp = sess->s_ttyp;
19697318Sphk	}
197104057Sphk	va_start(ap, fmt);
198104195Sphk	pca.tty = tp;
199104057Sphk	pca.flags = flags;
200104057Sphk	kvprintf(fmt, putchar, &pca, 10, ap);
20197318Sphk	va_end(ap);
20297318Sphk	logwakeup();
203111119Simp}
20497318Sphk
20597318Sphk/*
20697318Sphk * Ttyprintf displays a message on a tty; it should be used only by
20797318Sphk * the tty driver, or anything that knows the underlying tty will not
20898987Sphk * be revoke(2)'d away.  Other callers should use tprintf.
20997318Sphk */
21098987Sphkvoid
21198987Sphkttyprintf(struct tty *tp, const char *fmt, ...)
21297318Sphk{
21397318Sphk	va_list ap;
21498987Sphk	struct putchar_arg pca;
21597318Sphk	va_start(ap, fmt);
21698987Sphk	pca.tty = tp;
21797318Sphk	pca.flags = TOTTY;
21897318Sphk	kvprintf(fmt, putchar, &pca, 10, ap);
21997318Sphk	va_end(ap);
22097318Sphk}
221104057Sphk
222104195Sphkextern	int log_open;
223104057Sphk
224104057Sphk/*
22597318Sphk * Log writes to the log buffer, and guarantees not to sleep (so can be
22697318Sphk * called by interrupt routines).  If there is no process reading the
22797318Sphk * log yet, it writes to the console also.
22897318Sphk */
22997318Sphkvoid
230104195Sphklog(int level, const char *fmt, ...)
23197318Sphk{
23297318Sphk	register int s;
23397318Sphk	va_list ap;
23497318Sphk
23597318Sphk	s = splhigh();
23697318Sphk	logpri(level);
23797318Sphk	va_start(ap, fmt);
23897318Sphk
23997318Sphk	kvprintf(fmt, msglogchar, NULL, 10, ap);
24098987Sphk	va_end(ap);
24197318Sphk
24297318Sphk	splx(s);
24397318Sphk	if (!log_open) {
24497318Sphk		struct putchar_arg pca;
24597318Sphk		va_start(ap, fmt);
24697318Sphk		pca.tty = NULL;
24797318Sphk		pca.flags = TOCONS;
24898987Sphk		kvprintf(fmt, putchar, &pca, 10, ap);
249114532Sphk		va_end(ap);
25098987Sphk	}
251114532Sphk	logwakeup();
25297318Sphk}
25397318Sphk
25497318Sphkstatic void
25597318Sphklogpri(level)
25697318Sphk	int level;
25797318Sphk{
25897318Sphk	register char *p;
25997318Sphk
26097318Sphk	msglogchar('<', NULL);
26197318Sphk	for (p = ksprintn((u_long)level, 10, NULL); *p;)
26297318Sphk		msglogchar(*p--, NULL);
26397318Sphk	msglogchar('>', NULL);
26497318Sphk}
26597318Sphk
26697318Sphkvoid
26797318Sphkaddlog(const char *fmt, ...)
26897318Sphk{
269125755Sphk	register int s;
27097318Sphk	va_list ap;
27197318Sphk
27297318Sphk	s = splhigh();
27397318Sphk	va_start(ap, fmt);
27497318Sphk	kvprintf(fmt, msglogchar, NULL, 10, ap);
27597318Sphk	splx(s);
27697318Sphk	va_end(ap);
27797318Sphk	if (!log_open) {
27897318Sphk		struct putchar_arg pca;
27997318Sphk		va_start(ap, fmt);
28097318Sphk		pca.tty = NULL;
28197318Sphk		pca.flags = TOCONS;
28297318Sphk		kvprintf(fmt, putchar, &pca, 10, ap);
28397318Sphk		va_end(ap);
28497318Sphk	}
28597318Sphk	logwakeup();
28697318Sphk}
28797318Sphk
288125755Sphkvoid
28997318Sphkprintf(const char *fmt, ...)
