xref: /freebsd/sys/kern/subr_prf.c (revision daf1cffce2e07931f27c6c6998652e90df6ba87e)
1 /*-
2  * Copyright (c) 1986, 1988, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  * (c) UNIX System Laboratories, Inc.
5  * All or some portions of this file are derived from material licensed
6  * to the University of California by American Telephone and Telegraph
7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8  * the permission of UNIX System Laboratories, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)subr_prf.c	8.3 (Berkeley) 1/21/94
39  * $FreeBSD$
40  */
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/msgbuf.h>
46 #include <sys/malloc.h>
47 #include <sys/proc.h>
48 #include <sys/tty.h>
49 #include <sys/tprintf.h>
50 #include <sys/syslog.h>
51 #include <sys/cons.h>
52 
53 /*
54  * Note that stdarg.h and the ANSI style va_start macro is used for both
55  * ANSI and traditional C compilers.
56  */
57 #include <machine/stdarg.h>
58 
59 #define TOCONS	0x01
60 #define TOTTY	0x02
61 #define TOLOG	0x04
62 
63 /* Max number conversion buffer length: a u_quad_t in base 2, plus NUL byte. */
64 #define MAXNBUF	(sizeof(quad_t) * NBBY + 1)
65 
66 struct putchar_arg {
67 	int	flags;
68 	struct	tty *tty;
69 };
70 
71 struct snprintf_arg {
72 	char	*str;
73 	size_t	remain;
74 };
75 
76 struct	tty *constty;			/* pointer to console "window" tty */
77 
78 static void (*v_putc)(int) = cnputc;	/* routine to putc on virtual console */
79 static void  logpri __P((int level));
80 static void  msglogchar(int c, void *dummyarg);
81 static void  putchar __P((int ch, void *arg));
82 static char *ksprintn __P((char *nbuf, u_long num, int base, int *len));
83 static char *ksprintqn __P((char *nbuf, u_quad_t num, int base, int *len));
84 static void  snprintf_func __P((int ch, void *arg));
85 
86 static int consintr = 1;		/* Ok to handle console interrupts? */
87 static int msgbufmapped;		/* Set when safe to use msgbuf */
88 
89 /*
90  * Warn that a system table is full.
91  */
92 void
93 tablefull(tab)
94 	const char *tab;
95 {
96 
97 	log(LOG_ERR, "%s: table is full\n", tab);
98 }
99 
100 /*
101  * Uprintf prints to the controlling terminal for the current process.
102  * It may block if the tty queue is overfull.  No message is printed if
103  * the queue does not clear in a reasonable time.
104  */
105 int
106 uprintf(const char *fmt, ...)
107 {
108 	struct proc *p = curproc;
109 	va_list ap;
110 	struct putchar_arg pca;
111 	int retval = 0;
112 
113 	if (p->p_flag & P_CONTROLT && p->p_session->s_ttyvp) {
114 		va_start(ap, fmt);
115 		pca.tty = p->p_session->s_ttyp;
116 		pca.flags = TOTTY;
117 		retval = kvprintf(fmt, putchar, &pca, 10, ap);
118 		va_end(ap);
119 	}
120 	return retval;
121 }
122 
123 tpr_t
124 tprintf_open(p)
125 	register struct proc *p;
126 {
127 
128 	if (p->p_flag & P_CONTROLT && p->p_session->s_ttyvp) {
129 		SESSHOLD(p->p_session);
130 		return ((tpr_t) p->p_session);
131 	}
132 	return ((tpr_t) NULL);
133 }
134 
135 void
136 tprintf_close(sess)
137 	tpr_t sess;
138 {
139 
140 	if (sess)
141 		SESSRELE((struct session *) sess);
142 }
143 
144 /*
145  * tprintf prints on the controlling terminal associated
146  * with the given session.
147  */
148 int
149 tprintf(tpr_t tpr, const char *fmt, ...)