29098066Sphk{
29197318Sphk	va_list ap;
29297318Sphk	register int savintr;
29397318Sphk	struct putchar_arg pca;
29497318Sphk
29597318Sphk	savintr = consintr;		/* disable interrupts */
296104064Sphk	consintr = 0;
297114491Sphk	va_start(ap, fmt);
29897318Sphk	pca.tty = NULL;
29997318Sphk	pca.flags = TOCONS | TOLOG;
300105551Sphk	kvprintf(fmt, putchar, &pca, 10, ap);
301105551Sphk	va_end(ap);
302152971Ssobomax	if (!panicstr)
303152967Ssobomax		logwakeup();
30497318Sphk	consintr = savintr;		/* reenable interrupts */
30597318Sphk}
306111119Simp
30798987Sphkvoid
30898987Sphkvprintf(const char *fmt, va_list ap)
30998987Sphk{
31098987Sphk	register int savintr;
31198987Sphk	struct putchar_arg pca;
31298987Sphk
31398987Sphk	savintr = consintr;		/* disable interrupts */
31498987Sphk	consintr = 0;
31598987Sphk	pca.tty = NULL;
31698987Sphk	pca.flags = TOCONS | TOLOG;
31797318Sphk	kvprintf(fmt, putchar, &pca, 10, ap);
31898987Sphk	if (!panicstr)
319114532Sphk		logwakeup();
32097318Sphk	consintr = savintr;		/* reenable interrupts */
32197318Sphk}
32297318Sphk
32397318Sphk/*
32498987Sphk * Print a character on console or users terminal.  If destination is
32598987Sphk * the console then the last MSGBUFS characters are saved in msgbuf for
32698987Sphk * inspection later.
32798987Sphk */
32898987Sphkstatic void
329104087Sphkputchar(int c, void *arg)
33098987Sphk{
33198987Sphk	struct putchar_arg *ap = (struct putchar_arg*) arg;
33298987Sphk	int flags = ap->flags;
33398987Sphk	struct tty *tp = ap->tty;
33498987Sphk	if (panicstr)
33598987Sphk		constty = NULL;
33698987Sphk	if ((flags & TOCONS) && tp == NULL && constty) {
33798987Sphk		tp = constty;
338104087Sphk		flags |= TOTTY;
33998987Sphk	}
34098987Sphk	if ((flags & TOTTY) && tp && tputchar(c, tp) < 0 &&
34198987Sphk	    (flags & TOCONS) && tp == constty)
34298987Sphk		constty = NULL;
34398987Sphk	if ((flags & TOLOG))
34498987Sphk		msglogchar(c, NULL);
34598987Sphk	if ((flags & TOCONS) && constty == NULL && c != '\0')
346104064Sphk		(*v_putc)(c);
34797318Sphk}
34897318Sphk
349105551Sphk/*
35097318Sphk * Scaled down version of sprintf(3).
351104064Sphk */
352114491Sphkint
353104064Sphksprintf(char *buf, const char *cfmt, ...)
35497318Sphk{
35597318Sphk	int retval;
356125755Sphk	va_list ap;
35797318Sphk
35897318Sphk	va_start(ap, cfmt);
35998066Sphk	retval = kvprintf(cfmt, NULL, (void *)buf, 10, ap);
36097318Sphk	buf[retval] = '\0';
36197318Sphk	va_end(ap);
36297318Sphk	return retval;
36397318Sphk}
36497318Sphk
36597318Sphk/*
366112552Sphk * Put a number (base <= 16) in a buffer in reverse order; return an
367133318Sphk * optional length and a pointer to the NULL terminated (preceded?)
368112552Sphk * buffer.
369133314Sphk */
370133314Sphkstatic char *
371133314Sphkksprintn(ul, base, lenp)
372133314Sphk	register u_long ul;
37397318Sphk	register int base, *lenp;
37497318Sphk{					/* A long in base 8, plus NULL. */
37597318Sphk	static char buf[sizeof(long) * NBBY / 3 + 2];
376	register char *p;
377
378	p = buf;
379	do {
380		*++p = hex2ascii(ul % base);
381	} while (ul /= base);
382	if (lenp)
383		*lenp = p - buf;
384	return (p);
385}
386
387/*
388 * Scaled down version of printf(3).
389 *
390 * Two additional formats:
391 *
392 * The format %b is supported to decode error registers.
393 * Its usage is:
394 *
395 *	printf("reg=%b\n", regval, "<base><arg>*");
396 *
397 * where <base> is the output base expressed as a control character, e.g.
398 * \10 gives octal; \20 gives hex.  Each arg is a sequence of characters,
399 * the first of which gives the bit number to be inspected (origin 1), and
400 * the next characters (up to a control character, i.e. a character <= 32),
401 * give the name of the register.  Thus:
402 *
403 *	kprintf("reg=%b\n", 3, "\10\2BITTWO\1BITONE\n");
404 *
405 * would produce output:
406 *
407 *	reg=3<BITTWO,BITONE>
408 *
409 * The format %r passes an additional format string and argument list
410 * recursively.  Its usage is:
411 *
412 * fn(char *fmt, ...)
413 * {
414 *	va_list ap;
415 *	va_start(ap, fmt);
416 *	printf("prefix: %r: suffix\n", fmt, ap);
417 *	va_end(ap);
418 * }
419 *
420 * Space or zero padding and a field width are supported for the numeric
421 * formats only.
422 */
423int
424kvprintf(char const *fmt, void (*func)(int, void*), void *arg, int radix, va_list ap)
425{
426#define PCHAR(c) {int cc=(c); if (func) (*func)(cc,arg); else *d++ = cc; retval++; }
427	char *p, *q, *d;
428	int ch, n;
429	u_long ul;
430	int base, lflag, tmp, width, ladjust, sharpflag, neg, sign, dot;
431	int dwidth;
432	char padc;
433	int retval = 0;
434
435	if (!func)
436		d = (char *) arg;
437	else
438		d = NULL;
439
440	if (fmt == NULL)
441		fmt = "(fmt null)\n";
442
443	if (radix < 8 || radix > 16)
444		radix = 10;
445
446	for (;;) {
447		padc = ' ';
448		width = 0;
449		while ((ch = *(u_char *)fmt++) != '%') {
450			if (ch == '\0')
451				return retval;
452			PCHAR(ch);
453		}
454		lflag = 0; ladjust = 0; sharpflag = 0; neg = 0;
455		sign = 0; dot = 0; dwidth = 0;
456reswitch:	switch (ch = *(u_char *)fmt++) {
457		case '.':
458			dot = 1;
459			goto reswitch;
460		case '#':
461			sharpflag = 1;
462			goto reswitch;
463		case '+':
464			sign = 1;
465			goto reswitch;
466		case '-':
467			ladjust = 1;
468			goto reswitch;
469		case '%':
470			PCHAR(ch);
471			break;
472		case '*':
473			if (!dot) {
474				width = va_arg(ap, int);
475				if (width < 0) {
476					ladjust = !ladjust;
477					width = -width;
478				}
479			} else {
480				dwidth = va_arg(ap, int);
481			}
482			goto reswitch;
483		case '0':
484			if (!dot) {
485				padc = '0';
486				goto reswitch;
487			}
488		case '1': case '2': case '3': case '4':
489		case '5': case '6': case '7': case '8': case '9':
490				for (n = 0;; ++fmt) {
491					n = n * 10 + ch - '0';
492					ch = *fmt;
493					if (ch < '0' || ch > '9')
494						break;
495				}
496			if (dot)
497				dwidth = n;
498			else
499				width = n;
500			goto reswitch;
501		case 'b':
502			ul = va_arg(ap, int);
503			p = va_arg(ap, char *);
504			for (q = ksprintn(ul, *p++, NULL); *q;)
505				PCHAR(*q--);
506
507			if (!ul)
508				break;
509
510			for (tmp = 0; *p;) {
511				n = *p++;
512				if (ul & (1 << (n - 1))) {
513					PCHAR(tmp ? ',' : '<');
514					for (; (n = *p) > ' '; ++p)
515						PCHAR(n);
516					tmp = 1;