150 {
151 	register struct session *sess = (struct session *)tpr;
152 	struct tty *tp = NULL;
153 	int flags = TOLOG;
154 	va_list ap;
155 	struct putchar_arg pca;
156 	int retval;
157 
158 	logpri(LOG_INFO);
159 	if (sess && sess->s_ttyvp && ttycheckoutq(sess->s_ttyp, 0)) {
160 		flags |= TOTTY;
161 		tp = sess->s_ttyp;
162 	}
163 	va_start(ap, fmt);
164 	pca.tty = tp;
165 	pca.flags = flags;
166 	retval = kvprintf(fmt, putchar, &pca, 10, ap);
167 	va_end(ap);
168 	logwakeup();
169 	return retval;
170 }
171 
172 /*
173  * Ttyprintf displays a message on a tty; it should be used only by
174  * the tty driver, or anything that knows the underlying tty will not
175  * be revoke(2)'d away.  Other callers should use tprintf.
176  */
177 int
178 ttyprintf(struct tty *tp, const char *fmt, ...)
179 {
180 	va_list ap;
181 	struct putchar_arg pca;
182 	int retval;
183 
184 	va_start(ap, fmt);
185 	pca.tty = tp;
186 	pca.flags = TOTTY;
187 	retval = kvprintf(fmt, putchar, &pca, 10, ap);
188 	va_end(ap);
189 	return retval;
190 }
191 
192 extern	int log_open;
193 
194 /*
195  * Log writes to the log buffer, and guarantees not to sleep (so can be
196  * called by interrupt routines).  If there is no process reading the
197  * log yet, it writes to the console also.
198  */
199 int
200 log(int level, const char *fmt, ...)
201 {
202 	register int s;
203 	va_list ap;
204 	int retval;
205 
206 	s = splhigh();
207 	logpri(level);
208 	va_start(ap, fmt);
209 
210 	retval = kvprintf(fmt, msglogchar, NULL, 10, ap);
211 	va_end(ap);
212 
213 	splx(s);
214 	if (!log_open) {
215 		struct putchar_arg pca;
216 		va_start(ap, fmt);
217 		pca.tty = NULL;
218 		pca.flags = TOCONS;
219 		retval += kvprintf(fmt, putchar, &pca, 10, ap);
220 		va_end(ap);
221 	}
222 	logwakeup();
223 	return retval;
224 }
225 
226 static void
227 logpri(level)
228 	int level;
229 {
230 	char nbuf[MAXNBUF];
231 	register char *p;
232 
233 	msglogchar('<', NULL);
234 	for (p = ksprintn(nbuf, (u_long)level, 10, NULL); *p;)
235 		msglogchar(*p--, NULL);
236 	msglogchar('>', NULL);
237 }
238 
239 int
240 addlog(const char *fmt, ...)
241 {
242 	register int s;
243 	va_list ap;
244 	int retval;
245 
246 	s = splhigh();
247 	va_start(ap, fmt);
248 	retval = kvprintf(fmt, msglogchar, NULL, 10, ap);
249 	splx(s);
250 	va_end(ap);
251 	if (!log_open) {
252 		struct putchar_arg pca;
253 		va_start(ap, fmt);
254 		pca.tty = NULL;
255 		pca.flags = TOCONS;
256 		retval += kvprintf(fmt, putchar, &pca, 10, ap);
257 		va_end(ap);
258 	}
259 	logwakeup();
260 	return (retval);
261 }
262 
263 int
264 printf(const char *fmt, ...)
265 {
266 	va_list ap;
267 	register int savintr;
268 	struct putchar_arg pca;
269 	int retval;
270 
271 	savintr = consintr;		/* disable interrupts */
272 	consintr = 0;
273 	va_start(ap, fmt);
274 	pca.tty = NULL;
275 	pca.flags = TOCONS | TOLOG;
276 	retval = kvprintf(fmt, putchar, &pca, 10, ap);
277 	va_end(ap);
278 	if (!panicstr)
279 		logwakeup();
280 	consintr = savintr;		/* reenable interrupts */
281 	return retval;
282 }
283 
284 int
285 vprintf(const char *fmt, va_list ap)
286 {
287 	register int savintr;
288 	struct putchar_arg pca;
289 	int retval;
290 
291 	savintr = consintr;		/* disable interrupts */
292 	consintr = 0;
293 	pca.tty = NULL;
294 	pca.flags = TOCONS | TOLOG;
295 	retval = kvprintf(fmt, putchar, &pca, 10, ap);
296 	if (!panicstr)
297 		logwakeup();
298 	consintr = savintr;		/* reenable interrupts */
299 	return retval;
300 }
301 
302 /*
303  * Print a character on console or users terminal.  If destination is
304  * the console then the last bunch of characters are saved in msgbuf for
305  * inspection later.
306  */
307 static void
308 putchar(int c, void *arg)
309 {
310 	struct putchar_arg *ap = (struct putchar_arg*) arg;
311 	int flags = ap->flags;
312 	struct tty *tp = ap->tty;
313 	if (panicstr)
314 		constty = NULL;
315 	if ((flags & TOCONS) && tp == NULL && constty) {
316 		tp = constty;
317 		flags |= TOTTY;
318 	}
319 	if ((flags & TOTTY) && tp && tputchar(c, tp) < 0 &&
320 	    (flags & TOCONS) && tp == constty)
321 		constty = NULL;
322 	if ((flags & TOLOG))
323 		msglogchar(c, NULL);
324 	if ((flags & TOCONS) && constty == NULL && c != '\0')
325 		(*v_putc)(c);
326 }
327 
328 /*
329  * Scaled down version of sprintf(3).
330  */
331 int
332 sprintf(char *buf, const char *cfmt, ...)
333 {
334 	int retval;
335 	va_list ap;
336 
337 	va_start(ap, cfmt);
338 	retval = kvprintf(cfmt, NULL, (void *)buf, 10, ap);
339 	buf[retval] = '\0';
340 	va_end(ap);
341 	return retval;
342 }
343 
344 /*
345  * Scaled down version of vsprintf(3).
346  */
347 int
348 vsprintf(char *buf, const char *cfmt, va_list ap)
349 {
350 	int retval;
351 
352 	retval = kvprintf(cfmt, NULL, (void *)buf, 10, ap);
353 	buf[retval] = '\0';
354 	return retval;
355 }
356 
357 /*
358  * Scaled down version of snprintf(3).
359  */
360 int
361 snprintf(char *str, size_t size, const char *format, ...)
362 {
363 	int retval;
364 	va_list ap;
365 
366 	va_start(ap, format);
367 	retval = vsnprintf(str, size, format, ap);
368 	va_end(ap);
369 	return(retval);
370 }
371 
372 /*
373  * Scaled down version of vsnprintf(3).
374  */
375 int
376 vsnprintf(char *str, size_t size, const char *format, va_list ap)
377 {
378 	struct snprintf_arg info;
379 	int retval;
380 
381 	info.str = str;
382 	info.remain = size;
383 	retval = kvprintf(format, snprintf_func, &info, 10, ap);
384 	if (info.remain >= 1)
385 		*info.str++ = '\0';
386 	return retval;
387 }
388 
389 static void
390 snprintf_func(int ch, void *arg)
391 {
392 	struct snprintf_arg *const info = arg;
393 
394 	if (info->remain >= 2) {
395 		*info->str++ = ch;
396 		info->remain--;
397 	}
398 }
399 
400 /*
401  * Put a NUL-terminated ASCII number (base <= 36) in a buffer in reverse
402  * order; return an optional length and a pointer to the last character
403  * written in the buffer (i.e., the first character of the string).
404  * The buffer pointed to by `nbuf' must have length >= MAXNBUF.
405  */
406 static char *
407 ksprintn(nbuf, ul, base, lenp)
408 	char *nbuf;
409 	register u_long ul;
410 	register int base, *lenp;
411 {
412 	register char *p;
413 
414 	p = nbuf;
415 	*p = '\0';
416 	do {
417 		*++p = hex2ascii(ul % base);
418 	} while (ul /= base);
419 	if (lenp)
420 		*lenp = p - nbuf;
421 	return (p);
422 }
423 /* ksprintn, but for a quad_t. */
424 static char *
425 ksprintqn(nbuf, uq, base, lenp)
426 	char *nbuf;
427 	register u_quad_t uq;
428 	register int base, *lenp;
429 {
430 	register char *p;
431 
432 	p = nbuf;
433 	*p = '\0';
434 	do {
435 		*++p = hex2ascii(uq % base);
436 	} while (uq /= base);
437 	if (lenp)
438 		*lenp = p - nbuf;
439 	return (p);
440 }
441 
442 /*
443  * Scaled down version of printf(3).