517				} else
518					for (; *p > ' '; ++p)
519						continue;
520			}
521			if (tmp)
522				PCHAR('>');
523			break;
524		case 'c':
525			PCHAR(va_arg(ap, int));
526			break;
527		case 'd':
528			ul = lflag ? va_arg(ap, long) : va_arg(ap, int);
529			sign = 1;
530			base = 10;
531			goto number;
532		case 'l':
533			lflag = 1;
534			goto reswitch;
535		case 'n':
536			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
537			base = radix;
538			goto number;
539		case 'o':
540			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
541			base = 8;
542			goto number;
543		case 'p':
544			ul = (u_long)va_arg(ap, void *);
545			base = 16;
546			PCHAR('0');
547			PCHAR('x');
548			goto number;
549		case 'r':
550			p = va_arg(ap, char *);
551			if (!func) {
552				n = kvprintf(p, func, d, radix, ap);
553				d += n;
554			} else {
555				n = kvprintf(p, func, arg, radix, ap);
556			}
557			retval += n;
558			break;
559		case 's':
560			p = va_arg(ap, char *);
561			if (p == NULL)
562				p = "(null)";
563			if (!dot)
564				n = strlen (p);
565			else
566				for (n = 0; n < dwidth && p[n]; n++)
567					continue;
568
569			width -= n;
570
571			if (!ladjust && width > 0)
572				while (width--)
573					PCHAR(padc);
574			while (n--)
575				PCHAR(*p++);
576			if (ladjust && width > 0)
577				while (width--)
578					PCHAR(padc);
579			break;
580		case 'u':
581			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
582			base = 10;
583			goto number;
584		case 'x':
585			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
586			base = 16;
587number:			if (sign && (long)ul < 0L) {
588				neg = 1;
589				ul = -(long)ul;
590			}
591			p = ksprintn(ul, base, &tmp);
592			if (sharpflag && ul != 0) {
593				if (base == 8)
594					tmp++;
595				else if (base == 16)
596					tmp += 2;
597			}
598			if (neg)
599				tmp++;
600
601			if (!ladjust && width && (width -= tmp) > 0)
602				while (width--)
603					PCHAR(padc);
604			if (neg)
605				PCHAR('-');
606			if (sharpflag && ul != 0) {
607				if (base == 8) {
608					PCHAR('0');
609				} else if (base == 16) {
610					PCHAR('0');
611					PCHAR('x');
612				}
613			}
614
615			while (*p)
616				PCHAR(*p--);
617
618			if (ladjust && width && (width -= tmp) > 0)
619				while (width--)
620					PCHAR(padc);
621
622			break;
623		default:
624			PCHAR('%');
625			if (lflag)
626				PCHAR('l');
627			PCHAR(ch);
628			break;
629		}
630	}
631#undef PCHAR
632}
633
634/*
635 * Put character in log buffer.
636 */
637static void
638msglogchar(int c, void *dummyarg)
639{
640	struct msgbuf *mbp;
641
642	if (c != '\0' && c != '\r' && c != 0177 && msgbufmapped) {
643		mbp = msgbufp;
644		if (mbp->msg_magic != MSG_MAGIC ||
645		    mbp->msg_bufx >= MSG_BSIZE ||
646		    mbp->msg_bufr >= MSG_BSIZE) {
647			bzero(mbp, sizeof(struct msgbuf));
648			mbp->msg_magic = MSG_MAGIC;
649		}
650		mbp->msg_bufc[mbp->msg_bufx++] = c;
651		if (mbp->msg_bufx >= MSG_BSIZE)
652			mbp->msg_bufx = 0;
653		/* If the buffer is full, keep the most recent data. */
654		if (mbp->msg_bufr == mbp->msg_bufx) {
655			if (++mbp->msg_bufr >= MSG_BSIZE)
656				mbp->msg_bufr = 0;
657		}
658	}
659}
660