444  *
445  * Two additional formats:
446  *
447  * The format %b is supported to decode error registers.
448  * Its usage is:
449  *
450  *	printf("reg=%b\n", regval, "<base><arg>*");
451  *
452  * where <base> is the output base expressed as a control character, e.g.
453  * \10 gives octal; \20 gives hex.  Each arg is a sequence of characters,
454  * the first of which gives the bit number to be inspected (origin 1), and
455  * the next characters (up to a control character, i.e. a character <= 32),
456  * give the name of the register.  Thus:
457  *
458  *	kvprintf("reg=%b\n", 3, "\10\2BITTWO\1BITONE\n");
459  *
460  * would produce output:
461  *
462  *	reg=3<BITTWO,BITONE>
463  *
464  * XXX:  %D  -- Hexdump, takes pointer and separator string:
465  *		("%6D", ptr, ":")   -> XX:XX:XX:XX:XX:XX
466  *		("%*D", len, ptr, " " -> XX XX XX XX ...
467  */
468 int
469 kvprintf(char const *fmt, void (*func)(int, void*), void *arg, int radix, va_list ap)
470 {
471 #define PCHAR(c) {int cc=(c); if (func) (*func)(cc,arg); else *d++ = cc; retval++; }
472 	char nbuf[MAXNBUF];
473 	char *p, *q, *d;
474 	u_char *up;
475 	int ch, n;
476 	u_long ul;
477 	u_quad_t uq;
478 	int base, lflag, qflag, tmp, width, ladjust, sharpflag, neg, sign, dot;
479 	int dwidth;
480 	char padc;
481 	int retval = 0;
482 
483 	ul = 0;
484 	uq = 0;
485 	if (!func)
486 		d = (char *) arg;
487 	else
488 		d = NULL;
489 
490 	if (fmt == NULL)
491 		fmt = "(fmt null)\n";
492 
493 	if (radix < 2 || radix > 36)
494 		radix = 10;
495 
496 	for (;;) {
497 		padc = ' ';
498 		width = 0;
499 		while ((ch = (u_char)*fmt++) != '%') {
500 			if (ch == '\0')
501 				return retval;
502 			PCHAR(ch);
503 		}
504 		qflag = 0; lflag = 0; ladjust = 0; sharpflag = 0; neg = 0;
505 		sign = 0; dot = 0; dwidth = 0;
506 reswitch:	switch (ch = (u_char)*fmt++) {
507 		case '.':
508 			dot = 1;
509 			goto reswitch;
510 		case '#':
511 			sharpflag = 1;
512 			goto reswitch;
513 		case '+':
514 			sign = 1;
515 			goto reswitch;
516 		case '-':
517 			ladjust = 1;
518 			goto reswitch;
519 		case '%':
520 			PCHAR(ch);
521 			break;
522 		case '*':
523 			if (!dot) {
524 				width = va_arg(ap, int);
525 				if (width < 0) {
526 					ladjust = !ladjust;
527 					width = -width;
528 				}
529 			} else {
530 				dwidth = va_arg(ap, int);
531 			}
532 			goto reswitch;
533 		case '0':
534 			if (!dot) {
535 				padc = '0';
536 				goto reswitch;
537 			}
538 		case '1': case '2': case '3': case '4':
539 		case '5': case '6': case '7': case '8': case '9':
540 				for (n = 0;; ++fmt) {
541 					n = n * 10 + ch - '0';
542 					ch = *fmt;
543 					if (ch < '0' || ch > '9')
544 						break;
545 				}
546 			if (dot)
547 				dwidth = n;
548 			else
549 				width = n;
550 			goto reswitch;
551 		case 'b':
552 			ul = va_arg(ap, int);
553 			p = va_arg(ap, char *);
554 			for (q = ksprintn(nbuf, ul, *p++, NULL); *q;)
555 				PCHAR(*q--);
556 
557 			if (!ul)
558 				break;
559 
560 			for (tmp = 0; *p;) {
561 				n = *p++;
562 				if (ul & (1 << (n - 1))) {
563 					PCHAR(tmp ? ',' : '<');
564 					for (; (n = *p) > ' '; ++p)
565 						PCHAR(n);
566 					tmp = 1;
567 				} else
568 					for (; *p > ' '; ++p)
569 						continue;
570 			}
571 			if (tmp)
572 				PCHAR('>');
573 			break;
574 		case 'c':
575 			PCHAR(va_arg(ap, int));
576 			break;
577 		case 'D':
578 			up = va_arg(ap, u_char *);
579 			p = va_arg(ap, char *);
580 			if (!width)
581 				width = 16;
582 			while(width--) {
583 				PCHAR(hex2ascii(*up >> 4));
584 				PCHAR(hex2ascii(*up & 0x0f));
585 				up++;
586 				if (width)
587 					for (q=p;*q;q++)
588 						PCHAR(*q);
589 			}
590 			break;
591 		case 'd':
592 			if (qflag)
593 				uq = va_arg(ap, quad_t);
594 			else if (lflag)
595 				ul = va_arg(ap, long);
596 			else
597 				ul = va_arg(ap, int);
598 			sign = 1;
599 			base = 10;
600 			goto number;
601 		case 'l':
602 			if (lflag) {
603 				lflag = 0;
604 				qflag = 1;
605 			} else
606 				lflag = 1;
607 			goto reswitch;
608 		case 'o':
609 			if (qflag)
610 				uq = va_arg(ap, u_quad_t);
611 			else if (lflag)
612 				ul = va_arg(ap, u_long);
613 			else
614 				ul = va_arg(ap, u_int);
615 			base = 8;
616 			goto nosign;
617 		case 'p':
618 			ul = (uintptr_t)va_arg(ap, void *);
619 			base = 16;
620 			sharpflag = (width == 0);
621 			goto nosign;
622 		case 'q':
623 			qflag = 1;
624 			goto reswitch;
625 		case 'n':
626 		case 'r':
627 			if (qflag)
628 				uq = va_arg(ap, u_quad_t);
629 			else if (lflag)
630 				ul = va_arg(ap, u_long);
631 			else
632 				ul = sign ?
633 				    (u_long)va_arg(ap, int) : va_arg(ap, u_int);
634 			base = radix;
635 			goto number;
636 		case 's':
637 			p = va_arg(ap, char *);
638 			if (p == NULL)
639 				p = "(null)";
640 			if (!dot)
641 				n = strlen (p);
642 			else
643 				for (n = 0; n < dwidth && p[n]; n++)
644 					continue;
645 
646 			width -= n;
647 
648 			if (!ladjust && width > 0)
649 				while (width--)
650 					PCHAR(padc);
651 			while (n--)
652 				PCHAR(*p++);
653 			if (ladjust && width > 0)
654 				while (width--)
655 					PCHAR(padc);
656 			break;
657 		case 'u':
658 			if (qflag)
659 				uq = va_arg(ap, u_quad_t);
660 			else if (lflag)
661 				ul = va_arg(ap, u_long);
662 			else
663 				ul = va_arg(ap, u_int);
664 			base = 10;
665 			goto nosign;
666 		case 'x':
667 			if (qflag)
668 				uq = va_arg(ap, u_quad_t);
669 			else if (lflag)
670 				ul = va_arg(ap, u_long);
671 			else
672 				ul = va_arg(ap, u_int);
673 			base = 16;
674 			goto nosign;
675 		case 'z':
676 			if (qflag)
677 				uq = va_arg(ap, u_quad_t);
678 			else if (lflag)
679 				ul = va_arg(ap, u_long);
680 			else
681 				ul = sign ?
682 				    (u_long)va_arg(ap, int) : va_arg(ap, u_int);
683 			base = 16;
684 			goto number;
685 nosign:			sign = 0;
686 number:
687 			if (qflag) {
688 				if (sign && (quad_t)uq < 0) {
689 					neg = 1;
690 					uq = -(quad_t)uq;
691 				}
692 				p = ksprintqn(nbuf, uq, base, &tmp);
693 			} else {
694 				if (sign && (long)ul < 0) {
695 					neg = 1;
696 					ul = -(long)ul;
697 				}
698 				p = ksprintn(nbuf, ul, base, &tmp);
699 			}
700 			if (sharpflag && (qflag ? uq != 0 : ul != 0)) {
701 				if (base == 8)
702 					tmp++;
703 				else if (base == 16)
704 					tmp += 2;
705 			}
706 			if (neg)
707 				tmp++;
708 
709 			if (!ladjust && width && (width -= tmp) > 0)
710 				while (width--)
711 					PCHAR(padc);
712 			if (neg)
713 				PCHAR('-');
714 			if (sharpflag && (qflag ? uq != 0 : ul != 0)) {
715 				if (base == 8) {
716 					PCHAR('0');
717 				} else if (base == 16) {
718 					PCHAR('0');
719 					PCHAR('x');
720 				}
721 			}
722 
723 			while (*p)
724 				PCHAR(*p--);
725 
726 			if (ladjust && width && (width -= tmp) > 0)
727 				while (width--)
728 					PCHAR(padc);
729 
730 			break;
731 		default:
732 			PCHAR('%');
733 			if (lflag)
734 				PCHAR('l');
735 			PCHAR(ch);
736 			break;
737 		}
738 	}
739 #undef PCHAR
740 }
741 
742 /*
743  * Put character in log buffer.
744  */
745 static void
746 msglogchar(int c, void *dummyarg)
747 {
748 	struct msgbuf *mbp;
749 
750 	if (c != '\0' && c != '\r' && c != 0177 && msgbufmapped) {
751 		mbp = msgbufp;
752 		mbp->msg_ptr[mbp->msg_bufx++] = c;
753 		if (mbp->msg_bufx >= mbp->msg_size)
754 			mbp->msg_bufx = 0;
755 		/* If the buffer is full, keep the most recent data. */
756 		if (mbp->msg_bufr == mbp->msg_bufx) {
757 			if (++mbp->msg_bufr >= mbp->msg_size)
758 				mbp->msg_bufr = 0;
759 		}
760 	}
761 }
762 
763 static void
764 msgbufcopy(struct msgbuf *oldp)
765 {
766 	int pos;
767 
768 	pos = oldp->msg_bufr;
769 	while (pos != oldp->msg_bufx) {
770 		msglogchar(oldp->msg_ptr[pos], NULL);
771 		if (++pos >= oldp->msg_size)
772 			pos = 0;
773 	}
774 }
775 
776 void
777 msgbufinit(void *ptr, size_t size)
778 {
779 	char *cp;
780 	static struct msgbuf *oldp = NULL;
781 
782 	cp = (char *)ptr;
783 	msgbufp = (struct msgbuf *) (cp + size - sizeof(*msgbufp));
784 	if (msgbufp->msg_magic != MSG_MAGIC || msgbufp->msg_ptr != cp) {
785 		bzero(cp, size);
786 		msgbufp->msg_magic = MSG_MAGIC;
787 		msgbufp->msg_size = (char *)msgbufp - cp;
788 		msgbufp->msg_ptr = cp;
789 	}
790 	if (msgbufmapped && oldp != msgbufp)
791 		msgbufcopy(oldp);
792 	msgbufmapped = 1;
793 	oldp = msgbufp;
794 }
795 
796 #include "opt_ddb.h"
797 #ifdef DDB
798 #include <ddb/ddb.h>
799 
800 DB_SHOW_COMMAND(msgbuf, db_show_msgbuf)
801 {
802 	int i, j;
803 
804 	if (!msgbufmapped) {
805 		db_printf("msgbuf not mapped yet\n");
806 		return;
807 	}
808 	db_printf("msgbufp = %p\n", msgbufp);
809 	db_printf("magic = %x, size = %d, r= %d, w = %d, ptr = %p\n",
810 	    msgbufp->msg_magic, msgbufp->msg_size, msgbufp->msg_bufr,
811 	    msgbufp->msg_bufx, msgbufp->msg_ptr);
812 	for (i = 0; i < msgbufp->msg_size; i++) {
813 		j = (i + msgbufp->msg_bufr) % msgbufp->msg_size;
814 		db_printf("%c", msgbufp->msg_ptr[j]);
815 	}
816 	db_printf("\n");
817 }
818 
819 #endif /* DDB */
820